Loss of control Accident Hiller UH-12A N2686,
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ASN Wikibase Occurrence # 227190
 
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Date:Monday 11 September 2017
Time:11:00
Type:Silhouette image of generic UH12 model; specific model in this crash may look slightly different    
Hiller UH-12A
Owner/operator:Private
Registration: N2686
MSN: 168
Year of manufacture:1950
Total airframe hrs:2653 hours
Engine model:Franklin 6V350
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Category:Accident
Location:Griffith, IN -   United States of America
Phase: Unknown
Nature:Training
Departure airport:Griffith, IN (05C)
Destination airport:Griffith, IN (05C)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The flight instructor was providing dual flight instruction to a student pilot in the helicopter. About 10 minutes into the flight, while in a 3-5 ft hover, the student began to lose helicopter control and the helicopter began to spin to the right. Because the student could not regain control, the instructor took the controls, but the helicopter did not respond to cyclic inputs and left pedal input. At this point, the instructor assumed there was a loss of thrust from the tail rotor. He rolled the throttle off, and the helicopter settled to the ground and landed hard. After the landing, the instructor observed that the tail rotor and tail rotor driveshaft were not spinning and heard a grinding noise near the connection of the transmission output shaft and the tail rotor driveshaft. The instructor found that the tail rotor guard had broken off the helicopter and was about 20 ft away. The instructor could not recall if or when the tail rotor guard struck the ground. Examination of the helicopter revealed that the tail rotor driveshaft had failed near the output shaft of the tail rotor drive assembly. Substantial damage was incurred to the tail rotor and tailboom. Maintenance records were not available. Because neither the student nor the instructor could regain helicopter control, it is likely that the tail rotor driveshaft failed in flight, which led to the loss of tail rotor thrust and subsequent loss of tail rotor control.




Probable Cause: The loss of tail rotor thrust due to a failed tail rotor driveshaft, which resulted in a loss of tail rotor control and a hard landing.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CEN17LA375
Status: Investigation completed
Duration: 1 year and 10 months
Download report: Final report

Sources:

NTSB

Location

Revision history:

Date/timeContributorUpdates
15-Jul-2019 18:03 ASN Update Bot Added

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