Hydraulic hose failure and broken wire led to crash landing of cargo plane in 2023, NTSB report says

CNN

2 days ago

Air travel safety
Airplane crashes
Federal agenciesFacebookTweetLink
Follow
A FedEx plane landed with its landing gear up, skidding off the runway in Chattanooga, Tennessee in 2023 after a leak in a hydraulic hose caused the system to fail and a broken wire kept the backup system from working, according to a final National Transportation Safety Board report.
Federal Express flight 1376, operating a Boeing 757, took off from Chattanooga Metropolitan Airport-Lovell Field late in the evening of October 4, 2023, headed to Memphis.
When the pilots raised the landing gear, the fluid pressure and quantity in the left hydraulic system, which operates the gear, decreased and an alarm sounded in the cockpit.
'Gear disagree. The gear is not coming down,' the first officer is quoted as saying on the cockpit voice recorder.
The crew declared an emergency and planned to return to the airport.
They repeatedly tried to lower the landing gear using a backup system but were unsuccessful.
'The crew used all available resources and included some non-standard attempts at troubleshooting,' the report said.
When landing, the plane skidded for nearly a mile along the ground, crashing into antennas and ending up 830 feet off the end of the runway.
The three people on board were not hurt but struggled to open the aircraft doors before evacuating down an emergency slide.
The NTSB report praised the crew for being 'calm and professional throughout the accident sequence of events' and 'actively soliciting feedback and input and crosschecking with one another to ensure everyone was working with the same mental model.'
After the crash landing, inspections found that hydraulic fluid leaked from a hose that opens the door for the left landing gear and had fully depleted the supply. Investigators determined the damage to the more than 35-year-old hose was likely caused by fatigue after it was, at some point, overloaded with force.
An electrical wire used to operate a backup system was found to be broken, which is why the alternative method of lowering the gear didn't work either.
Since the accident, FedEx started inspecting these backup landing gear extension systems after every 275 hours of flight, the NTSB said.
Investigators also found a misrouted strap and missing parts on the escape side latch on the left door, which kept it from opening during the emergency. The right door of the plane also did not have all the slide's latch hardware, which caused it to initially jam when the crew was trying to evacuate.
The plane was manufactured in 1988, after the Federal Aviation Administration had mandated these latches be changed, and the NTSB could not determine why they were used on this aircraft.
A FedEx inspection found 24% of its planes with similar latches were missing parts, the NTSB said. No other aircraft were found to have misrouted straps.
The NTSB reviewed Boeing's parts catalog and FedEx's maintenance manuals and found that they had 'inconsistent depictions' of the latches, and none showed all required modifications.
'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 report said.
As a result of this accident, Boeing issued a notice to other operators of the 757 around the world to inspect their latches and provided details on what they should include.
The NTSB issued recommendations to Boeing to update their manuals and parts catalog to 'to ensure they depict the correct configuration' for the latches and called on the FAA to require inspections of the latches 'and modify or replace them, if necessary, so they comply with the correct configuration.'