85-23-51 R1 BOEING VERTOL COMPANY: Amendment 39-5253. Applies to Boeing Vertol Model 234 series helicopters certificated in any category.
Compliance is required as indicated unless already accomplished.
To prevent possible hazards in flight associated with a cracked main rotor head vertical hinge pin, accomplish the following:
(a) Prior to further flight, conduct a visual inspection of the forward and aft main rotor head vertical hinge pins, P/N 114R2172-1, internal surface with a light assisted bore-scope for cracks.
(b) After the initial inspection of paragraph (a), repeat the inspection prior to the first flight of each day.
(c) Within the next 150 hours time in service from March 31, 1986, conduct an eddy current inspection of the internal surfaces of the forward and aft main rotor head vertical hinge pins, P/N 114R2172-1, in accordance with the instructions contained in Boeing Vertol Document D210-12089-1 titled "Eddy Current Inspection Requirements for Detection of Cracks in P/N 114R2172, Vertical Hinge Pins." Upon accomplishment of this paragraph, the daily bore-scope inspection of paragraph (b) may be eliminated.
(d) Within the next 500 hours time in service from March 31, 1986, remove from the helicopter the main rotor head vertical hinge pins and conduct a magnetic particle inspection in accordance with Boeing Airplane Company document BAC 5424 titled "Magnetic Particle Inspection" Class B.
(e) Remove from service vertical hinge pins found cracked and replace with a serviceable part prior to further flight.
(f) Any alternate method of compliance with the AD which provides an equivalent level of safety may be used when approved by the Manager, New York Aircraft Certification Office, Federal Aviation Administration, 181 South Franklin Avenue, Valley Stream, New York 11581.
The manufacturer's specifications and procedures identified and described in this directive are incorporated herein and made a part hereof pursuant to 5 U.S.C. 552(a)(1). All persons affected by this directive who have not already received these documents from the manufacturer may obtain copies upon request to Boeing Vertol Company, Boeing Center, P.O. Box 1858, Philadelphia, Pennsylvania 19142. These documents may also be examined at the Office of the Regional Counsel, FAA Southwest Region, Federal Aviation Administration, 4400 Blue Mound Road, Fort Worth, Texas 76106.
This amendment becomes effective March 31, 1986, as to all persons except those to whom it was made immediately effective by telegraphic AD T85-23-51 issued November 20, 1985, which contained part of this amendment.