# NTSB ATL93LA069: John Thomason Laco 145, N89ST, Tuskegee, AL, April 3, 1993

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: April 3, 1993, 12:10 local (18:10 UTC)
- Place: Tuskegee, AL
- Coordinates: 32.389648, -85.68077 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=32.3896&lon=-85.6808&mi=10
- Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report November 3, 1993
- Report: Approved by Office Director
- NTSB case key (mKey): 8732
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ATL93LA069
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/8732/pdf
- Page: https://openairdocs.org/ntsb/ATL93LA069

## Probable cause

THE OVERLOAD FAILURE OF THE TAIL WHEEL LEAF SPRINGS, WHICH RESULTED IN A LOSS OF DIRECTIONAL CONTROL DURING THE LANDING ROLL.

## 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,tailwheel assembly - failure,total (cause)
  - landing gear,tailwheel assembly - overload
- Loss of control - on ground/water, landing - roll
- On ground/water encounter with terrain/water, landing - roll

## Analysis

THE PILOT REPORTED THAT HE WAS PERFORMING A NORMAL LANDING; THE TAIL WHEEL TOUCHED DOWN FIRST, THEN THE MAINS. DURING THE LANDING ROLL, DIRECTIONAL CONTROL WAS LOST, AND THE AIRCRAFT GROUND LOOPED. THE INVESTIGATION REVEALED THAT THE TAIL WHEEL LEAF SPRINGS HAD FAILED. THERE WAS CORROSION ON ONE OF THE FRACTURE SURFACES; HOWEVER, METALLURGICAL EXAMINATION OF THE SPRINGS REVEALED THAT ALL FRACTURES WERE FROM OVERLOAD. THE PILOT REPORTED THAT ALL OF THE LEAF SPRINGS WERE NOT LOCATED; THEREFORE, A COMPLETE METALLURGICAL STUDY WAS NOT POSSIBLE. THE AIRCRAFT TOTAL TIME WAS 26 HOURS; HOWEVER, THE LEAF SPRINGS WERE INSTALLED IN A USED CONDITION, AND THE MAINTENANCE HISTORY OF THE SPRINGS WAS NOT AVAILABLE.

## Aircraft

- Registration: [N89ST](https://openairdocs.org/deregistered/N89ST-1993-05-04), registration cancelled 1993-05-04, S/N JT1 (OpenAirDocs)
- Reported make and model: JOHN THOMASON LACO 145
- Registry model: [Thomason John LACO 145](https://openairdocs.org/model/thomason-john-laco-145) (registry code 0569131) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: JT-1
- Airframe hours: 26
- Engines: CONTINENTAL O-300-C 145 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Operator: Grimes, Charles J.
- Registered owner: Thomason, John
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Annual, June 20, 1992, 22 hours before
- Departed: NONE, SMITHS, AL
- Airport: 06A, Tuskegee Municipal, runway 31, 5,000 × 100 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 63; private; airplane ratings: single-engine land; medical: class 3, valid medical--w/ waivers/lim; seat: rear; flight hours: 424 total, 19 in this make and model, 1 in the last 90 days

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 54 °F, dew point 28 °F
- Altimeter: 30.00 inHg
- Observed at: AUO, 15 nm away

## 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 19930403007789A](https://openairdocs.org/incident/19930403007789A), Apr 3, 1993: Amtr LACO145, Tuskegee, AL, Substantial damage. Landed tailwheel first. Leaf springs broke caused ground loop. Fractures from corrosion and overstress.

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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