Analysis of cracked main gear box housings of helicopters

Bhaskaran, TA and Venkataswamy, MA and Sujata, M and Keshab, Barai and Bhaumik, SK (2003) Analysis of cracked main gear box housings of helicopters. Project Report. National Aerospace Laboratories, Bangalore.

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Abstract

Two cracked Main Gear-Box (MGB) housings of a particular type of helicopter were referred to the laboratory for analysis. A fatigue crack of length about 35 mm was observed in the MGB housing of helicopter PPA-01 on the vertical web adjacent to the booster mounting area. The fatigue crack was found to start at one of the edges of the cutout and propagated progressively over a period of time. The nature, location and length of the crack in MGB housing of the helicopter PPA-02 were found similar to that observed in helicopter PPA-01. Since the fatigue crack origin in both the housings was lost due to surface grinding prior to opening the cracks, inference was drawn from other evidences that fatigue was stress related. The most probable reason for fatigue crack initiation appears to be the high stress concentrations at these locations. Certain design modifications are suggested to reduce the stress concentrations and thereby enhancing the fatigue life of the component.

Item Type: Proj.Doc/Technical Report (Project Report)
Uncontrolled Keywords: Helicopter;MGB housing;magnesium castings;fatigue;stress concentrations
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: Mrs Manoranjitha M D
Date Deposited: 05 Aug 2011 13:32
Last Modified: 05 Aug 2011 13:32
URI: http://nal-ir.nal.res.in/id/eprint/9809

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