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Resistance to Fatigue when Exposed to Continuous Bending Test

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According to PMA DO 9.21-4420 test procedures

The PMA DO 9.21-4420 test procedures describes a demanding test for conduit fatigue when exposed to continuous repetitive bending. 
The conduit is fixed at the top of the apparatus, it passes over and under two pulley wheels. 
A weight is suspended at the bottom end simulating the weight of cables within the conduit. 
The pulley wheels move up and down continuously bending the conduit twice through 180° over its entire length. 
The test is performed at 23°C and 50% r.h. and continues until the first signs of damage occur.