Engines on Airbus SE’s new A220 aircraft must undergo stepped-up inspections for compressor rotor cracks after a third in-flight shutdown, U.S. aviation regulators said, calling the matter an “urgent safety issue.”
The Federal Aviation Administration’s updated requirements are scheduled to be published in the federal register Tuesday. They follow a Saturday directive from Transport Canada, which said A220s should only be flown at 94% of full power above 29,000 feet and must stay below 35,000 feet during icing conditions because using the de-icer could cause the engine to overheat.
Airbus has been struggling with malfunctions on Pratt & Whitney geared turbofan engines, which have experienced several in-flight shutdowns in recent months. Deutsche Lufthansa AG’s Swiss airline unit temporarily grounded its fleet this month after a “serious” engine problem forced a Geneva-bound plane from London to divert to Paris instead. Swiss, the world’s biggest operator of the narrow-body aircraft, resumed operations with the jet a day later.
The risk of operating the affected engines without initial and repetitive inspections of low-pressure compressor rotors “is unacceptable,” the FAA said. Failure of the rotor can release engine debris at high speeds and potentially damage aircraft.
The most recent failure occurred after 1,654 engine cycles but within 300 cycles of new software from Pratt being installed, the FAA said. A problem with that software, produced earlier this year, is being investigated as a possible cause of the engine problems, aggravated by altitude and air speed, said a person familiar with the matter.
The earlier failures occurred after 154 and 230 flight cycles, the FAA said. A cycle is typically a flight, although the word also covers test runs for maintenance or any other time an engine is started. Inspections under an earlier order found cracks in rotors of spare engines installed on planes already in service. Those engines had fewer than 50 flight cycles since they were put in use.
“We believe this guidance, which was based on investigation findings and flight test data to date, mitigates a condition that could lead to the recent issues experienced with the low pressure compressor,” Pratt, a unit of United Technologies Corp., said in a statement.
Inspections carried out last week on a majority of engines in operation produced “no findings,” Pratt said. “The engine continues to meet airworthiness criteria.”
Airbus said in a statement that the measures were initially recommended by the manufacturer. It’s standard practice “for Transport Canada, as the primary airworthiness authority for the A220 aircraft type, to mandate operators to comply with the operational measures,” the company said.
The European planemaker acquired control of the A220 program from Montreal-based Bombardier Inc. last year.
Under the FAA order, engines that have accumulated less than 300 cycles and those with recently installed software must be inspected within the next 50 flight cycles from Sept. 26.
They must be re-inspected every 50 cycles until they accumulate 300. Zero-time spare engines must be inspected within 15 flight cycles. Fifty cycles equals seven to 10 operating days, while 15 cycles is about two to three days, the agency said. The compressors have to be removed and replaced if specified damage is found.
France’s air-safety bureau has organized a public search next month to locate pieces of an engine that fell from a Swiss A220 flight in July. Titanium parts may have fallen in unoccupied woodlands near the towns of Perrigny-sur-Armancon and Cry, France, the country’s Bureau d’Enquetes et d’Analyses said on Twitter.
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