# NTSB SEA91LA188: Waco KNF, Wendover, UT, July 24, 1991

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 24, 1991, 08:15 local (14:15 UTC)
- Place: Wendover, UT
- Coordinates: 40.970195, -111.510513 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.9702&lon=-111.5105&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report September 28, 1992
- Report: Approved by Office Director
- NTSB case key (mKey): 41494
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=SEA91LA188
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/41494/pdf
- Page: https://openairdocs.org/ntsb/SEA91LA188

## Probable cause

PILOT INSTALLED AN IMPROPER 'O' RING WHICH RESTRICTED NORMAL LANDING GEAR EXTENSION AND SUBSEQUENT LOSS OF CONTROL BY THE PILOT.

## Sequence of events

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

- Loss of control - on ground/water, landing - roll
  - directional control - not maintained, pilot in command (cause)
  - landing gear,main gear shock absorbing strut - movement restricted (cause)
  - maintenance,installation - improper, other maintenance personnel (contributing factor)
  - aircraft preflight - poor, pilot in command (contributing factor)
  - terrain condition - soft (contributing factor)
- Nose over, landing - roll

## Analysis

THE PILOT OF THE WACO KNF WAS UNABLE TO CONTROL HIS AIRCRAFT WHEN IT PULLED HARD TO THE RIGHT UPON LANDING.  THE AIRCRAFT RAN OFF THE SIDE OF THE RUNWAY AND FLIPPED OVER IN THE SOFT DIRT.  THE PILOT HAD ADDED AN UNAUTHORIZED O-RING ON TOP OF THE OLEO STRUT SEAL.  HE SAID THAT THE SEAL WAS LEAKING AND HE WAS UNABLE TO FIND A REPLACEMENT IN THE LOCAL AREA, WHILE ON A CROSS-COUNTRY FLIGHT.  AFTER DEPARTURE THE NEXT MORNING THE STRUT FAILED TO FULLY EXTEND, WHICH CAUSED THE AIRCRAFT TO BECOME DIFFICULT TO CONTROL UPON LANDING.

## Aircraft

- Registration: NC698N (not matched to a registry record)
- Reported make and model: WACO KNF
- Category: Airplane
- Serial number: 3246
- Engines: KINNER K-5 100 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: William C. Phelps
- Registered owner: William C. Phelps
- Departed: EKO, ELKO, NV
- Flight plan: VFR
- Airport: ENV, Wendover Field, runway 12, 8,000 × 150 ft, macadam

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 63; commercial; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 3, valid medical--no waivers/lim.; flight hours: 7,663 total, 55 in this make and model, 5,484 as pilot in command, 12 in the last 90 days, 11 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Visibility: 50 statute miles
- Lowest ceiling: none
- Temperature: -0 °F, dew point -0 °F

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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