# NTSB WPR24LA074: Beck Michael J Sonex, N920MB, Auburn, WA, January 16, 2024 - Type: NTSB accident investigation - Classification: Accident · No injuries · Class 3 · Limited · Final report - Date: January 16, 2024, 11:30 local (19:30 UTC) - Place: Auburn, WA · 3998 Auburn Way N - Coordinates: 47.342702, -122.2224 (estimated) - Nearby events: https://openairdocs.org/map.md?lat=47.3427&lon=-122.2224&mi=10 - Phase of flight: [Initial climb](https://openairdocs.org/ntsb-phases/350) (OpenAirDocs' grouping) - Defining event: [Initial climb: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) - Highest injury: No injuries - Injuries: 1 uninjured - Status: Completed, report February 11, 2026 - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: FAA - NTSB case key (mKey): 193669 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR24LA074 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/193669/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=193669 - Page: https://openairdocs.org/ntsb/WPR24LA074 ## Probable cause Water contamination within the fuel regulator air-reference system, which resulted in improper fuel metering and a loss of engine power during initial climb. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Engine fuel and control: fuel controlling system](https://openairdocs.org/ntsb-findings/01057320): Aircraft › Aircraft power plant · Damaged/degraded (probable cause); cases with it: [Beck Michael J SONEX, 1 case](https://openairdocs.org/ntsb-findings/01057320/cases.md?model=05632AZ), [All aircraft, 59 cases](https://openairdocs.org/ntsb-findings/01057320/cases.md) ## Sequence of events The events NTSB coded, in order, by phase of flight. The defining event best describes what happened. - [Initial climb: Powerplant sys/comp malf/fail](https://openairdocs.org/ntsb-events/340) (defining event); cases with it: [Beck Michael J SONEX, 1 case](https://openairdocs.org/ntsb-events/340/sequence.md?model=05632AZ), [All aircraft, 820 cases](https://openairdocs.org/ntsb-events/340/sequence.md) - [Initial climb: Loss of engine power (partial)](https://openairdocs.org/ntsb-events/342); cases with it: [Beck Michael J SONEX, 1 case](https://openairdocs.org/ntsb-events/342/sequence.md?model=05632AZ), [All aircraft, 1,858 cases](https://openairdocs.org/ntsb-events/342/sequence.md) - [Initial climb: Loss of engine power (total)](https://openairdocs.org/ntsb-events/341); cases with it: [Beck Michael J SONEX, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=05632AZ), [All aircraft, 3,820 cases](https://openairdocs.org/ntsb-events/341/sequence.md) ## Analysis The pilot of the experimental amateur-built airplane experienced a partial and then total loss of engine power shortly after takeoff. The pilot performed a forced landing onto a road, where the airplane collided with a signpost and sustained substantial damage. Postaccident examination revealed no mechanical anomalies with the engine or airframe fuel delivery system that would have precluded normal operation. However, water was found within the throttle body injector air-reference line and regulator diaphragm. This contamination likely led to inadequate fuel regulation, resulting in the power fluctuations observed by the pilot and eventual power loss. The investigation could not determine how water entered the system. ## Factual narrative On January 16, 2024, at 1130 Pacific standard time, a Sonex experimental amateur-built airplane, N920MB, was substantially damaged when it was involved in an accident near Auburn, Washington. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that during the initial climb, about 100 ft above ground level (agl), the engine exhibited a partial loss of power and the airplane began to descend. The pilot planned to land the airplane on a road straight ahead, but the engine regained power shortly thereafter, enabling the airplane to climb. After the airplane had climbed to about 200 ft agl, the engine surged, then exhibited a total loss of power. The pilot performed a forced landing onto a road while trying to return to the airport, during which the airplane struck a signpost. The airplane sustained substantial damage to both wings and the fuselage. The airplane was equipped with an AeroConversions Aerovee engine, which typically includes an AeroInjector throttle body fuel delivery system connected to the engine’s inlet manifold. In this typical configuration, a paper element filter connected directly to the AeroInjector’s air inlet performs air filtration. The accident airplane was modified by replacement of the AeroInjector system with a Rotec throttle body injector (TBI). The TBI was mounted underneath and to the rear of the engine and connected to the inlet manifold on top of the engine through a Y shaped inlet pipe. A paper element (similar to the typical configuration), mounted to the TBI air inlet with a honeycomb material spacer, performed air filtration. The TBI incorporated a separate “on demand metering” fuel regulator, which included a fuel priming feature. The regulator used air pressure tapped from the throttle body bore for reference. This reference was connected to the air side of a diaphragm within the regulator by a flexible, clear plastic line. Postaccident examination of the TBI revealed that the air pressure line, along with the air side of the diaphragm, was full of water. The rest of the engine, along with the airframe fuel delivery system, was examined and no additional anomalies were noted that would have precluded normal operation. The airplane’s belly was coated in a stream of oil; however, the engine did not exhibit any evidence of oil starvation, seizure, or catastrophic failure. Additionally, significant quantities of oil were found pooled under the engine at the accident site in an area where one of the rocker covers had detached at impact. ## Aircraft - Registration: [N920MB](https://openairdocs.org/aircraft/N920MB), registered now, S/N 1145, built 2013 (OpenAirDocs) - Reported make and model: BECK MICHAEL J SONEX - Registry model: [Beck Michael J SONEX](https://openairdocs.org/model/beck-michael-j-sonex) (registry code 05632AZ) (OpenAirDocs) - Registry engine: [Aeroconver AEROVEE](https://openairdocs.org/engine/aeroconver-aerovee) (registry code 01401, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 1145 - Year built: 2013 - Airframe hours: 219.4 - Engines: AeroConversions AeroVee 80 hp reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, May 10, 2023, 71.3 hours before - Departed: S50, Auburn, WA - Destination: Same as departure - Airport: S50, Auburn Municipal Airport, runway 35, 3,842 × 75 ft, asphalt - Equipment: Electronic primary flight display ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 56; injuries: none; private; airplane ratings: single-engine land; medical: sport pilot; last flight review October 19, 2023; seat: left; restraint: 4-point; flight hours: 699 total, 118 in this make and model, 699 as pilot in command, 28 in the last 90 days, 6 in the last 30 days, 1 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: calm - Visibility: 10 statute miles - Lowest ceiling: 23,000 ft broken - Temperature: 34 °F, dew point 7 °F - Altimeter: 29.97 inHg - Observed at: KSEA, 30 nm away - METAR: KSEA 161953Z 00000KT 10SM SCT180 BKN230 01/M14 A2997 RMK AO2 SLP159 T00061144 ## 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 20240116002059A](https://openairdocs.org/incident/20240116002059A), Jan 16, 2024: Beck Michael J SONEX, Auburn, WA, Substantial damage. PIC reported to the FAA inspectors that he conducted his normal checks before taking-off from Auburn airport (S50). No known issues during the… ## Docket (4 files) The files NTSB released with the investigation on February 11, 2026, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=193669. 4.4 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 9 pages, 2.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19834084&FileExtension=pdf&FileName=r_NTSB%20FORM%206120-Rel.pdfFinal_Redacted.pdf - Engine examination report (item 2, PDF, 8 pages, 6 photos, 1.2 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19833943&FileExtension=pdf&FileName=WPR24LA074%20Engine%20Examination%20Report-Rel.pdf - Release of aircraft wreckage, NTSB form 6120.15 (item 3, PDF, 2 pages, 456 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19833901&FileExtension=pdf&FileName=Wreckage%20Release_Redacted-Rel.pdf - Evidence control form (item 4, PDF, 1 page, 245 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19834094&FileExtension=pdf&FileName=Evidence%20Control%20Form-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.