# NTSB BFO91LA074: Clifton Dixon Polliwagen, N256PW, Chesterfield, VA, August 6, 1991

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Limited investigation · Final report
- Date: August 6, 1991, 10:00 local (14:00 UTC)
- Place: Chesterfield, VA
- Coordinates: 37.38985, -77.589286 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=37.3899&lon=-77.5893&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: Minor injuries
- Injuries: 1 minor
- Status: Completed, report May 5, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 11698
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=BFO91LA074
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/11698/pdf
- Page: https://openairdocs.org/ntsb/BFO91LA074

## Probable cause

THE PARTIAL LOSS OF ENGINE POWER CAUSED BY A MISALIGNED ROCKER ARM SPRING RESULTING IN A REDUCTION OF EXHAUST VALVE OPENING.

## 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, takeoff - initial climb
  - engine assembly,rocker arm/tappet - jammed (contributing factor)
- Forced landing, descent - emergency
- In flight collision with object, landing
  - object - tree(s)

## Analysis

THE PILOT WAS CONDUCTING ONE OF A SERIES OF FLIGHT TESTS OF HIS NEW HOMEBUILT AIRCRAFT. AFTER PERFORMING HIS PRETAKEOFF ENGINE RUN-UP, HE STARTED HIS TAKE-OFF ROLL. THE ENGINE PERFORMANCE SEEMED BETTER THAN USUAL UP TO AN ALTITUDE OF 200 FEET. THE ENGINE THEN STARTED TO LOSE POWER AND THE AIRCRAFT BEGAN TO DESCEND. THE AIRCRAFT STRUCK SOME TREE TOPS AND CRASHED TO THE GROUND, COMING TO REST, INVERTED. A POSTFLIGHT INVESTIGATION OF THE ENGINE REVEALED THAT THE NUMBER THREE EXHAUST VALVE SPRING HAD SLIPPED FROM ITS POSITION CAUSING A PARTIAL REDUCTION OF POWER.

## Aircraft

- Registration: [N256PW](https://openairdocs.org/deregistered/N256PW-1992-01-13), registration cancelled 1992-01-13, S/N 1 (OpenAirDocs)
- Reported make and model: CLIFTON DIXON POLLIWAGEN
- Registry model: [Dixon Clifton E JR POLLIWAGEN](https://openairdocs.org/model/dixon-clifton-e-jr-polliwagen) (registry code 05613RL) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 1
- Airframe hours: 3
- Engines: Volkswagen 411/914 65 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: Clifton E. Dixon
- Registered owner: Clifton E. Dixon
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Annual, October 17, 1990, 9 hours before
- Airport: W98, Chesterfield City

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 59; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--w/ waivers/lim; seat: left; flight hours: 479 total, 8 in this make and model, 414 as pilot in command, 2 in the last 90 days, 1 in the last 30 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 70° at 8 knots
- Visibility: 8 statute miles
- Lowest ceiling: none
- Temperature: 79 °F, dew point 64 °F
- Altimeter: 30.00 inHg
- Observed at: RIC, 15 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 19910806032029A](https://openairdocs.org/incident/19910806032029A), Aug 6, 1991: Amtr POLLIWAGON, Richmond, VA, Destroyed. Engine lost power on climbout. Mushed into trees. NR3 exhaust valve spring was misaligned causing power loss.

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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