AD/As 355/60 Amdt 5 Tail Rotor Blade Trailing Edge (Cth)

AIRWORTHINESS DIRECTIVE

On the effective date specified below, and for the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/AS 355/60 Amdt 4 and issues the following 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 AS 355 (Twin Ecureuil) Series Helicopters

AD/AS 355/60 Amdt 5 Tail Rotor Blade Trailing Edge 6/2009

Applicability:

Model AS 355 helicopters, versions E, F, F1, F2, N and NP, equipped with a tail rotor blade part number listed below:

355A12-0031-01, -02, -03, -04, -05, -06, -07, -08, -09, -11, -12, -13, -14.
355A12-0040-00, -01, -02, -03, -04, -05, -07, -08.
355A12-0050-00, -01, -02, -03, -04, -05.

Requirement:

1.    Visually inspect the tail rotor blades in accordance with paragraph 2.B.1. of Eurocopter AS 355 Alert Service Bulletin (ASB) No. 05.00.38 Revision 2, or later EASA approved revision.

If a crack is detected during any inspection, before further flight, accomplish the instructions specified in paragraph 2.B.2. of ASB No. 05.00.38 Revision 2, or later EASA approved revision.

2.    Accomplish the instructions of Repair Sheet FR CN 376 or FR CN 453 on tail rotor blades part number 355A12-0050-00, -01, -02, -03, -04, -05 with serial numbers listed in paragraph 2.B.2.a. of ASB No. 05.00.38 Revision 3, or later EASA approved revision, and on blades with serial numbers below 8419; for which the annotation “repaired as per Work Card 64.10.00.872” or “repaired as per Work Card 64.10.20.712” is recorded on the log card.

3.    No person shall install tail rotor blades with a part number that is listed in the applicability section of this Directive on any Model AS 355 helicopter, unless they have been inspected and repaired, as necessary, in accordance with paragraph 2.B.1 of ASB No. 05.00.38 Revision 3, or later EASA approved revision.

Note:  EASA AD 2009-0039 refers.

Compliance:

1.    At each check after the last flight of the day (ALF check), and thereafter at intervals not exceeding 10 flight hours between two successive checks.

2.    No later than 31 March 2009, unless already accomplished.

3.    As of 9 April 2009.

The compliance times remain unchanged by this issue of the Directive.

This Directive shall be entered on the Maintenance Release as maintenance required.  The required visual inspection may be performed and certified by a Pilot in Command who has been trained to do the inspection by an appropriately qualified person.  In this case, a copy of the Requirement document and this Directive is to be carried in the aircraft.

This Amendment becomes effective on 4 June 2009.

Background:

The DGAC received a report of separation of a tail rotor blade trailing edge section due to crack growth in the blade skin.  The unbalance caused by the loss of a blade section can cause tail rotor gearbox separation.

Amendment 1 introduced certain actions to rotors installed on version N helicopters that are fitted with a 30mm trailing edge tab.

Amendment 2 introduced requirements to alleviate maintenance for tail rotor blades repaired as per Repair Sheet (FR) CN 376; as specified in the latest revision of the Requirement document.

Amendment 3 added a new Repair Sheet FR CN 453, and extended the repair accomplishment timescale accordingly; as specified in the Requirement document.

Amendment 4 introduced a correction to the Requirement 1 compliance; with no change to the technical requirements.

Amendment 5 is issued in response to a new EASA AD, which adds the Model
AS 355 NP helicopter to applicability, with no change to the technical requirements.  At the time this directive was issued, there were no AS 355 NP helicopters on the Australian Register.

David Villiers
Delegate of the Civil Aviation Safety Authority

17 April 2009