# NTSB MKC86FA151: Whittman WD (Bigx), N31637, Sheldahl, IA, July 19, 1986

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: July 19, 1986, 10:55 local (15:55 UTC)
- Place: Sheldahl, IA
- Coordinates: 41.859161, -93.689643 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=41.8592&lon=-93.6896&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 3 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 34073
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=MKC86FA151
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/34073/pdf
- Page: https://openairdocs.org/ntsb/MKC86FA151

## Sequence of events

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

- Fire, climb - to cruise
  - exhaust system,stack - leak (cause)
  - procedures/directives - not followed, pilot in command (contributing factor)
  - fuel system,carburetor - fumes (cause)
  - fuselage,skin - burned (contributing factor)
- Loss of control - in flight, descent - emergency
  - wing - burned (cause)
  - remedial action - not possible, pilot in command
- In flight collision with terrain/water, descent - uncontrolled
- Explosion, other

## Analysis

WITNESSES STATE THAT THEY SAW TWO AIRPLANES, ONE SILVER AND ONE RED, CLIMBING NORTHBOUND TO CRUISE ALTITUDE IN LOOSE FORMATION WHEN THE RED AIRCRAFT'S ENGINE BACKFIRED AND THE ANTIQUE FABRIC-COVERED AIRCRAFT STARTED BURNING. FLAMES FIVE TO EIGHT FEET IN LENGTH BEGAN CONSUMING THE AIRCRAFT'S LEFT BOTTOM ENGINE COMPARTMENT AND FUSELAGE UNDERSIDE AS THE PILOT WAS ATTEMPTING AN EMERGENCY DESCENT INTO A SOY BEAN FIELD, ACCORDING TO WITNESSES. THE AIRCRAFT HAD THE FIELD MADE, AND WAS AT APPROXIMATELY FIVE HUNDRED FEET ABOVE GROUND LEVEL WHEN THE LEFT WING CAUGHT FIRE, THE AIRCRAFT FLIPPED INVERTED, AND NOSED DIVED INTO THE SOY BEAN FIELD WHERE IT EXPLODED ON IMPACT.

## Aircraft

- Registration: [N31637](https://openairdocs.org/deregistered/N31637-2013-06-18), registration cancelled 2013-06-18, S/N 6, built 1944 (OpenAirDocs)
- Reported make and model: WHITTMAN WD (BIGX)
- Registry model: [Whittman WD](https://openairdocs.org/model/whittman-wd) (registry code 9790443) (OpenAirDocs)
- Registry engine: [Franklin 4AC150-40](https://openairdocs.org/engine/franklin-4ac150-40) (registry code 27002, reciprocating) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 6
- Airframe hours: 1400
- Engines: FRANKLIN 6A4-150-B3 150 horsepower reciprocating
- Damage: Destroyed
- Fire: In-Flight
- Flight: Personal, Part 91
- Registered owner: David F. Powell
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Annual, March 31, 1986, 1 hours before
- Departed: Y76, DES MOINES, IA
- Destination: MCW, MASON CITY, IA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 43; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; toxicology performed; flight hours: 570 total, 50 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: 350° at 6 knots
- Visibility: 12 statute miles
- Lowest ceiling: none
- Temperature: 84 °F, dew point 72 °F
- Altimeter: 29.00 inHg
- Observed at: DSM, 19 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 19860719034349A](https://openairdocs.org/incident/19860719034349A), Jul 19, 1986: Amtrwt TAILWIND, Sheldahl, IA, Destroyed, 2 fatal. The aircraft caught fire inflight and exploded on impact. Modified exhaust stacks ingited fabric covering.

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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