History of the Flight
On 5 March 2011, at 2210 local time, Emirates flight 132, a Boeing 777-200 (registration A6-EMH), departed from runway 32L at Moscow Domodedovo Airport, Russia, en route to Dubai International Airport, United Arab Emirates. At approximately 400 feet above ground level, the flight crew received an Engine Indication and Crew Alerting System (EICAS) message indicating thrust asymmetry. The climb continued above the minimum sector altitude, and the crew completed the relevant checklist. Later during the climb, the cabin crew reported hearing a loud bang and seeing sparks emanating from the right side of the aircraft. Subsequently, the flight crew received additional EICAS messages concerning the right engine's Electronic Engine Control normal mode, turbine overheat sensor, overheat circuit, and engine fire loop.
The crew performed the abnormal checklist as per the operator's procedures, which required selecting the Electronic Engine Control Mode to alternate mode. Flight recorder data showed two brief spikes in exhaust gas temperature during takeoff, followed by slightly erratic readings over a four-minute period. Approximately eight minutes after takeoff, all recorded engine parameters stabilized and remained normal for the remainder of the flight. The commander contacted Air Traffic Control (ATC) and requested a runway inspection; later, the co-pilot repeated the request in Russian. ATC reported no debris found, but subsequent airport authority inspections discovered pieces of the thrust reverser on the runway. The flight crew informed the operator of the EICAS messages, and the commander decided to continue the flight based on the available information. Upon arrival at Dubai, ATC reported that small pieces had separated from the aircraft during landing. The flight crew shut down the right engine immediately after vacating the runway and requested a runway inspection. Following normal passenger disembarkation, the commander was informed of the missing thrust reverser part.
Investigation Findings
The failed inner wall of the thrust reverser (left hand inner wall of the No. 2 engine, part number 315W5101-1) was returned to Boeing for forensic examination under the supervision of the National Transportation Safety Board (NTSB) at the request of the Air Accident Investigation Sector (AAIS). The detailed failure analysis revealed that an earlier repair had suffered some degree of adhesion failure between the adhesive film and the repaired core. The analysis concluded that the inner wall failed primarily due to residual thermal damage that was not addressed when the panel was initially inspected and repaired. The repair was ineffective due to inadequate cleaning of the core prior to repair and failure to expand the repair sufficiently to remove the thermal damage. Furthermore, the forensic examination indicated it was possible that the thrust reverser was mis-rigged, resulting in higher-than-normal loads that could have caused the weakened panel to fail.
Cause
The Air Accident Investigation Sector determined that the failure of the thrust reverser inner wall was primarily due to residual thermal damage that was not correctly inspected and repaired following previous exposure to high temperatures.
Safety Actions
In response, Boeing issued a series of service bulletins and the Federal Aviation Administration (FAA) issued Airworthiness Directive 2012-16-04, effective 3 October 2012, requiring replacement of the 8th stage engine bleed valve parts. The operator incorporated modifications including Service Bulletin 777-78-0082 and 777-78-0071 (new thermal protection system and cooling of the inner wall), Service Bulletin 75-G466 and 75-G765 (engine bleed valve modifications), and compliance with FAA AD 2012-16-04. Additionally, the operator proactively installed new thrust reverser inner walls on all RB211 Trent 800 engines, starting in August 2011 and completed in December 2012, to mitigate the risk of thermal degradation.