History of the Flight
The aircraft, a Boeing 777-236B (registration G-VIIA), was scheduled to fly from London Gatwick to Antigua with 272 passengers and 14 crew. The commander was aware that the aircraft had just completed maintenance. After normal engine start, the aircraft taxied for Runway 08R and took off at 1000 hrs on 26 June 2003. During the standard instrument departure, the aircraft was cleared to 6,000 feet and later accelerated to optimum climb speed. In calm flight conditions, both flight crew members felt a slight tremble. Cabin attendants near Doors L3 and R3 felt a thump and heard a loud bang. The commander assessed the damage and found the outer pane of a window near Seat 29A impact-damaged but inner pane intact. He decided to return to Gatwick. The aircraft dumped fuel and landed at 1047 hrs, approximately 10 tonnes above maximum landing weight. The fire and rescue services confirmed a missing panel from the fuselage behind the left wing root.
Aircraft Examination
Examination revealed that the Air Driven Unit (ADU) bay access door (No 197JL) was missing. The door measured 4.18 ft wide, 5.95 ft high, weighed about 70 lb, and was constructed of carbon-fibre skins bonded to a nomex honeycomb core. It was attached by three steel hinges on its top edge and retained by 13 push-release catches. All three hinges were fractured. Paint deposits and scrape markings on the fuselage indicated the door had rotated open, struck the fuselage, and over-traveled. Six deep gouges suggested sequential contact by protruding latch levers from catches on the door's forward edge.
Door and Catch Analysis
Each catch consisted of a spring-loaded latch lever that engaged a latch pad. When closed, the latch lever was retained by a trigger lever. The source reported that it was likely only one of the thirteen catches had been fastened. The door likely suffered overload failure from aerodynamic forces during acceleration, causing it to open and detach. Fragments of the door penetrated the cabin, and large parts landed near people on the ground. Multiple walk-round inspections by different personnel had failed to detect the open catches. The inadequate fastening apparently occurred during a routine maintenance check due to a deviation from standard procedures, a practice fostered by features of the maintenance system and may have been commonplace.
Safety Recommendations
One safety recommendation was made regarding human performance factors in the operator's maintenance and inspection systems.