COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES DH114 (Heron) Series Aeroplanes AD/DH114/29 Amdt 1 Main Undercarriage - Main and Damper NK Jack Bolts - Inspection and Modification Applicability: All Series 2 aircraft. Requirement: Inspect the attachment bolts at each end of the damper jack and at the top of the main jack for fatigue cracking as follows: 1. For aircraft fitted with attachment bolts P/No. 14-2U.299:- (a) Remove the bolts and inspect for cracking around the centre grease hole using a magnetic particle method. (b) Incorporate Modification No. 1536. 2. For aircraft fitted with attachment bolts P/No. 14-2U.631:- Remove the bolts and inspect for cracking around the centre grease hole using a magnetic particle method. Compliance: For Para. 1: (a) For aircraft inspected in accordance with the previous issue of this Directive - within 300 hours time in service from the previous inspection; and For all other aircraft - within 150 hours time in service after 31 May 1972; and For all other aircraft - thereafter at intervals not exceeding 300 hours time in service. (b) Before 31 December 1972. For Para. 2: Within 2400 hours time in service after the incorporation of modification 1536 and thereafter at intervals not exceeding 2400 hours time in service.