Amateur-built Kitfox accident near Valencia, California, July 7, 2009
On July 7, 2009 at about 7:30 pm local time, a amateur-built Kitfox, registered N926JB, was substantially damaged in an accident during enroute (cruise) near Valencia, California (Whiteman Airport). It was an instructional 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).
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The NTSB's probable cause their words, unchanged
The failure and separation of a propeller blade for undetermined reasons.
Source: NTSB aviation accident database, copy made October 4, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- July 7, 2009 · about 7:30 pm local time
- Place
- Valencia, California · Whiteman Airport · map
- Type
- Accident
- Injuries
- No one was hurt; 2 people were on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built Kitfox
- Registration
- N926JB · registry record · serial KBS 079
- Damage
- Substantial damage
- Flight
- Instructional flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
The pilot reported that he was flying back to the airport when the experimental airplane began to shake violently, which was accompanied by a loud noise. The propeller blades departed the airplane and the engine subsequently experienced an overspeed, followed by a loss of power. During a forced landing, the airplane encountered a ditch and spun 90 degrees. Metallurgical examinations of the blades could not determine the method of failure. Tests and calculations indicate that the engine could not rotate fast enough to liberate the blades unless their strength had been degraded in some way. Several possible sources of such degradation were observed, but none of them could be conclusively identified as the cause of the event. The strength of the blades was provided by the wood of the propeller, and the fractures in the wood of the three blades appeared similar, making no obvious difference to identify the initial separation. The blades were found very close to one another, suggesting that they were liberated at nearly the same point of rotation during a single revolution of the propeller. Assuming one blade had accumulated enough damage to initiate the event, the resulting unbalanced vibration was sufficient to eject the other two blades, in the process creating fractures similar to those on the damaged blade. The measured gap between hub halves was less than the expected gap for new, correctly installed blades. Such over-clamping of the hub is one problem that has apparently occurred in the past due to improper torquing. It is possible that the hub had previously been over-clamped to a greater degree, with subsequent adjustment leading to an under-clamped condition. Looseness in this area can lead to fatigue cracking, because it allows for the variations in stresses from repetitive loads to be maximized on the components being connected. Bird impact was ruled out, but the blade might have been struck by debris picked up during takeoff. Although there was no staining or other signs of degradation in the wood, one blade had an area that was susceptible to moisture due to a manufacturing defect, which could have allowed the decrease in the stiffness and strength of wood structures and may have played a role in liberating the blades.
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
- Part(s) separation from AC during enroute (cruise) defining event
- Loss of engine power (total) during enroute (cruise)
The NTSB's findings
- cause Aircraft › Aircraft propeller/rotor › Propeller system › Propeller blade section › Failure
- cause Not determined › Not determined › (general) › (general) › Unknown/Not determined
Flight instructor
- Certificate: airline transport pilot, flight instructor, commercial pilot
- Ratings: multi-engine land; multi-engine sea; single-engine land; single-engine sea; instructor: airplane multi-engine; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 8,433 hours in all; 8 in this make and model; 21 in the last 90 days; 3 in the last 30 days; 8,300 as pilot in command; 5,315 on instruments
- Last flight review: May 29, 2008
- Medical certificate: Class 2 (with waivers/limitations)
- Seat: rgt
- Injury: no injuries
Dual student
- Certificate: student
- Flight time: 30 hours in all; 28 in this make and model; 2 in the last 90 days; 2 in the last 30 days
- Medical certificate: Sport Pilot (with waivers/limitations)
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 278 hours
- Last inspection: condition inspection, September 15, 2008; 49 hours since
- Maximum gross weight: 1,200 lb
- Seats: 2
- Landing gear: fixed
- Engine: Rotax 912UL (piston); 0 hours total
The flight
- Departed from: WHP Los Angeles CA at 6:35 pm
- Destination: WHP Los Angeles CA
- Flight plan: not recorded
- A second pilot was aboard
Weather at the time
- Light: daylight
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 0°F (-18°C)
- Altimeter: 29.92 inHg
- Observation at 7:25 pm from WHP, 1 miles away
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flig | 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.
Other NTSB records under N926JB the same tail number, which may have belonged to a different aircraft at the time
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 WPR09LA340.