What happened
In early 2016, a resident in Engis, Belgium, discovered an aircraft component in their garden. The location was approximately 6 km from the end of runway 23L at Liege Airport (EBLG). Following an investigation by airport inspection services and mechanics, the object was identified as a panel from a thrust reverser door.
Tracing the part back to its origin, investigators determined the component belonged to a Rolls-Royce RB211-535C engine. The engine was installed on a Boeing B757-236(SF) operated by DHL, which had performed a cargo flight from Brussels Airport (EBBR) to Leipzig/Halle Airport (EDDP) on 3 November 2015. Aircraft records confirmed that the part was noted as missing during the flight's follow-up maintenance on 4 November 2015.
The investigation
Technical experts from Rolls-Royce performed a detailed examination of the part, which measured 57 cm by 21 cm. The investigation focused on the failure of the hinge assemblies that held the rear latch access door in place.
Analysis of the forward hinge assembly revealed that the hinge pin had completely disappeared from the retaining lugs. Furthermore, the rear hinge assembly showed evidence of a complete fracture of the two butt hinge lugs on the thrust reverser side. The deformation patterns indicated that once the forward hinge failed, the door was pulled downward by aerodynamic forces, causing the rear lugs to break under extreme overload.
Findings
Investigators concluded that the door assembly detached because the forward hinge pin migrated axially out of its position. This migration was caused by a combination of in-service wear and insufficient retention mechanisms, which allowed the pin to move forward until it disengaged entirely. Once the forward connection was lost, the resulting aerodynamic loading caused the subsequent failure of the rear hinge lugs.
Additionally, the investigation found that the existing aircraft maintenance program did not require a specific condition check for these hinges during scheduled inspections.