AD/EC 225/5 Main Rotor Blade Leading Edge Protective Strip (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 225 Series Helicopters

AD/EC 225/5 Main Rotor Blade Leading Edge Protective Strip 11/2008

Applicability:

EC 225 LP helicopters, all serial numbers fitted with Main Rotor Blades P/N 332A11.0050.00 or P/N 332A11.0055.00.

Requirement:

1.    Visually inspect and tap test the leading edge stainless steel protective strip on each of the main rotor blades in accordance with the instructions of Paragraph 2.B of Eurocopter EC 225 Alert Service Bulletin (ASB) 05A010 dated
28 June 2007.

Damage Criteria (i) If no crack, no cut and no de-bonding is found; or if blind de-bonding is found within the permissible criteria defined in Aircraft Maintenance Manual (MMA) Task 62-10-00-211; or if open de-bonding is found, located inside area D at the end of the blade main section on the blade tip cap side (see Figure 1 in the ASB) AND it is still within the permissible criteria defined in MMA Task 62-10-00-211, the helicopter may be returned to service until the next inspection in accordance with requirement (1) of this directive.

Damage Criteria (ii) If open de-bonding is found, located outside area D at the end of the blade main section on the blade tip cap side (see Figure 1 in the ASB), still within the permissible criteria defined in MMA Task 62-10-00-211; and/or if a cut is found in the blade root polyurethane protective strip AND no de-bonding of the area (see Figure 2 in the ASB); and/or if a crack is found in the blade leading edge, still within the permissible criteria defined in MMA Task
62-10-00-211, then perform requirement (2) of this AD.

2.    If detected damage matches the criteria in Requirement (1) (ii), Tap test the affected blade in accordance with the instructions of Paragraph 2.B.2.b and/or 2.B.2.c and/or 2.B.2.d, as applicable, of Eurocopter EC 225 ASB 05A010 dated 28 June 2007.  Otherwise, further repeat inspections are to be conducted in accordance with requirement (1).

If blind or open de-bonding is found or if a crack is found beyond the permissible criteria defined in MMA Task 62-10-00-211, replace the affected blade with an airworthy part before further flight.

Note:  EASA AD 2007-0180-E, dated 29 June 2007 refers.

Compliance:

1.    Within the next 15 flight hours after the effective date of this directive and then at intervals not to exceed 85 flight hours.

2.    Intervals not to exceed 15 flight hours.

This Airworthiness Directive becomes effective on 23 October 2008.

Background:

Recently, significant de-bonding of the stainless steel protective strip was discovered on main rotor blades installed on a Eurocopter EC 225 LP helicopter.  The initial investigation revealed rapidly progressing de-bonding which may be due to water that may have entered from the crack that was detected in the leading edge stainless steel protective strip.  This condition, if undetected, can result in loss of the main rotor blade stainless steel protective strip, and severe vibrations induced by the weight unbalance may occur.

This Airworthiness Directive requires the initial and repetitive inspection of the stainless steel protective strips on the leading edge of the main rotor blades and replacement of main rotor blades, as necessary.

David Villiers
Delegate of the Civil Aviation Safety Authority

27 August 2008