# NTSB CEN25LA054: American AA-1B, N6242L, Brenham, TX, December 1, 2024

- Type: NTSB accident investigation
- Classification: Accident · No injuries · Class 3 · Limited · Final report
- Date: December 1, 2024, 14:38 local (20:38 UTC)
- Place: Brenham, TX · Grass field
- Coordinates: 30.235094, -96.374447 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=30.2351&lon=-96.3744&mi=10
- Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping)
- Defining event: [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342)
- Highest injury: No injuries
- Injuries: 2 uninjured
- Status: Completed, report September 23, 2026
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Central Region
- Parties: Lycoming Engines, Federal Aviation Administration - Houston FSDO
- NTSB case key (mKey): 195575
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN25LA054
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/195575/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=195575
- Page: https://openairdocs.org/ntsb/CEN25LA054

## Probable cause

A partial loss of engine power due to an obstructed induction system from a mud dauber nest.

## Findings

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

- [Power plant: air intake](https://openairdocs.org/ntsb-findings/01057160): Aircraft › Aircraft power plant · Damaged/degraded (probable cause); cases with it: [American AA-1B, 1 case](https://openairdocs.org/ntsb-findings/01057160/cases.md?model=0630820), [All aircraft, 50 cases](https://openairdocs.org/ntsb-findings/01057160/cases.md)
- [Object/animal/substance: debris/dirt/foreign object](https://openairdocs.org/ntsb-findings/03022055): Environmental issues › Physical environment · Effect on equipment (probable cause); cases with it: [American AA-1B, 1 case](https://openairdocs.org/ntsb-findings/03022055/cases.md?model=0630820), [All aircraft, 101 cases](https://openairdocs.org/ntsb-findings/03022055/cases.md)

## Sequence of events

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

- [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342) (defining event); cases with it: [American AA-1B, 3 cases](https://openairdocs.org/ntsb-events/342/sequence.md?model=0630820), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md)
- [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [American AA-1B, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=0630820), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md)
- [Landing-landing roll: Landing gear collapse](https://openairdocs.org/ntsb-events/094); cases with it: [American AA-1B, 1 case](https://openairdocs.org/ntsb-events/094/sequence.md?model=0630820), [All aircraft, 1,787 cases](https://openairdocs.org/ntsb-events/094/sequence.md)

## Analysis

The pilot was conducting a personal flight when the airplane had a partial loss of engine power shortly after takeoff about 500 ft above the departure end of the runway. The pilot reported that the engine appeared to be running at idle power and he was unable to maintain altitude. The pilot completed a forced landing into a nearby grass field, during which the nose landing gear separated from the forward fuselage. The airplane’s left wing leading edge was substantially damaged during the forced landing. Examination of the engine did not reveal any evidence of a mechanical failure that would prevent normal operation. Visual examination of the engine’s exterior revealed that all four engine cylinders had evidence of mud dauber nests within their respective cooling fins. Additionally, a roughly 1.5-inch diameter mud dauber nest was found in the airbox between the air filter and the throat of the carburetor. Additionally, dirt with the same color as the mud dauber nest was observed within the carburetor throat and on the clean side of the air filter. The recovered mud dauber nest exhibited impressions consistent with the spacing of the wire coil that supported the flexible ducting associated with the carburetor heat system. As such, the mud dauber nest would not be visible during a preflight inspection. The flexible ducting also contained various-sized fragments of mud dauber nest debris. Based on the available evidence, it is likely the mud dauber nest became dislodged shortly after takeoff and partially obstructed the induction airflow into the carburetor, which resulted in a partial loss of engine power.

## Factual narrative

On December 1, 2024, about 1438 central daylight time, an American Aviation AA-1B airplane, N6242L, sustained substantial damage when it was involved in an accident near Brenham, Texas. The pilot and his passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that there was a partial loss of engine power shortly after takeoff from runway 34 at Brenham Municipal Airport (11R), Brenham, Texas. The partial loss of engine power occurred about 500 ft above the ground as the airplane flew over the departure end of the runway. The pilot reported that the engine appeared to be running at idle power and he was unable to maintain altitude, so he conducted a forced landing into a grass field north of the airport. The airplane’s nose landing gear separated during the forced landing. The airplane’s left wing leading edge was substantially damaged during the forced landing. The left wing exhibited a large semicircular impact likely due to a collision with the separated nose gear and/or with an anthill in the grass field. However, the leading-edge damage did not exhibit evidence of tire rubber transfer or scratching, nor did it contain anything resembling dirt/sand. Examination of the engine did not reveal any evidence of a mechanical failure that would prevent normal operation. A visual examination of the engine’s exterior revealed that all four engine cylinders had evidence of mud dauber nests within their respective cooling fins. Additionally, a roughly 1.5-inch diameter mud dauber nest was found in the airbox between the air filter and the throat of the carburetor, as shown in figure 1. Additionally, dirt with the same color as the mud dauber nest was observed within the carburetor throat and on the clean side of the air filter. The recovered mud dauber nest exhibited impressions consistent with the spacing of the wire coil that supported the flexible ducting associated with the carburetor heat system. The flexible ducting also contained various-sized fragments of mud dauber nest debris. The airplane had flown 4.7 hours since the last annual inspection that was completed on November 17, 2024. The air filter was replaced during the annual inspection. At the time of the accident, the engine had accumulated 531.7 hours since the last major overhaul that was completed on May 1, 1999. Figure 1. Mud dauber nest found in the airbox between the air filter and the throat of the carburetor. Red arrows point to the mud dauber nest. (Photos courtesy of Lycoming Engines and edited by NTSB)

## Aircraft

- Registration: [N6242L](https://openairdocs.org/aircraft/N6242L), registered now, S/N AA1B-0042 (OpenAirDocs)
- Reported make and model: AMERICAN AVIATION AA-1B
- Registry model: [American AA-1B](https://openairdocs.org/model/american-aa-1b) (registry code 0630820) (OpenAirDocs)
- Registry engine: [Lycoming 0-235 series](https://openairdocs.org/engine/lycoming-0-235-series) (registry code 41505, 4 cycle) (OpenAirDocs)
- Category: Airplane
- Serial number: AA1B-0042
- Year built: 1972
- Airframe hours: 2854.7
- Engines: Lycoming O-235-C2C 115 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Standard, Utility; Standard, Normal
- Last inspection: Annual, November 17, 2024, 4.7 hours before
- Departed: 11R, Brenham, TX
- Destination: 27XS, Brookshire, TX
- Airport: 11R, Brenham Municipal Airport, runway 34, 6,003 × 75 ft, asphalt
- Equipment: Stall warning system, ADS-B

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 25; injuries: none; flight instructor, commercial; airplane ratings: single-engine land; instrument ratings: airplane; medical: class 1; last flight review October 12, 2024; seat: right; restraint: 3-point; flight hours: 1,133 total, 2 in this make and model, 1,072 as pilot in command, 212 in the last 90 days, 48 in the last 30 days, 2 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: calm
- Visibility: 10 statute miles
- Lowest ceiling: 6,000 ft broken
- Temperature: 68 °F, dew point 41 °F
- Altimeter: 30.22 inHg
- Observed at: 11R, 1 nm away
- METAR: K11R 012035Z AUTO 00000KT 10SM BKN060 20/05 A3022 RMK AO2 T02000045

## 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 20241201019599A](https://openairdocs.org/incident/20241201019599A), Dec 1, 2024: American AA-1B, Brenham, TX, Substantial damage. Aircraft [privacy data omitted], a 1972 Grumman American AA-1B arrived with two occupants at 11R Brenham Municipal, at 1:29 p.m. coming from sport flyers…

## Docket (6 files)

The files NTSB released with the investigation on September 23, 2026, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=195575. 26.7 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 10 pages, 714 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20908966&FileExtension=pdf&FileName=01%20-%20Pilot%20Report_Redacted-Rel.pdf
- Airport manager statement (item 2, PDF, 2 pages, 745 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20907499&FileExtension=pdf&FileName=02%20-%20Airport%20Manager%20Statement_Redacted-Rel.pdf
- NTSB record of conversation (wreckage examination) (item 3, PDF, 7 pages, 3 photos, 862 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20909590&FileExtension=pdf&FileName=03%20-%20NTSB%20Record%20of%20Conversation%20(%20Wreckage%20Examination%20)-Rel.pdf
- Airframe logbook (excerpts) (item 4, PDF, 8 pages, 11.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20907509&FileExtension=pdf&FileName=04%20-%20Airframe%20Logbook%20(Excerpts)_Redacted-Rel.pdf
- Engine logbook (excerpts) (item 5, PDF, 8 pages, 12.7 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20908626&FileExtension=pdf&FileName=05%20-%20Engine%20Logbook%20(Excerpts)_Redacted-Rel.pdf
- Statement of party representatives to NTSB investigation (item 6, PDF, 1 page, 251 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20934990&FileExtension=pdf&FileName=NTSB%20Party%20Form%20(%20CEN25LA054%20-%20Lycoming%20Engines%20)_Signed_Redacted-Rel.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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