Jet Engine Failures

Metallurgical Failure Analysis of Low Pressure Turbine (LPT) Components From Jet Engine

Background to Failure Analysis Investigation


  • Excess vibration reported in Engine by Airplane Pilot
  • Engine teardown performed by Airline showed damage in LPT stages
  • Nozzle in Stage 2 NGV suspected to be root cause for failure
  • LPT components shipped to Kars’ Labs for metallurgical failure analysis

Objectives of Metallurgical Failure Analysis Investigation

  • What caused failure?
  • Did failure occur because of design issue, repair or manufacturing defect?
  • What steps need to be taken to prevent reoccurrence?

Failure Analysis Methodology

  • Test protocol written by Kars’ Labs
  • Tests witnessed by Airline, Engine Manufacturer and Repair Shop
  • Tests included Macrophotgraphy, Scanning Electron Microscopy, Metallurgical Cross Sections and Ultrasonic Tests

Failure Analysis Tests


As-Received Documentation




Scanning Electron Microscopy



Summary & Recommendations

  • Degradation of NGV Segment caused failure
  • Failure of related to material condition and not repair
  • Need for NDT technique to detect/measure IGO along inner surfaces of blades/segments
  • Number of repairs need to be limited