An Air New Zealand video for its staff reveals more detail of potential problems with Rolls Royce engines on nine of the airline's Dreamliners.

In the video for 12,000 staff, power plant supply engineer Logan Horrell says more frequent checks ordered by international safety regulators were looking for cracks in blades in engine compressors.

''This is a known issue which is part of the maintenance plan. If the engines fail they will be removed and sent to Singapore to the Rolls Royce facility for repair.''

The checks have caused a wave of disruption for thousands of international travellers and asked by chief operations officer Bruce Parton whether the affected Trent 1000 engines were lemons, Horrell says this is not unusual for any new engine type.


''These engines go through teething issues and once we repair the engine we expect it to be as reliable as any other engine.''

Checks have been ordered every 300 cycles (take off and landing) instead of every 2000 cycles.

Horrell said the inspection regime was ''extremely conservative".

Air New Zealand got the first of its Dreamliners in July, 2014. The first model of the plane first flew commercially in 2011.

Rolls-Royce has scrambled to work with Air New Zealand to inspect Dreamliner engines at the centre of the international alert.

The extra checks and range restrictions on flying have led to cancellations and rescheduling on the airline's network, and is the second round of disruption caused by the Trent 1000 engines in the last five months.

Last December a Tokyo-bound Air New Zealand flight suffered an apparent turbine blade failure shortly after takeoff which caused extensive damage and led to an engine shut down. A flight the next day to Buenos Aires also suffered an engine abnormality and returned to Auckland.

A Rolls-Royce spokesman said his company's staff would continue to support Air New Zealand engineers but were also expediting work on engines as much as possible for a number of airlines who have 383 engines affected by the checks ordered by European and United States safety regulators.

Rolls-Royce Trent 1000 engines on the production line. Photo / Supplied
Rolls-Royce Trent 1000 engines on the production line. Photo / Supplied

''Clearly we sincerely regret any disruption these actions may cause and we are working around he clock to reduce it wherever possible,'' he told the Herald.

The more frequent inspections covered by Rolls-Royce's engine care packages are likely to cost more than $500 million this year and lead to job losses in its corporate area.

The checks involve looking at an area of the compressor, and are done without removing the engine. While they can take only hours, if work is required this can lead to the engine being taken out of service for weeks.

Air New Zealand has the affected engines — which cost about $14m each — on nine of its 11 Dreamliners. The most recently delivered aircraft have Trent 1000 TEN engines that are not affected.

A US Federal Aviation Administration airworthiness directive issued this week detailed potential risks from faulty compressors and also restricted the distance aircraft with ''Package C'' Trent 1000 aircraft are able to fly from alternative airports.

Air New Zealand's first Boeing 787-9 Dreamliner arrives at Auckland Airport. Photo / Peter Meecham
Air New Zealand's first Boeing 787-9 Dreamliner arrives at Auckland Airport. Photo / Peter Meecham

The FAA directive means they can fly no further than two hours, 20 minutes from airports, down from five and a half hours.

Rolls-Royce has found that intermediate pressure compressor (IPC) stage 2 blades have a resonant frequency that is ''excited'' by the airflow conditions existing in the engine during operation at high thrust settings under certain temperature and altitude conditions.

The compressor is a set of spinning discs with small titanium alloy blades which squeezes the air drawn in by the fan at the front of the engine, preparing it for further squeezing in the high pressure compressor and eventually being mixed with fuel and ignited in the combustor.

"The resultant blade vibration can result in cumulative fatigue damage that can cause blade failure and consequent engine shutdown,'' the FAA said.

In the event of a single engine in-flight shutdown during the cruise phase of flight, thrust on the remaining engine is normally increased to maximum continuous thrust, the FAA said.

During a diversion following a single engine shutdown the remaining engine may operate at maximum thrust for a prolonged period, under which the compressor blades would be exposed to the resonant frequency condition.

The part of 383 Rolls-Royce Trent 1000 engines now under increased scrutiny. Photo / Supplied
The part of 383 Rolls-Royce Trent 1000 engines now under increased scrutiny. Photo / Supplied

"Therefore, an ETOPS ( Extended-range Twin-engine Operational Performance Standards) diversion will put the remaining engine at an operating condition that would significantly increase the likelihood of failure of the remaining engine.

"In addition, if the remaining engine already had cracked IPC stage 2 blades, the likelihood of the remaining engine failing will further increase before a diversion can be safely completed."

Trent 1000 engines have 18,000 individual components.

Airlines including Japan's ANA, Norwegian and Virgin Atlantic are also affected by the alert.

Rolls-Royce says in order to manage the increase in the number of inspections of engines and to undertake any maintenance required, it has increased its maintenance, repair and overhaul capacity by more than 300 per cent over the past two years, including doubling the number of lines it has in Britain and creating a dedicated Trent 1000 capability at a joint-venture facility in Singapore, where Air New Zealand engines requiring repairs are sent.