Known Fuel-Icing Problem on Boeing 777

Approximately 220 of the 736 Boeing 777s currently in service around the world are equipped with the Rolls-Royce Trent 800-series engines, which can allegedly suffer from ice-induced fuel constriction in flight. Investigators studying the British Airways 777 that crashed short of Heathrow in January (with no fatalities) and a Delta Airlines 777 that temporarily lost power at altitude last November believe the jets’ fuel systems can compromise fuel flow at the fuel/oil heat exchangers due to ice accretion that ultimately stifles the engines’ thrust.

In the opinion of the NTSB, current precautions are insufficient to prevent the possibility of a fatal crash and the aircraft concerned will be flying in that condition for at least six more months. This news comes after both the NTSB and the AAIB released recent reports, and several solutions are being investigated to alleviate the problem.

The issue is apparently due largely to the fact that the type carries about 50 feet of unheated fuel-pipes as part of its fuel system. Rolls Royce is working on the problem but any modification to the fuel system will require extensive testing and certification that might take more than 12 months. However, the NTSB is recommending that a suitable solution be found and instituted within six months.

An anti-icing fuel additive is one interim solution being considered, but a drawback of the additive is the requirement for more frequent maintenance. The cost of any temporary “fix” is a major concern, but the problem has already allegedly caused of two separate un-commanded rollbacks on passenger-carrying flights and remains an ongoing safety concern pending resolution.