What happened
On 19 August 2008, a Short 360-600 Variant 100, registration G-GPBV, was performing a commercial cargo flight departing from Inverness Airport. During the initial climb through 6,000 ft, the crew detected a strong smell of electrical burning originating from the area behind the flap lever.
In response to the smell, the crew declared an emergency. Following instructions from Air Traffic Control, the aircraft descended to 3,500 ft. The crew attempted to don their oxygen masks; however, the co-pilot encountered significant difficulty using the equipment. While the commander successfully donned his mask and received oxygen, he struggled to maintain effective communication with the co-pilot and ATC. Following their pre-flight emergency plan, the crew returned to Inverness for an ILS approach to Runway 05 and landed the aircraft safely. Fire crews and an engineer met the aircraft upon arrival, and there were no injuries to the crew.
The investigation
The investigation focused on the source of the electrical odor and the crew's difficulty with the oxygen systems. Investigators identified that water had leaked through window seals, entering the area around the flap lever and causing an electrical short circuit.
Regarding the oxygen masks, it was discovered that the masks and oxygen systems on G-GPBV were different from those installed on the operator's other two Short 360 aircraft. Because the crew's training had been conducted using the different equipment, they were not sufficiently familiar with the specific hardware on this aircraft.
Findings
- Water ingress through faulty window seals caused an electrical short circuit behind the flap lever.
- The crew's inability to use the oxygen masks effectively was due to a lack of familiarity with the specific system installed on this particular aircraft.
- The window seals have since been repaired by the operator.