Tests have indicated that operation of a water-scavenge system on Rolls-Royce Trent-powered Airbus A330s does not pose a risk of ice accretion in the fuel lines, and authorities intend to withdraw a safety notice on the matter.
The tests followed an incident in which an A330 experienced a temporary fuel-flow restriction in both engines, followed by a recovery.
Suspicion that the operation of the water-scavenge system had been a contributing factor led the European Aviation Safety Agency, in March 2010, to require deactivation of the automatic standby fuel pump scavenge system.
But EASA says it has reviewed the situation in the wake of “extensive” investigations by Rolls-Royce and Airbus into fuel-system icing risk.
These tests have “confirmed” that operation of the water-scavenge system, located at wing rib 3, “does not induce any risk” of accreted ice blocking the fuel-feed system, it states, and scavenge deactivation is "no longer required".
EASA adds that a new fuel-oil heat exchanger on Trent engines, redesigned as part of anti-icing measures taken in the wake of the Boeing 777 accident in 2008 at London Heathrow, is more tolerant to the release of ice.