COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell Helicopter Textron 47 (All Variants) Series Helicopters AIRWORTHINESS DIRECTIVE For the reasons set out in the background section, the CASA delegate whose signature appears below revokes Airworthiness Directive (AD) AD/BELL 47/92 Amdt 4 and issues the following AD under subregulation 39.1 (1) of CAR 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. AD/BELL 47/92 Amdt 5 Applicability: All models. Main Rotor Blade Grips 2/2001 TX Requirement: 1. Inspect the internal threaded portion of each main rotor blade grip barrel using eddy current procedure DOA/NDI/EC6. Copies of this procedure are available from the Authority. 2. Retire the main rotor blade grips from service before exceeding 5000 hours time in service. Note: Grip assemblies part number 47-120-252-5 are not approved for use in Australia. Compliance: Unless the initial inspection is already accomplished, at the threshold of 600 hours component time since new or within 25 hours time in service after 21 December 2000, whichever occurs later. Repeat thereafter at intervals not to exceed 600 hours component time in service until retired in accordance with Requirement 2. Note: Compliance with the requirements of this Directive permits operation beyond the retirement life stipulated in the manufacturer's documentation. This amendment becomes effective on 21 December 2000. Background: Numerous fatigue cracks in the internal threads of the main rotor blade grips have been detected in-service by the specified eddy current procedure, which would not be detectable by dye penetrant methods. To control this risk of failure, the previously substantiated 5,000 hour retirement life was reintroduced. The previous issue of this Directive and Transport Canada AD CF-1988-08 required eddy current inspections at the same initial inspection threshold, with the TC AD 300 hour repeat interval being the only difference. FAA AD 86-06-08 R1 required a fluorescent dye penetrant inspection method, a 1,200 hour threshold and a 300 hour repeat interval. COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES A new FAA AD, 2000-18-51, requires a liquid penetrant or eddy current inspection at significantly reduced inspection intervals and establishes a 1,200 hour retirement life. The changes were prompted by the results of an accident investigation and a field survey; findings not supported by Bell. Amendment 5 retains the inspection method and the repetitive inspection interval, but changes the initial inspection threshold. This change is in response to Transport Canada AD CF-1988-08 R1 which was prompted by three cases of cracks being found before the initial inspection threshold. The Authority has received several MDRs of cracked blade grips that were found before the initial 1200 hour inspection threshold. Amendment 4 of this Airworthiness Directive became effective on 12 October 1985. Amendment 3 of this Airworthiness Directive became effective on 30 June 1985. The original issue of this Airworthiness Directive became effective on 2 July 1985. William Ronald Smith Delegate of the Civil Aviation Safety Authority 19 December 2000 The above AD is notified in the Commonwealth of Australia Gazette on 21 December 2000.