A statement released by the FAA has highlighted new problems with some of Boeing’s 737 Max jets and an older model.
Boeing informed the FAA that certain 737NG and 737 Max leading edge slat tracks may have been improperly manufactured and may not "meet all applicable regulatory requirements for strength and durability".
Slat tracks are used to guide the slats located on the leading edge of an airplane’s wings. Boeing has not been informed of any in-service issues related to this batch of slat tracks.
A separate service bulletin will go to 737 Max operators to do inspections before the Max fleet returns to service. Boeing has identified 20 737 Max airplanes that are most likely to have the parts in question. Operators will be asked to check an additional 159 Maxs to ensure a thorough assessment.
Following an investigation conducted by Boeing and the FAA Certificate Management Office (CMO), the FAA has determined that up to 148 parts manufactured by a Boeing sub-tier supplier are affected.
Boeing has identified groups of both 737NG and 737 Max airplane serial numbers on which these suspect parts may have been installed. 32 NG and 33 Max are affected in the US Affected worldwide fleet are 133 NG and 179 Max aircraft.
"The affected parts may be susceptible to premature failure or cracks resulting from the improper manufacturing process," said the FAA. "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's 737 Max jet has been grounded since March following two deadly crashes that have been linked to a separate concern about a piece of software in the plane.
However, just recently Boeing issued a software update which it hoped would solve the issues which have been highlighted as the cause of the incidents.
“We are committed to supporting our customers in every way possible as they identify and replace these potentially non-conforming tracks,” said Kevin McAllister, President & CEO of Boeing commercial airplanes.
The FAA will issue an Airworthiness Directive to mandate Boeing's service actions to identify and remove the discrepant parts from service.
Operators of affected aircraft are required to perform this action within 10 days. The FAA also alerted international civil aviation authorities of this condition and required actions.