N977FD

HISTORY OF FLIGHTOn October 4, 2023, about 2347 eastern daylight time (EDT), FedEx flight 1376, a Boeing 757-236, sustained a failure of its left hydraulic system shortly after takeoff from CHA. The airplane turned back to CHA, and, while preparing to land, the landing gear failed to extend normally. The landing gear also failed to extend using the alternate extension system. The flight crew declared an emergency and the airplane sustained substantial damage during the emergency landing. The two flight crewmembers and a jumpseat occupant onboard the airplane were not injured. The flight was operating under the provisions of Title 14 Code of Federal Regulations (CFR) Part 121 as a non-scheduled domestic cargo flight from CHA to Memphis International Airport (MEM), Memphis, Tennessee.

According to postaccident flight crewmember statements, the airplane had no maintenance issues before the flight, and the push-back, engine start, and taxi were all uneventful. The captain was the pilot flying, and the FO was the pilot monitoring.

CVR data indicated that the flight was cleared for takeoff by the CHA local control (LC) controller at 2221:54 EDT. The Runway Awareness Advisory System (RAAS) announced “On runway two zero” at 2222:58, and the engines were audible accelerating to high power shortly afterward. As the aircraft accelerated, the FO made the following callouts: thrust set, eighty knots, V1, rotate, and positive rate. DFDR data showed that the gear weight-on-wheels transitioned from ground to air at about 2223:42. The captain called for gear up at 2223:44 and the FO raised the landing gear control lever to retract the landing gear. DFDR data showed that the landing gear lever handle was moved to its up position at 2223:47. The flight crew indicated that both the MLG and the NLG retracted to their up and locked positions. The completion of nose gear retraction was audible in the flight deck at 2223:58. DFDR data indicated that 11 seconds later, at 2224:09, the hydraulic fluid quantity and pressure in the left hydraulic system began to decrease. A left hydraulic system low quantity indication and master caution were recorded shortly thereafter (figure 1)

At 2224:17, CVR data indicated that the captain said, “Left hydraulic quantity.” At 2224:32, a caution beeper was audible while the FO communicated with the CHA approach controller. The captain called for flaps up and asked the FO to ask ATC to “see if we can just maintain runway heading.” A click consistent with flap handle movement was audible at 2224:47, followed by another caution beeper at 2224:52, and the captain stated, “Flaps disagree.” According to postaccident flight crewmember statements, immediately after placing the flap handle to its up (flaps 0) position, a TE FLAP DISAGREE message was displayed on the EICAS, along with an associated master caution light, a TRAILING EDGE discrete light, and the aural alert caution beeper.

Figure 1. Plot of the FDR data from the event takeoff.

At 2225:01, the captain said, “Autothrottles are off.” The FO reported to ATC that they were working an issue and requested permission to maintain the runway heading up to 5,000 ft, which was approved. Per the captain's direction, the FO began accomplishing the TE FLAP DISAGREE checklist in the QRH. CVR data indicated that the left hydraulic system pressure QRH items were completed at 2229:12, and the captain asked the FO to send the FedEx operations department a text informing them of the aircraft’s condition and asking whether they should return to Chattanooga or continue to Memphis. At 2230:53, the crew checked over the QRH checklist for the Trailing Edge Flap Disagree message. Both the TE FLAP DISAGREE and the Hydraulic System Pressure (L only) checklists indicated using Flaps 20 and Vref 20 for landing. Following the checklist, they set flap alternate modes for leading and trailing edge flaps and the FO completed landing performance calculations for the planned alternate landing configuration. They also discussed fuel state and determined that returning to Chattanooga would be the appropriate decision.

At 2237:10, the captain informed ATC of their need to return to Chattanooga and that they would still need some time to work checklist items before returning. The controller provided vectors to keep them north of the airport and asked if they would like to declare an emergency, which the captain declined. The crew continued to work together to complete appropriate checklists and input performance calculations for the aircraft’s non-normal condition into the flight management computer (FMC).

At 2246:30, the crew selected flaps 1 using the alternate flaps system and requested vectors from ATC for their instrument landing system (ILS) approach into Chattanooga runway 20. As they maneuvered for the approach the crew slowed and configured the airplane for landing through flap settings. Flap movements were slower than normal, which was expected due to the alternate configuration.

CVR data indicated that, at 2249:45, they reached their planned approach flaps configuration of 20 degrees and attempted to lower the landing gear. A triple chime was audible at 2249:50, and the captain said, “Gear disagree.” The first officer confirmed, “Gear disagree. The gear is not coming down.” At 2250:15, the captain contacted ATC to break off their approach and reported that they had an unsafe gear indication. Following the failed attempt to lower the landing gear, the crew went methodically through the Hydraulic System Pressure (L only) QRH checklist to determine the next steps. The crew determined that they would attempt an alternate gear extension. Because the checklist informed them that nose wheel steering would be inoperative following the alternate gear extension and the aircraft would not be able to clear the runway on its own, the crew declared an emergency with ATC at 2253:30. At 2254:34, the crew attempted the alternate gear extension procedure, and they verbalized that there were no lights indicating that the gear was down. The crew completed the procedure several more times over the next 7 minutes, including re-completing the Hydraulic System Pressure checklist in full.

At 2301:17, the crew brought the jumpseat occupant, who was another FedEx pilot, to the flight deck. The crewmembers and jumpseat occupant talked through the issues and troubleshooting that had been done so far and decided to radio FedEx operations to speak with a maintenance technician. While waiting for the technician they discussed their fuel remaining and made a fuel plan for when they would have to commit to landing.

At 2311:05, the flight crewmembers asked Chattanooga approach if they could conduct a low approach over the runway so that tower personnel could visually confirm the position of the landing gear. The airplane descended to about 150 ft above ground level and flew the length of the runway, which was followed by a go-around. Approach control relayed confirmation that the landing gear was not in the down position.

At 2326:22, the FedEx maintenance technician provided them two circuit breakers to cycle in an attempt to lower the landing gear with the alternate extension procedure, which was unsuccessful.

As the crew set the aircraft up for the final approach, they continued following the Gear Disagree checklist and worked other appropriate standard checklists as dictated by flight conditions. The flight was cleared to land by the tower at 2339:40. The captain briefed the FO that he was planning to aim close to the runway threshold and the FO verbally updated the captain on wind conditions and airspeeds. They agreed that the jumpseat occupant would open the L1 door when they landed. Initial audible indications of ground contact occurred at 2347:10, the RAAS reported 500 ft remaining at 2347:30, and audible indications of runway departure occurred at 2347:35. The recording ended three seconds later at 2347:38

The flight crew was unable to stop the airplane, and it slid off the departure end of runway 20 and impacted localizer antennas before coming to rest about 830 ft beyond the end of the runway (see figure 2).

Figure 2. Drone photograph of the airplane at the accident site. (Source: Aircraft Rescue and Fire Fighting)

After the airplane came to a complete stop, the flight crew performed the evacuation checklist in the QRH, and the jumpseat occupant attempted to open the L1 door (see figure 3, upper photo). The door rotated halfway open but would not open fully, and the slide did not deploy. The jumpseat occupant then attempted to open the R1 door, but it lodged on the slide pack. The jumpseat occupant used force to open the R1 door, and the slide deployed normally (see figure 3, lower photo). The flight crew and the jumpseat occupant exited the airplane through the R1 door and slide. Both flight crewmembers and the jumpseat occupant were uninjured. The event was classified as an accident because the airplane sustained substantial damage.

Figure 3. Photos of the airplane in its final resting position. (Source for upper photo: Chattanooga Fire Department; source for lower photo: FAA) AIRCRAFT INFORMATIONLanding Gear / Hydraulic System:

The Boeing 757 is equipped with three independent hydraulic systems: the left, right, and center. The left and right hydraulic systems are each powered by an engine-driven pump (EDP) and an alternating current motor pump (ACMP). The center system is powered by two ACMPs.

The hydraulic system incorporates a power transfer unit (PTU), which has a hydraulic motor pump and transfers hydraulic power from the right system to the left system. The PTU is automatically activated when the left EDP pressure is low or the left engine fails. When activated, the PTU powers a dedicated portion of the left hydraulic system, which operates the flaps and slats, landing gear, and nose wheel steering. If the PTU fails to develop pressure in the left system (as e...