Engine issues keep choppers on ground
New Zealand’s Civil Aviation Authority has grounded 21 helicopters because unapproved work on their engines means they’re not fit to be in the air.
Inspections at a maintenance firm that undertook repair work on the Rolls Royce/Allison 250-series turbine engines found drilling and grinding work had not been authorised by Rolls-Royce.
The engines are mostly fitted to Bell Jet Rangers and Hughes 500-series helicopters, with transport and agricultural operations most affected.
“The visits revealed departures from Rolls-Royce-approved enginemaintenance instructions that adversely affect the airworthiness of the engines,” CAA director of civil aviation Graeme Harris said.
“The primary issue relates to unauthorised drilling and grinding work done on safety-critical components within the engine compressor section,” Harris said.
Grounding the helicopters is the best way to ensure all engines are made safe while minimising effects on the aviation sector, the CAA says.
There are 41 engines needing parts repaired or replaced — 25 in New Zealand, 13 in Australia, two in Indonesia and one in Papua New Guinea. Other affected engines are being overhauled at the maintenance facility.
A new airworthiness directive requires 20 compressor sections to be repaired within 30 days, or 50 flight hours, and 21 compressor sections affected by grinding to be immediately withdrawn from service for repair — meaning 21 helicopters are now grounded. Affected components must be replaced or fixed before these engines return to service.
The CAA was also looking at all the organisation’s engine maintenance. It could not do any RR 250-series engine maintenance until after a detailed safety review.
Eight aircraft will be subject to the 30-day/50-flight-hour limit for replacement of the compressor section, with another 17 grounded immediately, after being allowed to fly to a repair facility.
The firm had fully co-operated.