The European Aviation Safety Agency (EASA) issued an emergency airworthiness directive EAD 2010-0042-E regarding the main fuel pump system and water scavenge system on certain Airbus A330 aircraft.
During a recent in-service event the flight crew of a Trent 700 powered A330 aircraft reported a temporary Engine Pressure Ratio (EPR) shortfall on engine 2 during the take-off phase of the flight. The ENG STALL warning was set. The flight crew followed the standard procedures which included reducing throttle to idle. The engine recovered and provided the demanded thrust level for the remainder of the flight.
Data analysis confirmed a temporary fuel flow restriction and subsequent recovery, and indicated that also engine 1 experienced a temporary fuel flow restriction shortly after the initial event on engine 2, again followed by a full recovery. The engine 1 EPR shortfall was insufficient to trigger any associated warning and was only noted through analysis of the flight data.
No flight crew action was necessary to recover normal performance on this engine. The remainder of the flight was uneventful.
Based on previous industry-wide experience, the investigation of the event has focused on the possibility for ice to temporarily restrict the fuel flow.
While no direct fuel system fault has been identified, the operation of the water scavenge system at Rib 3 cannot be excluded as being a contributory factor.
Testing and analysis are continuing to identify the root cause of the event.
The scenario of ice being shed and causing a temporary blockage in the engine fuel system may lead to a temporary fuel flow restriction to the engine. This may result in a possible engine surge or stall condition, and in the engine not being able to provide the commanded thrust.
Therefore, as a precautionary measure to reduce the possibility of ingesting ice into the engine fuel feed system, this AD requires to:
– deactivate the automatic Standby Fuel Pump Scavenge System, which operates during Taxi and Take-off by removing relays
Functional Item Numbers (FIN) 80QA1 and 80QA2 (this will not affect normal standby pump operation) for aeroplanes identified in the applicability section of this AD and on which this deactivation has not been performed in production through the modification 200801, and
– Prohibit the dispatch with one MAIN Fuel Pump inoperative on all aeroplanes identified in the applicability section of this AD.