4. Spare MGB’s incorporating bevel gears that have logged more than 6,600 flying hours and have not been installed since last overhaul:

Within 150 flight hours of installation, thereafter at 150 flight hour intervals or 1000 torque application cycles on helicopters that perform external load carrying missions, whichever occurs first.

Note 2: External Load Carrying missions are defined as those missions where a torque application frequency of more than 4 cycles per hour.

This Amendment becomes effective on 30 October 2003.

Background: This Amendment amends the inspection interval to take into consideration the stress imposed on the MGB bevel gear during external load missions. External load missions will increase the growth rate of any cracks that have formed. An increase in the number of inspections will be required for helicopters involved in such operations to prevent failure of the bevel gear.

Advice has been received from the manufacturer that a cracked bevel gear was discovered following detection of metal particles on the magnetic plug. Until the cause of the cracking can be determined a repetitive inspection has been put in place to prevent in flight failure of the bevel gear.

Amendment 1 of this Airworthiness Directive became effective on 23 January 2003.

The original issue of this Airworthiness Directive became effective on 3 October 2002.

Signature of Jim Coyne Delegate of the Civil Aviation Safety Authority

Jim Coyne

Delegate of the Civil Aviation Safety Authority 19 September 2003

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The above AD is notified in the Commonwealth of Australia Gazette on 8 October 2003.