# NTSB ERA24LA335: Hendrickson Glasair 3, N121CH, Oxford, ME, August 3, 2024 - Type: NTSB accident investigation - Classification: Accident · Serious injuries · Class 3 · Limited · Final report - Date: August 3, 2024, 11:25 local (15:25 UTC) - Place: Oxford, ME · On airport, approach end runway 33 - Coordinates: 44.1575, -70.48133 - Nearby events: https://openairdocs.org/map.md?lat=44.1575&lon=-70.4813&mi=10 - Phase of flight: [Landing](https://openairdocs.org/ntsb-phases/550) (OpenAirDocs' grouping) - Defining event: [Landing: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) - Highest injury: Serious injuries - Injuries: 1 serious - Status: Completed, report September 8, 2026 - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Eastern Region Aviation - Parties: FAA FSDO, Lycoming Engines, FAA/FSDO - NTSB case key (mKey): 194836 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=ERA24LA335 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/194836/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=194836 - Page: https://openairdocs.org/ntsb/ERA24LA335 ## Probable cause A loss of engine power for reasons that could not be determined. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Power plant](https://openairdocs.org/ntsb-findings/01057100): Aircraft › Aircraft power plant · Unknown/Not determined (probable cause); cases with it: [Claude Hendrickson GLASAIR 3, 1 case](https://openairdocs.org/ntsb-findings/01057100/cases.md?model=05641WL), [All aircraft, 198 cases](https://openairdocs.org/ntsb-findings/01057100/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Landing: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) (defining event); cases with it: [Claude Hendrickson GLASAIR 3, 1 case](https://openairdocs.org/ntsb-events/000/sequence.md?model=05641WL), [All aircraft, 1,703 cases](https://openairdocs.org/ntsb-events/000/sequence.md) - [Landing: Off-field or emergency landing](https://openairdocs.org/ntsb-events/440); cases with it: [Claude Hendrickson GLASAIR 3, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05641WL), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md) ## Analysis The purpose of the flight was to evaluate the experimental airplane’s takeoff and landing performance in accordance with the experimental aircraft phase one flight testing program. Following normal engine run-up and ground operations, and after multiple takeoffs and landings at another airport without incident, the pilot returned to the departure airport. While on the downwind leg of the airport traffic pattern, the pilot noted some engine roughness after reducing the engine power to 25 inches manifold pressure. He attempted to troubleshoot the problem with the ignition switches and the fuel selector. After returning the magnetos to the BOTH position, the engine lost all power. He turned the airplane toward the airport while again checking the ignition switches, then focused on performing a forced landing. The airplane did not have enough altitude and airspeed for the pilot to safely glide the remaining distance to the runway; after clearing a line of trees, the airplane impacted the perimeter road, struck a fence, and slid on its belly into the runway overrun area, stopping 100 ft short of the threshold. The airplane sustained substantial damage to the wings and fuselage. Postaccident examination of the airplane did not reveal any anomalies that would have prevented normal operation. Examination of the engine and all of its components was performed at the manufacturer, and two engine runs in a test cell were performed satisfactorily. The reason for the loss of engine power could not be determined. ## Factual narrative On August 3, 2024, about 1125 eastern daylight time, an experimental, amateur-built Glasair 3 airplane, N121CH, was substantially damaged when it was involved in an accident near Oxford, Maine. The airline transport pilot sustained serious injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 test flight. The flight was the airplane’s seventh test flight in phase 1 of the amateur build. The purpose of the flight was to evaluate takeoff and landing performance. Following normal engine run-up and ground operations, the pilot departed from Oxford County Regional Airport (81B), Oxford, Maine, and conducted multiple takeoffs and landings at Auburn/Lewiston Municipal Airport (LEW), Auburn, Maine, and at 81B. While on downwind leg of the airport traffic pattern at 81B, the pilot noted some engine roughness after reducing power to 25 inches manifold pressure. He attempted to troubleshoot the problem with the ignition switches and the fuel selector. After returning the magnetos to the BOTH position, the engine lost all power. He then turned the airplane toward the airport while again checking the ignition switches, then focused on performing a forced landing. After clearing some trees by extending the wing flaps, the pilot landed the airplane on the perimeter road, where it collided with a fence and came to rest in grass near the departure end of runway 33. The airplane sustained substantial damage to the wings and fuselage; the landing gear separated during the forced landing. Federal Aviation Administration (FAA) inspectors performed a postaccident examination of the airplane. The fuel selector was placed in the header tank position and fuel flow was observed from the firewall-mounted gascolator. The observed flow rate appeared adequate to provide the engine with sufficient fuel flow to sustain power. Fuel was drained into a clear container and visually inspected for debris and contamination. No debris or contamination was noted. The engine throttle, mixture, and propeller control cables operated smoothly and freely throughout their full range of motion. The ignition switch was tested with a digital multimeter. Both magneto P-leads from the airframe were present and operated properly. Additionally, the ignition switch wiring and associated wiring connections were visually inspected. Wiring associated with the ignition system appeared secure, properly connected, and serviceable with no obvious loose, frayed, or damaged wiring observed during the inspection. Flight control continuity was verified for the ailerons, elevator, and rudder. All corresponding cockpit controls operated freely throughout the observed range of motion and maintained continuity to their respective control surfaces. Postaccident examination of the airframe revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. Review of engine data provided by the mechanic showed that during the flight,fuel flow and manifold pressure adjustments matched until the end of the flight when the fuel flow seemed to remain at around 33 gallons per hour, even after the engine rpm had come to a complete stop. The engine was shipped to the manufacturer for examination and testing. The engine mounts were removed and the top two were fragmented from impact forces. Replacement engine mounts were then installed to facilitate an engine test run. The upper plugs were removed, the crankshaft was rotated a full 360° multiple times, compression and suction were observed on all cylinders in the correct firing order, and the impulse coupling could be heard snapping, confirming mechanical continuity throughout the engine. The No. 2 rocker box cover was removed and the crankshaft-to-camshaft timing was confirmed. The magnetos were timed at 23° before top center (BTC); the engine’s data tag shows the magneto timing should be 20° BTC. No damage was observed to the ignition leads. The sparkplugs were all finger tight; the electrodes were not worn, were black in color, and exhibited a carbon fouling condition per the Champion Aviation Check-A-Plug Chart AV-27. During the engine run, the rpm drops were within limits when testing the magnetos, 86.5 - 94.2 on both sides. No contamination was observed on the fuel inlet screen. The fuel pump remained secure to the accessory housing and the inlet and outlet fittings were in place. The engine-driven fuel pump produced within-limit fuel pressure during the engine run. The oil filter was removed and cut open. No metal particles were observed in the pleats of the oil filter element. The oil suction screen was not removed for examination. Two engine runs were performed on consecutive days; in both runs, the engine passed the production test. Fuel flow fluctuation was observed during full rated power operation; however, once the fuel tank pump was turned on, which applies 5 psi from the tank to the inlet of the engine-driven fuel pump, the fuel flow stabilized. The fuel flow transducer remained installed during the first run, and during the second run it was replaced with a union. Air was blown through the transducer, which was unobstructed and the paddle wheel could be heard spinning. ## Aircraft - Registration: [N121CH](https://openairdocs.org/deregistered/N121CH-2025-03-06), registration cancelled 2025-03-06, S/N 3395, built 2024 (OpenAirDocs) - Reported make and model: Hendrickson Glasair 3 - Registry model: [Claude Hendrickson GLASAIR 3](https://openairdocs.org/model/claude-hendrickson-glasair-3) (registry code 05641WL) (OpenAirDocs) - Registry engine: [Lycoming YIO-540 SERIE](https://openairdocs.org/engine/lycoming-yio-540-serie) (registry code 41779, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 3395 - Year built: 2024 - Airframe hours: 5 - Engines: Lycoming YIO-540-K1H5 300 horsepower reciprocating - Damage: Substantial damage - Flight: Flight test, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Departed: 81B, Oxford, ME - Airport: 81B, Oxford County Regional, runway 15, 2,997 × 75 ft, asphalt - Equipment: ADS-B ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 38; injuries: serious; airline transport, military, commercial, flight instructor; airplane ratings: multi-engine sea, single-engine land, multi-engine land, single-engine sea; instrument ratings: airplane, helicopter; medical: class 2, without waivers/limitations; last flight review May 5, 2024; seat: left; restraint: 4-point; flight hours: 8,922 total, 227 in this make and model, 8,557 as pilot in command, 250 in the last 90 days, 60 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: variable at 4 knots - Visibility: 10 statute miles - Lowest ceiling: 3,400 ft broken - Temperature: 73 °F, dew point 72 °F - Altimeter: 29.80 inHg - Observed at: LEW, 11 nm away - METAR: SPECI KLEW 031523Z AUTO VRB04KT 10SM FEW009 BKN034 OVC090 23/22 A2980 RMK AO2 ## 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 20240803019189A](https://openairdocs.org/incident/20240803019189A), Aug 3, 2024: Claude Hendrickson GLASAIR 3, Oxford, ME, Substantial damage. On 8/3/2024 a test flight was conducted on the accident aircraft. This was the seventh (7th) test flight in phase I for the aircraft and first test flight… ## Docket (10 files) The files NTSB released with the investigation on September 8, 2026, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=194836. 28.8 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 2.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=18724306&FileExtension=pdf&FileName=6120_Redacted-Rel.pdf - Fuel servo overhaul work order (item 2, PDF, 5 pages, 23.3 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20716545&FileExtension=pdf&FileName=Hendricksonfuelservo_Redacted-Rel.pdf - Investigation photographs (item 3, PDF, 7 pages, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20733167&FileExtension=pdf&FileName=Investigation%20Photographs-Rel.pdf - NTSB memorandum - FAA inspector statement (item 4, PDF, 3 pages, 71 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20716555&FileExtension=pdf&FileName=MOR-%20Inspectors%20statement-Rel.pdf - NTSB memorandum - Lycoming engine examination summary (item 5, PDF, 2 pages, 72 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20732828&FileExtension=pdf&FileName=MOR%20-%20Lycoming%20Engine%20Notes-Rel.pdf - Engine run test log sheets (item 6, PDF, 2 pages, 182 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20712187&FileExtension=pdf&FileName=Run%20Sheets%20june%2018%20and%2019_Redacted-Rel.pdf - Electronic devices - specialist's factual report (item 7, PDF, 9 pages, 946 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20728713&FileExtension=pdf&FileName=Report_ERA24LA335_260729_Final-Rel.pdf - Electronic devices - specialist's factual report - attachment 1 (item 8, CSV, 441 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20834015&FileExtension=csv&FileName=Attachment%201-Rel.csv - NTSB certification of party representative form (item 9, PDF, 14 pages, 337 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20711467&FileExtension=pdf&FileName=NTSB%20Party%20Form%20N121CH%20ERA24LA335%20Lycoming_Redacted-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 10, PDF, 2 pages, 130 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20716565&FileExtension=pdf&FileName=Master%20Evidence%20Control%20Form%20and%20Release_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. --- OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.