This article was provided by the FAA Aircraft Certification Office (ACO) Airframe, Propulsion and Services (ACE-118W) located in Wichita, Kansas.

The FAA has received a report, from an international authority, of a single-engine Cessna airplane that had the throttle control separate from the rod end that is attached to the carburetor. This airplane, like many others, but not all single-engine airplanes manufactured by Cessna, was equipped with a mechanism that enables the engine to automatically revert to full power when the throttle becomes disconnected from the fuel metering unit.

The FAA previously issued Airworthiness Directive (AD) 86-24-07 on the single-engine controls installation applicable to Cessna airplanes as well as Advisory Circular (AC) 20-143, Installation, Inspection, and Maintenance of Controls for General Aviation Reciprocating Aircraft Engines. The FAA also previously revised Title 14 of the Code of Federal Regulations (14 CFR) part 23, sections 23.1143(g) and 23.1147(b) to address the need for continued safe flight and landing in the event of a control separation at the engine fuel-metering device. These current rules are not
applicable to older in service airplanes.

The manufacturer’s service information, the FAA’s ACs, and ADs are the methods used to alert field maintenance personnel of the importance of providing adequate maintenance on in-service aircraft. The FAA continues to evaluate the reliability of engine-control installations applicable to small airplanes. The number of adverse reports applicable to these problems have reduced since the issuance of enhanced maintenance instructions, ACs, and ADs applicable to the controls installed on
reciprocating-engine airplanes.

Continued vigilance on the part of those individuals involved in inspection and maintenance must be maintained in order to keep the number of adverse reports associated with these components to a minimum. It should be noted that while some of the engines will revert to full power/mixture to enable continued safe flight and landing, many of the airplanes previously and currently produced primarily rely on proper maintenance of engine controls to ensure an adequate level of safety.