AD 87-15-11

87-15-11 SIKORSKY AIRCRAFT: Amendment 39-5680. Applies to Model S-61L, S- 61N, S-61NM and S-61R series helicopters certificated in all categories and S-61A and S-61V series helicopters certificated in restricted category equipped with main gearbox servo cylinder support brackets (P/N's S6135-20248-0 and -2) or bracket assemblies (P/N's S6135-20249-0 and - 1).

Compliance is required as indicated unless already accomplished.

To preclude possible fatigue failure of the main gearbox servo support bracket (P/N's S6135-20248-0 and -2) or bracket assembly (P/N's S6135-20249-0 and -1) accomplish the following:

(a) Replace the P/N's S6135-20248-0 and -2 servo support brackets or the P/N's S6135-20249-0 and -1 support bracket assemblies with serviceable parts in accordance with the following schedule:

(1) For Model S-61A, S-61L, S-61N, S-61NM, and S-61V helicopters, replace the servo support bracket or assembly within the next 25 hours time in service after the effective date of this AD or before the accumulation of 23,200 hours time in service on-the bracket or assembly, whichever occurs later. Thereafter, replace the bracket or assembly in intervals not to exceed 23,200 hours time in service.

(2) For the Model S-61R helicopter, replace the servo support bracket or assembly within the next 25 hours time in service after the effective date of this AD or before the accumulation of 6,200 hours time in service on the bracket or assembly, whichever occurs later. Thereafter, replace the bracket or assembly at intervals not to exceed 6,200 hours time in service.

(b) Operators who have not kept records of hours time in service on individual component parts that were installed at time of issuance of the initial rotorcraft airworthiness certificate shall substitute rotorcraft hours time in service.

(c) For purposes of complying with this AD, the hours time in service for individual components that were not installed at the time of issuance ofthe initial rotorcraft airworthiness certificate must be determined from operators rotorcraft records.

(d) Upon request, an alternate means of compliance which provides a level of safety equivalent to the requirements of this AD may be used when approved by the Manager, Boston Aircraft Certification Office, 12 New England Executive Park, Burlington, Massachusetts 01803, telephone (617) 273-7118.

(e) Upon submission of substantiating data by an owner or operator through an FAA maintenance inspector, the Manager, Boston Aircraft Certification Office, 12 New England Executive Park, Burlington, Massachusetts 01803, telephone (617) 273-7118, may adjust the compliance time specified in this AD.

This amendment, 39-5680, becomes effective on August 10, 1987.