ASN Wikibase Occurrence # 35935
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| Date: | Monday 29 June 1992 |
| Time: | 13:42 LT |
| Type: |  Robinson R22 |
| Owner/operator: | Sierra Academy Of Aeronautics |
| Registration: | N83858 |
| MSN: | 0337 |
| Total airframe hrs: | 4021 hours |
| Engine model: | Lycoming O-320-B2C |
| Fatalities: | Fatalities: 2 / Occupants: 2 |
| Aircraft damage: | Destroyed |
| Category: | Accident |
| Location: | San Pablo Bay, 3 miles northwest of Richmond, California -
 United States of America
|
| Phase: | En route |
| Nature: | Training |
| Departure airport: | Oakland, CA (KOAK) |
| (KOAK) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
THE STUDENT HAD RECORDED HER PRIMARY FLIGHT LESSON ON A TAPE RECORDER. AFTER REACHING THE PRACTICE AREA, THE CFI INSTRUCTED THE STUDENT TO TURN 180 DEG LEFT. THE STUDENT COMPLIED AND PERFORMED A SHALLOW BANK TURN. SECONDS LATER, WHILE CRUISING AT 2,200 FT, THE CFI BEGAN TALKING. IN MIDSENTENCE AN UNDETERMINED EVENT OCCURRED WHICH INTERRUPTED HIS SPEECH. A WIND-LIKE BACKGROUND NOISE STARTED, AND THE STUDENT EXCLAIMED 'HELP.' RADAR DATA CONFIRMED WITNESS REPORTS THAT THE TAIL BOOM AND M/R HAD SEPARATED IN LEVEL FLT. EXAM OF THE WRECKAGE INDICATED MAST BUMPING HAD OCCURRED, A M/R BLADE CRUSHED THE LEFT SIDE OF THE INBOARD TAIL CONE, AND THE ENTIRE MAST WITH ATTACHED M/R BLADES BROKE OUT OF THE TOP OF THE TRANSMISSION. THE OUTBOARD TAIL BOOM AND ROTOR ASSEMBLY HAVE NOT BEEN FOUND. EVIDENCE OF A MAIN ROTOR BLADE DIVERGENCE WAS FOUND. SPECTRUM ANALYSIS OF THE TAPE REVEALED NO ANOMALIES UNTIL THE CFI'S VOICE WAS TERMINATED. WITHIN 2 SECONDS THE ROTOR SPEED APPEARED TO SIGNIFICANTLY OSCILLATE AND ABRUPTLY END.
Probable Cause: A DIVERGENCE OF THE MAIN ROTOR FROM ITS NORMAL PLANE OF ROTATION FOR AN UNDETERMINED REASON(S) WHICH RESULTED IN ROTOR CONTACT TO THE TAILBOOM.
Accident investigation:
 |
|
Sources:
NTSB LAX92FA267
FAA register: 2. FAA: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?omni=Home-N-Number&nNumberTxt=83858
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 24-Oct-2008 10:30 | ASN archive | Added |
| 25-May-2016 12:44 | Dr.John Smith | Updated [Time, Operator, Location, Departure airport, Destination airport, Source, Narrative] |
| 20-Sep-2016 20:10 | Dr.John Smith | Updated [Source] |
| 21-Dec-2016 19:22 | ASN Update Bot | Updated [Time, Damage, Category, Investigating agency] |
| 11-Apr-2024 06:07 | ASN Update Bot | Updated [Time, Operator, Other fatalities, Departure airport, Destination airport, Source, Narrative, Accident report] |
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