Stalling Stall Training; Thoughts on the new ACS Approach

If you’re a new student pilot or a flight instructor, then you know the FAA changed the PTS (Practical Test Standards) for Private and Commercial Pilots to the ACS (Airmen Certification Standards). This is equivalent to the bureaucratic reorganizations that routinely reoccur and propel every Federal agency forward, especially when a new administrator takes the reigns, for the purpose of “streamlining” operations and putting someone’s new footprint out there, usually without accomplishing any long-term change that anyone can remember. I’ve paid attention to it but haven’t worried about it too much as a Light Sport instructor, though I am now hearing they’re about to do the same thing to Light Sport, making me sit up and take notice. If you know anything about what was changed, then you know that the slow flight and stall recovery parts of the test standard were “renovated” in an effort to reduce Loss of Control accident statistics, the thing that has been the big push in general aviation for the past few years. If you’re a follower of Rod Machado, then you probably have seen his tweets about how he disagrees with those changes. You can read his arguments against it in this blog: “The Stall Horn Fallacy of Stall Prevention.” Frankly, I agree with him, not only because of the arguments he makes about the learning and training processes but also because I have serious doubts that, from a safety standpoint, it’s a push in the correct direction. I come at this subject as a pilot who’s been around for a while (and interested in aviation safety for quite some time) and as a Light Sport instructor and a manned spaceflight safety analyst. As you’ll see, when I use a space shuttle based safety analysis on this subject, it casts doubt on the whole approach. (Some of will reinforce the arguments Rod was making.)

I personally believe a pilot needs to be able to handle an aircraft in any attitude and that “you fly like you train”. I’ve always taken pride in my ability to handle an airplane in slow flight and right through the stall, something that has given me a better understanding of airplane control in these regimes; I believe in preparing for the “bad day”. So, when you tell me that I’m supposed to only train pilots how to stay out of stalls and NOT how to recover from them if they get into one, it makes me squeamish. It’s like asking me to stick my head in the sand and telling me to take my students with me. It’s not that I don’t understand why the new approach is the way it is; I believe it is tied to the new aircraft certification standards re-write. Part of it is based on the rationale that stall/spin accidents that kill pilots occur too low for any recovery to take place, so it’s a waste of effort to try. (Kinda like “that person has no heartbeat, so just forget CPR and call the undertaker”.) Putting more effort into teaching pilots stall avoidance is always a good thing to do, but the argument that not teaching stall recovery is the way to get there because it “desensitizes” pilots to stall warning systems is not the way to do it (nor do I believe that desensitization is the main issue; how many hours have you spent “disregarding the stall horn? Should full throttle ALWAYS be the response to a stall horn going off? What about on those days gusty days when you’re on the approach and it’s burping at you? Is that a built-in form of desensitization?) The new aircraft certification standards DO put more emphasis on designing in stall warning and resistance systems and also DO mesh better with the new ACS stall response training; but that does nothing for the rest of the fleet that doesn’t share those design features and probably won’t be in widespread use for a decade. Most of the current fleet was designed under Part 23.207 (B) that says: “The stall warning may be furnished either through the inherent aerodynamic qualities of the airplane or by a device that will give clearly distinguishable indications under the expected conditions of flight.” So, there is no requirement that says a stall warning horn has to be included. (I suspect current ASTM standards for Light Sport also follow this approach because my Flight Design CTSW does not have a stall horn or a light…)

So, now, let me educate you a bit on how I’d look at this issue as a space shuttle safety guy.

When looking at how to eliminate or control hazards (and the hazard we are talking about here is loss of control in the form of a stall/spin), the shuttle program invoked a philosophy known as the “hazard reduction precedence sequence”. The sequence consisted of the following approaches:
1. Design for Minimum Hazard – Eliminate the hazard by design where possible. (In our case, make the airplane where it won’t stall or is extremely hard to.)
2. Safety Devices – Reduce known hazards which cannot be eliminated by use of safety devices as part of the system, subsystem, or equipment. (Stick shakers and ballistic recovery systems are examples of this one.)
3. Warning Devices – Employ devices that provide timely detection of the condition and the generation of a warning signal. (Stall horn, audible warnings, lights or other indicators…including angle of attack indicators…fit this category.)
4. Special Procedures – Used when the above approaches do not reduce the magnitude of the existing or potential hazards. (Pilot response to a stall or stall warning fall into this category.)

This list proceeds from the point of the strongest control of the hazard (1) to the weakest (4). For the case we’re talking about, a pilot responding to a stall horn with power or angle of attack reduction will be using 3 and 4. These are the weakest of the controls, i.e., hold the least amount of risk reduction. That said, the reality of a lot of general aviation flying is that we depend heavily on pilot training to reduce risk because of the nature of our aircraft, i.e., low weight and sophistication. That said, the rate of loss of control accidents over the last several decades has remained relatively constant; and since we are primarily dealing with it via the weakest of controls, there is little reason to suspect that training (once we are in the scenario) will have little impact on the rate. I also suspect that there are very often other causal factors (i.e., distraction due to aircraft or operational issues) involved in getting into the “bad day” that any training approach will not address, other than the big one involving “flying the airplane first” and taking the rest of the chips where they fall. I have no knowledge of whether this was considered when looking at the LOC accident rates; I suspect they all stopped at the “pilot eror” point without the substantive digging necessary (if it can be accomplished at all) to nail down the true “root causes”, which often lie deeper than people can or choose to look.

While we’re talking about this, I want to pull on one other analogy from a shuttle safety approach, i.e, the idea of system criticality and how this new training approach affects it. Shuttle had three classes of systems’ criticality. They were:

Crit 1 – systems that if they failed could cause loss of crew or vehicle
Crit 2 – systems that if they failed could cause loss of mission
Crit 3 – systems that, while desirable, would not cause either loss of mission or loss of crew or vehicle.

So, let’s apply this to a general aviation aircraft in this scenario.

Our current approach to the criticality of a stall warning system (because there’s no requirement that a pilot to respond to it and because there its operation is not required for VFR flight) would make it a Crit 3 item. The main responsibility lies with the pilot to recognize his aircraft is approaching a stalled condition and respond accordingly if it gets into it, whether the stall horn is working or not. The new focus on stall avoidance and making the pilot’s response DEPENDENT on the activation of the warning device would RAISE the criticality of the stall warning system if it was assigned one. Since the pilot’s reactions are based on the stall horn (or other warning system) and the ACS committee considered this an emergency, the criticality of the system (if I were rating it) would jump to Crit 1! You don’t fly without a Crit 1 system being operable! Since there are no FAR’s in place that require a stall warning device to be operable. This suggests a disconnect between the training approach which assumes the device will be in place and operable and the aircraft’s required systems. There is much better integration with the new design standards; but for now, this approach is very premature, even if I were not against it for other reasons.

The Best Trip Home That Didn’t Happen (Part 5/Conclusion)

The next Saturday (after I had returned from a trip to Reno, Nevada to attend the Tailhook Association’s 2017 convention and a reunion dinner of my Navy fighter squadron), I performed a quick “check flight” consisting of two touch and go’s and one full stop landing in our local pattern. There were no oil leaks and engine performance felt and sounded normal.
On Sunday, I came back out to take a longer flight involving some climbs at least up to 2500 ft; but as I headed out to the southeast to my favorite practice area, the CTSW began emitting a strange howling noise I had never heard before. Once again, I turned around and headed back to the airport. The winds were out of the north so we were landing on three –two; as I approached the airport, I heard and saw no other airplanes in the pattern so I made a bee-line for the end of the runway to get back on the ground. I landed without incident, taxied back to the hangar, pulled the cowling off with the help of my wife, performed a full power static run up, and listened for the noise. I didn’t hear it. That suggested to me that the noise was probably due to something associated with the airframe. It sounded like it was coming from an area above and ahead of my left ear, though I really wasn’t sure that it wasn’t transmitting through to there from somewhere else. Pointing toward it, though, was the fact that the wings had been pulled off as part of the conditional inspection. I couldn’t dismiss the probability that something had not being properly sealed up, especially considering everything else that had happened.

Judging it to be more of an annoyance than a safety risk, I launched again with my Go Pro mounted in the cockpit and recording. The sound showed up as I moved past ninety knots. I varied the power and heard no change in the noise but then noticed it decreased with airspeed. After landing, I took all the video I had and put together two clips. One began with footage that illustrated normal cockpit sounds and noise level but then switched to footage that contained the new noise. The other was a shorter clip from a flight that caught the noise starting up. I posted both clips to You Tube and then posted them to my aircraft’s online owner’s forum along with a question asking if anyone could identify the noise. Two owners, one of them a well-known CT mechanic, responded almost immediately. They both identified it as “tape noise”. Bolus tape is used to seal small gaps between several of the aircraft’s aerodynamic structures, the wing/fuselage joint being one of them. I was told to inspect the tape for any cracks or sections that weren’t sealing against the surfaces. Somewhere, the air was exciting the tape so it was acting like a reed in a musical instrument. It was hard for me to believe that tape could make a noise that loud, but I trusted what they were telling me and did an inspection the next day.

I didn’t find anything telling. I did notice the mechanic had used on a single strand of tape to seal the wings (versus multiple layers used previously), and that the tape in the front gap looked more depressed, even if it didn’t appear broken. I laid another strand of tape over the first, overlapping about 80% of it and the edge against the inner part of the wing. I took off and didn’t go far before the sound came back, though it delayed its appearance until 110 knots. After returning to the ground, I overlapped the other side of the original tape and the new layer so both strands were partially overlapped and ensured the seals against the lower fuselage were really tight and the tape ran all the way back to a bracket at the flaps, as the mechanic had instructed me to do. I launched out again and the noise did not show up, no matter what speed I flew. Once back on the ground, I laid one additional layer of tape over the installation on the other wing to hopefully ensure the same problem did not develop there later on.


All the problems seemed to be licked. The only thing I still felt I needed to do was put enough time on the engine while airborne air to ensure the push rod tube sealing at the head was good. So, I planned a flight from Pearland to Brenham via Houston Southwest and Lane to provide me that assurance. As I was checking tire pressures for that flight, I inadvertently pushed the nosewheel tire stem sideways and its joint ruptured, deflating the tire in in instant. (OMG!) It’s a small tire and I could not locate a tube for it at any local store, so I had to order one online and lost ANOTHER week! Luckily, the guys over at Air Professionals at the airport jumped on it and got her done as soon as I got the parts, and I finally launched out on that “check flight” eleven (COUNT ‘EM….11!) weeks after the airplane had been released from its conditional. I performed climbs to 1500, 2500, and 6500 feet, followed on the return with a climb to 5500 feet right after takeoff followed by a high speed, near idle descent to continuous low altitude cruise at 5400 RPM, 100 RPM below the engine’s maximum continuous operating limit (and the RPM I typically fly at in a headwind). I returned to Pearland about two hours after I took off and immediately got out and checked for oil leaks. There were NONE! What a RELIEF! Finally, all this crap appeared to be over; and I could go back to JUST FLYING!

I was grateful to the shop that performed the conditional that they hung in until most of it had been resolved, but I was more than unhappy with the time it had taken to get it all resolved and the low priority they had given the whole affair, especially considering it was all due to their errors (five in all), and how they stopped communicating when they didn’t have an answer. I was convinced that the mechanic knew his stuff but I was also convinced the whole thing had occurred because he rushed all the work and took shortcuts to complete it. Because of that, I will not return my aircraft to them for any work nor will I recommend them to any other Light Sport owners, even though they are manufacturer approved.

Here are my other “take-aways” from all this.

1. Don’t ignore what your gut is telling you; follow it! Believe me, when I first started feeling something was wrong, I didn’t instantaneously snap to the right answer, I wanted to ensure I was right, something you really can’t do. (Better dead than look bad?) I did take the time to investigate what was happening; but as I discovered that there were several small clues the airplane had an issue, I knew it was in my best interest to do what my gut was telling me to do, a lesson often hard learned through my life experience, including being in the middle of the space shuttle Columbia accident. And I did it not once but TWICE! While you can argue about what the oil leak rate was, what you can’t argue is there was a real if not totally quantifiable possibility of oil starvation and engine failure and whatever outcome that might have brought. When dealing with both machines and people, sometimes it’s the small things that you pick on that prove to be the most telling. Better to put your aircraft on the ground and be safe and wrong than stay in the air and be dead and right. (“I thought something was wrong…)

2. Knowing your aircraft and its systems involves not only what’s in your head but what’s in your senses and your experience. This was demonstrated in the small kinesthetic and audio clues that triggered my awareness while the gauges appeared to be telling me there was no problem. The motto in the space shuttle Mission Engineering Room (MER) during the Columbia era was: “In God we trust; all others bring data.” While that often does make sense, the Columbia accident (and the Challenger accident) and this experience showed there are often limits to that approach, and like most things invented by humans, nothing is absolute. It took me a long time to learn the hard way that to ignore what my senses are telling me (and they are giving me a very valuable but different forms of input) is as big a mistake as failing to reason things out. Sometimes, the data you need to make a logical decision just isn’t there. Welcome to Life!

3. You’re a pilot, a passenger, or CARGO! At different times, we all vacillate between those three states. It usually doesn’t kill us. But life does present those moments when you MUST become the pilot or failure to do so can have definite and sometimes serious consequences. As aviators, we often have to deal with other people who are in authority or have our fate in their hands. Sometimes the right thing to do is trust and follow; sometimes the right thing to do is rebel and take charge. How do you know when to do the latter? Go back to bullet point #1; when your gut is telling you something is wrong. In that case, be the pilot! Tell the air traffic controller you can’t or won’t comply (UNABLE or declare an EMERGENCY) or the mechanic where you think the problem is. Yes, there may be some pushback but ultimately no one is going to keep you safe but you. That doesn’t mean other folks won’t help you and you can thank them when and if they do; it’s that we’re all human and nobody’s perfect. BTW, if you sit on your hands and don’t say anything, even that you’re concerned, then you’ve moved from being a “passenger” to CARGO. Don’t complain to anyone if you get mishandled.

4. Stay cool and take it one step at a time! It’s one thing to think ahead to what can happen next and anticipate it; it’s quite another to overreact and elevate your risk beyond what is necessary to meet the moment. Bias your options toward the worst case; but be careful you don’t take it so far you create a BIGGER problem. Yes, sometime this involves your best guess, but that’s what your training is for. Stay with what you know and do what you need to in order to stay safe, including sacrificing the aircraft. Walking away is all that matters.

5. Have the patience to stay with it until it is COMPLETELY resolved. In all my years of owning and flying aircraft, this was the situation that tried my patience and my endurance the most. There were several times I was so exhausted and frustrated I almost turned it into a legal case, something I didn’t want to do and I knew would mainly be a win for the attorney. It also became so tiring that I was temped to do what was EASIER and shortcut the measures I felt needed to be taken to validate the aircraft’s safety and ASSUME that things were okay without proof. I could not do so without putting me and, more importantly, the people I care about (and others on the ground I didn’t know) at jeopardy that could be avoided. In the end, I followed each issue to a resolution and performed a “check flight” campaign I felt would push out any remaining flaws. I pushed the aircraft and engine into flight profiles similar to some flown on my more difficult cross-country flights, giving me some confidence I could re-employ the aircraft without undue concern in the same manner.

Eternal vigilance is not only the price of freedom but the cost of aviation.

(NOTE: If you haven’t read the whole thing and would like to do so without wading through the website, a pdf version of it is here.

The Best Trip Home That Didn’t Happen (Part 4)

I learned to pay attention to a little ditty when I was involved in Naval Aviation that goes like this: “It only takes one dumbsh*t to wipe out a thousand “atta’boys”.” That was about to apply to this evolution, as you shall see.

I was pretty impressed that the owner of the shop had flown the mechanic involved with this whole thing and his boss (also a mechanic and an IA) in a Citation down to fix my airplane. They roared in about 11 a.m.,jet blast reversers screaming them to a stop, and pulled into a parking spot near the FBO. My hangar is only a short walk away, so I headed toward the jet to escort them to my CT. After shaking hands, saying “hello”, and thanking the mechanics for coming, I walked them back to my airplane. They did a quick inspection that couldn’t reveal much; it had been a week since the airplane had flown and any oil that might help them pinpoint the leak had disappeared. So, we pulled the airplane out of the hangar, pointed the tail at only empty grass, and started the engine. Even though the ambient temperature was already in the nineties and climbing toward the century mark, it still took a few minutes before the engine hit its minimum operating temperature so the mechanic could open up the throttle while the IA searched for a leak. And found one. Unlike the other leaks, which had been at a single push rod seal at the bottom of a tube, this one was coming from the top; it was inside the head. They would have to not only take the head off but remove the push rod tubes and reseal them. The mechanic said he needed Loctite 620 to do that; and he didn’t have any. (So much for delaying five days to make sure they had the right parts.) The IA started immediately saying they’d “have to come back”, which meant to me they had no hesitancy about putting my airplane down for two more weeks; despite what had happened, the mechanic was going on a two week vacation the next day! I couldn’t believe what I was hearing and was determined not to let them off the hook easily; what sense did it make…especially after they had flown down in a Citation…to simply declare defeat and walk away before trying to see what could be done? I suggested they go to a nearby mechanic’s shop and see if there was any down there or if someone could tell us where we could get some locally before throwing it the towel. They didn’t want to do that. The IA asked the mechanic what Loctite would work, and after some checking, he said any 600 series Loctite would. From my hazy memory came a nagging that I had some Loctite, though I wasn’t sure what type or where it was. I found it after a short search; it was a bottle of Loctite 648. Giving them now no reason not to proceed, they took it and started taking the head apart.

The first words I got about how long it would take to do the repair was a couple of hours; so, after going over and meeting the shop’s owner to thank him for coming down and checking on whether I could do anything for them, I left to grab some lunch. When I got back, I sat and waited for the job to finish up, hoping to take the airplane for a short hop around the pattern to verify the fix. When the job was almost complete, they finally told me the airplane needed to sit for at least 24 hours for the Loctite to completely cure. That meant they would have to leave anyway, and I would once again be left with an unairworthy airplane for an uncertain and already LONG length of time. The IA promised to come back to perform a leak check in the next few days. I encouraged him to do just that.

The end of the week came with the IA saying couldn’t get transport down. Since he was convinced all we were after was a leak check, he asked if I would allow a mechanic’s shop on my field to assign someone to do the leak check whose time he would pay for. Wanting to move forward, I agreed. A day later, the local guy and I went out to the CT and, after I pulled the engine through and checked the oil, pulled it out of the hangar. As he inspected it closely to get a good look at its condition, I saw him hesitate as he looked in the area of the push rod tubes; but he didn’t say anything. I got in the CT, started it up, sat waiting for the engine to warm up, and then signaled him I was going to run it up. He nodded and I did, advancing the throttle in steps as he watched for leaks. When I shut the engine down, he called me aside and showed me where we had a new leak. This was back at the push rod seal…AGAIN!

“I thought that seal looked a little rolled up,” he said.

We put the airplane back up and I got on the phone with the IA in Dentin. He wasn’t sure how he was going to tackle it now with his Rotax certified mechanic gone. He admitted it was his problem, and I sent him a link to a website he could use to search for Rotax certified mechanics anywhere to help him out.

I gave him a day to work the problem and then got in touch with him again. He stated he was legal to do the repair himself and planned to have someone fly him down in a King Air in a day or two so he could. But as the time approached and the King Air ride didn’t work out, he said he didn’t have a way to get there (despite the fact that Southwest Airlines was flying multiple flights to Hobby every day and he could drive down in five hours if he was really motivated), so he asked if he could hire someone at KLVJ to do the work. Since I personally knew the mechanic who did the leak check had Rotax experience if not a formal certification and I was convinced having someone local pursue it was a better course, I agreed. I spoke to the owner of the local shop and he was fine with doing the work, though it would be the middle of the next week before he could get to it. Since that was about the same time the Denton crew could get to it if they pressed ahead, I didn’t see we’d gain anything by having the guys in Denton fly down; and, frankly, I felt it was time to move the work to someone with fresh eyes and hands.

I wrote an e-mail that included both shop owners and the Denton mechanic who had been so far unsuccessful at completing the work and discussed how I saw us proceeding if we had an issue after the next attempt to close it out. Bringing someone else in held the potential for complicating things if there was still an issue, especially since the airplane had not been flown since the push rod tubes had been reinstalled. I proposed a three way conversation for any issue, and that if anyone involved didn’t agree with what I was proposing, then we needed to halt moving forward in this manner. I didn’t hear anything back. I figured that, in actuality, no matter what the result, the original shop still would have legal responsibility to resolve the matter, especially since the second shop was working on their behalf. I knew I was taking some risk going this way, but I didn’t see I would be risking any more than I would by bringing the original mechanic back in. He had made already made FOUR attempts to “get her done”. I was just glad the shop manager (the IA) was standing behind their work regardless and was at least making some effort to get it all resolved.


Ten days later, nothing had happened. The owner of the local shop decided he didn’t want to get in the middle of it; and while I didn’t blame him for that, I was irritated at him for promising to get it done in a week and then not telling me he had decided not to work on the plane. I didn’t find out until I called the Denton shop and informed them nothing was happening. The owner of the Denton shop said he would come down on Thursday or Friday of that week but then shuffled the job back to the original mechanic who couldn’t come until Tuesday of the week following. (God forbid someone consider driving down from Denton on the weekend to get her done, even though almost sixty days had passed since this mess started.) On the Tuesday morning of the planned visit, I got a text as I waited to hear the mechanic was airborne that said instead he had wrecked his car on the way to the airport and wouldn’t make it. I responded that I was glad he was okay and also texted the shop manager and asked him to call me. A hour or two later, I called the IA and told him I didn’t think it was wise to continue to send the original mechanic and reminded him of his promise to come down and finish the job for him. He said he heard me and would get back to me with his next plan.

In the meantime, Hurricane Harvey spun up in the Gulf, making one of my worst fears about this continuing debacle come true. The un-airworthy state of my aircraft meant that flying her out of harm’s way was impossible, and I would have to take my lumps and hope her hangar would protect her. I won’t go through the horror show that Harvey was; and, obviously, the fate of one’s aircraft pales in comparison to trying to keep yourself and your loved ones safe and water out of your home. We were some of the most fortunate ones; we got no water in our house. Though we were trapped in the house for days, we had plenty of food and water and power the whole time. As it became clear we weren’t going to have to call for a water rescue, Harvey left, and the water began to recede, so my attention turned first to our cars (which didn’t get flooded though the carpeting in my convertible did get soaked by overflow from some drains) and then the airplane. A flooded Clear Creek not far from us cut us off reaching the airport, so there was no information about our airplane’s fate for days. As things were calming down, I texted the owner of the hangar and asked him if he could see its security cameras and, hence, our airplanes; while he had lost his internet connection, another pilot in my hangar had been out to it and let us know all the airplanes were untouched. It was a few more days before the creek receded enough to allow me to drive out to the airport and see for myself.

It was only a day or two later that Hurricane Irma formed; and as it barreled west, some of the early computer model runs were spewing out the possibility that Houston might be in its path. This prompted me to make an angry phone call to the guys at the Denton shop to light a fire and get them down here. I wanted the airplane ready to fly out; considering what we had been through, there was no way I was going to consider remaining in Houston if we were in for another hurricane hit. The problem mechanic said he’d be down on the following Tuesday (about a week later). I was expecting that to be the first day back at work and so I told them I needed for them to make their own arrangements to get around. I heard nothing until that Tuesday morning when I got an e-mail from the mechanic saying he wasn’t coming because he couldn’t get a rental car. I sent him back a very irritated e-mail telling him he should have called me and gotten on the airplane, and started a text conversation with his boss as well. Having finally reached the end of my patience, I told them they had until 1800 Friday to get my airplane up or I would take legal action against them (I did indeed have an attorney picked out.). They got the mechanic on a flight down on Southwest the next day. I made arrangements with my boss to do some work from home and take a short day to make it all work.

The mechanic FINALLY did make it the next day, and I picked him up at Hobby, drove him to my hangar, and left him to work. I asked him to call me about 20 minutes before he was ready to do a run-up to check his work; he said he would. Two hours later, I decided to see what was going on and returned to the airport to find the CT sitting outside the hangar getting ready for her run. After some initial problems getting the airplane to start, I got the engine running and we checked her out. The seal did not appear to be leaking. We talked about me doing a few trips around the pattern to verify the fix and I agreed to it, at least until I checked the winds and found them gusting up to the airplane’s demonstrated crosswind limit. I was exhausted from all I had been through and decided flying in those conditions wasn’t a good idea. So, we buttoned up the cowling, I taxied her out, and we did a full power static run instead. Again, there were no leaks; so I taxied the airplane back to the hangar and out her up. By then it was lunch time, so I took both of us over to Chick Fil A and then dropped the mechanic off at Hobby to catch his flight back to Denton.

(Continued; see Part 5).

Shooting an Aerodynamic Elephant

Since the reason I spend time blogging is an effort to “give back” by passing on my experiences and knowledge, I’ve focused some articles on the current turmoil in aerospace education concerning the generation of lift. The misinformation and misconceptions are quite widespread; they are now affecting most information sources pilots trust to be correct and that we are tested on. (Yes, I am now speaking to you, FAA, which all the pilot training organizations like AOPA, Gleim, and instructor published pilot books march in locked step with.) Worse, this misinformation is being passed on as fact by educational organizations entrusted with training youth. The bottom line is that we will likely suffer for a decade or more with people not really understanding how a wing works and having completely wrong ideas about it; hopefully, it will result in only having folks busting test scores and looking ignorant and not in an actual accident somewhere. The problem is that is not guaranteed and people usually find a way to make the most improbable things happen. Which is what proper education is supposed to guard against.

Wanting to help tackle the problem, I knew I needed to make sure that what I was writing, thinking, and teaching was correct; so, I began going back to my various aerodynamic texts and refreshing myself on the generation of lift. Some of those are texts I used to get my pilots’ ratings, some of those are texts still tagging along with me after my aerospace engineering degree (“Foundations of Aerodynamics”, Kuethe and Schetzer; “Airplane Aerodynamics”, Dommasch, Sherby, and Connolly; “Theory of Wing Sections”, Abbott and Doenhoff), and others were texts I had come to respect as good references (i.e., “Aerodynamics for Naval Aviators”). As I looked at what the controversies were and how they were spreading, I started re-examining what I knew and looking for the truth. As I integrated all I knew and went through the various arguments, I began realizing there was more to the picture than what my engineering education had taught me, though none of it was wrong. (I couldn’t say the same for the information I was seeing primarily on the Internet and that was creeping into pilot’s educational books, probably because of both an incomplete understanding by their authors and their reliance on Internet sources, which are sometimes difficult if not impossible to independently verify…not that anyone appeared to be going to the trouble.) I was specifically focusing on the shortcomings of the Bernoulli explanation (though I knew its basic heart of using pressure distributions to explain lift was correct) and how Newton’s Third Law was being misapplied..and, later, how the Coanda effect was being incorrectly drawn into the explanation of basic lift. (We NEVER discussed Coanda during any engineering class I took and my literature search only turned it up in a NASA paper on high-lift devices…for very good reasons!) I became convinced that a lot of the problem was centered around not considering the wing and air as a “system” and that the application of Newton’s Third Law really had more to do with interactions in the pressure field than it did with any kind of direct mechanism where “the wing pushes down on the air” (a.k.a AOPA).

Then, along came Doug McLean tackling the problem with his book: “Understanding Aerodynamics: Arguing from the Real Physics” (Wiley).

I can’t say enough good things about this book. It has become my main resource for enhancing my own understanding of this subject AND tackling the issue on the aerospace education front. It is a very technical read; but for most folks interested in understanding what’s really going on, if you do nothing but read Chapter 7 (“Lift and Airfoils in 2D Subsonic Speeds”), then you can come to understand where the “truth” lies.

I expect to be working on an explanation of the generation of lift that relies heavily on what he had to say; but all I want to address today is this. I strongly disagree with him on one thing: he believes it’s easier for most folks to understand lift using Newton’s Third Law. Most folks experience with Newton’s Third Law lies only with some kind of reaction engine (i.e., jet and rocket engines), and so they erroneously think that the wing lift occurs in exactly the same way (leading to little jets of air pushing out of the wing). But this is NOT where Newton’s Third Law comes into play with a fixed wing. This sentence from McLean’s book captures it well: quote: “The pressure differences exert the lift force on the airfoil, while the downward turning of the flow and the changes in flow speed sustain the pressure differences”. Newton’s Third Law does play quite a role in the generation of lift; lift is the wing’s overall reaction to the pressure imbalance while the Third Law (as well as the Second one) also plays a role in the creation and maintenance of the flow field that produces it.

BANG! Call that a shot of one “aerodynamic elephant”.

The Best Trip Home That Didn’t Happen (Part 3)

About ten days later, the airplane was fixed again. The mechanic had gone back in, rechecked the valves, and discovered that neither the intake or the exhaust valves were getting a complete seal. He had reworked them, done several ground runs over thirty minutes long, and had seen no issues. To be absolutely sure they had a fix, they decided to test fly the airplane and contacted Scott, a Light Sport pilot and instructor who had worked for them in the past and whom I personally knew, to fly the flight. Once I was sure Scott would be covered by my insurance, I okayed the flight, contingent upon him calling me and making sure we set up good test conditions. He did, and I shared with him everything I knew and had seen. A day or so later, both he and the mechanic manned up the CT and flew for a one hour and twelve-minute flight, performing multiple climbs up to 7500 feet. They were convinced there were no issues, so they talked Scott into flying the CTSW to Houston if I would run him over to Covey Trails, a pretty little airpark northwest of Pearland and Sugarland and on the west side of Houston. I agreed. It was a small price to pay not to have to go through the hassle of getting the CTSW back from Denton. We scheduled the flight for Wednesday morning, July 19th. Scott hoped to launch about 7 am and get to Pearland about 9 in a two-hour flight. It was theoretically possible to do it if you cut straight through the Class B with either no headwinds or winds in your favor, but I was skeptical it would actually happen that fast.

Scott launched only a few minutes later than he had hoped to; at about eight a.m., I received a text with a picture of the instrument panel and a comment: “Ugh! It’ll be a little while….”. I could see his groundspeed was 103 knots, his estimated time of arrival was one hour and fifty-six minutes, he was cruising level at 5500 feet, and he was just clearing the south side of the Dallas Class B. He didn’t feel or see he had any issues. Another text a few minutes later showed about the engine gauges: 5200 RPM, CHT at 180 degrees F, Oil Temp at 200 degrees, and Oil Pressure at 50 psi. Those were all normal readings.

I texted him back saying: “Dude, this is LIGHT SPORT!”

A little before nine-thirty in the morning, I left my house and drove out to the airfield where I parked my car at my hangar and walked over to the FBO. Inside, a radio was feeding in traffic calls; I heard him call five miles west and request the active runway: someone else called they were using runway 14 and Scott latched on. Even though I’ve seen plenty of photos of what the CT looks like in flight, I am always curious to see it for myself, so I walked outside and watched him cross the field directly over my head. Banking left, he swung into the downwind and expertly flew the base and final legs, making a gentle landing on one four before turning off on taxiway Bravo and heading for the FBO. I took a couple of cell phone shots of him coming toward me as I looked for any traces of oil in case the repair had not gone as thought. As he spun the airplane around a few feet away, I saw that the bottom quarter of the whole left side was covered in oil. Apparently, the oil had been leaking for a while because it had saturated a piece of white “speed tape” used to cover a gap between the rear fuselage and the lower tail cone and its front end was flopping loose. After Scott shut the airplane down and was unstrapping, I stepped up to his window and said: “Dude, you’ve got oil all down the left side of the airplane!”

“WHAT….?!” He stammered, as he then climbed out. We both took out our cell phones and snapped pictures. Once I got evidence of oil saturating the fuselage, I looked in the oil door to see if I could see where oil was hitting the inner cowling (I could and tried to take a cell phone picture of it that didn’t turn out.) and then popped open the door to the left baggage compartment to find, much to my surprise, the compartment was coated with oil. I momentarily paniced as I realized that the canvas satchel containing the aircraft logs were there and its top had been left unzipped open, calming down as I examined it and saw that the oil hadn’t gotten in. There was a roll of “speed tape” in the compartment that wasn’t exactly in good shape, and I pulled it aside to dry it off and see if it was salvageable. I wiped down what oil I could off the side of the compartment and the oil that had run down the baggage compartment door and collected in a little pool on the bottom of a rim. I had a spare liter of oil in that compartment, so I pulled it out to use on the next step.

Returning to the cowling, I opened the oil door and checked the engine’s oil level on the oil dipstick. Scott grunted as we both saw the stick was completely dry. I added 200 ml and checked again. Still dry. 400 ml more. Still dry. The rest of the liter. That topped it off! I asked Scott where the oil level was when he took off; he answered it was in the middle of the cutout section of the stick, which defines the Min to Max quantity. He thought that meant he took off half a liter low; but a check of the difference between Min and max is .43 liters, so a spot in the middle would mean he took off only .22 liters low. That meant the airplane had shed .78 liters of oil, 26 % of its total oil capacity.

With the oil level temporarily topped off, I started my wounded airplane up and taxied her back to my hangar. Once we had her buttoned up, Scott and I piled into my 2014 Mustang convertible and headed for Covey Trails. Unfortunately, our twenty-minute flight turned into about a two hour road trip for Scott and a four hour road trip for me, though Covey trails was one of the prettiest airparks I had ever seen. Too bad I didn’t get to do a grass field landing there. (Caveat: To anyone who’s thinking about dropping in unannounced, better bring $100 cash with you. That’s their “landing fee” unless one of the residents at the place vouches for you.)

Round 4 Begins

The shop where I had the work done and I conversed fro about a week about how this was now going to get resolved. They first said were coming down on Friday, July 21 but then pushed back to Tuesday the 25th because they were “waiting for parts”. Since no one had been down to examine the airplane and do a preliminary failure analysis, I had questions about what parts they were bringing but didn’t get an answer. I hoped that meant they were bringing everything they needed to completely rebuild the head. While there was every reason to think that the third oil leak was associated with a root cause we hadn’t mitigated or hadn’t identified, there was no guarantee of it. It could be that the continued operation of the engine with a fault had triggered another failure mode. Additionally, while the shop had been stepping up to get me transportation most of the time and take care of the issue, I wasn’t feeling there was any sense of urgency about getting my aircraft back up in the air, especially after I got a note from the mechanic that he was going on vacation on the 27th and started mentioning August 7th as the next date for us to pursue anything. I hadn’t fussed at them much until I got that, but I did then and let them know I was going to pursue “alternative remedies” soon. I wasn’t kidding; I had selected an aviation attorney to go have a conversation with, though going down that road was the vehicle of last resort. I was also talking to a local Rotax certified mechanic to see if he could “get her done”, even if I had to pay him out of my pocket, assuming he would come to Pearland to work.

Thankfully, the business owner for the shop that had done the work stepped in. I got a call from the head mechanic apologizing for the inconvenience (not the first time he had done that) and telling me the owner was flying him and the mechanic down on Wednesday, July 26th to get the airplane up in the air. I was told that no matter what the problem was (and even if something else had gone awry), they would return the aircraft the service. That was a huge relief to me. I personally liked the mechanic and still had confidence in him (though I wasn’t convinced he didn’t have some blind spots—who doesn’t?), so I was happy to hear they appeared to be REALLY stepping up to the bar! It’s when things are going to hell in a handbasket you really see the character of a person or a company; and this one was looking like one I wanted to continue to do business with (though I would reserve final judgement until we actually got a resolution).

They came, they went, and the airplane leaked again…!!! (Part 4 follows)

The Best Trip Home That Didn’t Happen (Part 2)

The repair of the CTSW took about another week. The shop had run out of push rod tube seals, so we lost a couple of days waiting on some to arrive. The repair itself only took a day or so once they got there; but Houston swings between days of good weather and bad in cycles during the summer and the good days had passed while we were waiting. Between a couple of weathered-in days and my desire to limit work impacts as much possible, the next attempt to get the airplane home looked to be on the weekend. Most of our weather was due to afternoon thunderstorms firing up, so leaving Denton in the morning made the most sense. That meant I’d have to either get up there the night before and stay overnight or get up there early in the morning and try to get back as fast as I could. To make things worse, the shop said they didn’t have any way to assist with the trip up until the following week. Allowing the whole thing to drag out until then would mean impacts to both my work and personal schedules I wanted to avoid, so my wife and I started exploring ways to get me up to Denton to fetch the airplane at the lowest cost. We had enough points in our airline accounts to pay for a ticket on Southwest Airlines for only a few bucks, so we used it to buy me a ticket up on Saturday morning, July 8th. I got one for a flight that arrived at Dallas Love at 8:30 in the morning.

The shop didn’t typically work on Saturday; but they were trying to move some other work forward so there would be folks there who could let me have my airplane. I didn’t think there was much chance of getting a ride from them when they were manning with a skeleton crew and didn’t want to depend on it; after looking at what ground transportation was available and what each cost, it wouldn’t cost me any more to rent a car than renting a ride, so that’s what I did. It would be a one way trip and I’d drop the car at the FBO. Having a car would also give me some options about getting lunch or a room if things went awry and I had to spend the night.

My wife dropped me at Houston Hobby at a little before six thirty on the Saturday morning. I was carrying only my flight gear and had positioned it plus anything else that might trigger a TSA security alarm in my flight bag so I could send it through their X-ray. I breezed through security and got to my gate to find our 737 already there. There were probably only about 40 people total on the whole flight, so getting a window seat was not a problem nor was launching on time.

I was keenly interested in the weather on the flight up; most of it seemed to be active to the east of Houston, i.e. good news for me if it stayed that way. We landed at Dallas Love a few minutes early and I beat feet out of the Terminal to the car rental busses, barely missing the one for Hertz rental as I stepped outside. A good fifteen minutes later, one showed up again and I rode it to the Hertz rental counter where my car was already waiting. I spent a few minutes checking her for damage and a few more checking her controls before plugging in a route to the Denton airport on the iPhone. It said I’d be there in 38 minutes. That was a lie; I-35 North was destroyed for construction and it took me an hour and 45 minutes to roll up to the shop and get out, hoping the mechanics were still there. They were; but they didn’t know I was coming, so they spent a few minutes on the phone making sure letting me have the airplane was okay while I performed a very thorough preflight, including a visual inspection of the engine compartment with the upper cowling off. There were no oil leaks anywhere and the oil level was at the top, right where I wanted it to be. Having a full tank of oil meant extra time in the air in the event of another leak.

By the time I got the preflight and weather briefings done, it was approaching lunch time. I had only snacked at breakfast time, so I felt I needed some real food to take with me since it would take close to three hours to get home. I needed to top off the fuel in the rental car anyway, so I headed out for a Chevron gas station some few miles away that I knew also had a Subway sandwich shop. I fueled up the car, got a sandwich and a bottle of cold water, and hustled back to the airfield where I turned in the car at the FBO (with some qualms in case I had to return but couldn’t see a good way to both hang onto it and turn it in as promised). I walked down to the shop and the CTSW, got the cockpit and me ready, and started the airplane up. After completing the post-start checklist, including getting courses laid into all my nav gear and the Go Pro camera started again, I taxied out for takeoff as I had a week before except I had no intention of overflying the area to the south. My plan was to fly out to the southwest as I had before and not to request flight following to leave me freer to deal with the airplane.

After completing my takeoff checks and taxiing up to the runway, I called the tower for takeoff. The controller told me to hold short again and asked me for my direction of flight, to which I responded “southwest”. A few moments after a Cessna transited in front of me down the runway, the controller issues me a “maintain runway heading and no delay” takeoff clearance with traffic inbound at one mile, which I accepted as I gunned the airplane forward, hitting full throttle as I rolled onto the runway centerline. Everything felt good, and the little CTSW lifted off quickly, climbing up several hundred feet before I retracted her flaps while continuing straight ahead. When the tower controller called me for a right turn, I rolled into it at her command before acknowledging it on the radios. Like I had before. I continued climbing to 2500 feet while heading southwest, switching off to Unicom frequencies when outside 8 miles.

I continued southwest over Propwash and onward to Copeland, where I again started a climb to 4500 feet while turning southwest. I had altered my planned course slightly to make it direct shot from Copeland to Bourland, closer to but clear of the Class D airspace belonging to Fort Worth NAS JRB, which I like to call Navy Fort Worth. I punched up the tower frequency and was surprised by the number of requests to transit their airspace, many of which were from departures from Fort Worth Meacham’s airport immediately to its east. The climb to 4500 feet was completely normal, and I started to relax, thinking that my problems with the CT might be over at last. I flew out from under the Dallas Class B’s southwestern ring and, with Bourland in sight, pushed the throttles up for a climb to 5500 as I swung more southeast.

Once again, I felt the vibration, the slight skipping, that I had seen before. I pulled the throttle back and started a right hand descending turn to return the way I had come. It was back to Denton again, no matter how much I hated to do it. Like last time, the gauges were showing me nothing unusual, and the engine was purring along like nothing was wrong as long as the throttle was not at full. I leveled the airplane down at 3500 and went to full throttle to see what I would get; the vibration returned and the RPM seemed to hang. I backed off the throttle, putting her at normal cruise, and pointed the nose east of Copeland, trying to run more directly back to Denton. The direct line clipped the Fort Worth Alliance Class B which I could stay above; instead I elected to fly a little bit northeast of the line rather than risk any kind of infringement. My nose stayed ready to sense the smell of burning oil, but I never did. I pulled into the left downwind for runway 18 paralleling a Cessna inside my right wing; the tower had him turn in close and first and I followed him around the corner to another safe landing.

The hangar doors at the shop were still open but no one seemed to be there. I stopped my airplane and shut her down and found one mechanic working on a Cessna Mustang who I explained to what had happened. As I unloaded my gear again, I checked the nosegear and saw another oil leak running down the strut at the same spot as before. Whatever was happening was BUSTING the seal! At that moment, any doubt I had about where the problem was located disappeared. I was very certain the problem was in the head, something I told the head mechanic when I got him on the phone. We also now knew that the problem wouldn’t appear until the airplane had been airborne for thirty to forty-five minutes, suggesting to both me and the head honcho that it was related to the overall thermal load, i.e., heat soakback, in the engine; and we knew it was busting the push rod seal. He responded that he knew what it was, i.e., a valve sticking open that was overpressurizing the push rod tube and then causing the seal to leak. I had seen valve problems in cars when racing as a kid, and I concurred with his analysis. We now could explain every symptom we were seeing. If we didn’t have the exact cause, we were damned close to it! He said he’d talk to the mechanic on Monday and, in the meantime, see what he could do about getting me back home. Unfortunately for me, he wasn’t able to come up with anything; so I re-rented my car, got a hotel room in Denton for the night, and wound up buying a ticket home on Southwest Airlines. Not the outcome I was looking for; but I once again was happy both me and the airplane were okay and I was convinced we were now on the right track to solving the problem.

The Best Trip Home That Didn’t Happen (Part1)

Our 2006 Flight Design CTSW in flight near San Leon, Texas.

Our Flight Design CTSW had been up in Denton, Texas for about five weeks getting her yearly conditional inspection, some preventative maintenance I wanted done, and replacement of all the rubber hoses used to run its Rotax 912 engine. I was ready for the airplane to come home. It had taken several weeks longer than expected due to weather delaying my delivery of the aircraft to the shop, a training interval for the mechanic, and a nasty surprise that developed during the last part of the work. A spark plug in the number four cylinder head had stripped during removal. (More on that in Part 3.)

The stripped spark plug removed from the #4 head.

The mechanic informed me that Rotax had removed any kind of repair of the spark plug cavity from the approved procedures, implying his only recourse was to replace the head. That added a week to the overall timeline and, worse, about two thousand dollars of expense we were not prepared for. I didn’t see I had much choice if I wanted to fly the airplane out, so I approved the purchase and installation of the new head as he recommended.

Getting and retrieving an airplane from a shop some two hundred fifty miles away is always challenging, but I had taken it there because the mechanic was both Flight Design approved and Rotax certified. I had flown it up and my wife had arrived later by car to pick me up and continue a family trip to Missouri and Kentucky. Getting the airplane home became a bigger issue. It was a five-hour drive (another five hours to return), a ticket on Southwest airlines (that would cost about $250 and you still had to get to Denton) or someone in another small airplane had to fly me up.

My planned GPS course in and out of KDTO from KLVJ. It is designed to avoid any Class B or D airspace in case weather or ATC clearances preclude entry.

The shop had mentioned they had a 205 they might be able to give me a lift in; so, I asked about they might do that so I could go get the CT. That airplane wasn’t available but they had someone else with an airplane who might be able to come get me; we arranged for me and that pilot to meet me at the Pearland FBO at 9 a.m. on Monday, July 3rd. He would be flying down in a Bonanza; it was a VERY nice F33A. He arrived and we left Pearland closer to 9:30 a.m., sneaking out under the floor of the Class B past West Houston airport, before eventually climbing to 4500 feet and leveling off. It was a very smooth ride, disturbed only by a few bumps due to the heat of the day. I was looking at the cumulus clouds dotting the skies around us while thinking about my trip back; daytime heating would grow them upward like flowers stretching for the sun. If I was quick getting back, I could get above them and avoid traveling in the hot, bumpy air below, something that would be impossible if they merged into a broken layer. Light Sport rules forbid overflying a ceiling so that you couldn’t tell where you were over the ground by looking down. Once I got Basic Med under me, I could fly my Light Sport airplane under Private Pilot rules and cheat that, but for now…

David Shulman, the pilot and owner of the Bonanza, was a professional pilot, and he talked about how he got there as we headed north. He had every approach control frequency between Houston and Dallas memorized, and we monitored Houston and then Waco’s approach controllers as we made our way. He aimed the airplane directly at Arlington’s Class D airspace at the bottom of the Dallas Class B, descended to 2500 feet, and requested clearance through the area from the tower, which it quickly approved. As soon as we zipped past, we quickly descended to 1500 to crawl under the floor of DFW Class B as we headed toward Ranger VOR, just south of Denton. Flying slightly west of a direct line to the fix to miss the western edges of the Surface to 10,000 DFW Class B, we traveled only a few minutes more before Denton was in sight and we were talking to their tower. They had us run a left downwind to runway 18 at two thousand feet and follow in some other traffic, which David did in a quick and professional manner. Moments later, we were shutting down his Bonanza on the ramp to the shop where my CT was; my airplane was sitting underneath an open hangar door in obvious anticipation of leaving soon today. I hoped to do exactly that.

After thanking David for a pleasant flight, I made my way to my airplane, did a quick look over, dropped my flight gear in its cockpit, found its mechanic, and had a chat. We discussed what had been done and how it had gone; he told me the logs were in the cockpit and the removed parts were there, too. I took a look at them and reviewed the log entries; happy with what I had found, I paid the bill (which was a bit lower than I had expected), and started preflighting the airplane. I didn’t find anything unexpected, so I pulled the airplane out of the hangar and got the cockpit ready to go. I ran my weather brief from my phone, turned on my Go Pro, an external GPS, and an iPad mini, called “CLEAR PROP!” and started by airplane up. My main navigational instrument was a Garmin 496; when I powered it up, I could barely see its screen. Considering it unusable, I shut the airplane back down, popped the 496 out of its holder, and started stepping through its settings. The backlight had somehow gotten turned down; I ran it up, reinstalled it, and restarted the CT. Once I was happy everything was ready to go, I gave my airplane some throttle and started to taxi.

At the end of the ramp, I stopped and called Denton Ground for taxi, also informing them I’d be requesting flight following. Using flight following usually had given me the most direct routing to Pearland. Once I was airborne, Regional approach would ask me what heading I wanted; I’d tell them “one eight zero” and they’d clear me south just west of the DFW surface class B at 3500 feet. I’d hold that until I was out of their hair and then turn a bit southeast to point at the west side of Houston’s Class B. Denton Ground gave me clearance to taxi and came back quickly with a squawk and a frequency for Regional, which I dutifully repeated back. I taxied south to the run-up area near the approach end of runway one-eight, did my take-off checks (including a run up, which was normal), dropped the flaps to fifteen degrees, and then taxied forward to the hold short where I gave tower a call. The controller asked me to “hold short”, which I acknowledged, nudging the nose of the airplane to the right to be able to see down final better. One Cessna later, the tower cleared me to go; acknowledging the call, I pushed the throttle forward, steering a long arc to the left, and hitting full power as the aircraft reached the runway centerline. I rotated at 42 knots, and the airplane leaped off the runway, climbing away at about 800 fpm. Right at about a thousand feet AGL, the tower approved a right turn out for me and advised me to switch up to Regional departure. I turned, acknowledged, switched frequencies, and called Regional, reporting in passing seventeen hundred. Regional answered immediately, letting me know I was in radar contact and giving me the latest altimeter setting. I continued the climb up toward twenty-five hundred as the realization crept in that I wasn’t going to be offered my usual course south. Must be holiday traffic, I thought. No worries. The course I was on would carry me southwest to the western edge of the Dallas Class B, where I would turn south and eventually southeast toward home.

I overflew Propwash and continued at 2500 feet until I hit Copeland where the floor of the Class B moved up to 5000. I shoved the throttle full forward to climb to 4500 feet and raised the nose to hold Vy. And when I did, I noticed both more vibration than usual and a barely perceptible series of “skips”. In all the time I’ve flown the CT, I had never felt anything like it. At my target altitude, I pushed the nose over to level flight; and as the airplane accelerated, I pulled the throttle back to cruise rpm, i.e., 5200. The vibration and the skipping went away.

I didn’t know what I had, but I knew something wasn’t normal. I continued to cruise level for a few more moments, but then pushed the throttle up to full power to see what would happen. The vibration seemed to return, vanishing as soon as I backed off the throttle even a little. Did I have a real problem here or not? After all, I had been out of my airplane for five weeks and I knew I was a bit reactive, knowing the head had been changed out and the most likely time for any issue is after someone’s done major work on your airplane. I felt like something was wrong, and I needed more assurance there wasn’t before I continued to trek toward Houston. I rolled into a medium bank right and pulled the power back, called Regional to let them know I was stopping my progress but didn’t get an answer, and descended to 2500 feet before leveling off heading southwest again. Regional called and asked what my on-course heading was going to be; not yet ready to abandon the idea of continuing home, I responded I would be turning to 180 shortly and then shoved the throttle to full to climb back to 4500 feet. Oil pressure, oil temperature, and cylinder head temperatures all were normal; but once again, the vibration returned at full power. After a few moments of experiencing it, I turned right, arcing back to head back to Denton in a descending turn that leveled at 2500 feet.

By now, my gyrations had gotten the attention of Regional approach, and the controller asked me if I needed any assistance because she was showing me heading northeast. I told her I had a problem “but it wasn’t big” and I was returning to Denton. She asked me if I needed assistance there and I responded in the negative; I didn’t feel I was in “emergency” territory yet, though I was prepared to go there if needed. I pushed the throttle up to full power as I cruised back toward the field at 3500 feet; the RPM pushed up to 5200 but that’s where it stayed. I felt like I usually would see the engine creep higher than that at this altitude; I was more convinced than ever something wasn’t right.

Because the Rotax 912 engine has twin carburetors that have to stay in sync, vibration issues are often due to the carbs being out of it. I had experienced that in flight when an air tube that keeps them together popped loose; there was a very increased vibration in the midrange, about 4000 RPM; at operation below or above that range, it smoothed out. It didn’t feel like what was happening; and though I couldn’t rule a carburetor issue out, I also knew that the most likely place for an issue was in the head since that component had been recently changed. It was a lesson I had learned not only as a pilot but as a NASA safety engineer dealing with the space shuttle; we often performed a risk analysis (though I didn’t do that one personally) to examine what a maintenance activity would perturb before approving its implementation.

The engine was producing good power and the gauges still looked good, but I was hedging my bets by staying at 3500 feet as long as possible. (The Class B floor was 4000 there.) My next checkpoint was Propwash, an airpark with a single north/south runway, and I could see its white block buildings clustered around the runway. Regional called, recommending I start a VFR descent, which I did. It was accompanied by the smell of burning oil. I had never smelled that before when flying the CTSW, and I now knew the situation was bit more serious than I had first thought.

Insert shows gauge location. Background shot shows start of approach into Denton. Look at where the “green” ranges are. Engine gauges are showing nothing unusual even though I’m smelling burning oil.

I dialed up the tower, reported my position, and requested a full stop landing. The tower gave me an immediate clearance to land. There were several aircraft in the pattern with me, and the tower controller mentioned as I swung into downwind that he had a departure to get out, which I thought I saw sitting at the hold short. The last thing I was going to do was allow a downwind extension to get a departure out…so I was keyed to declare an emergency as I passed abeam the approach threshold. Before I had to say anything, the tower asked me to make an immediate right base to help them with sequencing, and I happily and immediately complied. I kept the flaps up to keep up my approach speed and get on the ground sooner; I made an uneventful landing and taxied back to the shop the trip had started from.

I shut down the CT, got out, and opened the little oil door in the cowling to see the inside full of smoke.

I sauntered off to find some mechanics; mine had gone to lunch but the head guy was there, working on another airplane. After telling him I had experienced some “abnormal vibration and loss of power”, I pulled out my iPhone, texted my wife to tell her I had returned to Denton because of a problem, and looked over at the CT. Oil was flowing down the nosegear strut!! I took a picture and then fetched the head mechanic and he did the same as he also called my mechanic back from lunch.

The CTSW nosegear strut covered with oil from the leaking seal some minutes after landing.

When my mechanic got there, it only took him about a minute to pinpoint the oil leak; one of the push rod tube seals on the head that had been replaced was leaking. He said he had used seals that didn’t have a shelf life, pondering whether there might have been a material failure, and that pinching during installation was also a possibility.

The push rod seal after removal with damaged areas shown.

In any case, I left it up to him to go work. I wasn’t going anywhere else in the CTSW today; that was for sure.

While the head guy worked on getting me home, I grabbed my flight bag and my gear and walked up to the FBO that had some air conditioning to be comfortable while I waited. David agreed to run me back home later in the day; but he couldn’t get there until 6 p.m., so I spent the next four hours thinking that, while I was not happy about the problem or the additional delay getting my airplane home, I was very happy the incident had turned out okay and neither me nor my airplane had gotten hurt. I had discussed the failure with the mechanic; when I had suggested to him that the ultimate result of pressing ahead would have been engine oil starvation and seizure, he agreed and said he could not tell me how long I would have had before I would have encountered it. The one thing we both felt was right was…I would not have made it home without becoming a nightly news story, either because I performed an emergency landing (either successfully or unsuccessfully) or had chosen to use the airplane’s Ballistic Recovery System.

I had made the right decision…not only because of my experience as a pilot but because of my experience as a NASA safety engineer at the MER Safety Console during the Columbia accident. The engineer actually on duty when the crew was lost was Dave Witwer, one of my best friends, a fellow pilot and CFI who now flies for United. He and I had many talks about the value of following your feelings and taking action when you feel something is wrong. We are both strong believers in the value of intuition, which is often confused in the engineering community as operating on “emotion”. They are not the same. Intuition is the subconscious synthesis of your experience and knowledge; when the data is not there or is lying to you, it may be all you have. You ignore it at your own peril; paying attention to it can often save your life. In this case, it saved both me and my airplane.

And the role my intuition would play in getting this whole thing resolved was not over, yet…

Getting Lift Straight

As a pilot, an aerospace engineer, and an aerospace educator, I’ve been wrestling for at least the last year with how lift and aerodynamics were being taught. I’ve written a few blogs about it and protested to AOPA, the FAA, and the Civil Air Patrol in an effort to broach the problem. I have also dived back into my college aerodynamics books and other aerodynamics texts I own in an effort to re-examine what I knew and to see where I thought the holes were in my own knowledge. The timing was good. As I was doing this, I stumbled on Doug McLean’s excellent book: “Understanding Aerodynamics: Arguing for the Real Physics”. It has filled in a lot of the holes my college education didn’t. I’m still digesting the book; you’ve got to be interested in the subject to hang with it and is best digested if you have some technical background. That said, I STRONGLY encourage the above named organizations to go through section 7.3.3, “A Basic Explanation of Lift on an Airfoil, Accessible to a Non Technical Audience”. In particular, AOPA needs to bounce it off their “Essential Aerodynamics” course and the FAA needs to do so against their “Pilots Handbook of Aerodynamic Knowledge”. (I intend to take care of my CAP cadets, since I’m in the organization.) They are not the only ones by any means; many instructor written textbooks need to do the same.

Doug talks about the wing creating a downturn in the flow and that the wing’s reaction is lift (Newton’s Third Law). Most sources are interpreting this as the wing creating a downward “jet” of air (in the same way that a rocket engine reacts to a gas jet) and then confuse downwash over a wing as the downward jet the wing is reacting to. But his next statement points to the real meaning: “The aspects of the interaction that need to be explained further have to do with how the moving fluid actually pushes back.” He goes into that in the next section ( entitled “Lift is Felt as a Pressure Difference on the Airfoil Surfaces”. In other words, while the downward turning air is extremely important to the overall physics of the flow and lift generation, the lift is felt as a pressure difference that acts on the wing. (This is what I’ve been trying to say when I’ve protested against folks saying the wing pushes down on the air; it actually does…but…it doesn’t somehow shoot a big jet of air toward the ground that pushes the airplane into the sky. There are lots of momentum changes going on in the flow and engineers can calculate lift by analyzing that, but the answer is the same.)

Thankfully, even before I got ahold of Doug’s book, my own revisiting of the subject had convinced me that part of the issue was that the subject needed to be presented as a wing/air system instead of as individual pieces with more emphasis on the critical factors (like angle of attack) and less emphasis on poking the mechanical bear. I do agree that the cause and effect relationships of the flow need to be touched on; this was something that is lacking from every text I have (as Doug mentioned, college level aero texts tend to emphasize the math and skip the physicality, which drove me bonkers but I shrugged my shoulders and went on.) Like Doug, I am a big believer that technical subjects need to be taught correctly, that dumbing them down too much is a mistake, and there is usually a way to get to the right explanation if you try. Many people don’t, assuming that it’s okay to take any liberty; but the problem is often that doing so is like having an accident: everything appears to be okay until somebody gets hurt. As I said earlier, if you’re looking for a good explanation of how lift works, grab section 7.3 of his book and be sure to read and understand it.

Thankfully, the explanation of “Lift” on Wikipedia has already been updated while leaning heavily on Doug’s work, so the next generation of learners will be getting the right stuff. I’ll be putting together my own little pitch on this I can use with my own students, even while I go work on my Advanced Ground Instructor rating knowing I have to buy the FAA’s wrong answers on the aerodynamics portion of the test. Hopefully, this mess will get straightened out in the next year or so. We’ll hope truth can overcome the Internet and the current trend to believe in what you want to, even if it’s wrong. Otherwise, we risk running afoul of the words of Richard Feynman: “For a successful technology, reality must take precedence over public relations, for Nature cannot be fooled.”

Understanding Aerodynamics

If you’ve been reading this blog and especially the ones written about aerodynamics and how it’s being taught, you know I feel like there’s a lot of disinformation that’s being taught by people who purport to know better. Understanding aerodynamics is not as easy as it might first appear, and I’ve been re-examining what I know about it and especially wresting with how to write about and teach it. I consider it crucial to teach it at the most basic level I can while keeping it technically correct. I am unhappy to report that many organizations I have approached about incorrect technical educational issues have shown me nothing but apathy. This needs to change, especially in this age of immediate and widespread information dissemination. The Internet is a great thing; but a lot of stuff you see out on it, especially dealing with aerospace education and aerodynamics in particular, is incorrect. It’s one thing to just be wrong; it’s another thing to line your pockets while doing it.

One of the people stepping up to discuss some of this is Doug McLean, a retired aerodynamicist and physicist from Boeing. (Thanks, Doug, for restoring my faith in physicists.) He has written a book entitled: “Understanding Aerodynamics: Arguing for the Real Physics”. I have seen a different (and I believe original) subtitle that said something like “Common Misconceptions in Understanding Aerodynamics”. Frankly, I wished it had stayed that way to call a spade a spade and raise a flag about what’s going on. Anyway, it’s a good read for anyone really wanting a better understanding of aerodynamics and helps fill in many educational holes even at the college aero class level, since the explanations there often take you through the math..but not the physicality. While that did the job, it often left me with a lot of questions; I’m the kind of person who needs to link the abstract to the real to get it. (And I feel that connection is especially important when you’re trying to teach this stuff to general audiences.) That said, the book is a bit heavy for the layman, so you gotta be really wanting to get into the science to stick with it. You can get a good and somewhat lighter preview of what the book says by looking at the first 29 minutes or so of this video, which is a capture of a lecture he gave an engineering class about the book:

This whole controversy (and it really shouldn’t be one) has been good for me in that it has forced me to re-examine what I learned, find the places where I had misconceptions, drill down into the various technical explanations for lift and drag and see where they were right or wrong. I am even revisiting the technical foundations of my education (physics, calculus, and differential equations) when necessary, and it’s a process I’m still continuing. I’ve got a ways to go before I’m going to feel like I’ve got it down; it’s a lot more work than I thought it would be, and there are days when I ask myself why I’m doing it. But I like both learning and teaching, the latter most of all. At my age, I take a strong look at anything I’m putting a lot of time into since the long term payoff for me isn’t clear; but if it helps me be a better pilot, engineer, or educator…helps me teach the right thing to one pilot or STEM student..then I am convinced it will be worth it, which is why I soldier on.

Spin Training

Author’s Note: This was originally written back in 2011 when I was working on my Light Sport CFI. For another way to get some spin training than the old fashioned “strap your tail into an airplane and then hurl it at the ground”, see the blog “Flying For Flyquest (Part 2 of 3)” dated Nov 27, 2016.)

The requirements for it were not really clear. Both me and my CFI, Dave, had looked at the regulations and they seemed to be saying that even for a Light Sport Flight Instructor, a spin training endorsement was necessary. Regardless, it had been a while since I had an excuse for any kind of flying that turned the world on end, so I agreed to it. On a Monday morning with a cloud-filled sky, Dave rented a Citabria and we launched in it to do some spins.

The cloud deck was a bit of surprise as it hadn’t been in any of the weather forecasts I had looked at. It started moving in from the south, the direction of the Gulf of Mexico, as we were preflighting the Citabria together. We decided to launch because we could see some breaks in the clouds to the east over Galveston Bay, and that was where we were going to do our training. Dave slid into the fabric airplane’s back seat as I tried to remember how to get into the front. Pulling myself up, twisting one leg in and around the stick, and sliding into the seat, I finally sandwiched in. I reached back and grabbed the shoulder harnesses, pulling them over to my waist to attach them to my waist buckle. Once in, I connected my headset to the intercom jacks and pulled the headset over my head, resting it on my shoulders until we got ready to start. My habit was (and is) not to put them on until after the engine and intercom are on in case some reason comes up we need to exit quickly.

I’d gotten a little big in the past decade (I’ve gotten back to “fighting weight” since) and felt scrunched up against the instrument panel, though the control stick still was in a good place and I had plenty of room for my feet in between the rudder pedals when I didn’t need to be on them. The metal stick began moving around on its own; Dave was checking out his control throw. He couldn’t get the stick all the way back up against my seat because it was hitting me, and he felt that we would need to do a wheel landing because of it. While I felt I had enough stick throw to do a three-point landing from the front, I had not flown any taildragger in several years and Dave flew a Pitts as well as this airplane fairly frequently, so I deferred to him and said he needed to do the takeoff and landing instead of me as we had briefed. He acknowledged the call and we started through the prestart checklist, with me controlling the engine start since I was in the front. The engine started on the first try, and I told him he had the airplane. He acknowledged and taxied us forward.

We crossed La Porte’s runway 12/30, heading for 12, though the windsock was showing a little bit of life out of the west. I informed him that the terminal forecasts had shown by ten a.m. that the winds would be two-two-zero at ten gusting to sixteen. That was a little less than two hours away, and he was confident we would be down by then. Still, we talked about the proper control inputs for a crosswind to the right, i.e. , full right stick at the beginning of the takeoff declining toward the center as we gained speed but enough to keep the wind from picking up a wing. We performed our pre-takeoff checklist at the hold-short for 12 and Dave then made a radio call announcing our departure. We rolled onto the runway, aligned with white stripe centerline, the control stick “magically” full right. Dave slid the throttle forward, the engine roared, and we advanced down the runway. The stick came back fairly quickly and we were airborne. The airspeed seemed kinda slow to me, i.e., 45 mph, and I said something to Dave and he thought it was, too, even though the nose attitude looked correct. I looked to my right to make sure the little metal bug cover over the pitot tube was retracted and it was and then looked back at the airspeed indicator and it was showing 60. We both felt the airplane was performing okay and Dave asked me to take the airplane and I did. I continued a shallow climb straight ahead toward an oil tanker sailing into the Houston ship channel while I looked for holes to get us on top of the cloud deck, being also mindful that the floors of the Class B airspace were at 2000 and 4000 feet MSL over the bay, depending on where we were.

Dave asked me to turn to the south to align with some islands he wanted us to use as visual landmarks during the spins. The cloud base was at about 2000 feet and looked to be only a couple of hundred feet thick, but we both discussed our location and concurred we had crossed into the shelf where the Class B floor was at four thousand. I climbed us up through a couple of breaks in the deck, flying east and then south, and as we got glimpses of the shoreline to our east we could tell where we were. Dave asked me to climb to thirty-five hundred to give us some room above our imaginary three thousand foot recommended recovery height. So, I did as we continued cruising south toward what I thought might be a break in the clouds. We found a clearing in the clouds above one of the small islands Dave wanted to use.

“Hey let’s do them here,” he said. “Let me know when you’re ready and give me the airplane.”

“I’m ready,” I said. “You’ve got the airplane.”

He acknowledged he had control and immediately brought the throttle back and the carb heat on.

“I’m going to demo a spin to the right,” he said, as he held the nose where it was and let our airspeed bled off. The airplane didn’t have a stall warning horn; but as we slowed down and I started feeling like we were close to the stall, Dave said he was pulling the stick full back, ailerons neutral, and kicking in full right rudder. He did and the nose rotated right and down; I was suddenly looking straight down at the island below as it whipped around in a blur! As we rotated into the heading we gad started on, the rotation stopped, leaving us diving straight-nose down! As Dave pulled us out, the G-meter needle rolled to 3 g’s; the power came up and we moved back into a climb and I heard: “Your airplane!”.

“I’ve got the airplane,” I said, taking the stick back and continuing the climb. I had noticed as we were spinning down that there was more of a hole to the north than to the south, and that hole gave me more ground reference to work with. So, as we climbed, I turned us back to the north and steadied up in the direction.

“Your turn,” Dave said. “I want you to demo a one turn spin and recovery.”

“Ok,” I said, just as we hit our altitude. I immediately throttled back and brought the carb heat on while slowly bringing the stick back to hold the nose in a level flight attitude, telling Dave what I was doing as as I did it. We slid slower, slower, and NOW! Stick full back, I kicked full right rudder and held it in; the airplane rolled over like a dying hippo and spun, heading straight down! About a quarter turn before I hit my entry heading, I kicked full opposite rudder, quickly kicking it back to neutral as the rotation stopped while I simultaneously came forward on the stick, a bit too aggressively. We kicked into a very slight zero-g dive, which I quickly negated by beginning the pullout, shoving the throttle to full as the nose came up through the horizon.

“Nice job!” Dave said.

“Except for the part of floating you a little bit,” I laughed.

“I’d rather see you recover aggressively than not aggressive enough,” he countered.

Well, it was, as flying often is, a matter of “how much”. It had been just a small float, and I had essentially just “unloaded” the airplane which amounted to giving Dave a free, one-to-two second weightless ride he probably hadn’t anticipated. But a harder negative g recovery in another airplane, like the Pitts Dave often flew, could flip the airplane into an inverted spin. Ok, so it would take a LOT to get there; but still, it was a matter of degree.

We climbed back up and Dave took the airplane to demo a spin to the left. The nose did the same familiar slice and roll, and again tucked into a fast, rotating, near-vertical dive. Propeller driven airplanes often spin faster to the left than to the right because the engine torque adds to the rotational force with a leftward spin, but I didn’t really notice any difference. All I knew was that once it broke loose, the nose attitude down ad the rotational rate was steeper and faster than I remembered it. Despite my anxiety at not having done anything like this for quite a while, I was enjoying the hell out of it!

Dave gave the airplane back to me and as I set up, he emphasized that in this airplane the rudder force to get full left rudder was much higher than it was to go right. I acknowledged that as I immediately throttled back (initially forgetting the carb heat until reminded) and slowed us down and down, until we hit the stall and I kicked full left rudder. Again, the airplane rolled over and spun down; and again, as I neutralized the controls and stopped the spin, I floated us for a second before beginning the pullout and bringing us back up into a climb. During both his set of spins and mine, we were averaging five to six hundred feet altitude losses. We climbed back up toward thirty-five hundred feet as Dave talked to me about doing “incipient spins” next.

“I’m going to pretend I’m a student doing stalls and then do something wrong that starts us into a spin,” he said. “I want you to take the airplane and recover it.”

I acknowledged I was ready and watched as he leveled us back at thirty-five and began slowing the airplane down. Everything was going fine as we slowed into a stall but at the break, the airplane began rolling right, the nose slicing into the now ever-familiar signature of an upcoming spin. I called “My airplane!” as the bank hit about forty or fifty degrees, taking the stick and pulling the power back, rolling wings level, and then executing a pullout, adding power to get us back into a climb. Dave complimented me on the recovery and then took it and did it again, this time getting the airplane to break left. I took control of the airplane and got us righted again, losing only a couple of hundred feet…if that. Again, Dave complimented me on the recovery.

“Well, that’s all the training we have to do,” he said. “Is there anything else you want to do?”

“Yeah!” I answered. “Let’s go do another spin!!”

I started climbing for our altitude, looking forward to doing a spin for fun!

Dave asked me how much gas had in my left wing. I leveled the wings and the gauge needle was bouncing around close to a quarter of a tank, but the right wing gas gauge was bouncing between quarter and zero. While we didn’t think we really had a gas feed problem, we both agreed that the prudent thing was to knock it off and head back to the field where we could check it out on the ground. I dived us northward toward home field through a hole in the clouds; and once the airspeed and attitude was stable, the right wing showed about half a tank, closer to what we had been expecting. By that point, we were closer to home than not, so I decided to call it a day anyway. I felt good about what we had done.

I leveled us at a thousand feet about six or seven miles out from the airport and turned the airplane back over to Dave since he was performing the landing. We initially set up for a crosswind landing on 12 but then changed to runway 23 once we saw the windsock and that the winds had changed. Dave couldn’t see the airspeed indicator, so like I had done in my F-14 RIO days, I called airspeed for the pilot as he brought us down the approach. With just a slight “clunk”, Dave did a really nice wheel landing, brought the nose down once we had slowed, and taxied us back in.

I have to say that even though I had been an aerobatic pilot in my past, taking spin training for my Light Sport CFI was well worth it, required or not, and something I recommend to anyone going for their Light Sport rating, whether as a pilot or CFI. You probably will have to look elsewhere than where you are training in your Light Sport to find a spin certified airplane, though light sport aerobatic planes are hitting the market now, so who knows? No matter, have your favorite flight instructor or one he/she recommends to conduct this training and go with tim to spin around. It’s one or two hour of flight training that can save your life.