What happened
On 1 March 2013, a Boeing 737-377, registration G-CELS, was undergoing preparations for a ferry flight at London Gatwick Airport. During the pre-flight process, the crew observed smoke and sparks emanating from an overhead locker located above seats 1D, 1E, and 1F.
In response to the hazard, the commander ordered all cabin crew to evacuate the aircraft and initiated QRH drills. A MAYDAY was declared before the flight crew exited the cabin. The airport fire service attended the scene and determined that the source of the smoke was electrical arcing occurring across the pins of an electrical connector. This connector, which had previously supplied power to the No 2 galley unit, was located near damp sound insulation material. Following the incident, the power supply was checked, restored, and the crew resumed their preparations.
The investigation
An investigation by the operator's engineering department established that the arcing was caused by the electrical connector pins. Although the circuit breaker for the No 2 galley had been pulled and collared, voltage was still present at the connector pins.
Records showed that a 2012 Line Maintenance Work Request (LMWR) had previously been initiated to inspect the fleet for a similar issue. In the case of G-CELS, this inspection had identified that the connector remained live; however, the operator's administrative systems allowed the maintenance task to be officially closed before the necessary rectification work had been performed.
Findings
- The smoke and sparks originated from arcing across the pins of an electrical connector.
- The connector was positioned in close proximity to damp sound insulation.
- The operator's maintenance management system allowed a work request to be closed without verifying that identified repairs were finished.
- Despite the galley circuit breaker being tripped and collared, the connector remained energized.
Safety action
- The operator performed additional inspections on aircraft identified by previous maintenance records as potentially requiring work; one other aircraft was found to have a live connector despite the circuit breaker being tripped.
- The operator updated its procedures for managing LMWRs to ensure that any follow-up work identified during an inspection must be completed before the task can be closed.