AD 59-05-01

59-05-01 BELL: Applies to All Model 47 Helicopters Having Metal Tail Rotor Blades, P/N's 47-642-102-1; -5; -7; -9; -17; and -19 Installed.

Compliance required as indicated.

As a result of several cracks having occurred (in most instances following known damage due to the tail rotor striking water, tall grass, or underbrush) the following inspection of the metal tail rotor blades, to preclude loss of tail rotor control, must be accomplished as indicated:

(1) On trailing edge of blade, remove paint in the area of Numbers 3, 4, 5 and 6 rivets to the bare metal, with a suitable lacquer thinner only. Feather edges of remaining paint with thinner. DO NOT use sandpaper, steel-wool, or other sharp objects to remove paint. DO NOT use a paint stripper. NOTE: The removal of paint does not affect the balance.

(2) Visually inspect for chordwise cracks along the trailing edge of blade, in the area of rivets Numbers 3, 4, 5 and 6 counting from the butt end towards tip end.It is mandatory that the tail rotor blades be replaced if any cracks are found.

(3) If no cracks are found, it is mandatory that the bare metal portion of blades be left unpainted to facilitate daily inspection. To protect the bare metal, a thin coat of clear lacquer, cosmolene, or grease shall be applied to the area.

(4) Tail rotor blades, installed on float equipped helicopters or which have had any service time on float equipped helicopters, shall be inspected prior to each flight.

(5) Tail rotor blades installed on helicopters not operated on floats shall be inspected daily.

(Bell Service Bulletin No. 128SB, dated January 27, 1959, covers the same subject.)