# NTSB CEN26LA074: Pitts S1S, N401MS, Carbondale, IL, December 31, 2025

- Type: NTSB accident investigation
- Classification: Accident · Minor injuries · Class 3 · Limited · Final report
- Date: December 31, 2025, 16:03 local (22:03 UTC)
- Place: Carbondale, IL
- Coordinates: 37.769805, -89.245499 (estimated)
- Nearby events: https://openairdocs.org/map.md?lat=37.7698&lon=-89.2455&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: Minor injuries
- Injuries: 1 minor
- Status: Completed, report August 20, 2026
- Report: Approved by Office Director
- Investigation class: Class 3
- NTSB office: Central Region
- Parties: FAA
- NTSB case key (mKey): 202247
- NTSB case page: https://web.ntsb.gov/investigations/?ntsbnumber=CEN26LA074
- NTSB report (PDF, downloads): https://data.ntsb.gov/carol-repgen/api/Aviation/ReportMain/GenerateNewestReport/202247/pdf
- NTSB docket: https://data.ntsb.gov/Docket?ProjectID=202247
- Page: https://openairdocs.org/ntsb/CEN26LA074

## Probable cause

A loss of engine power due to fuel starvation resulting from an uncommanded change to the fuel servo mixture position due to the improperly installed mixture cable.

## Findings

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

- [Maintenance: installation](https://openairdocs.org/ntsb-findings/02062035): Personnel issues › Task performance · Owner/builder (probable cause); cases with it: [Michael W Stewart PITTS S1, 1 case](https://openairdocs.org/ntsb-findings/02062035/cases.md?model=05634AL), [All aircraft, 371 cases](https://openairdocs.org/ntsb-findings/02062035/cases.md)
- [Fluids: fuel](https://openairdocs.org/ntsb-findings/01071010): Aircraft › Fluids/misc hardware · Incorrect service/maintenance (probable cause); cases with it: [Michael W Stewart PITTS S1, 1 case](https://openairdocs.org/ntsb-findings/01071010/cases.md?model=05634AL), [All aircraft, 1,695 cases](https://openairdocs.org/ntsb-findings/01071010/cases.md)
- [Object/animal/substance: pole](https://openairdocs.org/ntsb-findings/03022010): Environmental issues › Physical environment · Contributed to outcome (probable cause); cases with it: [Michael W Stewart PITTS S1, 1 case](https://openairdocs.org/ntsb-findings/03022010/cases.md?model=05634AL), [All aircraft, 142 cases](https://openairdocs.org/ntsb-findings/03022010/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: [Michael W Stewart PITTS S1, 1 case](https://openairdocs.org/ntsb-events/341/sequence.md?model=05634AL), [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: [Michael W Stewart PITTS S1, 1 case](https://openairdocs.org/ntsb-events/440/sequence.md?model=05634AL), [All aircraft, 3,365 cases](https://openairdocs.org/ntsb-events/440/sequence.md)

## Analysis

The pilot reported that he had completed three touch-and-go landings followed by a low approach. As he began a climb after the low approach, the engine lost power about 400 feet above ground level (agl). The pilot was able to momentarily restore partial power by manually actuating the emergency fuel pump; however, the engine lost power again. He was unable to restore engine power and executed a forced landing on an airport perimeter road. The airplane subsequently struck a power pole which resulted in substantial damage to the airframe. A postaccident examination of the engine revealed no mechanical anomalies. No fuel was present in the fuel manifold when the fuel manifold was disassembled. Further examination revealed that the mixture control cable was not secured at the fuel injection servo. Movement of the cockpit mixture control resulted in corresponding flexing of the mixture cable outer sheath at the engine fuel injection servo. With the cockpit mixture control in the full rich position, the engine fuel injector mixture lever position corresponded to about mid-range. A full rich mixture setting at the fuel injector could not be achieved. Maintenance logbooks indicated that several fuel lines were replaced and a fuel flow transducer was installed about 3.6 hours before the accident. It is likely that the failure of the mixture cable sheath to be properly secured at the fuel injection servo allowed the cable to flex, resulting in an uncommanded change in the fuel servo mixture during the flight, resulting in a loss of engine power due to fuel starvation.

## Factual narrative

On December 31, 2025, at 1603 central standard time, a Pitts S1S airplane, N401MS, was substantially damaged when it was involved in an accident near Carbondale, Illinois. The pilot received minor injuries. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that he had completed three touch-and-go landings on runway 36R. He then completed a low approach over runway 18L and began a climb near the departure end of the runway. Upon reaching 400 ft agl, the engine lost power. The pilot was able to momentarily restore partial power by manually actuating the emergency fuel pump; however, the engine lost power again. Unable to maintain altitude, the pilot completed a forced landing on an airport perimeter road, then exited the road to the right and struck a power pole. The left wing separated from the airplane during the impact. Postaccident examination revealed the engine crankshaft was fractured which was consistent with the ground impact. Additionally, the left side of the engine no. 2 cylinder exhibited impact damage. No anomalies were noted with the engine; however, no indication of fuel was present at the fuel manifold when disassembled. Disassembly of the fuel manifold revealed the four cover screws were not safety wired and found loose, and the manifold diaphragm contained red silicone on both sides. Throttle control continuity and full motion of travel was confirmed from the cockpit to the engine fuel servo. A review of the maintenance logbooks indicated that several fuel lines were replaced aft of the firewall, and a fuel flow transducer was installed forward of the firewall along with an engine monitor, at 122.4 hours total airframe time, and 3.6 hours before the accident. Examination found the mixture control cable was not secured at the fuel injection servo. The mixture cable was secured by a cushion clamp on the engine mount about 10 inches from the servo, and the cable sheath was not secured near the servo. Safety wire used to secure the cable was found severed, and the cable outer sheath exhibited flexing when the cockpit mixture control was actuated. With the cockpit mixture control in the full rich position, the engine fuel injector mixture lever position corresponded to about mid-range. A full rich mixture setting at the engine fuel injector servo could not be achieved.

## Aircraft

- Registration: [N401MS](https://openairdocs.org/aircraft/N401MS), registered now, S/N 085, built 2015 (OpenAirDocs)
- Reported make and model: PITTS S1S
- Registry model: [Michael W Stewart PITTS S1](https://openairdocs.org/model/michael-w-stewart-pitts-s1) (registry code 05634AL) (OpenAirDocs)
- Registry engine: [Lycoming O-320-EXP](https://openairdocs.org/engine/lycoming-o-320-exp) (registry code 42406, reciprocating) (OpenAirDocs)
- Category: Airplane, amateur-built
- Serial number: 085
- Year built: 2015
- Airframe hours: 126
- Engines: Lycoming O320-G4 160 horsepower reciprocating
- Damage: Substantial damage
- Flight: Personal, Part 91
- Airworthiness certificate: Standard, Aerobatic; Special, Experimental (Special)
- Last inspection: Condition, June 23, 2025, 115.2 hours before
- Airport: MDH, Southern Illinois

## Flight crew

As NTSB recorded them. NTSB leaves out names.

- Pilot; age 26; injuries: minor; commercial, flight instructor; airplane ratings: multi-engine land, single-engine land; instrument ratings: airplane; medical: class 1, without waivers/limitations; last flight review February 3, 2025; seat: single; restraint: 5-point; flight hours: 2,126 total, 11 in this make and model, 1,908.2 as pilot in command, 116.7 in the last 90 days, 29.3 in the last 30 days, 4.8 in the last 24 hours

## Weather

- Conditions: Visual (VMC), Day
- Wind: 310° at 4 knots
- Visibility: 10 statute miles
- Lowest ceiling: none
- Temperature: 43 °F, dew point 30 °F
- Altimeter: 30.02 inHg
- Observed at: KMDH, 1 nm away
- METAR: METAR KMDH 312152Z 31004KT 10SM CLR 06/M01 A3002 RMK AO2 SLP167 T00611011

## 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 20251231020229A](https://openairdocs.org/incident/20251231020229A), Dec 31, 2025: Michael W Stewart PITTS S1, Murphysboro, IL, Destroyed. After a low pass on runway 18, the aircraft climbed to traffic pattern altitude and leveled off. Shortly after leveling off, the clamp on the mixture cable…

## Docket (5 files)

The files NTSB released with the investigation on August 20, 2026, on NTSB's docket system: https://data.ntsb.gov/Docket?ProjectID=202247. 15.2 MB in all.

- Pilot/operator aircraft accident report, NTSB form 6120.1 (item 1, PDF, 11 pages, 4.6 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19771002&FileExtension=pdf&FileName=6120%20-%20Pilot_Redacted-Rel.pdf
- Photos (item 2, PDF, 9 pages, 2.5 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19945367&FileExtension=pdf&FileName=CEN26LA074%20Photos%20Redacted-Rel-Rel.pdf
- Airport authority incident report (item 3, PDF, 5 pages, 104 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19939660&FileExtension=pdf&FileName=SIAA%20Incident%20Report_Redacted-Rel.pdf
- Engine examination report (item 4, PDF, 10 pages, 993 KB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19941212&FileExtension=pdf&FileName=M401MS%20Aircraft%20Examination%20Summary-Rel.pdf
- Maintenance records (item 5, PDF, 5 pages, 7.0 MB): https://data.ntsb.gov/Docket/Document/docBLOB?ID=19945377&FileExtension=pdf&FileName=NTSB%20Investigation%20Logbooks_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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