What happened
On August 18, 2019, a Boeing 757-251, registration N543US, operated by Delta Air Lines, arrived at Ponta Delgada Airport (LPPD) from New York (KJFK). The flight, DAL414, was performing a commercial air transport operation. While the crew had initially prepared for an ILS approach to runway 30, they were cleared for an RNAV (GNSS1) Z approach to runway 12.
During the approach, the crew managed speed variations on short final with adjustments to engine power and flight controls. The initial touchdown occurred normally on the left and right main landing gear. However, immediately following the main gear contact, the aircraft's nose pitched down abruptly, resulting in a hard nose gear touchdown. The aircraft decelerated rapidly and, at a speed of approximately 100kt, the pilot in command took control as the aircraft reversed direction on the runway and taxied to its assigned parking position. There were no injuries to the 7 crew members or 161 passengers, but the aircraft sustained substantial damage.
The investigation
The GPIAAF conducted a safety investigation to examine the aircraft damage and flight data. The investigation included an analysis of the flight and voice recorders, as well as a detailed assessment of the aircraft's physical condition. Post-flight inspections revealed damage to the lower front fuselage near the nose gear and the upper central fuselage area in front of the wing. The investigation team analyzed the nose landing gear, finding that while the shock strut was internally and externally intact, the axle exhibited a 2.03mm deformation consistent with a hard landing.
Findings
- The primary damage to the aircraft consisted of deformations in the primary fuselage structure, including deformed frames, stringers, and skin caused by compression stress.
- The nose landing gear axle was out-of-round by 2.03mm due to the impact.
- The aircraft's landing parameters, including a reference speed (Vref) of 133kt and the use of auto brake 4, were consistent with the operator's guidance for the destination airport.
- The investigation noted that while Boeing has issued technical bulletins (such as 757-48) regarding the risks of excessive nose-down elevator input during landing, such information may not always be effectively distributed to all flight crews.
- The investigation found no evidence of medical conditions affecting the crew or prior mechanical anomalies that would have contributed to the event.