# NTSB FTW91FA158: Beech K35, N817R, Tulsa, OK, August 25, 1991

- Type: NTSB accident investigation
- Classification: Accident · Serious injuries · Field investigation · Final report
- Date: August 25, 1991, 12:56 local (17:56 UTC)
- Place: Tulsa, OK
- Coordinates: 35.450817, -97.569076 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.4508&lon=-97.5691&mi=10
- Phase of flight: [Enroute](https://openairdocs.org/ntsb-phases/400) (OpenAirDocs' grouping)
- Highest injury: Serious injuries
- Injuries: 2 serious
- Status: Completed, report January 25, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 23278
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW91FA158
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/23278/pdf
- Page: https://openairdocs.org/ntsb/FTW91FA158

## Probable cause

TOTAL POWER LOSS DUE TO FAILURE OF THE CRANKSHAFT BEARINGS AND CONNECTING ROD CAP BOLTS RESULTING FROM THE MAINTENANCE FACILITIES' FAILURE TO OVERHAUL THE ENGINE. A FACTOR WAS THE LACK OF SUITABLE TERRAIN FOR THE FORCED LANDING.

## Sequence of events

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

- Loss of engine power, cruise
  - maintenance,overhaul,major - not performed, other maintenance personnel (cause)
  - engine assembly,bearing - failure,total (cause)
  - engine assembly,connecting rod bolt - failure,total (cause)
- Forced landing, descent - emergency
- In flight collision with object, descent
  - object - wire,static
- In flight collision with terrain/water, descent - emergency
  - terrain condition - none suitable (contributing factor)

## Analysis

DURING ROUTINE MAINTENANCE, THE ENGINE WAS RUN UP TO FULL POWER WITH THE AIRPLANE TOW BAR ATTACHED. AS THE NOSE STRUT COMPRESSED, THE PROPELLER STRUCK THE TOW BAR. A SERVICE BULLETIN ADDRESSES THIS ISSUE STATING THAT THE ENGINE SHOULD BE DISASSEMBLED AND INSPECTED FOR DAMAGE. THE MAINTENANCE FACILITY DID NOT ADVISE THE OWNER OF THE EXTENT OF THE DAMAGE INCURRED. AS A RESULT OF THE PROPELLER STRIKE, THE CRANKSHAFT MAIN BEARINGS ROTATED IN THE SADDLES, FAILING MECHANICALLY.  THIS RESULTED IN THE BLOCKAGE OF OIL PASSAGES AND THE SUBSEQUENT FAILURE OF THE NUMBER TWO CYLINDER CONNECTING ROD CAP BOLTS. TOTAL ENGINE FAILURE RESULTED. SUITABLE TERRAIN FOR THE FORCED LANDING WAS NOT AVAILABLE. IMPACT OCCURRED IN SOFT CULTIVATED TERRAIN.

## Aircraft

- Registration: [N817R](https://openairdocs.org/deregistered/N817R-1992-01-22), registration cancelled 1992-01-22, S/N D6015 (OpenAirDocs)
- Reported make and model: BEECH K35
- Registry model: [Beech K35](https://openairdocs.org/model/beech-k35) (registry code 1151524) (OpenAirDocs)
- Category: Airplane
- Serial number: DG015
- Airframe hours: 3090
- Engines: CONTINENTAL IO-470-C 250 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Hershel Maurer
- Registered owner: Hershel Maurer
- Airworthiness certificate: Standard, Normal
- Last inspection: Annual, September 1, 1990, 86 hours before
- Departed: SGF, SPRINGFIELD, MO
- Destination: HSD, SUNDANCE, OK
- Flight plan: IFR

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 52; commercial, private; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 2, valid medical--no waivers/lim.; seat: left; flight hours: 376 total, 115 in this make and model, 282 as pilot in command, 32 in the last 90 days, 26 in the last 30 days, 9 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 180° at 10 knots
- Visibility: 3 statute miles
- Lowest ceiling: 5,000 ft broken
- Temperature: 84 °F, dew point -0 °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 19910825036529A](https://openairdocs.org/incident/19910825036529A), Aug 25, 1991: Beech K35, Tulsa, OK, Substantial damage. Lost oil pressure. Engine seized. Hit wires on forced landing. Prior prop strike on towbar engine not examined.

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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