# NTSB LAX92FA374: Piper PA-23-160, N4305Y, Concord, CA, September 2, 1992

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: September 2, 1992, 14:41 local (21:41 UTC)
- Place: Concord, CA
- Coordinates: 38.000041, -122.030906 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=38.0000&lon=-122.0309&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 2 fatal
- Status: Completed, report September 14, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 27451
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX92FA374
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/27451/pdf
- Page: https://openairdocs.org/ntsb/LAX92FA374

## Probable cause

The following Probable Cause was modified on April18, 2007, as a result of new information provided to the NTSB.

THE IMPROPER INSTALLATION OF THE 1.75 INCH OD PLUG IN THE CRANKSHAFT BY UNKNOWN MAINTENANCE PERSONNEL WHICH RESULTED IN AN INADVERTENT FEATHERING OF THE LEFT ENGINE PROPELLER.

## Sequence of events

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

- Airframe/component/system failure/malfunction, go-around (vfr)
  - propeller system/accessories - ruptured (contributing factor)
  - maintenance,installation - improper, other maintenance personnel (cause)
  - fluid,oil - pressure too low (contributing factor)
  - propeller feathering - inadvertent (contributing factor)
- In flight collision with object, descent - uncontrolled
  - object - bridge/overpass
  - proper climb rate - not attained, pilot in command(cfi)

## Analysis

The following Brief was modified on April18, 2007, as a result of new information provided to the NTSB.

THE AIRCRAFT COLLIDED WITH A BRIDGE WHILE TRYING TO RETURN TO THE AIRPORT AFTER REPORTING AN EMERGENCY DURING THE PREVIOUS TOUCH AND GO LANDING. WITNESSES INDICATED BOTH ENGINES SOUNDED LIKE THEY WERE RUNNING AND BOTH PROPELLERS WERE TURNING. THE LEFT ENGINE PROPELLER WAS FOUND FEATHERED AFTER THE ACCIDENT. INVESTIGATION REVEALED A 1.75 INCH OD PLUG INSTALLED IN THE CRANKSHAFT TO SEPARATE OIL PRESSURE FROM THE PROPELLER GOVERNOR AND THE ENGINE CRANKCASE WAS BLOWN AFT DAMAGING THE NUMBER ONE ROD CONNECTING JOURNAL OIL TRANSFER TUBE. EXAMINATION OF THE PLUG DISCLOSED THAT IT WAS INSTALLED BACKWARDS.

## Aircraft

- Registration: [N4305Y](https://openairdocs.org/deregistered/N4305Y-2012-11-21), registration cancelled 2012-11-21, S/N 23-2028, built 1962 (OpenAirDocs)
- Reported make and model: PIPER PA-23-160
- Registry model: [Piper PA-23-160](https://openairdocs.org/model/piper-pa-23-160) (registry code 7102304) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 2028
- Engines: LYCOMING O-320-B3B 160 horsepower reciprocating
- Damage: Destroyed
- Fire: On-Ground
- Flight: Instructional, Part 91
- Operator: Chavossy, Louis
- Registered owner: Chavossy, Louis
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, January 23, 1992
- Departed: HWD, HAYWARD, CA
- Airport: CCR, Buchanan Field, runway 19, 4,400 × 150 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 40; flight instructor, private, commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, invalid medical for flight; seat: right; toxicology performed; flight hours: 800 total, 170 in this make and model, 650 as pilot in command, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 300° at 13 knots
- Visibility: 40 statute miles
- Lowest ceiling: none
- Temperature: 79 °F, dew point 52 °F
- Altimeter: 30.00 inHg
- Observed at: CCR, 1 nm away

## 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 19920902035109A](https://openairdocs.org/incident/19920902035109A), Sep 2, 1992: Piper PA23160, Concord, CA, Destroyed, 2 fatal. Lost left engine. Feathered. Apach not good one engine. CFI aware improper crankshaft installation. Ignored same.

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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