Aircraft

Airbus A330s and A340s fitted with Rolls-Royce Trent engines appear likely to require the same anti-icing modifications to fuel-oil heat exchangers already demanded on Trent 800-powered Boeing 777s.

Ice build-up on Trent 800 heat exchangers is suspected in two engine roll-back events on 777s, including last year's British Airways crash at London Heathrow. The modification to the exchanger's front face - mandated by the European Aviation Safety Agency - is designed to prevent this ice congestion.

But in a submission to the US FAA, Airbus has revealed that the modification is likely to extend to Trent 700s, an option on A330s, and Trent 500s which are the sole powerplant on the A340-500/600.

It follows an incident involving an Etihad Airways A330-200 which performed a go-around at Manchester on 19 May this year.

Both Trent 700 engines initially responded correctly but, as the aircraft climbed away, the left-hand powerplant "stagnated" before recovering after being throttled back, says the Airbus document.

Airbus states that investigations point to fuel-flow restriction as the "probable cause of the roll-back". While there were differences in the Trent 700's response, compared with the earlier Trent 800 events, restriction from icing "cannot be ruled out".

"Given the ongoing investigation into this phenomenon, Airbus has taken a precautionary approach by adding [the Etihad event] to the numerical risk analysis," says the airframer.

European Aviation Safety Agency regulators mandated the Trent 800 change through an airworthiness directive on 13 July.

But Airbus says: "It is intended to issue a similar [airworthiness directive] on Airbus aircraft applicable for the Trent 500 and the Trent 700 engines."

It is seeking approval from the FAA to install modified heat exchangers on Trent 700- and Trent 500-powered aircraft. The airframer has requested a two-year window, starting in October, in order to allow certification of the improved heat-exchanger face at aircraft level.

"Even if the scale of the threat has still to be defined, the enhanced [exchanger] has more capability to sustain ice release from the aircraft fuel system and its introduction is a good precautionary measure," adds Airbus.