History of the Flight
On 27 March 2014, at approximately 2147 UTC, a scheduled passenger flight operated by an Airbus A380 aircraft, powered by four Rolls-Royce Trent 900 engines, departed from Dubai International Airport, the United Arab Emirates, en route to London, the United Kingdom. There were 503 persons on board: 19 crewmembers and 484 passengers. The takeoff and initial climb were normal. Upon reaching approximately 2,000 feet altitude, an ECAM warning message of ENG FAIL appeared, indicating that the No. 3 engine had failed. The engine had suffered an uncommanded in-flight shutdown (IFSD); prior to that, all engine indications were normal. The flight crew declared a PAN and leveled the aircraft at 6,000 feet. At that altitude, an unsuccessful starter-assisted relight was attempted. According to the crew statement, there was no rotation of the engine's high pressure stage. The commander initiated fuel jettisoning for a return to the departure airport. At approximately 2249 UTC, the crew performed an uneventful landing after about one hour total flight time. After the aircraft arrived at the parking stand, operator maintenance staff confirmed that the No. 3 (right-hand inboard) engine had sustained an internal failure, as indicated by the engine master chip detector containing several metal chips. Visually, the engine showed no external damage. There were no injuries to passengers or crewmembers.
Aircraft and Engine Information
The incident aircraft was an Airbus A380-842, Australian registration VH-OQL. The engine involved was a Rolls-Royce Trent 972-84, serial number 91137, rated at 72,000 lbs thrust. It entered service in January 2011 and was installed on position No. 3 of the aircraft (MSN 0074). At the time of the event, the engine had 1,173 cycles since new (CSN) and 12,871 hours since new (TSN). All aircraft certificates were valid at the time of occurrence. In June 2013, during a shop visit for replacement of the high pressure turbine disc due to time expiry, the step-aside gearbox (SAGB) bearing support was found damaged and replaced. Since that shop visit, the engine operated 198 cycles and 2,224 hours, all on the incident aircraft.
Inspection Findings
Post-flight, the engine's electrical magnetic chip detector (EMCD) was inspected and found to have fuzzy deposits with metal contamination. During manual cranking via the external gear box (EGB), the EGB rotated but the high pressure spool did not, indicating a likely disconnection. Inspection revealed internal damage in the step-aside gearbox (SAGB). A borescope inspection of the internal gearbox (IGB), EGB, and transfer gear box (TGB) showed no primary or secondary damage. Timing marks on the driveshaft, adapter, and coupling were correctly aligned. The radial driveshaft had moved slightly down but was undamaged. The angled drive shaft (ADS) was removed and examined; a new balance test showed an unbalance condition outside acceptance limits. The drain holes were clear. The EGB, TGB, and ADS were returned to the manufacturer for examination.
Analysis
Based on the manual cranking test, the lack of HP spool rotation while the EGB rotated indicated a disconnection in the drive system. Such a disconnection in flight would cause an uncommanded engine shutdown. Damage was found in the SAGB, which is part of the drive system. Minor displacement in two bearing locations within the TGB was considered non-contributory to the event.