AIRCRAFT ENGINE OVERHAUL & INSPECTION

Our involvement in aero engines originally centred around the Aero Bonner Super Sapphire 200 h.p. aero engine.

Designed by Bill Bonner in the early seventies, it took to the air installed in a Chipmunk Mk22A in July 1979, and was an astounding technical success.

Bill flew it at the 1980 Farnborough Airshow, when the RAF put in a request to re-equip their fleet of Chipmunks with the Sapphire engine, and Rolls-Royce announced their desire to take over and manufacture the engine in quantity.

We were fairly high profile at Shoreham, and lots of customers asked us to overhaul, or rebuild, or tune their Lycoming/Rolls-Royce/Continental/De Havilland engines, and we were more than happy to oblige.

Also we were certifying the Sapphire engine and the installation in the Chipmunk through the CAA, and had a very good connections with higher authorities. This enabled us to obtain approval to modify the Bronze Gipsy Major heads with a steel S111 valve seat. We modified about 50 engine sets in all.

We also obtained approval to substantially raise the power of the Lycoming IO-360 engine, which was popular with British Aerobatic Team.

We prepared several R-R 0-200 engines for racing. A few successful Formula 1 aircraft, and one Kings Cup victory. Bill Bonner also won the Kings Cup in 1973.

With this background, we have been overhauling all types of engines since 1976. Bill Bonner holds a CAA D licence covering all types worldwide. The largest we have overhauled so far is a 425 h.p. Lycoming TIGO-541-E, out of a pressurised Navajo, and the smallest several R-R 0-200 engines, including everything in between.

All the engines we overhaul are dynamometer tested before release. This one of the most important features of the entire process. We initially run the engine under a light load and moderate speed to settle the bearings, cam, tappets etc, and then gradually increase load and speed to apply gas pressure to the rings to bed them in. Finally we almost invariably run the engine at full power for 60 minutes without a break. to ensure it is in perfect, reliable condition.