Originally Posted by
Eddie Dean
It is excessive wear of piston cylinders, overheating and suchlike. FWIW
From an associated article :
It is not yet clear if other operators of piston aircraft should take precautions.
Many in the aviation community have been privately expressing concerns for the past 12 months about the large number of helicopter engines with cylinders that have eroded or become damaged after only a few hundred hours in the air.
CASA has now declared it a problem, and stated it is seeing "increasing evidence of premature exhaust valve and valve guide wear, due to elevated combustion temperatures that will lead to degraded engine performance".
It is widely theorised the problem may be linked to the reduction of lead in aviation gas supplied to northern Australia a few years ago, from 0.86 to 0.56 per gram.