Accident Robinson R22 BETA N827SH,
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ASN Wikibase Occurrence # 308523
 
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Date:Friday 27 August 2021
Time:08:00 LT
Type:Silhouette image of generic R22 model; specific model in this crash may look slightly different    
Robinson R22 BETA
Owner/operator:1 Acadiana Helicopters Company LLC
Registration: N827SH
MSN: 3780
Year of manufacture:2005
Total airframe hrs:4301 hours
Engine model:Lycoming O-360-J2A
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Arnaudville, Louisiana -   United States of America
Phase: Landing
Nature:Ferry/positioning
Departure airport:New Iberia, LA
Destination airport:Arnaudville, LA
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
While attempting to land at a staging location for a planned aerial application flight, the helicopter began to rotate to the right. The pilot was unable to regain control. The helicopter skids impacted a dirt field, and the helicopter rolled over onto its right side. The helicopter sustained substantial damage to its main rotor blades and fuselage. Disassembly of the helicopter for recovery revealed the tail rotor output shaft was fractured into two pieces.
Examination of the output shaft revealed the fracture occurred between the mating tapered roller bearing and the bevel gear. The bevel gear side surface displayed progressive crack arrest marks consistent with fatigue cracking. Due to smear damage on the other fracture, it could not be determined if the fatigue cracking was the result of unidirectional bending fatigue (one origin) or reverse bending fatigue (two origins).

The tail rotor output shaft function is to drive the tail rotor blades. A failed tail rotor output shaft would result in the loss of drive to the tail rotor blades, which in turn would cause a loss of tail rotor thrust to counter main rotor torque and loss of yaw control.

Probable Cause: The loss of tail rotor drive due to a fatigue failure of the tail rotor gearbox output shaft, which resulted in a loss of control during landing.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CEN21LA389
Status: Investigation completed
Duration: 1 year and 4 months
Download report: Final report

Sources:

NTSB CEN21LA389

Location

Revision history:

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