AD/BELL 412/12 Amdt 5 - Vertical Fin Forward Spar
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COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
View image in the official source 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:
- 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.