# NTSB CEN11CA030: Conrad Theodore J Thorp T-18, N86TJ, Fredericksburg, TX, October 13, 2010

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Data collection · Final report
- Date: October 13, 2010, 10:00 local (15:00 UTC)
- Place: Fredericksburg, TX
- Coordinates: 30.243333, -98.909164 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=30.2433&lon=-98.9092&mi=10
- Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping)
- Defining event: [Approach-VFR pattern downwind: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340)
- Highest injury: No injuries
- Injuries: 1 uninjured
- Status: Completed, report April 12, 2011
- Report: Approved by Office Director
- NTSB office: Central Region
- NTSB case key (mKey): 77633
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN11CA030
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/77633/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=77633
- Page: https://openairdocs.org/ntsb/CEN11CA030

## Probable cause

The malfunction of the throttle clamp, which resulted in the pilot's inability to control the engine's power setting.

## Findings

NTSB's coded findings; those marked are part of the probable cause.

- [Engine controls: power lever](https://openairdocs.org/ntsb-findings/01057603): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [Conrad Theodore J THORP T-18, 1 case](https://openairdocs.org/ntsb-findings/01057603/cases.md?model=89510P6), [All aircraft, 95 cases](https://openairdocs.org/ntsb-findings/01057603/cases.md)
- [Performance/control parameters: airspeed](https://openairdocs.org/ntsb-findings/01062010): Aircraft › Aircraft oper/perf/capability · Not attained/maintained (probable cause); cases with it: [Conrad Theodore J THORP T-18, 1 case](https://openairdocs.org/ntsb-findings/01062010/cases.md?model=89510P6), [All aircraft, 1,681 cases](https://openairdocs.org/ntsb-findings/01062010/cases.md)

## Sequence of events

The events NTSB coded, in order, by phase of flight. The defining event best describes what happened.

- [Approach-VFR pattern downwind: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Conrad Theodore J THORP T-18, 1 case](https://openairdocs.org/ntsb-events/340/sequence.md?model=89510P6), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md)
- [Landing-landing roll: Runway excursion](https://openairdocs.org/ntsb-events/300); cases with it: [Conrad Theodore J THORP T-18, 1 case](https://openairdocs.org/ntsb-events/300/sequence.md?model=89510P6), [All aircraft, 3,643 cases](https://openairdocs.org/ntsb-events/300/sequence.md)

## Analysis

According to the pilot, he reduced engine power to slow the airplane for landing while on the downwind leg of the traffic pattern. He then attempted to increase power and the engine did not respond. The pilot maneuvered the airplane immediately toward the runway and it floated during the landing. When the airplane touched down, there was insufficient distance remaining to stop on the runway. The airplane departed the end of the runway and the pilot intentionally ground-looped the airplane to stay on the airport property, causing substantial damage to both wings. A postaccident examination of the engine revealed that the clamp securing the throttle controller end was allowing the cable to slip freely.

## Factual narrative

While flying the downwind leg for a full-stop landing, the pilot reduced engine power to slow the airplane for landing. When the pilot advanced the throttle, the engine did not respond. The pilot turned the airplane immediately for the runway. Due to the "tighter" pattern and increased airspeed, the airplane floated during the landing. When the airplane touched down on the runway, there was insufficient distance remaining for the airplane to stop on the runway. The airplane departed the end of the runway and the pilot ground looped the airplane to stay on the airport property. Substantial damage was sustained to both wings. An examination of the engine revealed that the clamp securing the throttle controller end was allowing the cable to slip freely.

## Aircraft

- Registration: [N86TJ](https://openairdocs.org/deregistered/N86TJ-2011-01-31), registration cancelled 2011-01-31, S/N C-4602 (OpenAirDocs)
- Reported make and model: CONRAD THEODORE J THORP T-18
- Registry model: [Conrad Theodore J THORP T-18](https://openairdocs.org/model/conrad-theodore-j-thorp-t-18) (registry code 89510P6) (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: C-4602
- Engines: LYCOMING O-320 SERIES 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Special, Experimental (Special)
- Departed: TS65, San Angelo, TX
- Destination: T82, Fredericksburg, TX
- Flight plan: Unknown
- Airport: T82, Gillespie County, runway 32, 5,001 × 75 ft, asphalt

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 72; injuries: none; commercial; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 3, with waivers/limitations; last flight review November 15, 2008; seat: left; flight hours: 9,450 total, 549 in this make and model

## Weather

- Conditions: Visual (VMC), Day
- Wind: 30° at 8 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 70 °F, dew point 52 °F
- Altimeter: 30.31 inHg
- Observed at: T82

## 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 20101013054439A](https://openairdocs.org/incident/20101013054439A), Oct 13, 2010: Thorp T-18, Fredericksburg, TX, Substantial damage. N86TJ landed in the last 1000 ft. of RUNWAY32 at T82 and ran off the runway into a fence that was 733 ft. from the runway. This caused substantial damage.

## Docket (2 files)

The files NTSB released with the investigation on December 10, 2010, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=77633. 521 KB in all.

- Pilot's statement (item 1, .PDF, 16 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40340135&FileExtension=.PDF&FileName=Pilot%27s%20statement-Master.PDF
- Photo: Accident overview (item 2, .PDF, 505 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40340136&FileExtension=.PDF&FileName=Photo%3A%20Accident%20overview-Master.PDF

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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