Montreal, Quebec - An investigation for a series of Airbus A220 failures suggests that a software change might have caused unexpected vibrations on the engines and at least three emergency landings.
On Oct. 15, the Lufthansa Group subsidiary SWISS International Airlines grounded its A220 fleet for more than a day after the third flight was forced to divert or return to the departure airport with engine damage.
In one of the incidents, compressor debris hit the engine casing and created a hole. In the most recent incident, the engine parts which fell apart because of vibration escaped from the back leaving the engine house intact.
The NTSB-led investigation focused on a recently updated engine software that may have caused vibrations that tore the engine parts.
After these incidents, Airbus and the manufacturer of the aircraft's PW1500G engines recommended pilots not to force engines above 95% of their maximum thrust while flying above 29,000 feet.
On the new-generation airplanes, engines are controlled by a software which interprets flight commands and tells the engines how to respond.
The engine problems with the SWISS A220s arose following a software upgrade, experts who are close to the matter told Reuters news agency.
Although the origin of the problem has not yet been confirmed and other possibilities have not been excluded, the engine manufacturer Pratt & Whitney is working on a new version of the software to fix the problem. The revised version of the software will be released in the first quarter of 2020, the same sources said.
EASA (European Aviation Safety Agency) has also said that it was monitoring the situation closely and coordinating with the FAA (Federal Aviation Administration).
On Oct. 24, Pratt & Whitney said that it was supporting the investigation and cooperating with the U.S. National Transportation Safety Board (NTSB) for further queries.
Airbus has launched a demonstration tour with one of the A220s of airBaltic in the Asia-Pacific region. The aircraft will land at nine airports in seven countries.
The first stop of the tour will be the Pacific island Vanuatu, home Air Vanuatu, the launch customer of the type in the Pacific region. The next stop will be Sydney and Brisbane in Australia. New Zealand (Auckland), New Caledonia (Noumea) and Papua New Guinea (Port Moresby) will follow these destinations.
On the way back to Europe, the aircraft will come over to Phnom Penh in Cambodia and Bangalore and New Delhi in India.
Static displays are planned at each destination, as well as demonstration flights for airline executives and other guests.