is a very efficient unit, transferring heat from the lubricating oil to the fuel.
In both cases, a build-up of ice on the FOHE
restricted the flow of fuel to the engine and as a result, the NTSB has called for a redesign of the FOHE
that would eliminate the potential of ice build-up.
Work continues on identifying a mechanism for generating, naturally, significant amounts of ice which when released can block the FOHE
or other components in the fuel feed system."
Pressure, for example, has been exerted on the FoHE to ensure that those hired on to the management team with GEF finance were chosen on the basis of their loyalty to Franjieh, not on their professional competence.
When rumors surfaced of plans to develop resorts there -- plans that could not have gone ahead without the approval if not participation of the Franjiehs', divisions already apparent within the FoHE between 'loyalists' and 'conservationists' became intractable.
"This ice would have travelled through the fuel feed pipes, where it could have formed a restriction on the face of the FOHE sufficient to cause the subsequent engine rollbacks," the AAIB says.
The NTSB has called on Rolls-Royce to carry out a redesign on the FOHE, while the AAIB has recommended that Boeing and Rolls-Royce jointly review "the aircraft and engine fuel system design for the Boeing 777 powered by Rolls-Royce Trent 800 engines to develop changes which prevent ice from causing a restriction to the fuel flow at the fuel oil heat exchanger".
The UK's Air Accidents Investigation Board yesterday issued a second interim report on the LHR crash that details extensive testing conducted by Boeing demonstrating that the accident likely was caused by FOHE
ice buildup that restricted fuel flow.
"The conditions that seem to have led to the British Airways accident are rare to start with, and the non-normal procedures we have in place will serve to minimize the effects these conditions will have on airplanes in flight until the new FOHEs
(fuel-oil heat-exchangers) are installed," a Boeing spokeswoman said.