What happened
On 29 September 2008, a Fokker F.28 Mark 0070, registration PH-KZB, arrived at Manchester Airport from Amsterdam Schiphol. After landing on Runway 23R and taxiing to its stand, the aircraft's right engine was shut down. Immediately following this, the flight crew detected a strong smell of electrical burning and observed smoke accumulating within the flight deck.
As the smoke became more prominent, the co-pilot opened the sliding window to attempt to clear the air. The commander, concerned by the smoke appearing to originate from various vents and behind the instrument panel, instructed the Cabin Service Supervisor to initiate an emergency evacuation. To prevent the situation from worsening, the flight crew shut down the Auxiliary Power Unit (APU) and disconnected the electrical power.
During the evacuation, passengers were directed to exit via the forward left airstair and the right overwing exit. While the evacuation was successful, 2 passengers sustained minor injuries while moving across the aircraft wing. The Airport Fire Service arrived promptly and confirmed that no active flames were present, though a strong burning smell persisted.
The investigation
Investigators examined the aircraft and the electrical systems to identify the source of the smoke. While initial inspections of the circuit breaker panels did not show obvious signs of fire, the smell of burning remained intense. Upon removing the emergency inverter unit, engineers found a strong electrical odor emanating from the cooling fan exit.
When the unit was tested on a power supply bench, smoke was observed emerging from the area around the cooling fan. Further disassembly revealed that a capacitor within the cooling fan's power supply circuit had completely burnt out. This component was part of a modification intended to reduce fan noise, and its failure was the direct cause of the smoke release.
Findings
- The smoke in the flight deck was caused by a capacitor in the emergency inverter cooling fan power supply circuit overheating and failing.
- The smoke was drawn from the inverter casing into the flight deck through gaps in the equipment panels.
- The failure of the capacitor was the primary cause of the smoke and burning smell.
- The capacitor was an older component, and its failure may be related to its service life, as similar overheating incidents had been recorded in the fleet previously.