AD 89-07-12

89-07-12 SIKORSKY AIRCRAFT: Amendment 39-6171.

Applicability: Model S-76 series helicopters, certificated in any category, that are equipped with tail rotor horn, P/N 76101-05006.

Compliance: Required as indicated, unless already accomplished.

To prevent possible fatigue failure of the tail rotor component, which could result in a reduction of directional control and hazardous tail rotor vibration in the helicopter, accomplish the following:

(a) Within the next 100 hours' time in service after the effective date of this AD or before the accumulation of 12,000 hours time in service, whichever occurs later, replace the tail rotor horn, P/N 76101-05006, with a serviceable tail rotor horn that has not exceeded 12,000 hours' time in service. Thereafter, replace the tail rotor horn P/N 76101-05006, with a serviceable tail rotor horn before the accumulation of 12,000 hours' time in service.

(b) Operators who have not kept records of hours' time in service on individual tail rotor horn component parts must substitute the hours' time in service of the tail rotor blade bonded assembly, P/N 76101-05020 or P/N 76088-20077.

(c) For purposes of complying with this AD, the hours' time in service for the individual tail rotor horn and blade components that were not installed at the time of issuance of the initial rotorcraft airworthiness certificate must be determined from 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, Engine and Propeller Directorate, Aircraft Certification Service, 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 Aviation Safety Inspector, the Manager, Boston Aircraft Certification Office, Engine and Propeller Directorate, Aircraft Certification Service, 12 New England Executive Park, Burlington, Massachusetts 01803, telephone (617) 273-7118, may adjust the compliance time specified in this AD.

This amendment (39-6171, AD 89-07-12) becomes effective on April 27, 1989.