The UK AAIB has released its final report
on the January 2008 crash landing of a British Airways Boeing 777 that suffered a (then) mysterious drop in engine thrust as the plane was on final approach to London Heathrow.
The probe discovered a new anomaly: soft ice in a high concentration and in certain conditions can block fuel flowage, and the fuel oil heat exchanger (FOHE) was determined to be the only possible place the ice could accumulate. (Investigators pegged the FOHE as the blockage location on the right engine, but lacked sufficient data to draw a firm conclusion on what happened to the left engine.)
The report makes 18 recommendations, nine of which were released in interim updates. Actions from these include Trent 800 airworthiness directives
adopted by EASA and FAA and a similar directive
for the Trent 500s and 700s that power Airbus long-range aircraft.
The new recommendations focus largely on certification and aircraft survivability issues. They are:
- Safety Recommendation 2009-091: It is recommended that the European Aviation Safety Agency introduce a requirement to record, on a DFDR, the operational position of each engine fuel metering device where practicable.
- Safety Recommendation 2009-092: It is recommended that the Federal Aviation Administration introduce a requirement to record, on a DFDR, the operational position of each engine fuel metering device where practicable.
- Safety Recommendation 2009-093: It is recommended that Boeing minimise the amount of buffering of data, prior to its being recorded on a QAR, on all Boeing 777 aircraft.
- Safety Recommendation 2009-094: It is recommended that Boeing apply the modified design of the B777‑200LR main landing gear drag brace, or an equivalent measure, to prevent fuel tank rupture, on future Boeing 777 models and continuing production of existing models of the type.
- Safety Recommendation 2009-095: It is recommended that the Federal Aviation Administration amend their requirements for landing gear emergency loading conditions to include combinations of side loads.
- Safety Recommendation 2009-096: It is recommended that the Federal Aviation Administration, in conjunction with the European Aviation Safety Agency review the requirements for landing gear failures to include the effects of landing on different types of surface.
- Safety Recommendation 2009-097: It is recommended that the Federal Aviation Administration require that Boeing modify the design, for the Boeing 777, of the indirect ceiling light assemblies, their associated attachments, and their immediate surroundings to ensure that the fluorescent tubes, or their fragments, will be retained in a survivable impact.
- Safety Recommendation 2009-098: It is recommended that the Federal Aviation Administration and the European Aviation Safety Agency, review the qualification testing requirements applied by manufacturers to cabin fittings, to allow for dynamic flexing of fuselage and cabin structure.
- Safety Recommendation 2009-100: It is recommended that the European Aviation Safety Agency mandate MSB4400-25MB059 Revision 3 to require the inspection and and replacement of the video monitor fittings on the Recaro seat model 4400.
Despite the focus above on making aircraft more durable in the event of a crash, it's worth nothing that all 136 passengers and 16 crew survived the accident, with but one "serious" injury resulting.
Access the full report and a section-by-section breakdown here