# NTSB DEN85FTI02: Benjamin Pitts S1U, N155LB, Fort Benton, MT, February 24, 1985

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Final report
- Date: February 24, 1985, 14:30 local (21:30 UTC)
- Place: Fort Benton, MT
- Coordinates: 47.979351, -110.79969 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=47.9794&lon=-110.7997&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16569
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN85FTI02
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16569/pdf
- Page: https://openairdocs.org/ntsb/DEN85FTI02

## Sequence of events

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

- Loss of engine power(total) - nonmechanical, takeoff - initial climb
  - fuel system - water (cause)
  - fluid,fuel - contamination (cause)
  - refueling - inattentive, fbo personnel (cause)
- Forced landing, descent - emergency
- On ground/water encounter with terrain/water, landing - roll
  - terrain condition - dirt bank/rising embankment

## Analysis

THE ACFT CONTACTED A DIRT BANK DURING A FORCED LANDING IN A FIELD FOLLOWING A LOSS OF PWR SHORTLY AFTER TAKEOFF. A LANDING WAS MADE AT FORT BENTON ARPT WHERE THE ACFT WAS SERVICED WITH 11.85 GALLONS OF 100 OCT AVGAS. POST ACCIDENT EXAMINATION OF THE ACFT REVEALED WATER CONTAMINATION IN THE CARBURETOR BOWL AND FUEL SYSTEM. A 1 QT JAR WAS FILLED WITH FUEL FROM THE FUEL LINE TO THE CARBURETOR. A 17/32 INCH LAYER OF AVGAS WAS PRESENT ON TOP OF WATER WHICH FILLED THE REMAINING PORTION OF THE JAR. THE ACFT WAS REFUELED FROM AN UNDERGROUND TANK. THERE WAS NO FILTERIZATION ELEMENT ON THE REFUELING EQUIPMENT.

## Aircraft

- Registration: [N155LB](https://openairdocs.org/deregistered/N155LB-1989-06-12), registration cancelled 1989-06-12, S/N 00184 (OpenAirDocs)
- Reported make and model: BENJAMIN PITTS S1U
- Registry model: [Benjamin Leslie W PITTS S-1U](https://openairdocs.org/model/benjamin-leslie-w-pitts-s-1u) (registry code 7221316) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 001-84
- Airframe hours: 514
- Engines: LYCOMING O-360-A2F 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Leslie W. Benjamin
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Unknown, July 5, 1984, 394 hours before
- Destination: SBX, SHELBY, MT
- Airport: 79S, Fort Benton

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 30; private; airplane ratings: single-engine land; medical: class 3, expired; seat: front; flight hours: 543 total, 50 in this make and model, 6 in the last 90 days, 6 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 30° at 20 knots, gusting 30
- Visibility: 40 statute miles
- Lowest ceiling: none
- Temperature: 45 °F, dew point 36 °F
- Altimeter: 29.00 inHg

## 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 19850224004299A](https://openairdocs.org/incident/19850224004299A), Feb 24, 1985: Amtrpt PITTSSPECIAL, Fort Benton, MT, Substantial damage. Engine quit on takeoff landed on road, wing hit dirt bank. Water in fuel. No water separator on airport fuel pump.

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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