Amateur-built PL 4 accident near Yates City, Illinois, May 10, 2014
On May 10, 2014 at about 5:15 pm local time, a 1972 amateur-built PL 4, registered N44PL, was substantially damaged in an accident during maneuvering near Yates City, Illinois (Tri-County airport). It was a personal flight under general aviation rules (Part 91). 1 person had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A loss of propeller thrust due to a failure of the reduction drive unit resulting from the improper installation of the unit. Contributing to the accident was a lack of documentation for the reduction drive unit installation.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 10, 2014 · about 5:15 pm local time
- Place
- Yates City, Illinois · Tri-County · map
- Type
- Accident
- Injuries
- 1 person had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built PL 4, built 1972
- Registration
- N44PL · registry record · serial 001
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
While in the airport traffic pattern, the airplane sustained a complete loss of thrust and an increase in engine speed, which the pilot interpreted as a loss of engine power to the propeller. He subsequently executed a forced landing to an open field. A postaccident examination revealed that the propeller reduction drive pulley had moved downward within the mounting bracket slot, creating slack in the cog belts that resulted in a loss of input drive power to the propeller. The reduction drive manufacturer did not provide any formal documentation for the installation. As a result, the pilot/builder was not aware that a secondary fitting to secure the pulley within the bracket needed to be installed with the drive unit components.
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
- Powerplant sys/comp malf/fail during maneuvering defining event
- Off-field or emergency landing during emergency descent
- Hard landing during landing
The NTSB's findings
- cause Aircraft › Aircraft propeller/rotor › Propeller system › (general) › Malfunction
- cause Personnel issues › Task performance › Maintenance › Installation › Owner/builder
- factor Organizational issues › Support/oversight/monitoring › Documentation/record keeping › (general) › Manufacturer
Pilot
- Certificate: commercial pilot
- Ratings: multi-engine land; single-engine land; single-engine sea
- Flight time: 4,263 hours in all; 53 in this make and model; 10 in the last 90 days; 3 in the last 30 days; 4,069 as pilot in command
- Medical certificate: Sport Pilot (with waivers/limitations)
- Seat: sngl
- Injury: minor injuries
The aircraft
- Airframe total time: 428 hours
- Last inspection: condition inspection, December 12, 2013; 53 hours since
- Seats: 1
- Landing gear: fixed
- Engine: Volkswagen CONVERSION (piston); 62 hours total
The flight
- Departed from: 2C6 Yates City IL at 4:45 pm
- Destination: 2C6 Yates City IL
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 200° at 5 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 73°F (23°C), dew point 46°F (8°C)
- Altimeter: 29.96 inHg
- Observation at 4:54 pm from PIA, 18 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
7 documents, released by the NTSB on December 15, 2014. 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.
| # | Document | What it is | |
|---|---|---|---|
| 1 | Pilot/operator Aircraft Accident Report, NTSB Form 6120.1 | PDF, 9 pages | View Download |
| 2 | Record of Conversation - Pilot | PDF, 1 page | View Download |
| 3 | Record of Conversation - Reduction Drive Manufacturer | PDF, 1 page | View Download |
| 4 | Photo 1 - Accident Airplane | PDF, 1 page | View Download |
| 5 | Photo 2 - Reduction Drive Bracket | PDF, 1 page | View Download |
| 6 | Photo 3 - Engine with Reduction Drive | PDF, 1 page | View Download |
| 7 | Photo 4 - Engine with Reduction Drive | PDF, 1 page | View Download |
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.