81-21-01: Erc Cargo Hook Assemblies

81-21-01 SOCIETE NATIONALE INDUSTRIELLE AEROSPATIALE (SNIAS): Amendment 39-4227. Applies to Model SA315B helicopters, equipped with Eastern Rotorcraft Corporation (ERC) cargo hook assemblies, P/N 17112-4, Serial Numbers 1 through 103, in accordance with Supplemental Type Certificate (STC) SH1735SW, certificated in all categories (Airworthiness Docket No. 81-ASW-33). Compliance required as indicated. To prevent possible failure of the ERC cargo hook support legs, P/N 12579-1, due to fatigue cracks, accomplish the following, unless already accomplished, within the next 100 hours' time in service after the effective date of this AD: a. For suspension assemblies, P/N 17112-4, which have accumulated 1,000 lifts or calendar months of service, whichever occurs first, accomplish a magnetic particle inspection of the lugs, P/N 12579-1, in accordance with Aerospatiale Helicopter Corporation Service Bulletin No. SB315-05, dated March 11, 1981, or an FAA-approved equivalent.b. If one lug is found to have cracks, remove and replace all four lugs in accordance with Aerospatiale Helicopter Corporation Service Bulletin No. SB315-04, dated January 20, 1981, or an FAA-approved equivalent. c. If no lugs are cracked, reinstall and accomplish magnetic particle inspections at intervals of 1,000 lifts or 12 calendar months, whichever occurs first, as required by paragraph a. of this AD. d. The inspections required by paragraph a. of this AD are not required after compliance with Aerospatiale Helicopter Corporation Service Bulletin No. SB315-04. e. The helicopter may be flown in accordance with FAR 21.197 to a base where inspections can be performed. f. For the purpose of complying with this AD, subject to acceptance by the assigned FAA maintenance inspector, the number of lifts may be determined by multiplying each helicopter's hours' time in service by the operator's fleet average lifts per hour for the helicopter type. This amendment becomes effective November 4, 1981.