64-28-02 HUGHES: Amendment 39-617. Applies to Models 269A, 269A-1, 269A-2 and 269B helicopters.
Compliance required as indicated.
Due to inadequate lubrication of the main rotor blade flapping hinge bearings, binding has occurred, resulting in overstressing and failure of one main rotor blade. To prevent main rotor blade overstressing and failure, accomplish the following:
(a) For helicopters having less than 100 hours' time in service on the effective date of this AD inspect the main rotor blade flapping hinge bearings for the condition indicated in (d), prior to the accumulation of 110 hours' time in service, unless already accomplished, and thereafter at periods not to exceed 400 hours' time in service from the last inspection.
(b) For helicopters having 100 hours' or more time in service on the effective date of this AD inspect the main rotor blade flapping hinge bearings for the condition indicated in (d), within the next 10 hours' time in service, unless already accomplished within the last 390 hours' time in service, and thereafter at periods not to exceed 400 hours' time in service from the last inspection.
(c) Within 10 hours' time in service, after the effective date of this AD, unless already accomplished within the last 15 hours' time in service, and thereafter at periods not to exceed 25 hours' time in service, apply MIL-G-25537 grease through the grease fittings to all main rotor blade flapping hinge bearings and inspect to ascertain that a thorough purging of the bearings has been achieved.
If new grease does not exude from all six bearings, inspect the bearings at the location where the grease does not exude, for the condition indicated in (d), before further flight.
(d) If bearings are found to be worn or damaged in excess of the limits specified in Hughes Service Information Notice No. 2A-39.1, 2A-1-06.1 or 2B-07-.1, remove from service before further flight.
(e) If the inner race of any bearing is found to be brinelled or worn in excess of the 0.002 inch limit specified in Hughes Service Information Notice No. 2A-39.1, 2A-1-06.1 or 2B- 07.1, remove the corresponding main rotor blade from service before further flight, and conspicuously mark it to prevent inadvertent return to service.
(f) If the inner race of any bearing is brinelled or worn, but not in excess of the 0.002 inch limit specified in Hughes Service Information Notice No. 2A-39.1, 2A-1-06.1 or 2B- 07.1, inspect the corresponding main rotor blade for skin cracks in the exposed areas adjacent to the edges of the blade root fitting beside the outboard bolt. Inspect both upper and lower surfaces of the blade, using a 4- to 6-power magnifying glass. If any cracks are found remove the blade from service before further flight.
(g) Starting with the effective date of this AD, conduct initial and repetitive inspections of all main rotor blades in a manner and at periods specified in Hughes Service Information NoticesNo. 2A-38 dated September 9, 1964, No. 2A-1-05 dated September 14, 1964, and No. 2B-06 dated September 16, 1964, or later revisions approved by FAA Western Region Aircraft Engineering Division.
(h) The following Hughes Service Information Notices or later FAA approved revisions are approved alternatives to those specified in (d), (e), (f) and (g) above:
Notice No. N-10.1 dated December 14, 1967, is an approved alternate to Notices 2A-38, 2A-1-05 and 2B-06.
Notice No. N-47 dated April 18, 1968, is an approved alternate to Notices 2A-39.1, 2A- 1-06.1 and 2B-07-.1.
This amendment becomes effective on July 6, 1968.