# NTSB WPR24LA160: Steen Skybolt, N873X, Santa Maria, CA, May 26, 2024 - Type: NTSB accident investigation - Classification: Accident · Minor injuries · Class 3 · Limited · Final report - Date: May 25, 2024, 17:15 local (May 26, 2024, 00:15 UTC) - Place: Santa Maria, CA · 2.7 miles South Santa Maria Public Airport/Capt G Allan Hancock Field - Coordinates: 34.860556, -120.45083 - Nearby events: https://openairdocs.org/map.md?lat=34.8606&lon=-120.4508&mi=10 - Phase of flight: [Approach](https://openairdocs.org/ntsb-phases/500) (OpenAirDocs' grouping) - Defining event: [Approach-VFR pattern base: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) - Highest injury: Minor injuries - Injuries: 1 minor - Status: Completed, report May 27, 2026 - Report: Approved by Office Director - Investigation class: Class 3 - NTSB office: Western Pacific Region - Parties: Federal Aviation Administration - NTSB case key (mKey): 194320 - NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=WPR24LA160 - NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/194320/pdf - NTSB docket: https://data.ntsb.gov/Docket?ProjectID=194320 - Page: https://openairdocs.org/ntsb/WPR24LA160 ## Probable cause A total loss of engine power during approach for reasons that could not be determined. ## Findings NTSB's coded findings; those marked are part of the probable cause. - [Aircraft](https://openairdocs.org/ntsb-findings/01050000): Aircraft › Aircraft power plant · Unknown/Not determined (probable cause); cases with it: [Freeman STEEN SKYBOLT, 1 case](https://openairdocs.org/ntsb-findings/01050000/cases.md?model=05655A1), [All aircraft, 151 cases](https://openairdocs.org/ntsb-findings/01050000/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 base: Unknown or undetermined](https://openairdocs.org/ntsb-events/000) (defining event); cases with it: [Freeman STEEN SKYBOLT, 1 case](https://openairdocs.org/ntsb-events/000/sequence.md?model=05655A1), [All aircraft, 1,703 cases](https://openairdocs.org/ntsb-events/000/sequence.md) ## Analysis The pilot had just purchased the airplane before departing on the cross-country flight. He conducted preflight fuel planning based on the airplane’s total fuel capacity and the fuel consumption rate he had calculated (28 usable gallons at 12 gallons per hour, respectively). The pilot filled the main tank for the flight and determined a fuel stop was not required. The pilot stated that after departure, and upon reaching his intended cruise altitude, he reduced power to 2,300 rpm, 23 inches of manifold pressure, and leaned the mixture to peak EGT followed by enriching 50°. Upon arrival to the destination airport, the pilot chose to extend the downwind leg to allow for a longer, stabilized approach. While turning left base to the runway, the engine sputtered two times and then lost all power. While troubleshooting, the pilot was unsuccessful at restarting the engine and initiated an emergency landing to a nearby field. At 300 ft above ground level (agl), he realized that the terrain was steeper than he originally thought. The pilot maneuvered the airplane to gain airspeed to overfly a hill in his flightpath. As the airplane passed over the hill, the pilot observed a set of high-tension power lines. He attempted to fly over the power lines; however, the tailwheel contacted a power line and the airplane subsequently pitched down, falling through trees, impacting terrain, and coming to rest inverted on a road. The previous owner of the airplane used the airplane to fly aerobatics and rarely flew the airplane over 30 minutes at a time before refueling. He typically operated the airplane with 25 gallons of fuel on these flights, and he estimated the engine’s fuel consumption was about 16 gallons per hour at a full-throttle power setting. When discussing the airplane relocation flight with the accident pilot, he suggested flying at a reduced airspeed, flying straight and level, and making a fueling stop en route. The pilot stated that the airplane remained inverted during the three to four hours it took to recover the airplane from the accident site. During that time, fuel leaked out of the main tank filler cap. The fuel selector lever was found in the On position. Continuity of the fuel system was established from the main fuel tank throughout the system to the pressure carburetor. Observing fuel in the fuel tank, the airplane was positioned in a level flight attitude, and the electric fuel pump was activated; initially no fuel pressure was observed. After about 15 seconds, the pump noise changed consistent with pump priming. Fuel was then observed dripping from the pressure carburetor, with the cockpit fuel pressure gauge indicating pressure within the green arc. Examination of the recovered engine revealed no pre-accident mechanical malfunction or failure that would have precluded normal operation. Although it is possible that the loss of engine power may have been fuel-related, it could not be substantiated with the available evidence. A calculatedfuel burn for the reported cruise power setting with a full rich mixture, equated to an approximate fuel burn of 15.8 gallons per hour for the 1.5 hour flight. The calculated fuel burn in a full rich condition would have resulted in about 3 gallons of useable fuel remaining. In a leaned configuration, it’s likely there could have been up to 10 gallons of fuel remaining. ## Factual narrative On May 25, 2024, about 1715 Pacific daylight time, an experimental amateur-built Steen Skybolt airplane, N873X, was substantially damaged when it was involved in an accident near Santa Maria, California. The pilot sustained minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he had recently purchased the airplane and was relocating it from Lodi, California, to his home airport in Santa Maria, California (202 nautical miles). Before departure, the pilot topped off the main fuel tank (29 gallons total, 1 gallon unusable) and verified that the fuel selector was selected to the main tank. For the 1.5-hour flight to Santa Maria, the pilot calculated a planned fuel burn of 12 gallons per hour based on previous flights, which would result in about 7.7 gallons of usable fuel remaining upon arrival. The pilot stated that after he climbed to 5,500 ft mean sea level, he reduced power to a setting of 23 inches of manifold pressure and 2,300 rpm, and then leaned to peak EGT, and then enriched the mixture by 50°. The arrival and prelanding checks were described as normal. The pilot chose to extend the downwind leg to allow for a longer, stabilized approach. During the descent, while making a left base turn with 10–20° of bank and reducing engine power, the engine sputtered twice and then lost all power. The pilot completed the engine failure checklist but was unable to restore engine power. Unable to reach the runway, the pilot initiated an emergency landing in a nearby field. While on final approach about 300 ft agl, the pilot observed rising terrain and lowered the nose to increase airspeed and clear a hill. Although the airplane cleared the terrain, it was unable to clear adjacent high-tension power lines. The pilot pitched the nose up, clearing the propeller and main landing gear; however, the tailwheel contacted a power line, resulting in a rapid deceleration and a nose-down pitch attitude of about 70–80°. The tailwheel subsequently released from the power line, and the airplane descended through a large tree, impacting terrain on a private gravel road. The airplane came to rest inverted, resulting in substantial damage to the upper left wing and horizontal stabilizer. The pilot reported that the airplane remained inverted and leaked fuel from the main tank fuel cap for about three to four hours until it was turned upright by the recovery company. A postaccident examination of the engine was performed on the recovered airplane. The two top engine mounts were fractured consistent with impact damage. The mechanical fuel pump and the left magneto were separated from their mounts consistent with impact damage. The upper spark plugs indicated between normal and worn-out normal with some black deposits within the electrode area. After removing the damaged propeller, the crankshaft was free and easy to rotate in both directions using a hand tool. Thumb compression was observed inproper firing order on all six cylinders. Mechanical continuity was established throughout the rotating/reciprocating group and accessory section during hand rotation of the crankshaft. The valvetrain was observed to function normally during hand rotation of the crankshaft. Normal lift action was observed at each rocker arm. The gas path and combustion signatures observed at the spark plugs and exhaust system components displayed coloration consistent with normal operation. No oil residue was observed in the exhaust system gas path. Engine control continuity was established. The fractured fuel pump actuator arm moved normally on its cam when the engine was rotated. The right magneto timing was within normal range. Exhaust manifolds were free of obstruction. After opening the oil filter, no particulates were found. No pre-accident mechanical malfunctions were found with the engine during the examination that would have precluded normal operation. The fuel selector lever was found in the On position. Fuel system continuity was established from the fuel tank to the pressure carburetor. Observing fuel in the fuel tank, the airplane was positioned in a level flight attitude, and the electric fuel pump was activated; initially, no fuel pressure was observed. After about 15 seconds, the pump noise changed consistent with pump priming. Fuel was then observed dripping from the pressure carburetor, with the cockpit fuel pressure gauge indicating pressure within the green arc. The Bendix pressure carburetor was removed and tested, and it functioned normally, responding appropriately to airflow changes. The previous owner stated that he used the airplane to fly aerobatics and rarely flew the airplane over 30 minutes at a time before refueling. He typically operated the airplane with 25 gallons of fuel on these flights, and he estimated the engine’s fuel consumption was about 16 gallons per hour at a full-throttle power setting. When discussing the airplane relocation flight with the accident pilot, he suggested flying at a reduced airspeed, flying straight and level, and making a fueling stop en route. A calculated fuel burn for the reported cruise power setting of 23 inches of manifold pressure and 2,300 rpm, utilizing Lycoming’s performance chart, at sea level, with a full rich mixture, equated to an approximate fuel burn of 15.8 gallons per hour. The calculated fuel burn in a full rich condition would have resulted in about 3 gallons of useable fuel remaining. In a leaned configuration, it’s likely there could have been up to 10 gallons of fuel remaining. ## Aircraft - Registration: [N873X](https://openairdocs.org/aircraft/N873X), registered now, S/N 1 (OpenAirDocs) - Reported make and model: STEEN SKYBOLT - Registry model: [Freeman STEEN SKYBOLT](https://openairdocs.org/model/freeman-steen-skybolt) (registry code 05655A1) (OpenAirDocs) - Registry engine: [Lycoming 0-540 series](https://openairdocs.org/engine/lycoming-0-540-series) (registry code 41532, reciprocating) (OpenAirDocs) - Category: Airplane, amateur-built - Serial number: 1 - Year built: 1977 - Airframe hours: 770 - Engines: LYCOMING O-540-E485 250 horsepower reciprocating - Damage: Substantial damage - Flight: Personal, Part 91 - Airworthiness certificate: Special, Experimental (Special) - Last inspection: Condition, August 12, 2023 - Departed: K1O3, Lodi, CA - Destination: Same as departure - Airport: SMX, Santa Maria Pub/Capt G Allan Hancock Fld, runway 30, 8,004 × 150 ft, asphalt - Equipment: None ## Flight crew As NTSB recorded them. NTSB leaves out names. - Pilot; age 47; injuries: minor; airline transport; airplane ratings: single-engine land, multi-engine land; instrument ratings: airplane; medical: class 1, with waivers/limitations; last flight review January 15, 2024; seat: rear; restraint: 5-point; flight hours: 13,377 total, 3 in this make and model, 13,096 as pilot in command, 37 in the last 90 days, 116 in the last 30 days, 0 in the last 24 hours ## Weather - Conditions: Visual (VMC), Day - Wind: 290° at 21 knots, gusting 26 - Visibility: 10 statute miles - Lowest ceiling: none - Temperature: 61 °F, dew point 54 °F - Altimeter: 30.02 inHg - Observed at: KSMX - METAR: KSMX 260021Z 29021G26KT 10SM FEW032 16/12 A3002 RMK AO2 PK WND 28027/0001 T01610117 $ ## 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 20240525007179A](https://openairdocs.org/incident/20240525007179A), May 25, 2024: Freeman STEEN SKYBOLT, Santa Maria, CA, Substantial damage. The PIC of the accident airplane had just bought the aircraft in lodi, CA and was flying back to his hanger in Santa Maria, CA (smx). Before departure he… ## Docket (8 files) The files NTSB released with the investigation on May 27, 2026, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=194320. 688 MB in all. - Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 3.8 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20290148&FileExtension=pdf&FileName=6120%20WPR24LA160%20Santa%20Maria,%20CA_Redacted-Rel.pdf - Memorandum for record a�� telephone interviews (item 2, PDF, 3 pages, 107 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20143738&FileExtension=pdf&FileName=MOR_Redacted-Rel.pdf - Maintenance records (item 3, PDF, 24 pages, 680 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20216472&FileExtension=pdf&FileName=Engine%20Airframe%20Prop%20Logs_Redacted-Rel.pdf - Engine and fuel system exam (item 4, PDF, 6 pages, 392 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20289849&FileExtension=pdf&FileName=Engine%20and%20Fuel%20System%20Exam_-Rel.pdf - Airflow performance bendix pressure carburetor report (item 5, PDF, 4 pages, 2.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20240256&FileExtension=pdf&FileName=NTSB%20N873X%20Pressure%20Carb%20report%209-24-2024_Redacted-Rel.pdf - Photo array (item 6, PDF, 3 pages, 1.1 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20156203&FileExtension=pdf&FileName=Photo%20array%20WPR24LA160-Rel.pdf - Skybolt spec (item 7, PDF, 2 pages, 329 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20359885&FileExtension=pdf&FileName=Skybolt%20Spec-Rel.pdf - Fuel consumption plot (item 8, PDF, 2 pages, 394 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=20385852&FileExtension=pdf&FileName=Fuel%20Consumption%20Plot-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.