Special Investigation

Photos: Air NZ’s damaged 787 engine

Photos of one of Air New Zealand's Boeing 787 Dreamliner engines which failed this week in-flight show damage to multiple turbine blades, at the rear, suggesting a part broke off and travelled through the engine.

That engine, on Tuesday morning's flight NZ99 bound for Tokyo with 282 people on board had to be shut down when it caused the aircraft to shake violently.

Passengers heard clunking sounds and electrical power went out temporarily after takeoff from Auckland airport. The plane concerned, which was the first of the airline's nine Dreamliners to go into service, has since been grounded.

On Wednesday another Dreamliner bound for Buenos Aires also had to turn back to Auckland when problems arose with an engine. That engine did not have to be shut down in flight.

Air New Zealand told Newsroom last night it was "extremely surprised by the two issues experienced this week".

Provided with the photos taken of the NZ99 engine after it landed back in Auckland, a spokeswoman said: "The cause of these incidents is yet to be determined and this is the role of the Transport Accident Investigation Commission. But the damage sustained on Tuesday suggests an engine part has travelled through the engine."

An aviation source told Newsroom: "The damaged blades are in the aft section of the turbine blade sections. It is likely the damage has resulted from a failure of a turbine blade or blades in an earlier section that has been spat out the back with a domino effect.”

"The damaged blades are in the aft section of the turbine blade sections." Picture: supplied

Passengers had said the captain announced a minor technical problem with one of the engines. When the plane landed, fire fighters sprayed the left-hand side of the aircraft.

Air New Zealand yesterday told the NZ stock exchange and the travelling public the engine issue would result in cancellations to some flights over "coming weeks". It listed changes until Sunday.

While the Dreamliner fleet was not grounded after the more serious Tuesday incident, Air NZ says both affected aircraft were taken out of service immediately upon landing back in Auckland.

Newsroom has been told of internal airline staff concern about the speed of Air NZ's broader response after the Tuesday engine failure, with no network-wide cancellations until Thursday and the Wednesday incident on the Buenos Aires flight occurring in between.

But the airline spokeswoman said: "In regard to the impact of the first aircraft being taken out of service – we were able to operate a normal schedule with some small tweaking the following day due to spare capacity in the network.

"Within a few hours of the second aircraft being taken out of service we formed a preliminary view on possible schedule impacts and worked overnight to adjust the schedule to keep these to a minimum. We finalised the schedule changes for Friday through to Sunday early [Thursday] afternoon and began the process of contacting customers."

The TAIC has opened inquiries into both events and will work with Air NZ, the engine maker Rolls Royce and safety regulators in the UK and United States as well as aircraft manufacturer Boeing.

Its chief commissioner Jane Meares said investigators were reviewing aircraft records, including flight recorders, examining the engines and interviewing flight crew.

"At this stage our investigation team is satisfied all parties are doing the right thing to ensure the continuing safety of the travelling public. Should the commission believe insufficient action is being taken at any time, then it has the ability to issue urgent recommendations while its inquiries continue."

"It is likely the damage has resulted from a failure of a turbine blade or blades in an earlier section that has been spat out the back with a domino effect.” Picture: supplied

The Aviation Analysis Wing website reports this is the second engine vibration incident involving Rolls Royce Trent series engines this year. An Air Asia A330 returned to base after severe in-flight shaking in August.

Rolls Royce told Air New Zealand its Dreamliner engines would now need maintenance sooner than previously planned but it did not have replacement engines available this week, thus the airline's cuts and changes to its services.

Commenters on the Aviation Herald website said the aircraft flying as NZ99 was the first pressed into service by Air NZ – two of its Dreamliners were actually built earlier but held back by Boeing for its certification programme. Boeing has had a programme of replacing rear turbine blades on the Trent 1000 engines.

Britain's Daily Telegraph reported Air New Zealand is the latest Rolls Royce customer to suffer problems with the Trent 1000 engines on the Dreamliner.

"Japanese airline ANA first reported issues with Trent 1000s in the summer of 2016. The problem was thought to relate to blades in the turbine corroding far earlier than expected, resulting in the engines being shut down. A few weeks later Virgin Atlantic said it was had also experienced similar troubles with its Trent 1000 engines. Both airlines took aircraft out service for urgent maintenance, causing hundreds of flight cancellations.

"Rolls – which has more than 400 of the US$10m engines in service – has acknowledged the problems. At the company’s half-year results in August it warned investors to 'expect increased activity in second half related to Trent 1000 maintenance programme to address a number of technical issues”, the paper said.

In response to the latest troubles Rolls said: “It’s not uncommon for long-term engine programmes to experience technical issues during their life and we manage them through proactive maintenance. This is the continuation of work which started last year to upgrade Trent 1000 engines to the latest standard.”

The Air New Zealand incidents have been reported worldwide, including on the BBC and by global agency Reuters.