Rolls-Royce is working to find a modification to its Trent 800 engine following recommendations by the UK Air Accidents Investigation Branch (AAIB). A second interim report on last year’s crash of a British Airways Boeing 777-200 at London Heathrow said modifications were necessary to reduce the risk of ice in fuel lines which the AAIB suspected causing a flow restriction and thrust rollback of the Trent engines. The AAIB recommended that regulatory authorities make mandatory any measures Boeing and Rolls-Royce propose. The US National Transportation Safety Board on 11 March issued an urgent safety recommendation calling on the US and European aviation authorities to require installation of the engine modifications within six months of its certification. The UK crash investigators also recommended aviation safety authorities investigate expanded use of an anti-icing fuel additive, already widely used in military aircraft and some business jets, although this would increase maintenance and other costs.