The Rotax 912 Rubber Replacement Requirement: Gumming Up S-LSA

My first exposure to the Rotax 912 has been flying it in the 2006 Flight Design CTSW my wife and I bought about three years ago. Generally, it has been a great little engine from an operational and maintainability standpoint. It sips 5 gals/hour at 75% power while propelling out CTSW at 112 knots giving truly respectable performance. That said, I can no longer recommend to my friends to buy S-LSA’s powered by this engine. The cost of maintaining and operating is significantly higher than I had thought due to one thing; Rotax’s requirement that every five years all the rubber in the motor be replaced. The cost is rolling in for most people between $2800-$4000, depending on which shop does the work. This adds $560 -$800 a year to your operating and maintenance costs. That’s not much in the overall scheme of things, but it does add up over the lifetime of owning the airplane.

Of course, the requirement is being defended as a safety concern, and it once again renews the argument about whether maintaining an aircraft using time constrained or conditioned constrained maintenance is best. No one wants to push an engine into a mechanical failure, so it’s easy to argue that replacing components before they wear out is the way to go. However, that ignores the fact that any major maintenance activity itself induces an increase in risk of engine failure whether due to a maintenance error or introduction of a new but faulty component. (And some owners have already experienced problems–partial loss of engine power–after this maintenance since it can introduce contamination in the fuel system very easily.) Additionally, it’s also easy to argue that “flying is expensive” and expect the owners of the aircraft to just suck up this expense, which belies the fact that the idea behind light sport itself was to help reduce the cost of aviation in order to increase both pilot starts and longevity. Assuming that the cost of this “after the fact” requirement hits the high end ($4000/5 years) and that one flies 100 hours per year, then the owner will have paid out at least $12000 in addition to the regular costs of inspection and maintenance by the time the engine hits its 2000 TBO. That’s an additional 50% over the cost of an overhauled or news engine and makes Lycomings and Jubirus start looking a lot more attractive. I believe it will be only a matter of time before the market starts catching up to this. In the meantime, I’m cranking in an additional $60-$100/month to our expected expenses to account for this maintenance.

I’m not crazy about selling my CT, but I have to be honest and say I am looking at it because of this expense. Flight Design has to also realize that we will not consider moving to a different FD airplane because they use the Rotax 912 across the board. It’s too bad I’m having to think about this at all, but we’re not made of money and I’m not renting my plane out so I can try to recover the expenses from those operating costs. If this requirement hit in the car industry, you can bet there’d be a huge outcry for the manufacturer to absorb some or all of those costs, and the government might step in to enforce it. It’s the perception that all airplane owners are rich that stops that from happening in a case like this, and there are too many of us that know that’s not true. I hate to go back to being a renter, but it’s something I’m looking at once again. My other and perhaps better option is to move to an experimental. I’m not sure what I’m going to do.

(NOTE: A little over two months after I wrote this, a renter hit a bird with our CT. While the airplane was in the shop after being repaired, a fuel hose replaced during the 5 year replacement cycle split, flooding the cockpit with fuel. While this was quickly repaired and mainly resulted in minor damage to the carpet, it could have been catastrophic if it had happened in flight. We were lucky. It was a graphic illustration of the risks that can be entailed using “time-only” driven maintenance.)