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 singleengine
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 singleengine
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.