AD/EC 135/21 Rear Structure / Tail Boom (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.

Eurocopter EC 135 Series Helicopters

AD/EC 135/21 Rear Structure / Tail Boom 13/2008 TX

Applicability:

Models EC135 P1(CDS), EC135 P1(CPDS), EC135 P2(CPDS), EC 135 P2+, EC 135 T1(CDS), EC 135 T1(CPDS), EC 135 T2(CPDS), EC 135 T2+ helicopters, all serial numbers.

Requirement:

1.    Amend the basic Flight Manual (FLM), Section 4 Pre-Flight Check, by inserting pages 5 and/or 6 of Eurocopter Deutschland (ECD) EC135 Alert Service Bulletin (ASB) EC135-53A-022 original issue, or later EASA approved revision, into the FLM, as applicable to helicopter model; and inform the flight crew accordingly.

2.    Accomplish a visual inspection of the rear tube structure in accordance with ECD ASB EC135-53A-022 original issue, or later EASA approved revision.

The pilot is permitted to accomplish this inspection as part of the regular pre-flight checks, provided he/she has been trained to do the inspection by an appropriately qualified person.

If, during any inspection required by this Directive, cracks are detected within the ring frame as specified in the ASB, before further flight, contact ECD for approved corrective action instructions and accomplish those instructions accordingly.

Note 1:  The replacement of parts does not constitute terminating action for the repetitive inspection requirements of this Directive.

Note 2:  EASA Emergency AD 2008-0190-E refers.

Compliance:

1.    Before further flight after 15 October 2008.

2.    Before further flight after 15 October 2008, and thereafter before each first flight of a day.  Within 25 flight hours (+5 flight hours) after initial compliance, the required visual inspection must be accomplished once by qualified maintenance personnel, in accordance with ECD ASB EC135-53A-022 original issue, or later EASA approved revision.

This Airworthiness Directive becomes effective on 15 October 2008.

Background: During a recent pre-flight check on a Model EC135 helicopter, a crack was detected on the ring frame that connects the tail rotor Fenestron housing to the rear structure tube (tail boom).  The crack ran alongside one rivet row over almost half the circumference of the ring frame.  This condition, if not corrected, could lead to crack propagation remaining undetected, possibly resulting in loss of the Fenestron structure and loss of control of the helicopter.

David Villiers
Delegate of the Civil Aviation Safety Authority

14 October 2008