Grumman-Schweizer G-164B N8440K

Summary

On 6 July 2002 at about 14:45 local time, a Grumman-Schweizer G-164B registered N8440K was involved in an accident near Weiser, Idaho, 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

6 July 2002 at 14:45

Classification

Accident

Location

Weiser, Idaho, United States

Coordinates

44.2286, -116.9686

Aircraft

Grumman-Schweizer G-164B

Registration

N8440K

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Weiser → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

SEA02LA123

Nobody was injured.

The fracture of the number 3 cylinder exhaust pushrod resulting in the exhaust valve's inability to open during the exhaust cycle and the subsequent engine stoppage. Contributing factors were the ditch and elevated roadway which the aircraft crossed during the gear collapse.

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

Read the full NTSB narrative

The pilot of the "Agcat" cropduster had just taken off and was making his first spray run over a field when the Pratt & Whitney R-1340 engine began to run rough. He pulled up and executed a right turn away from obstacles crossing the Snake River during which the engine abruptly stopped. The pilot rolled out and executed a forced landing in a beet field during which the aircraft crossed an elevated dirt/gravel roadway bounded on its north and south edges by a shallow ditch, and the aircraft's landing gear separated from the airframe. The aircraft then nosed over and came to a stop. The engine, which had been overhauled and inspected 81 and 31 hours respectively, was examined. The examination revealed that the number 3 cylinder exhaust valve steel pushrod was broken near the rocker arm end of the rod and the rod displayed very slight bending deformation. The separation surfaces of the broken rod end were observed to be mechanically battered. Removal or separation of the exhaust pushrod results in the exhaust valve's inability to open during the exhaust phase cycle for the associated cylinder, and can result in hot exhaust from the cylinder back-flowing out the intake valve when it opens during the intake cycle.

Quoted verbatim from the NTSB record.