70-08-01 HUGHES: Amdt. 39-971. Applies to Model 269A, 269A-1, 269A-2, and 269B Series helicopters, certificated in all categories, which incorporate lead-lag and flapping hinge bolts, P/N HS 1446-10-68, with vendor identification AC impression-stamped on top of the bolt heads (hereafter referred to as AC bolts). If bolts do not have the vendor identification AC on the bolt head they are acceptable for continued service and no further action is required by this airworthiness directive.
Compliance required as indicated.
To detect cracks and failures in the AC bolts, P/N HS 1446-10-68, accomplish the following:
(a) Within 25 hours' time in service after the effective date of this AD, remove all AC bolts in accordance with Hughes Handbook of Maintenance Instruction (HMI). Perform a dye penetrant or magnaflux inspection of the AC bolts for evidence of cracking. NOTE: During this inspection particular attention should be directed to the area of the bolt shank at the radius of the bolt head.
(b) Any AC bolt which shows evidence of cracking must be conspicuously and permanently marked to prevent its inadvertent return to service. Any AC bolt inspected per (a), above, which exhibits no evidence of cracking may be identified with a green dot painted in the recessed head of the bolt.
(c) Prior to further operation following the accomplishment of (a), above, install bolts P/N HS 1446-10-68 without vendor identification AC on the bolt heads or AC bolts which have a green dot painted on the head as authorized by (b), above.
(d) Prior to each flight following reinstallation of bolts per (c), above, visually check each AC bolt, using the green dot in the head for ease of identification, to ascertain if there is any evidence of head separation from the body of the bolt. Any bolt showing evidence of head separation must be replaced with a serviceable bolt prior to further flight.
NOTE: The rotorcraft pilot may perform this visual check and determination regarding evidence of bolt head separation. For the requirements regarding this listing in the rotorcraft's permanent maintenance record of compliance and method of compliance with this provision of this AD, see FAR 91.173.
(e) Within 225 hours' time in service after the effective date of this AD but not prior to 175 hours time in service from such date, reinspect all AC bolts in service in accordance with (a), above. Permanently and conspicuously mark any AC bolts showing evidence of cracks as prescribed by (b), above, and replace such bolts with serviceable bolts prior to further operation. This one-time reinspection does not cancel the preflight check required by (d), above.
(f) Prior to 400 hours' time in service or within six months, whichever occurs first, after the effective date of this AD, replace all AC bolts with bolts, P/N HS 1446-10-68, without vendor identification AC impression-stamped on top of the bolt heads. The special inspections required by this AD may be discontinued when this AC bolt replacement program is accomplished.
(g) AC bolts removed from service prior to six months from the effective date of this AD for the purpose of compliance with (f), above, must be marked permanently and conspicuously to prevent their inadvertent return to service.
(Hughes Service Information Notice No. N-75.1 covers this same subject.)
This amendment becomes effective April 14, 1970.