# NTSB LAX91LA323: Cessna C-172P, N54694, Hesperia, CA, July 20, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 20, 1991, 11:30 local (19:30 UTC)
- Place: Hesperia, CA
- Coordinates: 34.049678, -117.239639 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=34.0497&lon=-117.2396&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report July 14, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27301
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX91LA323
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27301/pdf
- Page: https://openairdocs.org/ntsb/LAX91LA323

## Probable cause

A STUCK ENGINE THROTTLE DUE TO IMPROPER MAINTENANCE PROCEDURES.

## Sequence of events

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

- Loss of engine power(partial) - mech failure/malf, descent - normal
  - throttle/power lever,bellcrank - jammed (cause)
  - maintenance,replacement - not performed, company maintenance personnel (cause)
  - maintenance,overhaul - improper, other maintenance personnel (cause)
- Forced landing, descent - emergency
- In flight collision with object, descent - emergency
  - object - wire,transmission

## Analysis

THE PILOT DECIDED TO DIVERT TO HESPERIA DUE TO WEATHER.  DURING THE ENROUTE LET DOWN, THE PILOT DISCOVERED THAT THE THROTTLE CONTROL WAS FROZEN AND COULD NOT BE MOVED WHEN HE ATTEMPTED TO ADD POWER.  THE THROTTLE WAS FROZEN AT AN ENGINE POWER LEVEL INSUFFICIENT TO MAINTAIN LEVEL FLIGHT AND THE AIRCRAFT COLLIDED WITH HIGH TENSION POWER LINES WHILE ATTEMPTING TO MANEUVER TO THE RUNWAY.  THE AIRCRAFT WAS EXAMINED BY FAA AIRWORTHINESS INSPECTORS WHO CONFIRMED THAT THE THROTTLE WAS FROZEN IN AN INTERMEDIATE SETTING.  THE ENGINE WAS OVERHAULED ON JUNE 18, 1991.  AT THAT TIME THE CARBURETOR WAS ALSO OVERHAULED, INCLUDING THE INSTALLATION OF NEW THROTTLE BUSHINGS AND A SHAFT.  BETWEEN THE ENGINE OVERHAUL AND THE DATE OF THE ACCIDENT, THE AIRCRAFT DISCREPANCY LOG SHEETS MAINTAINED BY SOUTHBAY AVIATION DOCUMENTED SIX PRIOR COMPLAINTS BY RENTER PILOTS THAT THE THROTTLE WAS STICKING ON AN INTERMITTENT BASIS.  THE CORRECTIVE ACTION RECORDED ON THE DISCREPANCY SHEETS CONSISTED OF REPLACING THE THROTTLE CABLE.

## Aircraft

- Registration: [N54694](https://openairdocs.org/deregistered/N54694-1991-10-15), registration cancelled 1991-10-15, S/N 17275037 (OpenAirDocs)
- Reported make and model: CESSNA C-172P
- Registry model: [Cessna 172P](https://openairdocs.org/model/cessna-172p) (registry code 2072436) (OpenAirDocs)
- Category: Airplane
- Serial number: 17275037
- Engines: LYCOMING O-320-D2J 150 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: South Bay Aviation
- Last inspection: Unknown, January 2, 2000
- Departed: LAS, LAS VEGAS, NV
- Destination: TOA, TORRANCE, CA
- Flight plan: VFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 25; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; flight hours: 117 total, 30 in this make and model, 62 as pilot in command, 8 in the last 90 days, 6 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 210° at 15 knots
- Visibility: 12 statute miles
- Lowest ceiling: none
- Temperature: 84 °F

## 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 19910720028849A](https://openairdocs.org/incident/19910720028849A), Jul 20, 1991: Cessna 172P, Hesperia, CA, Substantial damage. Throttle became frozen in low power position. Landed off airport in soft field. Nosed over. Prior binding noted.

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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