Australian Robinson helicopters – AVGAS problems in hot northern regions.
AHIA Update by Robyn Ironside in The Australian 25 Oct 2019. An exhaustive investigation into helicopter issues in northern Australia has found a change in fuel composition is to blame. The Australian Helicopter Industry Association appointed an expert panel to undertake the investigation after a Civil Aviation Safety Authority inquiry was unable to reach a conclusion. This issues related to piston-engine-powered light utility helicopters, such as Robinson model R22 and R44 types, that began experiencing a higher rate of premature engine-cylinder failures.
AHIA president Ray Cronin said that prior to 2013 there were almost no warranty claims for engine cylinders, but since then more than 2,000 barrels had been changed in the region. In some cases, cylinder failure occurred within the first 100 hours of service, prompting industry officials to try to find the cause. Early investigations indicated extreme heat was the problem, but it was unclear what was producing that heat. Fuel seemed the obvious answer, but the AHIA ran into difficulty with manufacturers providing limited co-operation, citing “commercial sensitivity concerns”.
Extensive testing was able to ascertain that avgas supplied to aviation operators in northern Australia had undergone significant composition change between 2012 and 2018, with the lead content halved and aromatic hydrocarbons increasing.“The problem with aromatics is they create a slower burning process, and they get hotter through that process. You’re not seeing cylinder head temperature changes, but the exhaust gas temperature increase is massive,” Mr Cronin said. “The problem that creates is when enormously hot gases are going past the exhaust valve and heating that whole region up.” It did not help that helicopters operating in northern Australia were already exposed to elevated temperatures due to the climate and the type of work undertaken, such as mustering at low altitudes where the air is warmer.
Mr Cronin said the report had been provided to CASA and Deputy Prime Minister and Transport Minister Michael McCormack as well as AHIA members. “Our primary objective out of all of this is to see action taken to make this a safer industry,” he said. “We want to hear from CASA how they can contribute to make that happen.”His advice to helicopter operators in northern Australia was to “shop around” to ensure they were putting the right product in their aircraft and staying on top of maintenance.“They need to talk to their (avgas) suppliers, get certificates of composition of fuel, and find out what the percentage of aromatics is, the percentage of lead and make a decision,” he said.
A CASA spokesman confirmed that CASA had received the AHIA report and would respond as soon as possible. A spokesman for Viva Energy, which supplies avgas, said the company did not consider that the issues with the Robinson helicopters in the Northern Territory were related to fuel composition or specification. “In respect of this AHIA report, Viva Energy has not been approached by the AHIA or its investigation body for technical input, information, review or comment,” he said. “Viva Energy has only just been made aware of the report and we intend to analyse and provide a response to AHIA in due course.”
More soon - we are looking through a very well researched 52 page report.