54-24-02 LOCKHEED: Applies to 1049C, Serial Numbers 4520 Through 4548; Model 1049E, Serial Numbers 4549 Through 4556, 4558 Through 4560, and 4563 Through 4565; Model 1049D, Serial Numbers 4163 Through 4166.
Compliance required as indicated.
1. Perform a visual inspection of the outer wing main beam web between Stations 551 and 637, left and right, for cracks as soon as practical, and reinspect at intervals of approximately 125 hours until this area is reinforced as outlined in paragraph 2. If cracks are found repair and reinforce as per paragraph 2 immediately. Inspection for fuel stains alone as an indication of a crack is not sufficient due to the presence of sealant on the inside of the tank surface.
2. Reinforce the main beam web between wing Stations 551 and 637, left and right as soon as possible, convenient with aircraft check periods, but not later than 1,000 hours after receipt of parts from the manufacturer or March 1, 1955, whichever occurs first. This may beaccomplished by the addition of extruded aluminum alloy (75ST6) stiffeners (LS347-3), one between each of the original stiffeners in this area.
(Lockheed Service Bulletin No. 1049/SB-2559 describes this reinforcement.)