56-25-04 LOCKHEED: Applies to All Models 49, 149, 649, 649A, 749, 749A Aircraft; Model 1049 Serial Numbers 4001 Through 4024; Model 1049C Serial Numbers 4501 Through 4520 and 4523 Through 4538.
Compliance required at first block overhaul following receipt of parts or by March 1, 1958, whichever occurs first.
In view of the continuing series of incidents wherein flaps extend on one side of the aircraft out of symmetry with the other side, a means shall be installed which will automatically shut off the hydraulic power to the flap actuating motors whenever an asymmetrical condition exists. One method of accomplishing this means is described in Lockheed Service Bulletin No. 49/SB-794 for the 49/749 Series and No. 1049/SB-2270 for the 1049 Series.