What happened
On 18 May 2001, an AVRO RJ 100, registration G-BXAR, was operating a scheduled public transport flight from Dublin to London Gatwick. While cruising approximately 40 NM southeast of Dublin, the aircraft was accelerating through 290 knots at Flight Level 170 when a loud bang occurred. The crew experienced a slight yaw, and engine instrumentation indicated a loss of reading for the No 2 Exhaust Gas Temperature.
Following the impact, the crew observed that part of the No 2 engine cowling had detached and fallen into the Irish Sea. As a precaution, the pilot reduced thrust and subsequently shut down the No 2 engine after confirming the damage. The aircraft successfully returned to Dublin and landed without further incident. There were 90 passengers and 6 crew members on board, with no injuries reported.
The investigation
The investigation focused on the physical damage to the engine and the maintenance history of the aircraft. Post-flight inspections revealed that the rear fan cowling doors and the exhaust cone cowling had been torn away. The damage included torn thermocouple leads, a damaged engine jet pipe, and the loss of hinge fixings from the shoulder cowl. The force of the separation was significant enough to pull rivets through the structure.
Investigators examined the recent maintenance history of the No 2 engine. It was noted that the engine had undergone a replacement just days prior, following a sudden stop in Dusseldorf on 14 May 2001. During the subsequent service, the cowls had been opened and closed multiple times. Additionally, the aircraft had experienced several instances of pylon blow-out panels opening during recent flight sectors, which had prompted a seal replacement shortly before the separation event.
Findings
The investigation established that the separation of the cowling doors was caused by the failure of the hinge fixings on the underside of the aft shoulder cowl. While the exact primary trigger could not be definitively proven due to the loss of components in the sea, the investigation identified three potential causal factors:
- A structural failure of the forward upper attachment, potentially stemming from the engine's previous sudden stoppage.
- The upper hinge pin potentially working loose or being improperly installed during recent maintenance.
- The cowling not being correctly secured or closed following the engine change.
Safety action
Following the incident, the following safety recommendations were issued:
- The aircraft manufacturer should instruct operators to perform visual inspections of the shoulder cowl assembly and attachment points during engine changes.
- The maintenance manual should be updated to require a structural inspection of the pylon following any sudden engine stoppage.