Teledyne Continental Motors, Inc.
TM
Engine
Description
IOF-240 Series Engine Maintenance Manual
2-3
31 August 2007
Change 1
2-1.
General Engine Description
The IOF-240 engines are four-cylinder, four-stroke reciprocating aircraft engines
designed for fixed pitch, ground adjustable, or electric constant speed propellers. There is
no provision for a hydraulic propeller governor.
These horizontally-opposed, air-cooled, naturally-aspirated engines have a wet oil sump,
high pressure Lubrication System, an overhead plenum intake manifold, a side-mounted
accessory drive pad and provisions for a downdraft exhaust system.
The engines are equipped with a Full Authority Digital Engine Control (FADEC) System
for continuously monitoring and controlling ignition timing, fuel injection timing, and
fuel mixture. The microprocessor-based FADEC System monitors engine operating
conditions and then automatically sets the fuel mixture and ignition timing accordingly
for any given power setting. Consequently, FADEC engines do not require magnetos and
eliminate the need for manual fuel/air mixture control. There is no fuel mixture control
lever in a FADEC engine.
A FADEC-controlled engine differs from a non-FADEC engine in that a cylinder can be
leaned or enriched individually without affecting the other cylinders. The FADEC
System controls the fuel supplied to each cylinder using solenoid-actuated sequential port
fuel injectors. An engine-driven, positive displacement vane fuel pump supplies fuel as
required to the injectors. The fuel pump is directly driven at the same speed as the
crankshaft. Therefore, fuel flow and fuel pressure vary directly with engine speed. Fuel
exits the pump, passes through a 32-micron fuel filter situated between the engine-driven
fuel pump and the fuel distribution block, where it filters particulates larger than 10-
microns. From this point, fuel travels to each fuel injector.
Since the fuel system requires fuel with minimum vapor to operate normally, an electric
boost pump is required for starting the engine and during low RPM operation. Ignition
spark is timed to the engine’s crank position. The timing is variable from cranking speed
up to 2,000 RPM depending on engine load conditions. The spark energy varies with
respect to engine load.
The FADEC System is electrically powered by the aircraft’s primary electrical bus and a
secondary power source (SPS); it is not self-excited. The SPS may be an alternator or
battery. It is used to supply power to the FADEC System independently from the
aircraft’s primary bus. If the SPS is a battery, it will be constantly charged by the
aircraft’s primary power bus. The charging current supplied to the SPS battery is
monitored by the Health Status Annunciator (HSA) and the charging circuit is protected
by a circuit breaker.
Electrical power to the FADEC System is controlled from the cockpit by two switches
used to interrupt the primary power and secondary power. The pilot starts, enables, and
stops the FADEC System using a conventional aircraft-style Ignition Switch.
