# NTSB LAX92LA034: Robinson R-22B, N549SM, Riverside, CA, November 2, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: November 1, 1991, 16:43 local (Nov 2, 1991, 00:43 UTC)
- Place: Riverside, CA
- Coordinates: 33.200164, -117.349655 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=33.2002&lon=-117.3497&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report April 27, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27493
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX92LA034
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27493/pdf
- Page: https://openairdocs.org/ntsb/LAX92LA034

## Probable cause

THE FAILURE OF THE ENGINE TO TRANSMISSION DRIVE BELT AND THE PILOTS FAILURE TO CORRECTLY JUDGE OF THE LANDING FLARE DURING THE SUBSEQUENT AUTOROTATION.

## Sequence of events

In NTSB's coding before 2008 (https://www.ntsb.gov/GILS/Documents/codman.pdf).

- Airframe/component/system failure/malfunction, approach - vfr pattern - downwind
  - rotor drive system,main rotor drive belt - failure,total (cause)
- Forced landing, descent - emergency
- Hard landing, landing - flare/touchdown
  - flare - misjudged, pilot in command (cause)
  - lack of total experience, pilot in command

## Analysis

THE SOLO STUDENT WAS PRACTICING TAKEOFFS AND LANDINGS. WHILE DOWNWIND THE STUDENT SAID THE ENGINE RPM INDICATOR SUDDENLY PEGGED AT THE TOP OF THE GAUGE AND THE ROTOR RPM BEGAN RAPIDLY DECREASING. THE STUDENT INITIATED AN AUTO ROTATION. THE HELICOPTER LANDED HARD AND ROLLED OVER. EXAMINATION OF THE HELICOPTER BY FAA INSPECTORS REVEALED THAT THE FORWARD DRIVE BELT WAS SPLIT LONGITUDINALLY AND DISPLACED FROM THE TRANSMISSION PULLEY. THE AFT DRIVE BELT WAS FOUND OFF THE ENGINE AND TRANSMISSION PULLEYS. NO OTHER SYSTEM ABNORMALITIES WERE NOTED.

## Aircraft

- Registration: N549SM (not matched to a registry record)
- Reported make and model: ROBINSON R-22B
- Category: Helicopter
- Serial number: 1549
- Airframe hours: 1299
- Engines: LYCOMING O-320-B2C 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Instructional, Part 91
- Operator: Parflite, Inc.
- Registered owner: C. L. Marlow
- Airworthiness certificate: Standard, Normal
- Last inspection: AAIP, October 17, 1991, 49 hours before

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 25; student; medical: class 2, valid medical--w/ waivers/lim; seat: right; flight hours: 150 total, 63 in this make and model, 19 as pilot in command, 83 in the last 90 days, 29 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 280° at 8 knots
- Visibility: 4 statute miles
- Lowest ceiling: none

## FAA reports on this event (1)

The FAA's own accident and incident reports, matched to the aircraft by N-number and date (OpenAirDocs).

- [Accident 19911101048869A](https://openairdocs.org/incident/19911101048869A), Nov 1, 1991: Robsin R22BETA, Riverside, CA, Substantial damage. Engine overspeed and rotor RPM decay. Autorotated to hard landing. Rolled. Main rotor drive belt split. Came off.

From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model.

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