Journal of Failure Analysis and Prevention

, Volume 8, Issue 2, pp 176–182 | Cite as

Failure Analysis of Horizontal Hinge Pin Components from an Army Cargo Helicopter

  • Marc Pepi
  • Gary Wechsler
Technical Article---Peer-Reviewed


A horizontal hinge pin (HHP) assembly from an Army cargo helicopter was examined to determine the root cause of ring and roller fracture and spalling. Chemical analyses, metallography and hardness testing indicated that the rings and rollers conformed to the material requirements of the governing drawing. Metallography and visual and scanning electron microscopy indicated the failure likely initiated in the lag ring due to rolling contact fatigue (RCF) because of high service loads. Evidence of subsurface crack initiation was observed.


Failure analysis Horizontal hinge pin Army cargo helicopter Rolling contact fatigue 



Thanks are extended to the following ARL personnel for their assistance during this investigation: Scott Grendahl, Dr. Andrew Davis, Benjamin Hardisky, Chris Norfolk and Tom Juliano. The authors are also grateful for the manuscript review performed by Randy McFarland, AMCOM.


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Copyright information

© Society for Machinery Failure Prevention Technology 2007

Authors and Affiliations

  1. 1.US Army Research LaboratoryAberdeen Proving GroundUSA
  2. 2.Aviation and Missile CommandHuntsvilleUSA

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