Clapp SABERWING N120SW

Summary

On 11 June 2024 at about 00:00 local time, a Clapp SABERWING registered N120SW was involved in an accident near Valdosta, Georgia, United States. One person was on board and one was seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 June 2024 at 00:00

Classification

Accident

Location

Valdosta, Georgia, United States

Nearest airport

Valdosta Rgnl (VLD)

Coordinates

30.7676, -83.3028

Aircraft

Clapp SABERWING

Registration

N120SW

Category

Airplane

Year built

2014

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Flight Test

Phase of flight

Not recorded

Route

Valdosta → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ERA24LA258

1 person was seriously injured.

The total loss of engine power due to the shearing of the woodruff key that indexed the crankshaft gear and hub assembly to the crankshaft, which resulted in the gear and hub rotating from their indexed position and caused the crankshaft-to-camshaft timing to become misaligned.

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

Read the full NTSB narrative

The pilot departed the airport on a local flight to perform system checks of the experimental amateur-built airplane. During a functional check of the ignition system, while the pilot was selecting between the points and electronic ignition at a high engine power setting, the engine lost all power about 8 miles away from the airport. After multiple unsuccessful attempts to restart the engine, the pilot declared an emergency and executed a forced landing to a field. The airplane subsequently impacted a utility line and came to rest inverted in a field about 2 miles from the airport. The right wing, fuselage, and empennage sustained substantial damage. Postaccident examination of the automotive conversion engine revealed that the woodruff key that indexed the crankshaft gear and hub assembly to the crankshaft was sheared. The gear and hub assembly had rotated about 30° from its indexed position, resulting in the crankshaft-to-camshaft timing being out of alignment and a subsequent total loss of engine power. According to the pilot, who had built the engine about 17 years and 20 flight hours before the accident, when switching from points to electronic ignition sources, there was a small interval for the electronics to power up, resulting in a jolt across the engine when power was restored. The jolt, at a high power setting, was likely enough to rotate the gear and shear the woodruff key.

Quoted verbatim from the NTSB record.