# NTSB FTW86LA037: Boeing A75N1, N4935N, Yukon, OK, January 18, 1986

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: January 18, 1986, 15:33 local (21:33 UTC)
- Place: Yukon, OK
- Coordinates: 35.509231, -97.759101 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=35.5092&lon=-97.7591&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 21993
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=FTW86LA037
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/21993/pdf
- Page: https://openairdocs.org/ntsb/FTW86LA037

## Sequence of events

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

- Airframe/component/system failure/malfunction, landing - roll
  - landing gear,normal brake system - failure,total (cause)
- Nose over, landing - roll

## Analysis

THE LEFT BRAKE LOCKED AFTER THE AIRCRAFT ROLLED A SHORT DISTANCE DURING LANDING. AIRCRAFT SLOWED UNTIL ABOUT 20 MPH FORWARD SPEED AND THEN FLIPPED INVERTED AND STOPPED. POST ACCIDENT EXAMINATION REVEALED THE BRAKE SHOE RETURN SPRING ON THE LEFT BRAKE WAS BROKEN. REASON FOR THE SPRING FAILURE WAS NOT DETERMINED.

## Aircraft

- Registration: [N4935N](https://openairdocs.org/aircraft/N4935N), registered now, S/N 75-2087, built 1941 (OpenAirDocs)
- Reported make and model: BOEING A75N1
- Registry model: [Boeing A75N1(PT17)](https://openairdocs.org/model/boeing-a75n1-pt17) (registry code 1380134) (OpenAirDocs)
- Registry engine: [Continental W670 series](https://openairdocs.org/engine/continental-w670-series) (registry code 17018, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 75-2087
- Airframe hours: 2220
- Engines: CONTINENTAL W670-6A reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Registered owner: Darnell Oil Corp.
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, September 15, 1985
- Airport: F29, Page

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 55; private; airplane ratings: single-engine land; medical: class 3, valid medical--no waivers/lim.; flight hours: 376 total, 154 in this make and model, 236 as pilot in command, 33 in the last 90 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 10° at 14 knots, gusting 18
- Visibility: 1 statute miles
- Lowest ceiling: none
- Temperature: 55 °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 19860118002169A](https://openairdocs.org/incident/19860118002169A), Jan 18, 1986: Boeing A75N1, Yukon, OK, Substantial damage. Flipped inverted during rollout. Left brake locked when return spring broke.

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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