Failure analysis of Bolt-Blade fork (Big) of main rotor assembly of a helicopter

Suresh Kumar, M and Madan, M and Venkataswamy, MA and Sujata, M and Bhaumik, SK (2007) Failure analysis of Bolt-Blade fork (Big) of main rotor assembly of a helicopter. Project Report. National Aerospace Laboratories, Bangalore, India.

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Abstract

A cracked titanium alloy ‘bolt-blade fork’ of main rotor assembly of a helicopter was analyzed. Analysis showed that the flange of the collar near the hexagonal head of the bolt had fretting damages. Stress concentration arising from these damages led to premature fatigue crack initiation on the flange and the fatigue crack progressed to about 10 mm depth before it was detected during inspection. The composition and microstructure of the bolt material were found conforming to the specification DIN 65040.WL 3.7164.7. The grain flow direction in the bolt was found satisfactory. No metallurgical abnormalities were found responsible for fatigue crack initiation.

Item Type: Proj.Doc/Technical Report (Project Report)
Uncontrolled Keywords: Helicopter;Bolt-Blade fork;Fatigue;Fretting
Subjects: AERONAUTICS > Aeronautics (General)
CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Division/Department: Materials Science Division, Materials Science Division, Materials Science Division, Materials Science Division, Materials Science Division
Depositing User: Ms. Alphones Mary
Date Deposited: 27 Jul 2011 11:40
Last Modified: 27 Jul 2011 11:40
URI: http://nal-ir.nal.res.in/id/eprint/9603

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