Aeronca 11AC accident near Winchester, California, July 27, 2024
On July 27, 2024 at about 6:57 pm local time, a 1946 Aeronca 11AC, registered N86270, was substantially damaged in an accident during enroute (cruise) near Winchester, California. It was a personal flight under general aviation rules (Part 91). No one was hurt; 2 people were on board or involved. The weather was visual conditions (good weather).
The NTSB's probable cause their words, unchanged
A total loss of engine power due to a fatigue fracture of the crankshaft.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 27, 2024 · about 6:57 pm local time
- Place
- Winchester, California · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Aeronca 11AC, built 1946 · all 11ACs on the register
- Registration
- N86270 · registry record · serial 11AC-75
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot of the tailwheel-equipped airplane reported that, while nearing his intended destination on a cross-country flight, the engine lost partial power followed by a vibration and grinding sound. The pilot attempted to restore engine power by troubleshooting; however, the engine subsequently lost total power and he initiated a forced landing to an open field. When the main wheels touched the soft terrain, the airplane nosed over, which resulted in substantial damage to the left wing. Postaccident examination of the engine revealed metallic debris in the oil sump. The engine was disassembled by the previous owner, and the crankshaft was found fractured at the forward area of the No. 1 cylinder connecting rod journal. The entire fracture surface exhibited beach marks, consistent with high cycle fatigue over multiple duty cycles. The reason for the fatigue fracture was not determined. The engine was last overhauled about 60 years before the accident and had accumulated about 1,569 hours of operation since overhaul. The supplied logbook excerpts consisted of 2 entries, and as such, it could not be determined what engine work was accomplished since the overhaul was performed. The engine manufacturer’s recommended time between overhauls is 12 years or 1,800 hours since overhaul.
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
- Off-field or emergency landing during landing
- Nose over/nose down during landing
- Powerplant sys/comp malf/fail during enroute (cruise) defining event
The NTSB's findings
- Aircraft › Aircraft power plant › Engine (reciprocating) › Recip engine power section › Fatigue/wear/corrosion
Pilot
- Certificate: private
- Ratings: single-engine land
- Flight time: 249 hours in all; 69 in this make and model; 25 in the last 90 days; 13 in the last 30 days; 166 as pilot in command
- Last flight review: September 23, 2022
- Medical certificate: Class 3 (without waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Seats: 2
- Landing gear: fixed
- Engine: Cont Motor C85-12 (piston); 0 hours total
The flight
- Departed from: SDM San Diego CA
- Destination: HMT San Jacinto CA
Weather at the time
- Light: daylight
- Wind: from 200° at 11 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 95°F (35°C), dew point 50°F (10°C)
- Altimeter: 29.90 inHg
- Observation at 12:55 pm from KHMT, 4 miles away
Weather report (METAR): METAR KHMT 271955Z AUTO 20011KT 10SM CLR 35/10 A2990 RMK AO2=
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight crew | 1 | |||
| Passengers | 1 |
Documents from the investigation the NTSB's docket: the evidence folder behind the report
6 documents, released by the NTSB on May 27, 2026. 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, 11 pages | View Download |
| 2 | Mor - Pilot | PDF, 2 pages | View Download |
| 3 | Logbooks | PDF, 3 pages | View Download |
| 4 | Materials Laboratory Factual Report 25-083 | PDF, 5 pages | View Download |
| 5 | Continental Motors M-0 Manual, Chapter 6, Time Between Overhaul Requirements | PDF, 1 page | View Download |
| 6 | Photo Array | PDF, 2 pages | View Download |
The same docket at the NTSB · documents without a copy here are fetched from the NTSB when you open them.
About this page
Everything above comes from the NTSB's public accident database: the narrative, probable cause and findings are the NTSB's own words, and the coded tables behind its report (pilot, aircraft, flight, weather, injuries, sequence of events) are written out in plain English. Pilots' ages, home towns and medical details are left out on purpose. The documents and photographs are the NTSB's docket, the folder of records gathered during the investigation, shown as the NTSB released them (the NTSB redacts some personal details first) and listed under the NTSB's own titles. This site's own text never names pilots, passengers or anyone else involved. A preliminary report describes what is known soon after the event and can change; the final report, with the probable cause, usually follows one to two years later and this page is refreshed when it does. Case number WPR24LA261.