Cites Lowering Of Lead Levels In Avgas As A Possible Cause For The Problem

Australia's Civil Aviation Safety Authority (CASA) has issued a warning to operators of Robinson R22 and R44 helicopters concerning accelerated engine wear possibly caused by the lowering of the amount of lead in avgas.

CASA says that 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," according to a report from the Australian Broadcasting Corporation (ABC).

A few years ago, Australia lowered the allowable level of lead in avgas from 0.86 to 0.56 parts per gram.

CASA spokesman Peter Gibson called the potential wear an urgent matter. "Clearly the change in the fuel specification has to be looked at and a number of people are pretty convinced that's causing the problem, although there are a range of variables so we don't want to rush into it until we've got the evidence," Gibson said.

"A clear understanding of all potential causative factors need to be established before any solution can be recommended. It's also having an economic impact with helicopter companies now having to ground aircraft for longer durations and replacing cylinders more frequently."

John Armstrong, a pilot with more than 30 years experience, told the ABC that he knows of at least three engine failure incidents in the past year that can be attributed to the excessive wear. Andrew Lumsden, the chief engineer at North Australia Helicopters in the Northern Territory, said that his company has changed cylinders in engines with as few as 98 hours.

A stakeholder group made up of fuel producers, engine manufacturers, pilots, engineers and CASA has been formed to investigate the engine problem. It has not been specified whether the engine wear issue extends to aircraft other than R22 and R44 helicopters.

(Image from file)

FMI: Original report