Topic: | Re:Re:BA Flight Lands Short of Runway at Heathrow | |
Posted by: | Richard Jennings | |
Date/Time: | 05/02/09 15:12:00 |
"has there been an official report on the BA 'hard landing'?" An interim report was issued by the AAIB in September 2008. It's available online at http://www.aaib.dft.gov.uk/cms_resources/G-YMMM%20Interim%20Report.pdf It's only an interim report because investigations are still being pursued. Amongst the interim report's recommendations was a request that the safety authorities and manufacturers "introduce interim measures for the Boeing 777, powered by Trent 800 engines, to reduce the risk of ice formed from water in aviation turbine fuel causing a restriction in the fuel feed system". Those measures were introduced in a directive shortly after publication. The latest advice from Boeing, which tightens up the previous directive, follows an engine failure on a Delta Airlines flight in November 2008 which is thought to involve "similar factors" to the Heathrow crash. The problem appears to be that, in Rolls-Royce Trent engines, ice crystals can be deposited in the fuel/oil heat exchanger under conditions of very low temperatures and low power settings, and then when power is increased, the extra fuel flow causes the ice to cluster and impede the flow of fuel. The heat exchangers on the American engines that power 70% of Boeing 777s are of a different design which seems to prevent the ice problem. |