AD 58-11-03

58-11-03 LOCKHEED: Applies to All Models 18 Series and PV-1 Aircraft.

Compliance required as soon as possible, but not later than December 1, 1958.

Numerous reports have been received of cracks occurring at the base of the rudder cable attachment tangs, on rudder control quadrant, Lockheed P/N 53026. There is evidence that excessive clearance may exist between the tangs and the rudder cable attach fittings which permits a bending load to be applied at the base of the tangs, when the AN 5 attach bolts are tightened.

P/N 53026 should be inspected by means of a dye penetrant or equivalent inspection means in the areas noted above. If cracks are found, the parts must be replaced.

Furthermore, the means of attaching the rudder cables to the quadrant must be modified to preclude over-loading the attach tangs and subsequent occurrence of cracks due to the tightening of the attach bolts.

Two acceptable means of accomplishing the modification are noted below:

1. Replace both the AN 5 bolts with AN 4-12A bolts, AN 365 nuts and AN 960-516 washers, under the head and nut in conjunction with a 5/16 x 0.032-inch wall cadmium plated steel spacer 1-inch long as a sleeve. The length of the sleeve may protrude past the thickness of the washers a maximum of 1/16-inch or a minimum of 0.003 inch so that when tightened, the nut will bottom against the spacer and not on the washers.

NOTE: To compensate for machining tolerances and casting variation, additional washers or various length sleeves may be used to obtain the proper sleeve exposure.

2. Replace the AN 5 bolts with AN 25-20 clevis bolts, AN 516 washers, AN 320-5 nuts and AN 380-2-3 cotter pins.

NOTE: If more than 1/16-inch of bolt grip is exposed after installing the nut and washer, due to machining tolerances and casting variation, place additional washers under the head of the bolt to reduce the grip exposure to a minimum of 0.003-inch.

(Lockheed Service Bulletin No. 18/SB-150 covers this same subject.)