What happened
On 15 August 2010, a Boeing 767-31K, registration G-DAJC, was performing a commercial passenger service from Manchester to Dalaman, Turkey. Shortly after the aircraft reached its cruising altitude of FL3/70, the cabin manager reported smoke emerging from an oven in the forward galley.
In response, the commander ordered the circuit breakers for the forward galley ovens to be pulled. Despite this, acrid smoke continued to emerge from the area. Crew members used a BCF extinguisher on the right oven, followed by five additional extinguishers directed at both the left and right ovens. The commander subsequently isolated the utility busbar and declared a PAN call to Maastricht ATC to initiate a diversion. The aircraft landed safely at London Gatwick Airport at 0750 hrs. There were no injuries among the 324 passengers or 11 crew members on board.
The investigation
Investigators examined the forward galley ovens, which were removed from the aircraft by maintenance engineers. While the left oven showed no damage, the right oven revealed an electrical short circuit within its controller module. The investigation found that the 5 amp circuit breaker for the controller had tripped, which successfully prevented the overheating from escalating into a more serious fire.
Technical analysis of the controller's printed circuit board (PCB) showed damage at the junction where the ON-OFF switch is mounted. However, the extent of the burning on the copper tracks and soldered connections made it impossible to identify the specific trigger for the short circuit. The oven had been installed in the aircraft only eight days prior, following a recent service by an approved repair organisation that had certified the unit as serviceable.
Findings
- The smoke originated from the oven controller module rather than the oven units themselves, which caused initial confusion among the crew regarding the source of the smoke.
- An electrical short circuit occurred at the connection point between the oven controller's ON-OFF switch and its printed circuit board.
- The 5 amp circuit breaker functioned correctly, tripping as designed to limit current and prevent further damage.
- The maintenance history of the oven showed no recorded defects following its installation eight days before the incident.