On April 10, 1989, a Cessna 172RG (registration N9688B) operated by Dunbar, Lee R.& Jeffrey T. was involved in an aviation accident near Miamisburg, OH. No fatalities were reported. Investigators recorded the probable cause as: A chafed wire for the nose gear micro switch grounded against the airframe, causing the gear motor circuit breaker to open and stop gear extension prior to full extension of the left main gear. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During landing roll at an uncontrolled field, the left main gear of an IFR-flying aircraft collapsed. Examination revealed a chafed wire grounding the nose gear micro switch, causing the gear motor circuit breaker to open and stop gear extension. Additionally, an internal throttle warning switch failure prevented unsafe gear warnings.
Incident Overview
A pilot operating under Instrument Flight Rules (IFR) landed at an uncontrolled airfield. During the landing roll, the left main landing gear collapsed.
Examination Findings
Subsequent inspection of the aircraft revealed a chafed wire for the nose gear micro switch. This wire had grounded against the airframe, causing the gear motor circuit breaker to open. The circuit breaker opening stopped the gear extension process before the left main gear had fully extended.
Additionally, an internal failure of the throttle warning switch was discovered. This failure meant that the switch did not provide either a visual or an aural warning indicating an unsafe gear condition.
Probable cause
A chafed wire for the nose gear micro switch grounded against the airframe, causing the gear motor circuit breaker to open and stop gear extension prior to full extension of the left main gear. Additionally, an internal failure of the throttle warning switch prevented an unsafe gear visual or aural warning.
Frequently asked questions
What happened in the 10 Apr 1989 Cessna 172RG accident near Miamisburg, OH?
During landing roll at an uncontrolled field, the left main gear of an IFR-flying aircraft collapsed. Examination revealed a chafed wire grounding the nose gear micro switch, causing the gear motor circuit breaker to open and stop gear extension. Additionally, an internal throttle warning switch failure prevented…
Were there any fatalities in the 10 Apr 1989 Cessna 172RG accident?
No fatalities were recorded in this accident.
What aircraft was involved and where did it happen?
The accident on 10 Apr 1989 involved a Cessna 172RG, registration N9688B, operated by Dunbar, Lee R.& Jeffrey T., at Miamisburg, OH.
What was the probable cause of the accident?
A chafed wire for the nose gear micro switch grounded against the airframe, causing the gear motor circuit breaker to open and stop gear extension prior to full extension of the left main gear. Additionally, an internal failure of the throttle warning switch prevented an unsafe gear visual or aural warning.
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