62-27-02: Wood Tail Rotor Blades

62-27-02 BELL: Amdt. 522 Part 507 Federal Register December 28, 1962. Applies to All Model 47 Series Helicopters Equipped With P/N 47-642-020-1 Wood Tail Rotor Blades. Compliance required as indicated. There have been several failures of wood tail rotor blades resulting from wood deterioration. To preclude further wood blade failures the following must be accomplished: (a) Within 50 hours' time in service after the effective date of this AD: (1) Remove wood tail rotor blades in accordance with the applicable Bell Maintenance and Overhaul (M&O) Manual. (2) Remove the fiberglass wrapping from the root end area of blades and remove the fiberglass blade covering from areas underneath the wrapping in accordance with the applicable Bell M&O instructions for repair of wood main rotor blades. Cut blade covering by lightly sanding cover as a knife or other sharp instrument can cause damage. (3) Inspect root end of blades from root end of blade to 6 inchesoutboard for: (i) Elongated bolt holes. Maximum allowable diameter 0.260 inch. (ii) Decay of wood. Detection of decay can be made visually by noting discoloration of the basic material. (Generally decay will start as a grayish discoloration and deepens to a brown color during the later stages.) (iii) Cracks in the stainless steel leading edge strip and grip plates using at least a 5-power magnifying glass. (4) Blades found with bolt hole diameters exceeding 0.260 inch, with decay, or with any cracks, shall be removed from service prior to further flight. (5) Blades without defects may be returned to service after: (i) Recovering the blade root area in accordance with patching procedures given in the applicable Bell M&O Manual; and (ii) Rewrapping the root area with two pieces of MIL-P-8013 No. 181 fiberglass cloth 2 x 27 inches in accordance with Bell Service Bulletin No. 75 dated September 17, 1951. (b) Blades returned to serviceafter compliance with (a) shall be retired from service prior to the accumulation of 200 hours' time in service since reinstallation in accordance with (a). This directive effective January 29, 1963.