Casualties unknown

1999-12-28: Cessna 172L (N172GT) — New Orleans, LA

New Orleans, LA, US

On December 28, 1999, a Cessna 172L (registration N172GT) was involved in an aviation accident near New Orleans, LA. Investigators recorded the probable cause as: An intermittent short was found in the starter switch, which allowed the magnetos to remain ungrounded or 'hot' with the switch in the 'off' position. 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

While attempting to hand-prop a recalcitrant starter, the engine started unexpectedly. The unoccupied airplane jumped chocks, traveled forward, and struck a sea wall and hangar. A starter switch short was found.

Event Description

A pilot attempting to start an aircraft experienced difficulty when the starter's bendix drive gear failed to engage the starter ring gear. After the first failed attempt, the pilot secured the airplane by turning off the ignition, removing the key, pulling the throttle to idle, setting the parking brake, and exiting the aircraft. He then chocked the wheels and manually rotated the propeller until he felt one piston reach top center. Returning to the cockpit, he attempted another start, but the bendix drive gear still did not engage.

Again, the pilot turned off the ignition, removed the key, set the throttle to idle, and exited. As he manually rotated the propeller, the engine started. The airplane jumped the chocks and began moving forward without an occupant. It traveled some distance before impacting a sea wall and a hangar.

Pilot Actions and Statements

The pilot reported that he believed the mixture was off during the events. He performed the same shutdown procedure twice—turning off the ignition, pocketing the key, setting throttle idle, and exiting—before manually rotating the propeller.

Examination Findings

A post-accident examination of the starter system revealed an intermittent short in the starter switch. This short allowed the magnetos to remain ungrounded, or 'hot,' even when the ignition switch was in the 'off' position.

Probable cause

An intermittent short was found in the starter switch, which allowed the magnetos to remain ungrounded or 'hot' with the switch in the 'off' position.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X20248. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.