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.
The directive, published on Monday by the Federal Office for Civil Aviation (FOCA), follows a similar decision by Airbus Canada and the Canadian authorities, prompted by several technical problems in recent months.
FOCA notes that pilots should limit the power output of the A220s to 94% of the maximum, once the aircraft is flying at an altitude of 29,000 feet. Full gas-flying could lead to engine problems and damage, it says.
Furthermore, the planes 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.
The rules were prompted by several problems experienced by Swiss in recent months.
In August, a flight to London operated by the company had to make an emergency landing in Paris after losing several engine parts along the route. Then, two weeks ago, Swiss was forced to briefly ground its fleet of A220s for inspection, although all 29 were cleared to return to service soon after.
The temporary grounding forced the airline to cancel about 100 flights, affecting some 10,000 passengers.
Swiss relies heavily on the A220, also known as the Bombardier C-Series, which makes up almost half of its European fleet.