Airbus A220 planes, which make up almost half of the European fleet of Swiss International Air Lines, have been ordered to avoid flying at maximum power over a certain altitude.
Federal Office for Civil Aviation (FOCA), has limited the Pratt & Whitney PW1500G engine power output of the A220s to 94% of the maximum, once the aircraft is flying at an altitude of 29,000 feet (FL290).
Also, the A220s should not fly above an altitude of 35,000 feet when the weather conditions point towards the development of frost. At this altitude, according to Airbus, activating the anti-freeze system could lead to over-heating in the engine, thus setting off a fire alarm and leading to an emergency landing.
Pratt & Whitney confirmed on 16 October that it was continuing to work on determining the cause of PW1500G engine failures that have affected Swiss’ Airbus A220-300 fleet – a month on from a second in-flight shutdown, and the day after a third engine failure forced a diversion.
The temporary grounding forced the airline to cancel about 100 flights, affecting some 10,000 passengers.