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Accidents · NTSB CEN24LA286 · Final report

Piper PA46 accident near Radisson, Wisconsin, July 28, 2024

On July 28, 2024 at about 4:30 pm local time, a 1985 Piper PA46, registered N4646G, was substantially damaged in an accident during enroute (descent) near Radisson, Wisconsin. It was a personal flight under general aviation rules (Part 91). No one was hurt; 1 person was on board or involved. The weather was visual conditions (good weather).

The NTSB's probable cause their words, unchanged

The non-certificated mechanic’s failure to properly tighten and torque the fuel system pressure test port cap, which resulted in a total loss of engine power, and a subsequent forced landing.

Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.

What the record shows

Date
July 28, 2024 · about 4:30 pm local time
Place
Radisson, Wisconsin · map
Type
Accident
Injuries
No one was hurt; 1 person was on board or involved.
Weather
visual conditions (good weather)
Aircraft
Piper PA46 310P, built 1985 · all PA46s on the register
Registration
N4646G · no longer on the register · serial 46-8508101
Damage
Substantial damage
Flight
Personal flight · general aviation rules (Part 91)

The NTSB's narrative final · quoted from the NTSB record

The engine sustained a total loss of power when nearing the destination airport during a cross-country flight. The pilot performed a forced landing to a rural grass field and the airplane landed hard, coming to rest upright. The pilot was able to egress from the airplane without further incident. The airplane sustained substantial damage to the fuselage and the empennage. An on-site examination of the engine found that a cap was missing from the fuel pressure test port near the front top area of the engine. The test port is where a gauge would connect during maintenance work to test the fuel pressure. The test port and the aluminum housing that the port connects to both had blue staining. The exposed threading that the cap screws onto was found intact and the missing cap was not located. A review of the engine monitor performance data showed performance consistent with a total loss of engine power. The fuel flow rate had increased up to the maximum reading, about 80 gallons per hour, at the time the total loss of engine power occurred. A review of the most recent airplane maintenance records showed than an annual inspection was performed on the airframe, engine, and propeller about six weeks before the accident. The records reflected work completed on the fuel injection system, including the installation of new fuel injectors. According to the engine manufacturer, a fuel system operational check is required if fuel injectors are replaced. Test equipment is connected to the fuel pressure test port and a test is performed. Once the test work is completed, a cap is required to be tightened and torqued on the test port. The individual who performed the most recent annual inspections on the airplane did not hold an airframe and powerplant certificate, nor did he hold inspection authorization. The non-certificated mechanic signed off the annual inspections and returned the airplane to service using the airframe and powerplant mechanic certificate number of his deceased father, who held inspection authorization. The test port had blue staining present, and the exposed threading was found intact. The aluminum housing that the port connects to also had blue staining present. The blue staining was likely from a 100 low-lead fuel leak while in-flight. It is likely the loss of fuel and fuel system pressure caused a total loss of engine power. Based on the available evidence, it is likely that the non-certificated mechanic forgot to properly tighten and torque the fuel pressure test port cap, which resulted in a total loss of engine power. The non-certificated mechanic fraudulently represented himself as a certificated mechanic with inspection authorization and the appropriate knowledge, training, and experience by signing off the annual inspections and returning the airplane to service.

The complete narrative as the NTSB published it. The NTSB's docket holds the report as a PDF and any photographs, statements and other documents from the investigation.

The factual record from the NTSB's investigation tables, in plain English

What happened, in order

  1. Security/criminal event during prior to flight
  2. Aircraft maintenance event during prior to flight
  3. Loss of engine power (total) during enroute (descent) defining event
  4. Attempted remediation/recovery during emergency descent
  5. Off-field or emergency landing during landing
  6. Collision during takeoff/land during landing
  7. Evacuation during post (impact)

The NTSB's findings

  • Aircraft › Aircraft power plant › Engine (reciprocating) › (general) › Failure
  • Personnel issues › Task performance › Maintenance › Scheduled/routine maintenance › Maintenance personnel
  • Personnel issues › Experience/knowledge › Experience/qualifications › Qualification/certification › Maintenance personnel
  • Aircraft › Aircraft power plant › Engine fuel and control › (general) › Incorrect service/maintenance
  • Personnel issues › Action/decision › Action › Forgotten action/omission › Maintenance personnel

Pilot

  • Certificate: commercial pilot, private
  • Ratings: multi-engine land; single-engine land; single-engine sea; instrument: airplane
  • Flight time: 2,400 hours in all; 300 in this make and model; 23 in the last 90 days; 18 in the last 30 days
  • Last flight review: June 18, 2024
  • Medical certificate: Class 2 (with waivers/limitations)
  • Seat: left
  • Injury: no injuries

The aircraft

  • Airframe total time: 5,194.6 hours
  • Last inspection: annual inspection, June 15, 2024; 20 hours since
  • Maximum gross weight: 4,100 lb
  • Seats: 6
  • Landing gear: retractable
  • Engine: Continental Motors TSIO-550C (piston); 1,300 hours total

The flight

  • Departed from: 3CK Lake In The Hills IL at 2:30 pm
  • Destination: HYR Hayward WI
  • Flight plan: IFR

Weather at the time

  • Light: daylight
  • Wind: from 170° at 11 knots, gusting 14
  • Sky: scat at 1,800 ft
  • Temperature: 77°F (25°C), dew point 68°F (20°C)
  • Altimeter: 29.94 inHg
  • Observation at 11:15 am from KRCX, 18 miles away

Weather report (METAR): KRCX 281615Z AUTO 17011G14KT SCT018 25/20 A2994 RMK AO2 T02520199 PWINO

Injuries

FatalSeriousMinorNone
Flight crew1

Photographs from the investigation 5 pictures from the NTSB's docket, as the NTSB released them

The NTSB's photographs with the NTSB's captions, at screen size. Open a picture to see it full size or to report one that should not be shown.

Documents from the investigation the NTSB's docket: the evidence folder behind the report

12 documents, released by the NTSB on April 2, 2025. View them here, or download them; the NTSB redacts some personal details before release, and this site shows the NTSB's own titles rather than its file names.

The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.

Everything on this page comes from the NTSB's public records. The narrative, probable cause and findings are the NTSB's own words; the coded tables behind the report are written out in plain English, with pilots' ages, home towns and medical details left out. The documents and photographs are the NTSB's docket, shown as the NTSB released them. This site's own text never names anyone involved. A preliminary report can change; the final report usually follows one to two years later, and the page is refreshed when it does.