Boeing 747-433 Suffers Electrical Issues After Takeoff from London Heathrow
A Boeing 747-433 freighter aircraft, registered as G-ONEE, suffered electrical issues after departing from London Heathrow Airport on February 8, 2024. The problems began during takeoff and worsened during climb.
The loss of AC Bus 1 and 4 led to multiple system failures, including the loss of all pitot tube heating. The flight crew executed numerous checklists to address the issues, declared a PAN, and initiated a diversion to Amsterdam Schiphol Airport.
During descent, the aircraft encountered icing conditions, causing the pitot tubes to freeze and airspeed indicators to malfunction. The autopilot pitched the nose-down to regain indicated airspeed, resulting in an 18 kt overspeed before exiting icing conditions.
The investigation attributed the loss of power to water ingress into Generator Control Units (GCUs) 1 and 4, which was likely caused by an open L1 door during rain. Previous events had highlighted weaknesses in water ingress protection measures, leading to four safety recommendations from the AAIB.