Journal of Failure Analysis and Prevention

, Volume 18, Issue 1, pp 92–100 | Cite as

Investigation of In-Flight Shutdown of Turboprop Engine Due to Electrical Discharge Damage

  • Bokwon Lee
  • Gyu-Ho Kim
  • Ryan L. Karkkainen
  • Young-Ha Hwang
Technical Article---Peer-Reviewed


A turboprop training aircraft experienced an in-flight shutdown failure with complete seizure of its propeller. Disassembly of the mishap engine revealed that many of the engine components were severely damaged. The laboratory investigation of the failed engine components determined that mechanical failure of the driveshaft bearing in the gearbox was the principal contributing factor that led to in-flight complete seizure of the propeller shaft. Microscopic examination of the failed bearing remnants found electrical arc-induced pittings which played a role as crack initiation sites resulting in premature rolling contact fatigue cracking during continued engine operation. The investigation established clear evidence of electrical discharge damage (EDD) on engine components connecting from the starter-generator to the failed input driveshaft bearing. The evidence of EDD observed in multiple elements located along the electrical current path and the residual magnetism measurement suggested that the starter-generator is highly associated with the source of the EDD.


Electrical discharge damage Turboprop engine Bearing Starter-generator Electrical arc 



The author would like to acknowledge the assistance of all the staff members of the failure analysis lab in ATRI at various stages in this investigation. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.


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Copyright information

© ASM International 2018

Authors and Affiliations

  • Bokwon Lee
    • 1
  • Gyu-Ho Kim
    • 2
  • Ryan L. Karkkainen
    • 3
  • Young-Ha Hwang
    • 4
  1. 1.ATRI (Aero Technology Research Institute)DaeguRepublic of Korea
  2. 2.Department of Mechanical EngineeringUniversity of Texas at DallasRichardsonUSA
  3. 3.Department of Mechanical and Aerospace EngineeringUniversity of MiamiCoral GablesUSA
  4. 4.Korea Institute of Industrial TechnologyYeongcheon-siRepublic of Korea

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