Casualties unknown

2003-10-09: Cessna 177B (N30921) — Chinook, MT

Chinook, MT, US

On October 9, 2003, a Cessna 177B (registration N30921) was involved in an aviation accident near Chinook, MT. Investigators recorded the probable cause as: The carburetor separated from the engine due to missing nuts on the four carburetor mount retaining lug bolts, and the pilot's judgment was impaired by recent marijuana use during the forced landing attempt. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

An aircraft lost engine power due to a separated carburetor (missing nuts on mounting bolts), and a forced landing attempt failed when the pilot, impaired by recent marijuana use, misjudged crosswinds and struck a tree.

Incident Overview

During cruise flight, the aircraft experienced a sudden and complete loss of engine power. The pilot attempted to restart the engine but was unsuccessful, prompting a forced landing on a nearby gravel road.

Forced Landing Attempt

In the course of the forced landing, the pilot failed to adequately compensate for strong crosswinds. As a result, the aircraft inadvertently clipped the top of a tree located immediately adjacent to the approach end of the intended landing section of the road.

Post-Accident Inspection

A post-accident inspection of the engine revealed that the carburetor had separated from the engine in flight. The separation occurred because no nuts were present on any of the four carburetor mount retaining lug bolts. The carburetor mounting flange holes remained intact, and none of the four mounting bolts showed signs of damaged or distorted threads.

Pilot Impairment

Subsequent toxicological analysis determined that recent use of marijuana had impaired the pilot's judgment at the time of the forced landing attempt.

Probable cause

The carburetor separated from the engine due to missing nuts on the four carburetor mount retaining lug bolts, and the pilot's judgment was impaired by recent marijuana use during the forced landing attempt.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20031017X01769. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.