AD 84-19-51 R1

84-19-51 R1 SIKORSKY AIRCRAFT: Amendment 39-5008. Applies to Model S-76A helicopters Serial Numbers 76006, 76007, 760001 through 760339 certificated in all categories.

Compliance is required prior to further flight, unless already accomplished.

To prevent operation with damaged, bent, or fractured center firewall support stiffeners or doublers which could cut into the tail rotor driveshaft and cause loss of directional control of the helicopter, accomplish the following:

(a) Inspect the forward center firewall sections for missing fasteners and proper fit, as required in paragraphs E(1) through E(5)(C) of Sikorsky Alert Service Bulletin (ASB) 76-53-25 or FAA approved equivalent.

(b) If doubler, Part Number (P/N) 76070-20057-101, is cracked or fails to conform to the firewall contour or to the limits specified in ASB 76-53-25, paragraph E(5)(B), remove and replace as per paragraph E(5)(D) or FAA approved equivalent.

(c) If the rivets are not installed as required in paragraph (a) above, comply with paragraph E(5)(E) of ASB 76-53-25 or FAA approved equivalent.

(d) Remove the core section from the horizontal seal, P/N 76304-07003-127 or 76304-07003-137, on the aft engine cowl center section fixed or adjustable firewall assembly, P/N 76304-07003-041 or 76304-07003-044, respectively.

(e) Inspect stiffeners and doublers used to support the center firewall installation for fractures, distortions, or damage. Assure that the forward edges of the removable center firewall are properly engaged in the slots.

(f) Inspect the area between the number 1 section of the tail rotor driveshaft called out in Sikorsky Maintenance Manual (MM) SA 4047-76-2, Section 66-40-00, Figure 401, and the engine compartment center firewall for clearance in accordance with section 5-50-00 of the Airworthiness and Inspection Requirement Manual. If inadequate clearance is found, contact the Boston Aircraft Certification Office (617) 273-7113 or (617) 273-7001 prior to further flight.

(g) Helicopters not modified in accordance with Sikorsky Customer Service Notice 76-111 are required to accomplish the inspection of paragraph If) of this AD only.

(h) Special flight permits may be issued in accordance with FAR Sections 21.197 and 21.199 to operate helicopters to a base for accomplishment of this AD.

(i) Alternate repairs, modifications, or other means of compliance with the AD which provide an equivalent level of safety may be approved by the Manager, Boston Aircraft Certification Office, FAA, New England Region, 12 New England Executive Park, Burlington, Massachusetts 01803.

This amendment becomes effective March 7, 1985, as to all persons except those persons to whom it was made immediately effective by telegraphic AD's T84-19-51 issued September 27, 1984, and T84-19-51 R1 issued October 15, 1984, which contained this amendment.