Cracking reasons of a certain type of aircraft flap track bracket

The left flap track bracket of a certain type of general aircraft cracked during flight. The reasons for the cracking of the scaffold were studied by macroscopic observation, chemical composition analysis, scanning electron microscopy analysis, hardness testing and finite element analysis. The results show that the cracks originated from the sharp corner of the lower inflection point of the flap track bracket and the fracture showed the characteristics of fatigue strips, indicating that the bracket had fatigue cracking. The alternating stress caused by flap retraction and high cycle times were the main causes of fatigue cracking of the bracket. Installing reinforcement patches could improve the strength of the stress concentration area of the bracket.