Piper PA-60-601 accident near Lone Rock, Wisconsin, September 21, 1993
On September 21, 1993 at about 11:40 am local time, a Piper PA-60-601, registered N9825Q, was substantially damaged in an accident near Lone Rock, Wisconsin (Tri-County Regional airport). It was a flight of an unrecorded kind under charter and air-taxi rules (Part 135). 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
INADEQUATE MAINTENANCE AND EXCESSIVE AIRSPEED DURING THE LANDING APPROACH.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- September 21, 1993 · about 11:40 am local time
- Place
- Lone Rock, Wisconsin · Tri-County Regional · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Piper PA-60-601 · all PA-60-601s on the register
- Registration
- N9825Q · no longer on the register · serial 513130
- Damage
- Substantial damage
- Flight
- Flight of an unrecorded kind · charter and air-taxi rules (Part 135)
The NTSB's narrative final · quoted from the NTSB record
DURING CRUISE FLIGHT THE PILOT NOTICED A LOSS OF OIL PRESSURE AND AN INCREASE IN OIL TEMPERATURE ON THE LEFT ENGINE. HE SHUT DOWN THE ENGINE AND DIVERTED TO THE NEAREST AIRPORT. A VOR APPROACH WAS MADE AND DUE TO THE INABILITY TO MAINTAIN ALTITUDE, THE PILOT WAS UNABLE TO CIRCLE TO LAND ON THE LONGER RUNWAY. DURING THE LANDING ROLL, THE AIRPLANE OVERRAN THE END OF THE RUNWAY AND CONTACTED ROUGH TERRAIN. POST ACCIDENT INSPECTION REVEALED THE NUMBER 4 MAIN JOURNAL BEARING HAD SPUN. MATERIAL FROM THE BEARING AND THE DAMAGED CRANKCASE HAD CLOGGED THE OIL SUCTION SCREEN. WASHERS WERE FOUND ADDED TO THE OIL PRESSURE RELIEF VALVE IN AN ATTEMPT TO REGULATE THE OIL PRESSURE. THE ENGINE WAS OVERHAULED 350 FLIGHT HOURS PRIOR TO THE ACCIDENT.
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
Pilot
- Certificate: airline transport pilot
- Ratings: multi-engine land; single-engine land; instrument: airplane
- Flight time: 5,300 hours in all; 3,200 in this make and model; 150 in the last 90 days; 5,080 as pilot in command; 901 on instruments
- Medical certificate: Class 1 (valid medical--no waivers/lim.)
- Seat: left
The aircraft
- Airframe total time: 13,167 hours
- Last inspection: 100-hour inspection, September 3, 1993; 41 hours since
- Maximum gross weight: 6,000 lb
- Seats: 2
- Landing gear: retractable
- Engine: Lycoming IO-540-S1A5 (piston); 0 hours total
The flight
- Departed from: MWD Chicago IL at 10:35 am
- Destination: STP St. Paul MN
- Flight plan: IFR
- Runway 18, 2,590 ft by 40 ft
Weather at the time
- Light: night, dark
- Visibility: 7 statute miles
- Sky: overcast at 1,100 ft; not recorded at 1,100 ft
- Temperature: 57°F (14°C), dew point 55°F (13°C)
- Altimeter: 30.00 inHg
- Observation at 10:58 am from LNR
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
The docket, the folder of records gathered during an investigation (maintenance records, photographs, witness statements, examinations), has not been read from the NTSB for this case yet; the list appears here once it has. Open the docket at the NTSB.
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.