Published date: 12 March 2020

The Director of Civil Aviation Graeme Harris has grounded 21 helicopters due to safety concerns.

“This action results from recent CAA inspection and monitoring visits to a maintenance organisation that conducts repair and overhaul of Rolls Royce/Allison 250 series turbine engines.”  

“The visits revealed departures from Rolls Royce approved engine maintenance instructions that adversely affect the airworthiness of the engines.  The primary issue relates to unauthorised drilling and grinding work done on safety-critical components within the engine compressor section,” Mr Harris said.

  • The CAA has been working closely with the maintenance organisation and the engine manufacturer Rolls Royce to determine the safest means of ensuring all affected engines are returned to an airworthy state, while minimising the effects on the aviation sector. 
  • The maintenance organisation has been cooperating fully with the CAA and has completed a detailed review of all their compressor-section repairs and determined that 41 engines currently in service need to have parts repaired, or replaced, that they maintained incorrectly.  
  • They have compiled a list of affected engines and identified their locations as: 25 New Zealand; 13 Australia; 2 Indonesia; and 1 Papua New Guinea.  There are other affected engines part way through an overhaul in the maintenance facility.
  • The work between the CAA, the maintenance organisation and Rolls Royce has resulted in the issue of an Airworthiness Directive requiring 20 compressor sections affected by unauthorised drilling to be repaired within 30 days, or 50 flight hours, and 21 compressor sections affected by grinding to be immediately withdrawn from service for repair. 
  • In both cases affected components must be replaced or repaired before these engines can be returned to service.

Mr Harris continued: “The CAA is also currently conducting a more thorough review of all of the maintenance organisation’s engine maintenance practices. This review commenced today.  Further safety action may be necessary in due course but that is unknown at present. 

 “I have also taken action today to the maintenance organisation from conducting any further RR 250 series engine maintenance works until a detailed safety review can be completed.” he said

The impact of this safety action

  • 21 helicopters in the region will be grounded as a direct result of the Airworthiness Directive issued today. 
  • For New Zealand-based aircraft, this Airworthiness Directive will primarily affect helicopter operators conducting air transport and/or agricultural operat
  • Eight aircraft will be subject to the 30 day / 50 flight-hour limit for replacement of the compressor section and a further 17 will be grounded immediately (albeit a non-revenue flight to a repair facility will be permitted).



  • The Rolls Royce 250 series engines are primarily fitted to Bell Jet Ranger and Hughes 500 series helicopters but do have some other applications. 



Contact: Mike Richards, Manager Communications and Safety Promotion

CELL: 027 222 0290 MEDIA PHONE 027 763 0000