Accident Robinson R-22B N4015Y,
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ASN Wikibase Occurrence # 359146
 
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Date:Tuesday 11 April 1995
Time:10:48 LT
Type:Silhouette image of generic R22 model; specific model in this crash may look slightly different    
Robinson R-22B
Owner/operator:Resort Aviation
Registration: N4015Y
MSN: 1427
Year of manufacture:1990
Engine model:LYCOMING O-290
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Lakeport, CA -   United States of America
Phase: Approach
Nature:Training
Departure airport:
Destination airport:
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
THE STUDENT WAS DOING TAKEOFFS AND LANDINGS IN THE TRAFFIC PATTERN WHEN THE LOW ROTOR RPM WARNING HORN ACTIVATED. THE STUDENT WAS UNSUCCESSFUL IN EXTINGUISHING THE WARNING HORN BY THROTTLE AND COLLECTIVE MANIPULATION AND ENTERED AN AUTOROTATION. THE STUDENT DID NOT VERIFY THE MAIN ROTOR RPM BY THE ROTOR TACHOMETER. DURING THE TOUCHDOWN, ABOUT 1/4-MILE SOUTHEAST OF THE AIRPORT IN A SOFT FIELD, THE SKIDS DUG INTO SOFT SOIL AND THE HELICOPTER ROLLED OVER. A FAA INSPECTOR EXAMINED THE AIRCRAFT AND ENGINE, WHICH INCLUDED AN ENGINE START AND STATIC RUN-UP. THE ENGINE STARTED NORMALLY AND WAS EXERCISED THROUGHOUT ITS NORMAL POWER RANGE. MAINTENANCE RECORDS REVEALED A HISTORY OF FALSE LOW ROTOR RPM WARNING HORN ACTIVATIONS IN THE HELICOPTER DATING BACK 9 MONTHS. AFTER PILOTS WOULD REPORT THE WARNING HORN DISCREPANCY TO MAINTENANCE PERSONNEL, A SYSTEM COMPONENT WOULD BE CHANGED AND THE HELICOPTER RETURNED TO SERVICE; HOWEVER, THE PROBLEM PERSISTED. THE CFI'S SAID THEY TRAINED THE STUDENTS, INCLUDING THE ACCIDENT PILOT, HOW TO COPE WITH THE NUISANCE WARNING.

Probable Cause: the student's misjudged landing flare and his failure to verify the validity of the low rotor warning. Factors in the accident were the company management's continued use of the helicopter in flight training operations with a known discrepancy in the main rotor warning system, and the soft nature of the soil at the autorotation landing area.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: LAX95LA158
Status: Investigation completed
Duration: 5 months
Download report: Final report

Sources:

NTSB LAX95LA158

Location

Revision history:

Date/timeContributorUpdates
15-Mar-2024 07:29 ASN Update Bot Added

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