Cessna 172K accident near Lake Thomas A., California, May 24, 2002
On May 24, 2002 at about 1:45 pm local time, a Cessna 172K, registered N79944, was substantially damaged in an accident near Lake Thomas A., California (Reedley Municipal Airport). It was a personal flight under general aviation rules (Part 91). 1 person was seriously injured and 2 people had minor injuries. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
a partial loss of engine power due to the partial malfunction of the left magneto and leakage of the ignition leads for that magneto, due to inadequate maintenance inspections. Factors in the accident include the high density altitude, the maintenance personnel's failure to accomplish a service bulletin, and the effects of the pilot's manipulation of the mixture and carburetor heat controls.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- May 24, 2002 · about 1:45 pm local time
- Place
- Lake Thomas A., California · Reedley Municipal Airport · map
- Type
- Accident
- Injuries
- 1 person was seriously injured and 2 people had minor injuries.
- Weather
- visual conditions (good weather)
- Aircraft
- Cessna 172K · all 172Ks on the register
- Registration
- N79944 · no longer on the register · serial 17258271
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The airplane experienced a partial loss of engine power and collided with a tree stump during a precautionary landing on a beach. While climbing through 9,000 feet mean sea level (msl) the pilot leaned the airplane by relying solely on the exhaust gas temperature gauge. When reaching about 9,500 feet msl, about 1,500 feet above ground level over mountainous terrain, the pilot reported that the engine lost partial power. The propeller continued to turn, and the tachometer showed about 2,450 to 2,500 rpm, but the engine failed to produce enough power to sustain level flight. The pilot adjusted the mixture control, while also turning the carburetor heat to the on position, and applying full throttle. The engine failed to respond and the pilot made an approach to a sandy beach. The pilot flared the airplane about 2 feet above ground level, and the left wing collided with a tree stump, veering the airplane to the right. The elevation at the crash site was about 7,600 feet msl. A post accident investigation revealed that the left magneto exhibited excessive play at the cam end (points) of the main shaft. The subject magneto was later functionally tested, which revealed an intermittent spark on ignition lead T1. According to Textron Lycoming Mandatory Service Bulletin 515 the magnetos must be inspected every 500 hours. At the time of the accident, the magneto had accumulated a total time in service of 1,540.23 hours, and there was no maintenance entry indicating that the Service Bulletin had been complied with. While post accident tests showed that the left magneto was working only on an intermittent basis, information provided by Lycoming suggests that in and of itself the complete loss of one magneto would only result in a 3 to 5 percent loss of power. It is likely that the combined effects of the magneto malfunction, the high density altitude, and the pilot's manipulation of the mixture and carburetor heat all played roles in the engine's decreased performance capability.
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: private
- Ratings: single-engine land
- Flight time: 433 hours in all; 98 in this make and model; 5 in the last 90 days; 5 in the last 30 days; 390 as pilot in command
- Last flight review: February 17, 2001
- Medical certificate: Class 3 (valid medical--w/ waivers/lim.)
- Seat: left
- Injury: serious injuries
The aircraft
- Airframe total time: 3,676.9 hours
- Last inspection: annual inspection, May 16, 2002; 2.3 hours since
- Maximum gross weight: 2,300 lb
- Seats: 4
- Landing gear: fixed
- Engine: Lycoming O-320-E2D (piston); 0 hours total
The flight
- Departed from: O32 Reedley CA at 1:20 pm
- Destination: MLF Milford CO
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: from 320° at 8 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 61°F (16°C), dew point 45°F (7°C)
- Altimeter: 29.88 inHg
- Observation at 1:56 pm from KFAT, 50 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Crew | 1 | |||
| Passengers | 2 |
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.