Yamokoski William GLASTAR N4970Y

Summary

On 22 July 2012 at about 18:30 local time, a Yamokoski William GLASTAR registered N4970Y, operated by Yamokoski William, was involved in an accident near Chicago, Illinois, United States. One person was on board and one had minor injuries. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

22 July 2012 at 18:30

Classification

Accident

Location

Chicago, Illinois, United States

Nearest airport

None

Coordinates

41.6097, -87.4078

Aircraft

Yamokoski William GLASTAR

Registration

N4970Y

Category

Airplane

Engines

1

Operator

Yamokoski William

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Route

Osh Kosh → Benton Harbor

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN12LA470

1 person had minor injuries.

Failure of the automotive engine's reduction gearbox while in cruise flight.

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

Read the full NTSB narrative

The pilot was on a cross-country flight in an experimental airplane when the engine began to “race.” The pilot tried to reduce power by adjusting the throttle, but the engine and propeller were unresponsive. He then made a forced landing to a soft field, and the airplane nosed over. Examination of the automotive engine revealed that the spline-shaft and adapter gears in the reduction gearbox were worn, which resulted in the gearbox's failure. According to the pilot, the gearbox was not a regularly inspected item for this particular engine/gearbox combination. At the time it failed, the gearbox had accrued 247 total hours since new.

Quoted verbatim from the NTSB record.