US investigators are urging the Federal Aviation Administration (FAA) to require airlines to inspect Boeing 737 and 757 cabin door hardware after finding that many 757s contain components that fail to meet federal regulations.
The National Transportation Safety Board (NTSB) says in a newly released report that the issue involves a door component called a “bannis latch”, which is designed to release emergency evacuation slides. The slides are intended to deploy when an armed cabin door is opened.
The NTSB discovered the problem while investigating the 4 October 2023 emergency landing of a FedEx 757 at Chattanooga. That jet landed with its landing gear retracted. After coming to a stop, the occupants were unable to fully open its left-front cabin door. The door’s emergency slide also did not deploy due to a bannis latch not meeting requirements.
Instead, the occupants escaped from the right-front door.
The NTSB subsequently inspected FedEx’s 97 other FedEx 757s and found that 46 doors – nearly a quarter of the total – failed to comply with one of two airworthiness directives (ADs) related to bannis latches.
Additionally, the NTSB says an unnamed non-US operator found that three of four 757 doors it inspected contained bannis latches that also failed to meet requirements.
The problem “could lead to delayed evacuation during an emergency should the slide become jammed”, the NTSB says.
It adds that 727s and 737s contain the same latches, meaning the problem could also exist on some of those aircraft.
In response, the NTSB has asked the FAA to require 727, 737 and 757 operators to inspect the latches for compliance, and to update maintenance manuals to contain correct information.
“We take NTSB recommendations seriously and will respond within an appropriate timeframe,” says the FAA.
Neither Boeing nor FedEx responded to requests for comment.
An FAA airworthiness directive (AD) from 1986 requires bannis latches to have “three links… with two spacers”. But the latch on the FedEx jet that made an emergency landing in 2023 had only one link, causing “the slide pack to jam”, the NTSB says.
That jet had been delivered in 1988, meaning Boeing should have handed it over with bannis latches that complied with the 1986 AD. The FAA issued that order partly in response to a 737 door that malfunctioned during the 1985 evacuation of a British Airtours 737-200.
The NTSB’s report also says that FedEx’s maintenance manuals, several FAA ADs and Boeing’s 757 service bulletins, parts catalogue and maintenance manual contained incorrect diagrams of the latches.
“None of these resources depict the bannis latch with all required modifications,” the NTSB says. “These inconsistent, conflicting depictions would likely be confusing to maintenance personnel and could lead to the installation of and failure to detect nonconforming latches, which could result in another incident of an evacuation slide not deploying properly when needed.”
The NTSB says Boeing intends in May 2025 to update its aircraft maintenance manuals and illustrated parts catalogue to accurately depict the latches.
