# NTSB FTW89FA107: Pitts S-1S, N64652, Henryetta, OK, June 2, 1989

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Field investigation · Final report
- Date: June 2, 1989, 15:15 local (20:15 UTC)
- Place: Henryetta, OK
- Coordinates: 35.439785, -95.980529 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.4398&lon=-95.9805&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 3 serious, 2 minor; on the ground: 2 serious, 2 minor
- Status: Completed, report September 30, 1991
- Report: Approved by Office Director
- NTSB case key (mKey): 22773
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW89FA107
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/22773/pdf
- Page: https://openairdocs.org/ntsb/FTW89FA107

## Probable cause

AN ENGINE POWER LOSS DUE TO THE SEPARATION AND DEPARTURE OF AN EXHAUST STACK. THE STACK FAILED DUE TO POOR WELD. FACTOR(S) WAS: THE TERRAIN CONDITIONS OF THE SELECTED FORCED LANDING SITE.

## 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, cruise
  - exhaust system,stack - failure,total (cause)
  - maintenance,major repair - poor, other maintenance personnel (cause)
  - exhaust system,stack - separation (cause)
- Forced landing, approach - vfr pattern - final approach
- In flight collision with object, approach - vfr pattern - final approach
  - object - wire,transmission (contributing factor)
  - terrain condition - hidden obstruction(s) (contributing factor)
- On ground/water collision with object, landing - roll
  - object - vehicle (contributing factor)

## Analysis

POWER LOSS OCCURRED DUE TO SEPARATION AND DEPARTURE OF LOWER 1/2 RT EXHAUST STACK. PLT MADE A FORCED LANDING ON THE 2 NORTHBOUND LANES OF A DIVIDED HWY. ON SHORT FINAL, THE ACFT STRUCK POWER LINES, CRASHED, AND SLID INTO A TRUCK TRAVELLING NORTH. A PASSENGER CAR, TRAVELLING SOUTH, BECAME ENTANGLED IN THE WIRES AND WAS SUBSEQUENTLY REAR ENDED BY ANOTHER BEHICLE. THE POWER LINE POLES WERE MASKED FROM VIEW BY TREES ON BOTH SIDES OF THE ROAD. EXAMINATION OF THE EXHAUST STACK REVEALED THAT IT HAD UNDERGONE EXTENSIVE POST-MANUFACTURE REPAIRS IN THE AREA OF THE SEPARATION. THERE WAS EVIDENCE OF EXTENSIVE WELD FUSION ZONE POROSITY IN THE AREA THAT HAD BEEN WELDED. WELD FUSION ZONE POROSITY HAS BEEN ATTRIBUTED IN THE PAST TO POOR SURFACE PREPARATION AND WELD REPAIR TECHNIQUES.

## Aircraft

- Registration: [N64652](https://openairdocs.org/deregistered/N64652-2013-04-30), registration cancelled 2013-04-30, S/N 731-H, built 1977 (OpenAirDocs)
- Reported make and model: PITTS S-1S
- Registry model: [Andreas PITTS SPECIAL S-1](https://openairdocs.org/model/andreas-pitts-special-s-1) (registry code 7220761) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 731-H
- Airframe hours: 55
- Engines: LYCOMING O-320-B2B 160 horsepower reciprocating
- Damage: Destroyed
- Fire: In-Flight
- Flight: Personal, Part 91
- Operator: Arsenault, Donald S.
- Registered owner: Lorene Swahn
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Annual, October 25, 1988, 15 hours before
- Departed: MLC, MC ALESTER, OK
- Destination: BVO, BARTLESVILLE, OK

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 40; commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: front; flight hours: 2,300 total, 15 in this make and model, 2,300 as pilot in command, 30 in the last 90 days, 15 in the last 30 days, 4 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 210° at 9 knots
- Visibility: 15 statute miles
- Lowest ceiling: none
- Temperature: 88 °F, dew point 70 °F
- Altimeter: 30.00 inHg
- Observed at: MLC, 35 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 19890602014239A](https://openairdocs.org/incident/19890602014239A), Jun 2, 1989: Amtrpt PITTSSPECIAL, Henryetta, OK, Destroyed. Change in engine noise. Exhaust stack broke. Engine lost power. Hit power line over road. Caused vehicle pile up.

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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