The internal Federal Aviation Administration (FAA) memorandum of 24 January concerning the British Airways flight 038 B777 crash 17 January at Heathrow is apparently not for public consumption, or release if specifically requested under the Freedom of Information Act (FOIA). Reason: the information is based on “Preliminary Reports” and is “For Official Use Only” (FOUA). These caveats are printed prominently at the bottom of each of the seven pages of the memorandum, facilitating denial of release under FOIA.

Much of the memorandum’s contents are public knowledge already, but it does contain some juicy details. For example, “The flight deck door opened on its own during landing.” Recall that this is the new bulletproof and lockable cockpit door now found on all airliners. The fact that it popped open on its own during landing will no doubt prompt a review of this and other door designs.

The FAA memorandum also indicates that the airplane “is considered a hull loss.” Given the extensive damage to the wings and main landing gear, and the twisting of the fuselage, the fact of the airplane being a write-off should not be surprising.

Regarding the “dual engine rollbacks” to idle power in the moments before impact, the FAA said the investigation by the UK’s Air Accidents Investigation Branch is concentrating on:

“• Ice in the fuel somehow limiting the fuel flow to the engines. A maintenance message indicating excessive water in the center tank was [sent] during taxi on the two previous flight legs, although it cleared itself both times. The airplane was being operated in a high humidity, cold environment, conducive to ice formation

“• Small-sized contamination building up in the engine fuel systems somehow limited the fuel flow to engine. All the fuel samples have tested for contamination of larger particles (sizes outside the fuel specification). Testing has been started looking for small particles (greater than 5 microns).

“• Engine hardware failures sending inaccurate data to the engine electronic control (EEC) causing the EEC to demand insufficient fuel. A preliminary review of the EEC data from the right engine shows erratic combustor inlet pressure (P30). A leaking P30 sense line could cause this, or the EEC receiving a higher than actual fuel flow parameter.

“• Software coding problems in the EEC causing the EEC to demand insufficient fuel. British Airways installed a new engine EEC software revision in December 2007. The software was approved in May 2006. There were several changes to the software as part of the revision. Two items seem remotely related to the accident: improvements to low power stall recovery logic and fan keep out zones for ground maintenance.”