NTSB Identification: CEN09IA456
14 CFR Part 91: General Aviation
Incident occurred Sunday, July 19, 2009 in West Chicago, IL
Probable Cause Approval Date: 10/19/2009
Aircraft: CESSNA 172R, registration: N77AF
Injuries: 2 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
A previous maintenance entry in the airplane logbook indicated that the firewall was replaced and the airplane returned to service. The airplane had been operated for about 63 hours when the throttle control cable became unscrewed from the rod end of the throttle assembly during an instructional flight. The flight instructor and student pilot lost throttle control during an approach to a destination airport when engine speed increased to about 2,200-2,300 rpm. The flight instructor landed the airplane without further incident. The throttle control assemblies for the airplane do not have a key way at the throttle control knob to prevent rotation of the cable and unscrewing of the cable from the rod end should the jamnut become loose. The operator recommended that a safety device and not just a jamnut be installed to prevent the throttle control from disconnecting from the rod end.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: A partial loss of engine power due to the detachment of the throttle control cable from the throttle assembly during a landing approach. Contributing to the accident was the lack of a redundant means to preclude the detachment of the cable from the throttle assembly. Full narrative available
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