72-25-04 SIKORSKY: Amdt. 39-1571. Applies to all Sikorsky S-61A, S-61B, S-61D, S- 61L Series prior to SS No. 61454, S-61N Series prior to SS No. 61493, S-61R, S-61V helicopters certificated in all categories.
Compliance required as indicated.
To prevent hazards in flight due to loss of main rotor control as a result of cracked primary servo mounting bracket retaining nuts, accomplish the following:
(a) Within the next 25 hours time in service after the effective date of this Airworthiness Directive, remove all MS21042-6 or MS20365-624C retaining nuts from the primary servo mounting brackets, P/N S613520249, and replace with P/N MS21045-6 retaining nuts in accordance with Sikorsky Service Bulletin No. 61B35-18 dated 10 November 1972 or later revision approved by the Chief, Engineering and Manufacturing Branch, FAA, New England Region.
(b) Upon request with substantiation data submitted through an FAA maintenance inspector, the compliance time specified in this AD may be increased by the Chief, Engineering and Manufacturing Branch, FAA, New England Region.
(c) Equivalent methods of compliance must be approved by the Chief, Engineering and Manufacturing Branch, FAA, New England Region.
This amendment becomes effective December 15, 1972.