The US Federal Aviation Administration has ordered an immediate fix to the latest version of Boeing Co's 747-8 plane, saying a software glitch could cause it to lose thrust when close to landing and fly into the ground.
The FAA's so-called airworthiness directive covers Boeing's 747-8 and 747-8F planes with certain General Electric Co engines. It calls for replacing defective software with a new, improved version.
The rule, the fourth such directive involving the 747-8, directly affects seven airplanes in the United States, the FAA said.
If adopted internationally, the rule would cover a larger number. Boeing's website said it had delivered 66 of the four-engine jets, the company's largest, to customers worldwide since the model was introduced in October 2011.
The problem never caused a problem in flight, Boeing said.
Because of the seriousness of the safety issues, the directive takes effect April 9, skipping the usual comment period, although comments can still be submitted, the FAA said.
Boeing said data analysis indicated a potential problem, and it advised customers last year to update the software. It said it believed the majority of operators had already done so.
The risk of failure was "extremely remote," Boeing said.
GE said it owned the software and jointly analysed it with Boeing, but plane maker decided to recommend the software change to customers.
According to the FAA, the risk arises when a plane is changing back into "air mode" while performing a "rejected or bounced landing." That change halts hydraulic pressure used to stow the engine thrust reversers, which slow the plane on landing, the agency said.
Without hydraulic pressure, the reversers may not stow fully and might redeploy, which "could result in inadequate climb performance at an altitude insufficient for recovery, and consequent uncontrolled flight into terrain," the FAA said.
Unidentified business jet/VIP customers own the eight passenger models of the aircraft in the United States, according to Boeing's website. Air cargo company Atlas Air is the largest US commercial owner of the jet, with a fleet of eight 747-8F freighters.
Among passenger carriers, Lufthansa is the largest operator, with 11. It said its planes were unaffected by the directive.
"GE has confirmed that all our engines already have the software update that is required by the FAA," a spokesman said on Wednesday.
China's Cathay Pacific has 13 freighters and Cargolux, based in Luxembourg, has nine.
Korean Airlines Co, Nippon Cargo Airlines Co Ltd and Volga-Dnepr UK Ltd also own 787-8F freighters, according to Boeing's website.