Failure of Cheetah Helicopter Body Structure at Mixing Unit Attachment

Raghuram, AC and Radhakrishnan, S and Raju, KN and Krishnan, RV and Venkataswamy, MA and Ramachandran, V (1988) Failure of Cheetah Helicopter Body Structure at Mixing Unit Attachment. Project Report. National Aerospace Laboratories, Bangalore.

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Abstract

In Cheetah helicopters, the mixing unit assembly is a critical part of the flight control system. It is held thr fasteners to four lugs which are welded to two horizontal members of the tubular frame. The tubular frame is charged with nitrogen gas under pressure. Development of a crack in the tubular structure results in nitrogen gas leak which can be detect by a telltale indicator. In a few Cheetah helicopters flying at high altitudes, gas leakage at the welded joint of a Lug has been reported. One such joint was examined in detail. Microscopic examination confirmed the presence of a crack on the, tube wall, directly below the lug . Investigation revealed that the tube had cracked by fatigue due to excessive flexural load.

Item Type: Monograph (Project Report)
Uncontrolled Keywords: Cheetah helicopter, mixing unit attachment, lug joint, fatigue crack, flexural load.
Subjects: CHEMISTRY AND MATERIALS > Chemistry and Materials (General)
Depositing User: Users 10 not found.
Date Deposited: 01 Aug 2012 08:07
Last Modified: 01 Aug 2012 08:07
URI: http://nal-ir.nal.res.in/id/eprint/10684

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