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Casualties unknown

Rudder Trim Switch Spring Failure Causes Yaw and Emergency Landing (N708ZW)

Battle Creek, MI, US

On May 15, 1984, a DE Havilland DHC-7-102 (registration N708ZW) was involved in an aviation accident near Battle Creek, MI. Investigators recorded the probable cause as: Failure of the centering spring (P/N 42M4231137) at a fatigue crack. 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

During cruise, a first officer felt a snap in the rudder trim rotary switch, which then rotated freely. The aircraft began yawing, so the crew disabled the trim via circuit breaker and landed with full right rudder trim. Examination found the centering spring failed from a fatigue crack.

Incident Description

While cruising at 7,000 feet MSL, the first officer was trimming the rudder using the rotary switch on the center console. During this action, he felt a 'snap' inside the switch. Subsequently, the switch would rotate freely between the stops. The aircraft began yawing left and right until the crew pulled the appropriate circuit breaker to disable the rudder trim. Following the disablement, they landed with full right rudder trim applied.

Examination Findings

An examination of the switch revealed that a centering spring, part number 42M4231137, which is designed to load the switch to the neutral/off position, had failed at a fatigue crack.

Probable cause

Failure of the centering spring (P/N 42M4231137) at a fatigue crack.

Frequently asked questions

What happened in the 15 May 1984 DE Havilland DHC-7-102 accident near Battle Creek, MI?

During cruise, a first officer felt a snap in the rudder trim rotary switch, which then rotated freely. The aircraft began yawing, so the crew disabled the trim via circuit breaker and landed with full right rudder trim. Examination found the centering spring failed from a fatigue crack.

What aircraft was involved and where did it happen?

The accident on 15 May 1984 involved a DE Havilland DHC-7-102, registration N708ZW, at Battle Creek, MI.

What was the probable cause of the accident?

Failure of the centering spring (P/N 42M4231137) at a fatigue crack.

More accident analyses

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001214X39497. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.