What happened
On September 1, 2023, a Boeing 767-332ER(WL), registration N175DN, was performing a scheduled commercial flight from Václav Havel International Airport (LKPR) to John F. Kennedy International Airport (KJFK). Shortly after departing from runway 24, at an altitude of approximately 1,500 feet MSL, the flight crew heard a loud bang originating from the right side of the aircraft.
Following the noise, the right engine experienced a failure, characterized by dropping N1 and N2 indications and rapidly rising Exhaust Gas Temperature (EGT). The engine flamed out and shut down. The flight crew immediately stabilized the aircraft, declared an emergency, and executed the appropriate Quick Reference Handbook (QRH) procedures. The crew decided to return to Prague for an emergency landing.
The aircraft returned to LKPR and performed an overweight landing on runway 2 and 4. Although the landing was uneventful, the crew utilized autobrakes and minimized braking on the right side due to high temperature readings on the right brakes. No injuries were sustained by the passengers or the crew.
The investigation
The investigation, conducted by the Air Accidents Investigation Institute, examined crew testimonies, flight recorder data (DFDR and CVR), air traffic control communications, and an analysis of the engine provided by the manufacturer. Investigators focused on the mechanical state of the right engine and the sequence of events during the climb phase.
Findings
- The engine failure was caused by the fracture of a 5th stage high-pressure compressor (HPC) blade.
- The detached blade caused extensive internal damage to subsequent stages of the HPC, HPT, and LPT, rendering the engine damaged beyond repair.
- There was no evidence of foreign object debris (FOD) or birdstrike.
- The primary cause of the blade fracture could not be definitively determined because secondary damage to the fracture surfaces prevented the identification of the original fatigue crack.
- The flight crew was experienced, properly qualified, and managed the emergency situation effectively according to trained procedures.
- Meteorological conditions at the time of the incident were appropriate and did not contribute to the failure.
Safety action
- AAII recommends that the engine manufacturer, Pratt & Whitney, perform electron microscope scanning and evaluation on every engine blade fracture whenever there is a suspicion that a blade failure was the initiating event of an occurrence, to better detect primary defects.