Cable Tension Test

The report focuses on operations of a cable pulley system within the nose landing gear of a Bombardier Global Express. The Manual release system is observed to lose pre-tension in the nose landing gear cable loop. Series of tests were performed to single out two possibilities that could be responsible for the tension loss. The two main causes were identified as structural deformation within the system and cable creep over time. With these tests it was confirmed that there is loss in tension when pulley cluster assembly was subjected to fixed load for longer duration of time, whereas, when the pulley cluster assembly was tested under similar loading for 5 days, negligible loss in tension was observed. The test was designed to last for 53 days but due to the outbreak of a pandemic, the entire test took 105 days to be completed. Additional investigation to eliminate stress relaxation within the cable within the structure, as a possible cause for the tension loss, will have to be carried after this test. Unwinding of the cable in the pulley cluster assembly was determined to be the primary cause of tension loss. The reason for the loss in tension could be a combination of both the above-mentioned causes. However, the test protocols performed here reveal the tension drop but more tests are required to conclusively determine the reason for tension drop.