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AD/R44/22 Amdt 1 - Main Rotor Blade Leading Edge and Tip Cap Area Skin

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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/R44/22 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.
Robinson R44 Series Helicopters
AD/R44/22 Amdt 1
Main Rotor Blade Leading
Edge and Tip Cap Area Skin
4/2008 DM
 
Applicability:
Model R44 and R44 II model helicopters, with main rotor blades part number C106-2 or C106-5 installed.

Requirement:
1.    Main rotor blades installed on helicopters:
(a)   Inspect the main rotor blade for exposed skin-to-spar bond line, then, using 10x or higher magnification, visually inspect each main rotor blade for skin separation along the leading edge of any exposed (bare metal) blade skin aft of the skin-to-spar bond line on the lower surface of each main rotor blade.
(b)   Perform a “tap test” to detect any separation or void on the skin-to-spar bonded areas on the lower blade skin aft of the skin-to-spar bond line of each main rotor blade using a suitably weighted coin.
(c)   Remove main rotor blade tip cover of each main rotor blade.  Using 10x or higher magnification, visually inspect the blade tip area exposed when the blade tip covers were removed.  “Tap test” the skin-to-cap bond joints on both upper and lower surfaces.
(d)   If the main rotor blade has been found airworthy, refinish the main rotor blade according to the Compliance Procedure, paragraphs 3 through 7, of Robinson R44 Service Letter SL-32 Revision A, dated 29 March 2007.
2.    If any corrosion, separation, or any void is detected by the Requirement 1 inspections, the main rotor blade is unairworthy and must be replaced.
3.    (a)   Visually check for any exposed (bare metal) blade skin aft of the skin-to-spar bond line on the lower surface of each main rotor blade within the outboard 24-inches, paying particular attention to the last 10-inches before the tip.
(b)   Should any exposed (bare metal) blade skin aft of the skin-to-spar bond line on the lower surface of any main rotor blade be found, then Requirements 1(a) through 1(d) of this directive must be accomplished.

 
 
 
Note 1:  Damage to the skin-to-spar bond line may be limited by maintaining a protective coating over the bond line area in accordance with Requirement 1 para (d).
This Directive shall be entered on the maintenance release as maintenance required.  The Requirement 3 (a) visual inspection may be performed and certified by the Pilot in Command who has been trained to do the inspection by an appropriately qualified person.  In this case, a copy of this Directive is to be carried in the aircraft.
Note 2:  FAA AD 2007-26-12 Amdt 39-15314 and FAA Approved Alternate Method of Compliance (AMOC) for AD 2007-26-12 refer.

Compliance:
1.    (a) to (c)  Within 10 hours time in service after 18 January 2008, unless already accomplished and thereafter within each 100 hours or 12 months Time In Service, whichever comes first.
1.    (d)  Whenever the main rotor blade has been found airworthy in accordance with the Requirements of this AD, and if any portion of the skin-to-spar bond line is exposed.
2.    Before further flight.
3.    (a)   Before each flight.
3.    (b)   Before further flight

 
This Amendment becomes effective on 29 February 2008.

Background:
The FAA received eleven reports of main rotor blade debond, some occurring in flight causing the pilot to experience excessive vibrations and land as a consequence, and some found during routine maintenance.  The actions specified in this Directive are intended to detect blade skin debond and to prevent blade failure and subsequent loss of control of the helicopter.

David Villiers
Delegate of the Civil Aviation Safety Authority
18 February 2008