Diagnosing piston failure
This section is designed to guide you through the detection of engine
conditions which lead to piston failure in two stroke ultralight aircraft engines. It will
also aid you in analysis of the reason which caused those failures.
A sound knowledge of the relationship between the conditions that caused the failure and
the operational environment of the engine can help direct owners to area's of maintenance
that will lead to increasing service life of the engine.
Analyzing piston failure is very complex, due to the many variables. In many cases the
failure was caused by a combination of borderline conditions, during the operation
of the engine.
To determine the type of failure you must first disassemble the engine - refer to
section for disassembly instructions.
During removal of the piston observe the condition of the bearings, wrist pins, cir
clips, rings and connecting rod, cylinder interior and exterior. Look for obvious damage,
discolouration, scratches or unusual marks.
If only one piston has failed carefully look at the other to see if you can see early
stage of failure which will help diagnose reasons for the failure.
Failures can be related to "time" thus it is important that all available
information re the engine be available. Pilot logs, engine maintenance records etc. can
help trace the reason for the failure.
During disassembly of the engine you
are performing an "autopsy"
do not destroy evidence - observe as you
here for Piston failure - Cold Seizure
here for information on engine gauges - and how they can help prevent an