# NTSB LAX83FA124: Thorp T-18, N3124, Simi, CA, March 5, 1983

- Type: NTSB accident investigation
- Classification: Accident · Fatal · Field investigation · Final report
- Date: March 5, 1983, 12:00 local (20:00 UTC)
- Place: Simi, CA
- Coordinates: 40.370075, -121.610488 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=40.3701&lon=-121.6105&mi=10
- Phase of flight: [Unknown](https://openairdocs.org/ntsb-phases/990) (OpenAirDocs' grouping)
- Highest injury: Fatal
- Injuries: 1 fatal
- Status: Completed
- Report: Approved by Office Director
- NTSB case key (mKey): 23433
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=LAX83FA124
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/23433/pdf
- Page: https://openairdocs.org/ntsb/LAX83FA124

## Sequence of events

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

- Airframe/component/system failure/malfunction, unknown
  - flight control,stabilator attachment - failure,total (cause)
  - maintenance,annual inspection - inadequate, other maintenance personnel (cause)
  - lack of total experience in kind of aircraft, pilot in command (cause)
  - flight control,stabilator attachment - fatigue (cause)
- In flight collision with terrain/water, descent - uncontrolled

## Analysis

THE ACFT CRASHED IN A SCHOOL PLAYGROUND IN A STEEP UNCONTROLLED DESCENT. WITNESSES SAID THE ACFT WAS OBSERVED IN A 60 DEGREE NOSE DOWN ATTITUDE AT ABOUT 1000 FT AGL AND THIS CONTINUED UNTIL GROUND IMPACT. THE ENGINE WAS PRODUCING HIGH POWER AT THIS TIME. NO WITNESSES SAW THE ACFT BEFORE THE DIVE. EXAMINATION REVEALED THAT THE COCKPIT CONTROL STICK HAD FAILED AND THE AILERON AND STABILATOR CROSS-BAR RIGHT MOUNTING POST TUBE WELDED AREA FAILED PRIOR TO THE ACCIDENT. A PRE-EXISTING CRACK HAD EXISTED FOR SOME TIME ON THE CROSS-BAR TUBE WHEN THIS TUBE FAILED THE FLT CONTROLS JAMMED WHICH PREVENTED THE PLT FROM CONTROLLING THE ACFT.

## Aircraft

- Registration: [N3124](https://openairdocs.org/deregistered/N3124-2012-09-25), registration cancelled 2012-09-25, S/N MC68, built 1965 (OpenAirDocs)
- Reported make and model: THORP T-18
- Registry model: [Thorp T-18 MODIFIED](https://openairdocs.org/model/thorp-t-18-modified) (registry code 89510QA) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: MC-68
- Airframe hours: 506
- Engines: LYCOMING O-320B 160 horsepower reciprocating
- Damage: Destroyed
- Flight: Personal, Part 91
- Operator: Eric J. Shaw & Associates
- Registered owner: Ted J. Mason
- Airworthiness certificate: Special, Experimental (Special)
- Last inspection: Annual, December 15, 1982, 7 hours before
- Departed: VNY, VAN NUYS, CA

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 19; private; airplane ratings: single-engine land, multi-engine land; medical: class 3, valid medical--no waivers/lim.; seat: left; toxicology performed; flight hours: 195 total, 5 in this make and model, 118 as pilot in command, 18 in the last 90 days, 6 in the last 30 days, 1 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Not reported
- Wind: 170° at 5 knots
- Visibility: 10 statute miles
- Lowest ceiling: 3,000 ft broken
- Altimeter: 30.00 inHg
- Observed at: VYN, 13 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 19830305006099A](https://openairdocs.org/incident/19830305006099A), Mar 5, 1983: Amtrth THORPT18, Simi Valley, CA, Destroyed. Aileron and stabilator crossbar right mounting post tube welded. Area failed prior to accident.

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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