# NTSB DEN85LA151: Beech B35, N5099C, Chinook, MT, June 7, 1985

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: June 7, 1985, 14:35 local (20:35 UTC)
- Place: Chinook, MT
- Coordinates: 48.470439, -109.210952 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=48.4704&lon=-109.2110&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 4 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 16692
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=DEN85LA151
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/16692/pdf
- Page: https://openairdocs.org/ntsb/DEN85LA151

## Sequence of events

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

- Loss of engine power(total) - nonmechanical, cruise - normal
  - reason for occurrence undetermined (cause)
- Forced landing, descent - emergency
  - emergency procedure - improper, pilot in command (contributing factor)
- In flight collision with object, landing - flare/touchdown
  - terrain condition - high obstruction(s) (contributing factor)
  - maneuver - performed, pilot in command
  - object - fence (contributing factor)

## Analysis

ABOUT 10 MIN AFTER TAKEOFF, THE ACFT WAS DAMAGED DURING A FORCED LANDING AFTER THE ENG BEGAN SPUTTERING & THEN LOST POWER. THE PLT REPORTED THAT HE MADE A NORMAL TAKEOFF WITH THE COWL FLAPS OPEN & THE MIXTURE RICH. AFTER CLIMBING ABOUT 1100 FT (TO 3500 FT MSL), HE CLOSED THE COWL FLAPS & LEANED THE MIXTURE SLIGHTLY. ABOUT 2 TO 3 MIN LATER, THE ENG BEGAN SPUTTERING. THE PLT OBSERVED THE OIL TEMP RISING. HE SAID HE OPENED THE COWL FLAPS, TURNED ON THE CARB HEAT, CHANGED THE FUEL SEL & CHECKED THE MAGNETOS. THE ENG LOST ALL POWER & THE PLT ATTEMPTED TO LAND ON A ROAD. HOWEVER, HE MANEUVERED TO AVOID POWER LINES THEN ELECTED TO LAND IN A FIELD. DURING THE APCH TO LAND, THE ACFT HIT A FENCE & WAS DAMAGED. A LACK OF FUEL WAS NOTED IN THE FUEL LINE LEADING TO THE CARBURETOR. THE ACFT HAD BEEN REFUELED WITH 37 GAL OF UNLEADED AUTOMOTIVE FUEL. THE AIR TEMP WAS REPORTED AS 85 DEG. NO PRE-ACCIDENT PROBLEM WAS FOUND THAT WOULD HAVE CAUSED A LOSS OF POWER, VAPOR LOCK OR OTHER ENG/FUEL SYS PROBLEM. THE WOBBLE PUMP WAS NOT USED WHILE ATTEMPTING TO RESTORE PWR.

## Aircraft

- Registration: N5099C (not matched to a registry record)
- Reported make and model: BEECH B35
- Category: Airplane
- Serial number: D-2361
- Airframe hours: 5326
- Engines: CONTINENTAL E-185-11 205 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Martin Williamson
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, December 3, 1984, 37 hours before
- Departed: CHINOOK, MT
- Destination: SPEARFISH, SD

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 53; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: left; flight hours: 1,414 total, 59 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 270° at 10 knots
- Visibility: 30 statute miles
- Lowest ceiling: none
- Temperature: 84 °F

## 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 19850607023489A](https://openairdocs.org/incident/19850607023489A), Jun 7, 1985: Beech B35, Chinook, MT, Substantial damage. Engine quit after level off. Struck fence posts during landing. Probable vapor lock. Unapproved unleaded fuel used.

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.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.