Zenith STOL CH701 N701WJ

Summary

On 29 November 2019 at about 23:45 local time, a Zenith STOL CH701 registered N701WJ was involved in an accident near Byron, California, 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

29 November 2019 at 23:45

Classification

Accident

Location

Byron, California, United States

Nearest airport

Byron Airport (C83)

Coordinates

37.8303, -121.6261

Aircraft

Zenith STOL CH701

Registration

N701WJ

Category

Airplane

Year built

2019

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Flight Test

Phase of flight

Not recorded

Route

Byron → Byron

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

WPR20LA035

Nobody was injured.

The pilot/builder's improper construction of the cowling, which resulted in inadequate venting of the engine, its overheating, and a partial loss of engine power.

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

Read the full NTSB narrative

The pilot stated that he fabricated and installed a cowling on the airframe prior to the flight. During the initial climb, the engine experienced a partial loss of power and the water temperature climbed above the maximum temperature. The pilot made a forced landing at the departure airport and encountered wind during the approach. The airplane was pushed off the runway and landed hard in the grass; the airplane came to rest inverted.  The engine manufacturer provided instructions to builders to ensure there is proper venting over the engine. The pilot stated that he did not use any plans to build the cowling and did not perform any tests of the venting. The cowling was open on the bottom but did not have aft venting. As a result, the air pressure behind the radiator likely increased to be equivalent to that of the ram air, resulting in the engine overheating and experiencing detonation, leading to the loss of engine power.

Quoted verbatim from the NTSB record.