Amateur-built ZODIAC CH 601 XLB accident near Hubbard, Oregon, August 2, 2015
On August 2, 2015 at about 11:00 pm local time, a 2012 amateur-built ZODIAC CH 601 XLB, registered N234S, was substantially damaged in an accident during enroute near Hubbard, Oregon. It was a personal flight under general aviation rules (Part 91). 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
A severe propeller vibration due to the pilot's improper installation of the propeller spacer assembly, which necessitated an engine shutdown, an off-airport landing, and a collision with a sprinkler system.
Source: NTSB aviation accident database, copy made October 5, 2026. Docket and reports at the NTSB.
What the record shows
- Date
- August 2, 2015 · about 11:00 pm local time
- Place
- Hubbard, Oregon · map
- Type
- Accident
- Injuries
- No one was hurt; 1 person was on board or involved.
- Weather
- visual conditions (good weather)
- Aircraft
- Amateur-built ZODIAC CH 601 XLB, built 2012
- Registration
- N234S · registry record · serial 7165
- Damage
- Substantial damage
- Flight
- Personal flight · general aviation rules (Part 91)
The NTSB's narrative final · quoted from the NTSB record
While approaching the destination airport in the experimental amateur-built airplane, the pilot felt an engine vibration and elected to shut down the engine and conduct a precautionary landing to a nearby field. During the landing sequence, the airplane's left wing collided with a ground sprinkler system, which resulted in substantial damage. Postaccident examination of the engine revealed no anomalies. The propeller had been removed from the crankshaft flange by the pilot following the accident. Examination of the flange revealed numerous fractures in the threaded alignment holes, and the alignment screws were worn. Additionally, five of the six "lightning" holes displayed cracking. Examination of the propeller spacer revealed that two bores were missing bushings. All six bolts were fitted with two washers; one affixed to each bolt head and a larger washer between the bolt head and the spacer. The larger washers exhibited rotational deformation consistent with contact with the fixed washers. All six bolts were bent, and it could not be determined if the bolts were safety wired at the time of the accident. The bolt bushings appeared to be "homemade" and of different lengths, with bolt holes drilled off-center. It is likely that the irregular, non-standard bushings prevented the proper installation and torqueing of the propeller bolts, which led to the vibration experienced during the accident flight.
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
- Sys/Comp malf/fail (non-power) during enroute defining event
- Collision with terrain or object (not controlled flight into terrain) during landing (landing roll)
The NTSB's findings
- cause Aircraft › Aircraft propeller/rotor › Propeller system › Propeller assembly › Incorrect service/maintenance
- cause Personnel issues › Task performance › Maintenance › Modification/alteration › Owner/builder
Pilot
- Certificate: flight instructor, commercial pilot, sport pilot
- Ratings: multi-engine land; single-engine land; instructor: airplane single-engine; instructor: instrument airplane; instrument: airplane
- Flight time: 2,350 hours in all; 80 in this make and model; 12 in the last 90 days; 3 in the last 30 days
- Last flight review: April 25, 2015
- Medical certificate: None
- Seat: left
- Injury: no injuries
The aircraft
- Airframe total time: 80 hours
- Last inspection: annual inspection, November 2, 2014; 10 hours since
- Maximum gross weight: 1,320 lb
- Seats: 2
- Landing gear: fixed
- Engine: Lycoming O-290 G (piston); 80 hours total
The flight
- Departed from: 5S9 Estacada OR at 10:45 pm
- Destination: 7S9 Hubbard OR
- Flight plan: none
Weather at the time
- Light: daylight
- Wind: at 4 knots
- Visibility: 10 statute miles
- Sky: clear
- Temperature: 81°F (27°C), dew point 52°F (11°C)
- Altimeter: 29.92 inHg
- Observation at 10:53 pm from UAO
Injuries
| Fatal | Serious | Minor | None | |
|---|---|---|---|---|
| Flight 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.