Warning devices involving a British Aerospace PLC BAe 146-300, VH-EWR, Melbourne, Victoria, on 31 July 1994

When the aircraft encountered icing conditions at 3000 feet on climb the following annunciator lights illuminated:

• #2 INTAKE LOW PRESSURE
• #2 AIR FAULT
• #4 AIR FAULT
• #2 AIR VALVE
• #4 AIR VALVE

The aircraft returned to Melbourne for a normal landing. Maintenance replaced the #2 engine intake low pressure switch and carried out satisfactory ground runs. During later testing the intake low pressure switch was found to be serviceable.

Further checks were carried out on the performance of the number 2 and 4 engines during the overnight service, but the fault was unable to be reproduced. The flight data recorder was not examined to ascertain the flight and engine parameters at the time of the incident.

Maintenance noted that low duct temperatures will give an AIR LOW TEMP warning which will cause the AIR FAULT and AIR VALVE lights to come on. Maintenance advised that it was necessary to maintain 90% N2 to obtain satisfactory airframe anti-ice performance thereby maintaining adequate intake duct temperatures.

Maintenance asked that if the fault reappeared the pilots should supply the N2 figures. The fault has not reappeared.

Significant Factors

The following factors were considered relevant to the development of the incident.

1.The aircraft was flown in icing conditions with thrust settings below those required to maintain adequate anti-ice performance.

2.The reason why this occurred was not established.