COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Helio Courier Series Aeroplanes AD/HELIO/1 Amdt 1 Applicability: All models. Wing Centre Section Main Spar Carry Thru Assembly 1/87 Requirement: 1. For aircraft incorporating wing main spar centre section carry thru assembly P/N 295-030-401, inspect the carry- thru assembly in accordance with Para B) of FAA AD 82-16-08. 2. Modify the wing centre section carry-thru assembly P/N 391-030-401 or 295-030- 401 as applicable, by installing a full span (wing joint to wing joint) fail safe reinforcement of the lower tube in accordance with a scheme approved by the Secretary. FAA STC's SA 1590CE and SA 1728CE, respectively, are approved schemes. 3. After modification in accordance with 2 above, inspect the carry-thru assembly in accordance with Para D) of FAA AD 82-16-08. Compliance: For Para 1: At intervals not exceeding 100 hours time in service, until modified in accordance with Para 2. For Para 2: For land planes - prior to exceeding 2000 hours time in service. For float planes or aircraft which have at any time had floats installed - prior to exceeding 2000 hours equivalent land plane time in service. To convert float plane time to equivalent land plane time, multiply by two. For Para 3: At intervals not exceeding 1500 hours time in service. Background: Fatal accidents have occurred overseas as a result of fatigue failures of the wing spar carry-thru assembly lower tube or end fitting. This Directive combines the requirements of the previous AD/HELIO/1 and AD/HELIO/3 Amdt 1 but provides for fail safe reinforcement modification rather than retirement. Most importantly, it eliminates confusion over the "modification" aspect of those earlier AD's; it was not clear that the modification referred to is the joint to joint straps across the full span of the lower tube, rather than the end reinforcement only (ie. the P/N 295-030-401 configuration).