Hudson ZODIAC CH 601 XLB N234S

Summary

On 2 August 2015 at about 23:00 local time, a Hudson ZODIAC CH 601 XLB registered N234S, operated by Ralph A Hudson, was involved in an accident near Hubbard, Oregon, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

2 August 2015 at 23:00

Classification

Accident

Location

Hubbard, Oregon, United States

Coordinates

45.1800, -122.7436

Aircraft

Hudson ZODIAC CH 601 XLB

Registration

N234S

Category

Airplane

Year built

2012

Engines

1

Operator

Ralph A Hudson

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Estacada → Hubbard

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR15LA228

Nobody was injured.

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.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

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.

Quoted verbatim from the NTSB record.