What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
(-23) An inspection of the wreck concluded that the engine had failed. The engine has been sent back to the manufacturer for analysis. Honeywell rep. Dave looper coordinated the shipping and inspection. (.4)according to the pilot, he was about 30 minutes into the post inspection maintenance flight at about 350 to 400 feet AGL, when he heard a loud 'bang' and engine RPM decayed to zero. His choice of autorotation site required use of main rotor RPM to clear trees and he landed hard and rolled over. The T-53-L-13B engine underwent factory disassembly examination, with FAA oversight. Material analysis determined that portions of the 2nd stage gp turbine disc had fractured and separated due to peak strain low cycle fatigue, resulting in structural and imbalance damage and engine failure. No material, lubrication, or fuel control defects were identified that would have contributed to the disc separation.
As the FAA filed it
(-23) AN INSPECTION OF THE WRECK CONCLUDED THAT THE ENGINE HAD FAILED. THE ENGINE HAS BEEN SENT BACK TO THE MANUFACTURER FOR ANALYSIS. HONEYWELL REP. DAVE LOOPER COORDINATED THE SHIPPING AND INSPECTION. (.4)ACCORDING TO THE PILOT, HE WAS ABOUT 30 MINUTES INTO THE POST INSPECTION MAINTENANCE FLIGHT AT ABOUT 350 TO 400 FEET AGL, WHEN HE HEARD A LOUD 'BANG' AND ENGINE RPM DECAYED TO ZERO. HIS CHOICE OF AUTOROTATION SITE REQUIRED USE OF MAIN ROTOR RPM TO CLEAR TREES AND HE LANDED HARD AND ROLLED OVER. THE T-53-L-13B ENGINE UNDERWENT FACTORY DISASSEMBLY EXAMINATION, WITH FAA OVERSIGHT. MATERIAL ANALYSIS DETERMINED THAT PORTIONS OF THE 2ND STAGE GP TURBINE DISC HAD FRACTURED AND SEPARATED DUE TO PEAK STRAIN LOW CYCLE FATIGUE, RESULTING IN STRUCTURAL AND IMBALANCE DAMAGE AND ENGINE FAILURE. NO MATERIAL, LUBRICATION, OR FUEL CONTROL DEFECTS WERE IDENTIFIED THAT WOULD HAVE CONTRIBUTED TO THE DISC SEPARATION.
NTSB investigation
The NTSB’s investigation of this event, with its probable cause and findings. Matched to this report by N-number and date.