The FAA has proposed an AD that would require the early replacement of thousands of aftermarket ECI Titan cylinders used on big-bore Continental engines. The FAA believes the proposed AD would hit at least 6,000 airplane owners at a total cost of more than $82 million.
This proposed AD is a perfect example of the FAA using the AD club to beat on what is really an airplane ownership issue. I guarantee that some ECI cylinders will crack and develop other problems, and so will some cylinders from any other manufacturer. It’s what cylinders do. If you haven’t had to repair or replace cylinders you either don’t own an airplane, or haven’t flown very much.
Cylinders are the wear item on any air cooled piston engine. They are the focal point for heat and stress. Though cylinder design and metals have improved over the decades, cylinder life is still unpredictable.
The proposed AD points to an unspecified number of cracks in ECI Titan cylinder heads, and also to some unannounced number of cylinder head-to-barrel failures. The aluminum head in any cylinder is joined to the steel barrel through a hot-cold process that permanently locks the two components together. If the aluminum head cracks severely at the head-to-barrel junction the head can separate making that cylinder inoperative.
So? An engine will continue to produce a large majority of its rated power after a head-to-barrel separation occurs. Oil loss will be minimal. Vibration will be scary, but the engine won’t break out of the mounts. The cylinder failure is a big bucks maintenance hassle for the airplane owner, but it won’t kill him. And the proposed AD doesn’t indicate that ECI cylinder failures caused any specific accident, or fatal crash.
Under FAA certification theory the failure of an engine is assumed. The reliability of any engine, piston or turbine, is not good enough to meet the high bar of “improbable” required to be the only difference between life and death.
In singles the backup to the engine is the 61 knot stall speed. The speed limit is set so that the amount of energy that must be dissipated in the forced landing after the engine fails is controlled and the outcome is likely survivable. In twins the second engine is required to be able to keep you flying after one engine fails. If a twin stalls at 61 knots or less there is no engine-out performance requirement.
On the other hand, ADs are supposed to be reserved to correct real safety of flight items. For example, if there is a problem with the primary structure of an airplane, or the flight controls, failure of those items in flight would almost certainly lead to a fatal crash. If a wing breaks off, or a tail surface departs, your chances are essentially nil. So those components must perform as designed and certified. If they don’t, an AD is necessary to correct the defect.
I’ve lost count of how many cylinders I have had to replace or have repaired over the decades, but it’s a lot. Usually it is valves that cause the cylinder problem, but I have had premature cylinder barrel wear, and several cracked heads. I haven’t had a head-to-barrel separation failure, but I did have a rocker boss failure that did the same thing by rendering that cylinder totally inop during flight.
In every case the cylinder failure is a pain in the wallet, not a threat to life. I’m sure there are owners of ECI cylinders who wish they had bought some other brand. But that could be said of owners of any brand of cylinder when it develops problems, and they all do sometime. To force thousands of airplane owners to replace cylinders that are working ok at the moment to spend millions of dollars to replace them is plain crazy. Who’s to say that whatever cylinders go on in place of the ECI Titans will fare any better?
Every airplane owner holds their breath over cylinder reliability, but not during flight. It’s at inspection time when the shop gets out the compression tester and other gear that cylinder fright grips all of us owners. And that’s as it should be. Cylinders are an ownership hassle, not a safety of flight item. The proposed AD would force thousands to spend millions and probably make the engines less safe because there is a chance the new cylinders will be installed incorrectly and the engine could then suddenly fail. This AD proposal needs to be withdrawn.