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

Bokwon Lee, Gyu Ho Kim, Ryan L. Karkkainen, Young Ha Hwang

Research output: Contribution to journalArticlepeer-review


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.

Original languageEnglish (US)
Pages (from-to)92-100
Number of pages9
JournalJournal of Failure Analysis and Prevention
Issue number1
StatePublished - Feb 1 2018


  • Bearing
  • Electrical arc
  • Electrical discharge damage
  • Starter-generator
  • Turboprop engine

ASJC Scopus subject areas

  • Materials Science(all)
  • Safety, Risk, Reliability and Quality
  • Mechanics of Materials
  • Mechanical Engineering


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