Accident Robinson R-22 N22431,
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ASN Wikibase Occurrence # 360197
 
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Date:Saturday 9 July 1994
Time:13:50 LT
Type:Silhouette image of generic R22 model; specific model in this crash may look slightly different    
Robinson R-22
Owner/operator:Palm Beach Helicopters Inc.
Registration: N22431
MSN: 0494
Year of manufacture:1985
Total airframe hrs:2884 hours
Engine model:LYCOMING O-320-B2C
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Category:Accident
Location:Sanford, FL -   United States of America
Phase: Taxi
Nature:Survey
Departure airport:
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
THE HELICOPTER WAS IN A 15 FOOT HOVER WHEN IT BEGAN TO SPIN TO THE RIGHT AND DESCEND. THE PILOT WAS UNABLE TO CONTROL THE HELICOPTER AND IT CRASHED INTO THE WATER. A WITNESS ON THE GROUND OBSERVED THE TAILROTOR SLOW DOWN JUST PRIOR TO THE HELICOPTER STARTING TO SPIN TO THE RIGHT. EXAMINATION OF THE HELICOPTER AFTER THE ACCIDENT INDICATED THE TAILROTOR DRIVESHAFT WAS SEPARATED AT THE LAST COUPLING PRIOR TO THE TAILROTOR GEARBOX. THE TAILROTOR GEARBOX WAS FREE TO TURN AND ONE TAILROTOR BLADE WAS BENT AT A 90 DEGREE ANGLE. THE OTHER TAILROTOR BLADE WAS NOT DAMAGED. METALLURGICAL EXAMINATION OF THE SEPARATED TAILROTOR DRIVESHAFT INDICATED IT SEPARATED DUE TO TORSIONAL OVERSTRESS IN THE NORMAL DIRECTION OF ROTATION. THE DRIVESHAFT HAD ACCUMULATED 887 TOTAL HOURS SINCE IT WAS INSTALLED NEW IN JUNE 1992. THE HELICOPTER HAD BEEN SUBJECTED TO AN OVERSPEED AND TWO GROUND DAMAGE OCCURRENCES TO THE TAIL STABILIZERS IN THE LAST 150 FLIGHT HOURS.

Probable Cause: THE FAILURE OF THE TAILROTOR DRIVESHAFT FOR UNDETERMINED REASONS RESULTING IN LOSS OF TAILROTOR DRIVE. THIS RESULTED IN THE HELICOPTER SPINNING UNCONTROLLED AND DESCENDING FROM A HOVER UNTIL IT CRASHED IN THE WATER.

Accident investigation:
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Investigating agency: NTSB
Report number: MIA94LA176
Status: Investigation completed
Duration: 4 months
Download report: Final report

Sources:

NTSB MIA94LA176

Location

Revision history:

Date/timeContributorUpdates
15-Mar-2024 18:57 ASN Update Bot Added

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