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Helicopter Engine Failure Due to Carburetor Air Box Misinstallation (N7885S)

Lost Hills, CA, US

On July 23, 1996, a Bell 47-G5 (registration N7885S) was involved in an aviation accident near Lost Hills, CA. Investigators recorded the probable cause as: The carburetor air box was installed with the wrong gasket and mispositioned so that one of four attachment bolts was missing, leading to partial ingestion of the gasket and foreign material into the carburetor throat. 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 2026-07-04Data APIEditorial standards

A helicopter lost engine power shortly after liftoff due to a carburetor air box installed with a wrong gasket, mispositioned, and missing one of four attachment bolts, allowing ingestion of gasket and foreign material.

Incident Overview

During a flight to ferry the helicopter back to its home base, the pilot landed to take on additional fuel. After liftoff, at an altitude of approximately 100 to 150 feet above ground level, the pilot experienced a complete loss of engine power.

Postaccident Examination

A postaccident examination revealed that the carburetor air box had been installed with an incorrect gasket and was mispositioned. One of the four attachment bolts was missing. The gasket was partially ingested into the carburetor throat. Additionally, a foreign material, identified as a dusting product, was found coating the carburetor throat area, having entered through the void left by the missing bolt and incorrect gasket.

Findings

The examination determined that the improper installation of the carburetor air box, including the wrong gasket and mispositioning, combined with the missing attachment bolt, led to the ingestion of gasket material and foreign matter into the carburetor, resulting in a loss of engine power.

Probable cause

The carburetor air box was installed with the wrong gasket and mispositioned so that one of four attachment bolts was missing, leading to partial ingestion of the gasket and foreign material into the carburetor throat.
Maintenance error

Frequently asked questions

What happened in the 23 Jul 1996 Bell 47-G5 accident near Lost Hills, CA?

A helicopter lost engine power shortly after liftoff due to a carburetor air box installed with a wrong gasket, mispositioned, and missing one of four attachment bolts, allowing ingestion of gasket and foreign material.

What aircraft was involved and where did it happen?

The accident on 23 Jul 1996 involved a Bell 47-G5, registration N7885S, at Lost Hills, CA.

What was the probable cause of the accident?

The carburetor air box was installed with the wrong gasket and mispositioned so that one of four attachment bolts was missing, leading to partial ingestion of the gasket and foreign material into the carburetor throat.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001208X06298. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.