COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Bell Helicopter Textron 412 Series Helicopters AD/BELL412/12 Amdt 5 Applicability: All models. Vertical Fin Forward Spar 6/93 DM Requirement: 1. For helicopters fitted with fin spar cap P/N 212-030-447-001: Inspect the spar cap for cracks, corrosion and doubler debonding in accordance with Bell ASB 412-92- 65. Note: FAA AD 93-02-07 refers. Note: All fin spar caps P/N 212-030-447-001 should have been modified with a cold bonded doubler in accordance with Bell ASB 412-85-20 not later than 31 March 1986. Amendment 2 to this AD referred. 2. For helicopters fitted with fin spar cap P/N 212-030-447-101: 1. If cap thickness is greater than or equal to 0.190 inches when measured as shown in Bell ASB 412-86-24, no further action is required by this AD; b. If cap thickness is less than 0.190 inches and the cap has been modified with a cold bonded doubler in accordance with Bell ASB 412-86-24, inspect for cracks, corrosion and doubler debonding using the inspection technique described in Part I of Bell ASB 412-92-65. Inspect at intervals not exceeding 100 hours time in service or 25 flight operation days, whichever occurs earlier, until replaced by a new cap P/N 212-030-447-101 in accordance with Bell ASB 412-92-65; c. If cap thickness is less than 0.190 inches, but not less than 0.155 inches, and the cap has not been modified with a cold bonded doubler in accordance with Bell ASB 412-86-24, inspect for cracks in accordance with the inspection technique described in Part I of Bell ASB 412-85-20 Revision B. Inspect at intervals not exceeding 20 hours time in service or 5 flight operation days, whichever occurs earlier, until replaced with a new cap P/N 212-030-447-101 in accordance with Bell ASB 412-92-65. Note: All fin spar caps P/N 212-030-447-101 that were less than 0.155 inches thick should have been modified with a cold bonded doubler in accordance with Bell ASB 412-86-24 not later than 31 December 1986. AD/BELL 412/16 (incorporated into this AD at Amendment 3) referred. Compliance: Inspect within 25 hours time in service from 26 March 1993. Re-inspect at intervals not to exceed 25 hours time in service, until replaced with a new cap P/N 212-030-447-101 in accordance with Bell ASB 412-92-65. COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY SCHEDULE OF AIRWORTHINESS DIRECTIVES Background: P/N 212-030-447-001 fin spar caps with a cold bonded doubler fitted in accordance with Bell ASB 412-85-20, and undersized P/N 212-030-447-101 fin spar caps with a cold bonded doubler fitted in accordance with Bell ASB 412-86-24, require inspections because of reports of cracks originating from corrosion under the doublers. P/N 212-030-447-101 fin spar caps with thicknesses between 0.155 inches and 0.190 inches, and which have not had a cold bonded doubler fitted, require inspection because the fatigue strength of this size cap has not been demonstrated. The format of this AD has changed to improve clarity; the only technical change is a reduction of the inspection interval for modified -001 spar caps from 100 hours to 25 hours, introduced by Bell Alert Service Bulletin 412-92-65.