At least a half dozen Cirrus SR22T aircraft have lost power on takeoff and crashed. According to the National Transportation Board, in each case the aircraft pumped too much fuel to the engine, causing it to flood. That remains ongoing danger. According to the National Transportation Safety Board:
until the Federal Aviation Administration requires implementation of appropriate mitigating actions to prevent the loss of engine power due to excessive fuel flow in the SR22T, additional accidents may occur due to this hazard.”
NTSB AIR-22-04
What’s going on? Why do the SR22T engines flood?
The SR22T’s engine is the TSIO-550K engine, manufactured by Continental Motors. Cirrus rigs the aircraft’s fuel system to pump up to that engine up to 42 gallons per hour. But Continental Motors tested and certified the TSIO-550-K engine to only 37.5 gallons per hour. That’s the limitation set forth in the engine’s installation manual and its type design data. It’s no surprise then, that as Cirrus has the fuel system rigged, the TSIO-550-K engines tend to flood — Cirrus is operating the engines in excess of their certificated fuel flow limit.
The real question is whether, given that the fuel flows exceed the engine’s certificated maximum, the aircraft’s certification is even valid.
Each engine installed in an aircraft must have a valid type certificate issued by the FAA. (Federal Aviation Regulation 23.903(a).) If an engine is operated so that its fuel flows exceed its certificated limitations, then the type certificate is invalidated. Without a valid engine certification, the aircraft cannot be certificated. To be airworthy, an aircraft must have both a valid engine and a valid aircraft certificate. According to FAA guidance,
non-compliance with the engine manufacturer’s installation requirements can invalidate the type certification status of the engine, making the engine non-compliant with § 23.903(a)(1). This, in turn, would prevent certification of the airplane under part 23. Examples of engine requirements that could be affected by the airplane installation may include, but are not limited to, the following: 1. Fuel delivery flow and pressure requirements. . .”
(Federal Aviation Administration Advisory Circular AC-16A.)
In order to legally operate the TSIO-550-K engine at the increased fuel flows, Cirrus might have applied for and obtained from the FAA a “supplemental type certificate” for the engine, approving the higher fuel flows upon a showing that the higher flows were safe. But it did not. Accordingly, as installed in the SR22T, the TSIO-550-K engine does not comply with Continental’s installation manual or the engine’s type design data. Under the FAA regulations, it would appear the aircraft does not have proper and valid certifications and thus is not airworthy.
