Owners of aircraft powered by Gipsy Major engines are being contacted by the UK Civil Aviation Authority (CAA) with updated maintenance advice. The new guidance follows data analysis conducted by the CAA which identified a possible trend involving the engine type. Tiger Moths, Chipmunks and Austers are amongst the aircraft fitted with Gipsy Major engines.  

Owners of affected aircraft are advised to ensure routine checks on these engines are carried out by a maintenance organisation or person experienced on the engine type. Checks should also be carried out if incidents of low compression are noticed in the engine when turning the propeller by hand, or if the engine is found to be running rough. Owners are also advised to ensure they are using the most appropriate fuel at all times.

The advice follows an emerging trend, identified by the CAA, of rough running engines, and even engine failures, involving Gipsy Major engines. Analysis suggests that the use of AVGAS (100LL) fuel in these engines could cause reliability problems particularly with cylinder heads, valves and valve seats.

As well as contacting all owners of affected aircraft types listed on the national aircraft register, the CAA is also issuing guidance material to continuing airworthiness maintenance organisations. 

Information sheet and Poster