What happened
On 12 February 2006, a McDonnell Douglas DC8, registered HB-IGH, was performing a takeoff roll on Runway 03L at O.R. Tambo International Aerodrome (FAJS). As the aircraft reached an indicated airspeed of approximately 80 knots, the crew heard a loud bang, and the aircraft began drifting toward the right side of the runway.
Upon detecting a low N1 (Low pressure Compressor Speed) on the number three engine, the crew immediately aborted the takeoff. The aircraft was subsequently taxied back to the terminal, where all passengers and crew disembarked safely. There were 0 fatalities and 0 injuries resulting from the event.
The investigation
SACAA AIID investigators examined the aircraft and the engine components following the incident. A post-incident inspection of the number three engine revealed that debris had been found within the engine exhaust pipe.
Detailed examination of the engine hardware identified a failed C-clip as the primary issue. This specific component is responsible for securing the High Pressure Turbine (HPT) Shroud Support and the HPT Shroud. The failure of this clip allowed for the machining of the HPT blade tips and the subsequent liberation of the HPT shroud into the primary flow path.
Records indicated that the aircraft had undergone a scheduled service (C4/B1/B2/CPCP) on 04 February 2006, just eight days prior to the incident. At the time of the failure, the aircraft had accumulated an additional 33.90 flying hours since that last inspection.
Findings
- The engine malfunction was caused by the failure of a C-clip holding the HPT Shroud Support and the HPT Shroud.
- This mechanical failure led to the liberation of the HPT shroud into the engine's primary flow path.
- The resulting engine damage caused a drop in N1 speed, necessitating the aborted takeoff.