More than 300 Boeing 737 jets are being checked for a defect that could cause further problems for airlines operating the aircraft.
The company has ordered some airlines to replace a part on the planes’ wings, in a move that could affect more than 100 737 NGs - an earlier generation 737 aircraft.
The Boeing 737 Max has been grounded worldwide for 12 weeks following the death of 346 people in two fatal crashes of an Ethiopian Airlines flight and a Lion Air disaster in Indonesia in October.
Boeing said on Sunday that it is working with federal regulators and contacted airlines about potential problems discovered in one batch of "slat tracks" produced by a supplier.
Slats are movable panels that extend along the wing's front during take-offs and landings to provide additional lift. The tracks guide the slats and are built into the wing.
The company said it has identified 21 planes most likely to have the parts in question, and it's advising airlines to check an additional 112 planes.
That total does not include the 737 Max aircraft that could also have the parts in question.
The Federal Aviation Administration on Sunday disclosed the new problem involving the grounded fleet, saying more than 300 of the troubled plane and prior 737 generation may contain improper manufactured parts which need to be quickly replaced.
The FAA said “We have determined that up to 148 parts manufactured by a Boeing sub-tier supplier are affected.
“The affected parts may be susceptible to premature failure or cracks resulting from the improper manufacturing process.
“Although a complete failure of a leading edge slat track would not result in the loss of the aircraft, a risk remains that a failed part could lead to aircraft damage in fight.”
Boeing said it has identified 21 737 NGs most likely to have the suspect parts and is advising airlines to check an additional 112 NGs. The NG is the third-generation 737 that the company began building in 1997.
The FAA said it will issue an Airworthiness Directive to require Boeing's service actions to identify and remove the parts from service.
It said operators will be required to perform this action within 10 days, but can continue to fly the planes during the 10-day period before the parts are removed.
Agencies contributed to this report.
