What happened
On 7 September 2003, a Boeing 757-236, registration G-CPER, operated by British Airways, was performing a scheduled passenger flight from London Heathrow to Paris. Shortly after takeoff, the flight crew detected a hot oil smell in the cockpit that had been present since engine startup. As a precaution, the crew donned oxygen masks and diverted the aircraft to London Gatwick Airport.
During the ILS approach to Gatwick using flap 30, the aircraft exhibited a significant tendency to drift to the right of the localiser once the autopilot was disconnected. The crew had to apply substantial manual left roll control to prevent the aircraft from turning right, maintaining this input until touchdown. There were no injuries to the passengers or crew, and the aircraft landed safely.
The investigation
The AAIB investigation focused on the maintenance history of the aircraft, which had recently undergone a 26-day major maintenance check. Investigators established that the flight control difficulties were caused by the failure to reinstall two specific access panels, 666AR and 666BR, on the right-hand outboard flap. These panels had been misplaced on a hangar rack among similar-looking parts and were not identified during subsequent inspections.
Furthermore, the investigation examined the engine oil servicing procedures. It was found that incorrect methods were used to service the engine oils, which likely contributed to the odor in the cabin. The investigation also looked into the maintenance culture, specifically regarding the practice of "blind stamping," where staff certify tasks without verifying completion, and the lack of effective oversight by the airline's quality assurance systems.
Findings
- The primary cause of the flight control issues was the absence of flap access panels on the right wing.
- Maintenance personnel incorrectly certified the reinstallation of the panels without actually performing the work.
- The technician responsible for certification exceeded his authorized privileges by certifying work he did not perform.
- A maintenance culture existed where staff frequently failed to certify tasks prior to the end of their shifts, passing responsibility to others.
- Inappropriate engine oil servicing procedures were used, which may have caused the observed oil smells.
- The airline's Quality Assurance Programme failed to detect these substandard maintenance practices.