56-15-01 BELL: Applies to Model 47H1 Helicopters, Serial Numbers 1347 Through 1356.
Compliance required as soon as possible, but not later than August 15, 1956.
In order to prevent tail boom skin cracking in the area of the aft ballast, it is necessary to complete a revised aft ballast provision installation utilizing Bell Kit No. 47-2406-1B. In addition it is also necessary to install Bell Kit No. 47-2406-1A, Antitorque Control Pulley Brackets Installation, at this same time to permit the installation of the new tail rotor control cable assembly, P/N NAS 302 R-66-5537. This revised antitorque control system installation is required to provide adequate clearance with the new aft ballast provision installation.
(Bell Mandatory Service Bulletin No. 110 dated June 1, 1956 covers this same subject.)