AD 86-17-02

86-17-02 ROGERSON HILLER CORP.: Amendment 39-5367. Applies to Model UH-12D, UH-12E, and UH-12E4 series helicopters, including military Models OH-23F and OH-23G, and all those converted in accordance with STC's SH177WE and SH178WE, certificated in any category, equipped with main rotor blade fork P/N 52110-3.

Compliance is required as indicated, unless already accomplished.

To detect cracks and prevent failures which have occurred in the main rotor blade fork P/N 52110-3 at the outboard tension-torsion bar retention bolt hole, accomplish the following:

(a) Within the next 10 hours' time in service after the effective date of this AD, verify that each installed P/N 52110-3 fork has a serial number permanently displayed on its outer surface. Remove from service forks found not to be serialized and replace with serialized parts.

(b) Perform a daily visual check of P/N 52110-3 forks for cracks in the area of the outboard tension-torsion bar retention bolt hole. Washers and nuts need not be removed for this inspection. This check may be performed by the pilot.

NOTE: For the requirements regarding the listing of compliance and method of compliance with this AD in the aircraft's permanent maintenance record, see section 91.173.

(c) On forks having 240 or more hours' time in service on the effective date of this AD, within the next 10 hours' time in service, unless already accomplished within the last 90 hours' time in service, and within each 100 hours' time in service thereafter from the last inspection, accomplish the inspection specified in (e).

(d) On forks having less than 240 hours' time in service on the effective date of this AD, accomplish the inspection specified in (e) prior to the accumulation of 250 hours' time in service and within each 100 hours' time in service thereafter from the last inspection.

(e) Perform a dye penetrant inspection, or FAA-approved equivalent, of the bolt hole and adjacent milled surfaces. For this inspection, remove the nut, washer, and pin.

(f) Replace cracked rotor forks with like serviceable parts prior to further flight.

(g) Special flight permits may be issued in accordance with sections 21.197 and 21.199 to operate aircraft to a base for the accomplishment of inspections required by this AD.

(h) An alternate method of compliance which provides an equivalent level of safety may be approved by the Manager, Seattle Aircraft Certification Office, FAA, Northwest Mountain Region.

This amendment supersedes Amendment 39-3540 (44 FR 50035), AD 79-18-04. This amendment becomes effective August 22, 1986.