The UK Aircraft Accident Investigation Branch published a new intermediary report about the crash-landing of the British Airways Boeing 777 in Heathrow on the 17th of January. This report presents the results of initial investigations and a recommendation.

Up to now, the investigators tested various parts of the engines and fuel system, analyzed fuel sampled at various points of the fuel supply lines, checked the data recorded by the black-boxes and other non-volatile memory… and found nothing explaining this accident. Amongst confirmed factors, the report confirms that the airplane was configured for landing, and landing gear was down.

The recommendation relates to the sequencing of actions to be carried by the Captain and First Officer before an evacuation. The current procedures plans that the Captain closes the fuel valves, and the First Officer activates the fire extinguishers, as a preventive measure. These actions were carried parallely, according to checklists, and the First Officer activated the fire extinguishers before the Captain did shut the fuel valves off.

Because of this particular sequence, the valves remained open, contributing to the fuel leakage. The recommendation is to introduce a sequencing action to make sure the Captain shuts off the valves before the First Officer activates the fire extinguishers. This is obviously not a contributing factor in this accident, the recommendation is simply a positive side effect.

The causes of the accident are still obscure, so we will have to wait more until the investigators can establish what occured…

Links:
New update from the UK AAIB
Initial post about the accident
First post on initial report
Post on initial report update