What happened
On 27 December 2012, a Boeing 777-200, registration V8-BLF, was climbing through FL1CO after departing London Heathrow for Dubai. During the climb, the crew heard a loud rumbling noise accompanied by slight vibration and an Exhaust Gas Temperature (EGT) exceedance in the right engine. Although engine parameters remained within normal limits after the crew completed emergency checklists, the commander elected to return to Heathrow as a precaution.
The aircraft performed a two-engined approach and landed on Runway 27L. Due to the aircraft's weight at the time of landing, a local standby was initiated by emergency services. Following the flight, a physical inspection revealed that a significant portion of the inboard thrust reverser inner wall on the right engine was missing, which had caused damage to the engine nozzle.
The investigation
The AAIB investigation established that a large amount of composite material from the thrust reverser inner wall had been liberated. Some of this debris was later recovered from a property in Broxbourne, Hertfordshire.
Technical examination of the engine components revealed that one of the four compression rods, which are responsible for managing hoop stresses in the inner wall, was not properly engaging the receptor cups when the thrust reverser was in the closed position. This misalignment caused the end of the compression rod to damage the insulation blanket in that specific area. While the investigation found no evidence of heat-related distress to the structure, the loss of material was confirmed.
Findings
- The right engine thrust reverser inner wall suffered structural failure, leading to the liberation of composite material.
- A compression rod was not correctly engaging its receptor cup when the thrust reverser was closed.
- This misalignment resulted in damage to the insulation blanket at the end of the compression rod.
- The incident was one of fifteen similar occurrences of thrust reverser break-up known to the aircraft manufacturer at the time.