56-21-04 RUSSELL: Applies to Safety Belts Equipped With Russell Manufacturing Co.'s 2 Inch Rusco Tog-L-Lok Safety Belt Buckle.
Compliance required as soon as possible but not later than December 30, 1956.
Recurring instances have been reported wherein Russell Model RM-3 and RM-4 belt assemblies have slipped and unlocked under relatively low tension loads. Accordingly, it has been determined that safety belt assemblies RM-3 and RM-4 manufactured between July 1, 1954, and August 1, 1956, as meeting Technical Standard Order C22b standards and equipped with Rusco Tog-L-Lok buckles, are unairworthy and must be reworked or replaced with belt assemblies that conform to TSO-C22b standards. Due to the need for precise jigs to accomplish the rework of these assemblies, reworking in the field is not feasible. However, the Russell Manufacturing Co. has submitted satisfactory substantiating data for reworking the unsatisfactory safety belt assemblies at the factory.
In addition to the above difficulty, some of the faulty Tog-L-Lok buckles may have been sold as, or on, military surplus equipment and, therefore, there is some likelihood that other companies or individuals may have renovated or manufactured and sold safety belt assemblies which incorporate these faulty buckles. The characteristics of these buckles are such that if the assembly does not slip or unlock under a maximum tensile load of 100 pounds, the belt assembly is satisfactory. Accordingly, a maximum tensile load of 100 pounds need be applied to these belt assemblies to check their airworthiness. If the assembly does not slip or unlock under this load, the assembly may be considered satisfactory and rework or replacement is not necessary.