AD/AB139/5 Exhaust Tailpipe Assembly (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.

Agusta AB139 and AW139 Series Helicopters

AD/AB139/5 Exhaust  Tailpipe Assembly 4/2008

Applicability:

AB 139 and AW 139 helicopters, all serial numbers, except 31002, 31003, 31004 and 31007, if equipped with Tailpipe Assemblies having Part Number (P/N) 3G7800L00131 (LH) or 3G7800L00231 (RH).

Requirement:

1.    For AB 139 helicopters - inspect the tailpipe assembly in accordance with the instructions of Agusta BT 139-069 Revision A dated 8 November 2006 or later approved revision.

2.    For AW 139 helicopters - inspect the tailpipe assembly in accordance with the instructions of Agusta BT 139-069 Revision A or later approved revision.

3.    If heat damage or cracks are found in the exhaust area residing inside the cowling, replace the damaged tailpipe assembly with an airworthy part in accordance with the Agusta AW139 Aircraft Maintenance Publication (AMP).

4.    If cracks are found in the exhaust area residing outside the cowling that turn off abruptly from the original direction or are outside the allowable limits established by Agusta BT 139-069 Rev. A, or later approved revision, replace the cracked tailpipe assembly with an airworthy part in accordance with the Agusta AW139 Aircraft Maintenance Publication. (AMP).

5.    If cracks are found in the exhaust area residing outside the cowling that are within the allowable limits established by Agusta BT 139-069 Rev. A, or later approved revision one of the following repairs must be accomplished:

a)    Drill a stop hole at the end of the crack and perform an inspection to verify that crack length does not increase. If the crack length increases to the limits established by Agusta BT 139-069 Rev. A, or later approved revision, replace the cracked tailpipe assembly with an airworthy part in accordance with the Agusta AW139 Aircraft Maintenance Publication (AMP).

b)    Repair in accordance with the instructions of Agusta BT 139-069 Rev. A.

6.    Thereafter, repeat the applicable inspection as detailed in Requirement 1 or 2 of this AD and accomplish the follow-up actions, as required.

Repair or replacement of the affected tailpipe assembly does not constitute terminating action for the repetitive inspection as detailed in Requirement 6 of this AD.

Note:  EASA AD 2006-0360-E dated 29 November 2006 refers.

Compliance:

1.    Within 30 days after the effective date of this AD unless previously accomplished.

2.    Within 30 days after the effective date of this AD unless previously accomplished.

3.    Before further flight after the effective date of this AD.

4.    Before further flight after the effective date of this AD.

5.    Before further flight after the effective date of this AD.

6.    At intervals not to exceed 25 flight hours.

This Airworthiness Directive becomes effective on 10 April 2008.

Background:

Field reports have shown that the Agusta AB/AW 139’s Tailpipe Assembly is prone to cracks.  To prevent any cracks from developing into failure of the exhaust tailpipe assembly, a repetitive inspection and, if necessary, replacement is required by this AD.

David Punshon
Delegate of the Civil Aviation Safety Authority

27 February 2008