Cracking causes of oil transfer hose

Oil leakage occurred in the oil transfer hose of an aircraft, which was checked to be caused by hose cracking. The causes of hose cracking were analyzed by means of macro observation, fracture analysis, infrared spectroscopy and thermogravimetric test. The results showed that the cracking of oil hose was fatigue cracking, and the crack originated from the root of thread groove. The stress aging of oil transfer hose after assembly led to the decline of its fatigue performance. Under the action of alternating stresses such as vibration and internal fuel pressure, the crack originated from the damage position at the root of the groove and finally fatigue cracking occurred.