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ASM Failure Analysis Case Histories

Handbook of Case Histories in Failure Analysis

Edited by
Khlefa A. Esaklul
Khlefa A. Esaklul
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ASM International
Volume
2
ISBN electronic:
978-1-62708-215-0
Publication date:
1993
Book Chapter

Failed Main Rotor Pitch Horn Bolt from an Army Attack Helicopter

By
Victor K. Champagne
Victor K. Champagne
United States Army Research Laboratory, Materials Directorate
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;
Marc Pepi
Marc Pepi
United States Army Research Laboratory, Materials Directorate
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;
Gary Wechsler
Gary Wechsler
United States Army Research Laboratory, Materials Directorate
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Published:
1993
Page range:
388 - 391

Abstract

One of the two AISI 4340 steel pitch horn bolts from the main rotor hub assembly failed while in service. Optical microscope revealed evidence of corrosion pitting in regions adjacent to the fracture. Fractographic examination utilizing a scanning electron microscope revealed multiple crack origins which assumed a “thumbnail” shape and displayed surface morphologies which resulted from intergranular decohesion. Many of the crack sites initiated from corrosion pits. Energy dispersive spectroscope performed on areas within the crack initiation site showed the presence of chlorides. The failure was attributed to stress-corrosion cracking. Short- and long-term recommendations to prevent future failures are given.

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Victor K. Champagne, Marc Pepi, Gary Wechsler, 1993. "Failed Main Rotor Pitch Horn Bolt from an Army Attack Helicopter", Handbook of Case Histories in Failure Analysis, Khlefa A. Esaklul

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