AD/A330/57 Engine Icing Conditions During Descent Operational Procedure (Cth)

AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.001(1) of CASR 1998.  The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

Airbus Industrie A330 Series Aeroplanes

AD/A330/57 Engine - Icing Conditions During
Descent - Operational Procedure 9/2006 TX

Applicability:

AIRBUS A330 aircraft, -201, -202, -203, -301, -302 and -303 models.

Requirement:

Incorporate the following amendment into the Aircraft Flight Manual (AFM). The amendment may be accomplished by including the text detailed below or by including A330 AFM TR 4.03.00/27 into the AFM.

“ICING CONDITIONS EXPECTED DURING DESCENT

•      If icing conditions (including ice crystals) are expected during descent:

•      At top of descent, or at the latest before entering the expected icing conditions:

Select ENG ANTI ICE and WING ANTI ICE to ON.

Select PACK FLOW at HI.

•      Below 10 000 ft:

Resume normal operation.”

Note:  EASA Emergency AD 2006-0212-E dated 13 July 2006 refers.

Compliance:

From the effective date of this AD.

This Airworthiness Directive becomes effective on 19 July 2006.

Background:

Several A330 aircraft equipped with General Electric (GE) CF6-80E1 engines experienced an engine flame out during descent, 2 to 3 seconds after engine acceleration upon aircraft altitude capture, under inclement weather conditions.  In all cases, the engines restarted and then operated normally.

The analysis has shown that at high altitude an accretion of the conventional ice or ice crystals in the engine fan or booster stages during descent at low engine power can shed in significant amount into the core inlet upon engine acceleration when the variable bleed valve doors close.  This ice ingestion will then increase the water/air ratio leading to flame smothering.

This situation if not corrected can lead to the temporary loss of both engines thrust in flight which constitutes an unsafe condition.  In order to mitigate the risk of a dual engine flame out in flight, this AD mandates the operational procedure which increases the fuel/air ratio in the engine during the descent and under inclement weather conditions.

James Coyne
Delegate of the Civil Aviation Safety Authority

16 July 2006