61-18-02: Tail Rotor Modification

61-18-02 BRANTLY: Amdt. 327 Part 507 Federal Register August 24, 1961. Applies to All Model B-2 Helicopters prior to Serial No. 112. Compliance required within the next 25 hours' time in service after effective date of this directive unless already accomplished. Investigation of a recent Model B-2 helicopter accident indicated evidence of limited tail rotor control. Accordingly, in order to provide directional control over a wider main rotor r.p.m. range, the following modification and rerigging of the tail rotor is required: (a) Modify the rudder control arm P/N B2-284-1 as follows. (1) Disconnect the vertical rudder rod P/N B2-251-5 at its top end by removing the AN 3-10A bolt. (2) Drill a 1/16-inch diameter hole and then enlarge to 0.187-inch diameter 1/2 inch inboard (center to center) from the existing hole in the rudder control arm P/N B2-284-1. Deburr edges. (3) Cut off the end of the rudder control arm P/N B2-284-1 with the old 0.187-inch hole 0.344-inch outboard from the centerline of the new 0.187-inch hole (0.250-inch edge distance from new hole) and perpendicular to the longitudinal axes of the rudder control arm. Break all sharp edges. (4) Rerig the tail rotor in accordance with the manufacturer's instructions, Service Bulletin No. 15. (Brantly Service Bulletin No. 15 dated June 23, 1961, covers this subject.) This directive effective August 29, 1961.