# NTSB CEN13LA406: American Champion 7GCBC, N255SF, Lufkin, TX, July 3, 2013

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Limited investigation · Final report
- Date: July 3, 2013, 11:40 local (16:40 UTC)
- Place: Lufkin, TX
- Coordinates: 31.147777, -94.770835 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=31.1478&lon=-94.7708&mi=10
- Phase of flight: [Maneuvering](https://openairdocs.org/ntsb-phases/450) (OpenAirDocs' grouping)
- Defining event: [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report July 30, 2014
- Report: Approved by Office Director
- NTSB office: Central Region
- Parties: Federal Aviation Administration
- NTSB case key (mKey): 87455
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN13LA406
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/87455/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=87455
- Page: https://openairdocs.org/ntsb/CEN13LA406

## Probable cause

The restricted movement of the carburetor’s forked needle valve within its seat due to the mechanic’s misadjustment of the valve clip forks, which resulted in fuel starvation.

## Findings

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

- [Engine fuel and control: fuel control/carburetor](https://openairdocs.org/ntsb-findings/01057322): Aircraft › Aircraft power plant · Malfunction (probable cause); cases with it: [American Champion 7GCBC, 1 case](https://openairdocs.org/ntsb-findings/01057322/cases.md?model=21101PL), [All aircraft, 195 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md)
- [Engine fuel and control: fuel control/carburetor](https://openairdocs.org/ntsb-findings/01057322): Aircraft › Aircraft power plant · Incorrect service/maintenance (probable cause); cases with it: [American Champion 7GCBC, 1 case](https://openairdocs.org/ntsb-findings/01057322/cases.md?model=21101PL), [All aircraft, 195 cases](https://openairdocs.org/ntsb-findings/01057322/cases.md)
- [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Maintenance personnel (probable cause); cases with it: [American Champion 7GCBC, 1 case](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=21101PL), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md)

## Sequence of events

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

- [Maneuvering-low-alt flying: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341) (defining event); cases with it: [American Champion 7GCBC, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=21101PL), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md)
- [Emergency descent: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [American Champion 7GCBC, 2 cases](https://openairdocs.org/ntsb-events/440/sequence.md?model=21101PL), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md)
- [Emergency descent: Collision with terr/obj (non-CFIT) ](https://openairdocs.org/ntsb-events/470); cases with it: [American Champion 7GCBC, 9 cases](https://openairdocs.org/ntsb-events/470/sequence.md?model=21101PL), [All aircraft, 10,189 cases](https://openairdocs.org/ntsb-events/470/sequence.md)

## Analysis

The pilot was flying a pipeline patrol flight about 500 feet above ground level. About 6 miles south of the destination, the engine abruptly lost power. The pilot observed that both fuel tanks contained a usable level of fuel. Additionally, he saw no obvious issues with the mixture setting, carburetor heat, magnetos, throttle position, and fuel shutoff valve. The pilot landed the airplane in a field with high vegetation, which resulted in strut damage. The pilot did not report any fuel or oil leaks. During a postaccident examination, the engine was intermittently operational. The engine would produce power when the carburetor was "tapped" after the engine stopped. A carburetor examination revealed that the accelerator pump was operational and that the fuel screens were clear of debris. However, the forked needle valve's movement within its seat was restricted. The valve clip forks were observed resting on the valve seat when the carburetor's throttle body was inverted. The carburetor maintenance manual specified that a minimum clearance must exist between the forked valve clip and the valve seat. It is likely that the restricted movement of the carburetor's forked needle valve resulted from the mechanic's misadjustment of the valve clip forks, which subsequently caused the engine to lose power due to fuel starvation.

## Factual narrative

On July 3, 2013, about 1140 central daylight time, an American Champion Aircraft model 7GCBC airplane, N255SF, impacted high vegetation and terrain during a forced landing following a loss of engine power near Lufkin, Texas. The airline transport rated pilot and his passenger were uninjured. The airplane sustained substantial damage to its wing struts. The aircraft was registered to and operated by KCSI Aerial Patrol Inc. under the provisions of 14 Code of Federal Regulations Part 91 as an aerial observation flight. Day visual flight rules (VFR) conditions prevailed for the flight, which did not operate on a VFR flight plan. The flight originated from the Texas Gulf Coast Regional Airport (LBX), near Angleton, Texas, about 0945 and was destined for the Angelina County Airport (LFK), near Lufkin, Texas. According to the pilot's accident report, the airplane was serviced with a full load of fuel at LBX. The purpose of the flight was a working pipeline patrol flight, which was flown at 500 feet above ground level. Weather was VFR with light to variable wind. After a radio call to area traffic at LFK to state position and intention, the pilot continued the pipeline patrol flight. About six miles south of LFK, there was an abrupt loss of engine power. The pilot checked fuel tank levels, which were 1/2 tank on the left side and "a little more" than 1/4 tank on the right side. Additionally he checked the mixture setting, carburetor heat, magnetos, throttle position, and the fuel shutoff valve. The pilot observed no obvious issues. The pilot contacted the LFK common traffic advisory frequency, announced the airplane's engine trouble, and indicated that he would be conducting a forced landing about five miles to the south of the LFK. The pilot landed the airplane in a field with high vegetation. He did not report any fuel or oil leaks as he checked and secured the airplane. A Federal Aviation Administration inspector examined the airplane and confirmed the substantial damage. The airplane was recovered and the operator started the engine after the accident. The operator indicated that when the carburetor was "tapped" after an engine stoppage, the engine would start producing power again. The carburetor was shipped to the investigator in charge for a tear down examination. It was a Marvel-Schebler MA-4SPA model carburetor marked with part no. 10-3678-32. The carburetor's accelerator pump link was manufactured with three holes. The selection of a link hole is model specific. The accelerator pump plunger stem was secured in a link hole that was not specified for the accident carburetor part number. The accelerator pump was operational and it ejected a test fluid when the throttle linkage was rotated by hand. Disassembly revealed that the carburetor's fuel screens were clear of debris. The carburetor was equipped with a solid blue epoxy float. The needle valve's movement within its seat was restricted. The forked valve clip's forks were observed to rest onthe valve seat when the carburetor's throttle body was inverted. The Marvel-Schebler aircraft carburetor maintenance manual describes procedures for overhauling the manufacturer's carburetors. It describes how to determine and adjust the specified minimum clearance that must exist between the forked valve clip and the valve seat on solid blue epoxy float equipped carburetors.

## Aircraft

- Registration: [N255SF](https://openairdocs.org/aircraft/N255SF), registered now, S/N 1287-2000, built 2000 (OpenAirDocs)
- Reported make and model: AMERICAN CHAMPION AIRCRAFT 7GCBC
- Registry model: [American Champion 7GCBC](https://openairdocs.org/model/american-champion-7gcbc) (registry code 21101PL) (OpenAirDocs)
- Registry engine: [Lycoming 0-320 series](https://openairdocs.org/engine/lycoming-0-320-series) (registry code 41508, reciprocating) (OpenAirDocs)
- Category: Airplane
- Serial number: 1287-2000
- Year built: 2000
- Airframe hours: 2842.4
- Engines: LYCOMING O-320-B2B 180 horsepower reciprocating
- Damage: Substantial damage
- Flight: Aerial observation, Part 91
- Operator: Kcsi Aerial Patrol Inc
- Registered owner: Kcsi Aerial Patrol Inc
- Airworthiness certificate: Standard, Normal
- Last inspection: 100 hour, June 19, 2013
- Departed: LBX, ANGLETON/LAKE JACKSON, TX
- Destination: LFK, Lufkin, TX
- Airport: LFK, Angelina County

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 51; injuries: none; flight instructor, airline transport; airplane ratings: single-engine sea, single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review September 18, 2011; seat: front; restraint: 3-point; flight hours: 4,046 total, 995 in this make and model, 3,473 as pilot in command, 281 in the last 90 days, 118 in the last 30 days, 5 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: variable at 6 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 84 °F, dew point 64 °F
- Altimeter: 30.04 inHg
- Observed at: KLFK, 5 nm away

## Docket (6 files)

The files NTSB released with the investigation on April 15, 2014, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=87455. 14.6 MB in all.

- Pilot/Operator Aircraft Accident Report, NTSB Form 6120.1 (item 1, .PDF, 3.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40397338&FileExtension=.PDF&FileName=Pilot%2FOperator%20Aircraft%20Accident%20Report,%20NTSB%20Form%206120.1-Redacted.PDF
- Communication Summary - Operator Findings (item 2, .PDF, 79 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40411231&FileExtension=.PDF&FileName=Communication%20Summary%20-%20Operator%20Findings-Master.PDF
- Overhauler's Teardown Statement (item 3, .PDF, 809 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40411232&FileExtension=.PDF&FileName=Overhauler%27s%20Teardown%20Statement-Redacted.PDF
- Photo 1 - View of the float, clip, fork, and valve seat (item 4, .PDF, 3.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40397766&FileExtension=.PDF&FileName=Photo%201%20-%20View%20of%20the%20float,%20clip,%20fork,%20and%20valve%20seat-Master.PDF
- Photo 2 - View of the inlet screen (item 5, .PDF, 4.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40397775&FileExtension=.PDF&FileName=Photo%202%20-%20View%20of%20the%20inlet%20screen-Master.PDF
- Photo 3 - View of the accelerator pump screen (item 6, .PDF, 3.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=40397777&FileExtension=.PDF&FileName=Photo%203%20-%20View%20of%20the%20accelerator%20pump%20screen-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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