ROTAX 277 CC ultralight aircraft engine troubleshooting
The 277 Rotax engine is probably the most trouble free engine, in the Rotax family.
Problems have been reported however with motor mounts, on such planes as the Falcon, Skyseeker, and Challenger, and should be an area of regular inspection. These mounts are similar in most cases to those used on the 185 cc Rotax and have been reported to shear, careful preflight inspections recommended of this area by all pilots using single cylinder Rotax engines.
Another problem that has occurred is in the use of a belt drive system with the 277. Early model 277 engines used a plastic bearing liner to support the crankshaft bearings in the crankcase.
Overtightening of the belts on a belt reduction system can cause this plastic liner to compress, allowing the bearing and crankshaft to move inside the crankcase halves.
This can permit the magneto to come in contact with the lighting coils and stator plate, located on the mag end of the crankshaft. For the proper way to adjust a drive belt system when used on the 277 cc Rotax engine contact the REDUCTION DRIVE MANUFACTURER, the ultralight manufacturer, or write Ultralight Alerts Covering the World of Ultralight Aviation .
Another reported problem is in the exhaust system supplied by manufacturers of some ultralight aircraft. The exhaust system supplied by Rotax is specially tuned, to provide the best performance and reliability possible, some manufacturers in adapting this exhaust system to their design have changed the tuning length of the exhaust to better fit the cosmetics of their design.
An example of this is the early model Chinook aircraft in Canada. The manufacturer in redesigning the exhaust to fit his design changed the tuning, and performance on the engine to such an extent that in some cases only 65 % of the available thrust was obtained. You should check to see whether your aircraft is equipped with this exhaust.
Another commonly reported problem is with the wrist pin bearings on the 277. These bearings have been reported to wear out causing considerable damage to the engine when they do. Rotax has recently introduced a new cageless wrist pin bearing to help eliminate some of the problems in this area.