BA038 crash landing investigation update

The Air Accidents Investigation Branch (AAIB) has recently published a Special Bulletin (that is available here) dealing with the BA038 incident at London Heathrow. Even if the investigation is still underway, the bulletin is particularly interesting since it indicates that there were no anomalies in the major aircraft systems and these were not affected by any failure that can be considered as the accident’s root cause. According to the study, both the autopilot and the autothrottle worked as expected and the engine control systems provided the correct inputs to the engine before the reduction o thrust was experienced by the crew. Even fuel contamination was discarded. However, the investigation surfaced signs of abnormal cavitation in both engines’ high pressure fuel pumps, even if the manufacturer declared that, despite cavitation, both were still able to ensure full fuel flow delivery.
Interestingly, the bulletin contains a Safety Recommendation (that was accepted by Boeing) to notify to the 777 operators that have not incorporated the Boeing Service Bulletin 777-28-0025 yet, the need to change the fire and evacuation checklists according to a procedure that requires to activate the fuel control switch to cut-off prior to operation of the fire handle in strict sequencing. In fact, the investingation discovered that after the crash landing of the G-YMMM, the engine fuel spar shut-off valves (that are designed to cut off the fuel flow to the engine when needed) were in an OPEN position because of a wiring arrangement and lead to a fuel leakage that could have had distrastrous consequences in case of fire.