M6 FADEC Additional Information

MPPI’s Malibu M-6 utilizes Aerosance’s PowerLinkä FADEC (Full Authority Digital Electronic Control) system, which replaces the traditional ignition system and provides full control of ignition, timing, fuel mixture/delivery/injection and spark ignition.  FADEC monitors engine operating conditions (crankshaft speed, top dead center position, induction manifold pressure, induction air temperature) and then automatically adjusts the fuel-to-air ratio, mixture and ignition timing accordingly for any given power setting to attain optimal performance.

The FADEC system includes the following major components:

• Low Voltage Harness – This harness connects all essential components of FADEC and acts as a signal transfer bus interconnecting the ECU’s, aircraft power sources, ignition switch, Speed Sensor Assembly, annunciators and temperature and pressure sensors.
• High Voltage Harness (Electronic Ignition System) – Includes traditional spark plug wires.
• ECU’s (Electronic Control Units) – The three ECU’s, which are mounted to the back of the firewall in the front storage compartment, are the heart of the FADEC system, providing both ignition and fuel injection control to operate the engine with maximum efficiency.  Each ECU, which contains two microprocessors (referred to as a computer), controls two cylinders.  Each computer controls its own assigned cylinder and is capable of providing redundant control for the other computer’s cylinder.

The ECU computers constantly monitor the engine speed and timing and use this information in combination with manifold air pressure and temperature to calculate air density and determine the mass air flow into the cylinder during the intake stroke.  The computers calculate percent of engine power and use this information to determine the fuel required for either best power or best economy mode of operation.  The computer then precisely times the injection event and the duration of the injector “on” time for the correct fuel-to-air ratio.  The computer then sets the spark ignition event and timing based on the power calculation.  EGT’s are measured to verify the air ratio calculations were correct.  This process is repeated by each computer for its own assigned cylinder on every combustion/power cycle.  The ECU control channels are independent and there are no shared electronic components between the control channel pair within one ECU.  They also operate on independent and separate power supplies, however, if one control channel fails, the other control channel in the pair within the same ECU is capable of operating both the assigned cylinder and the other opposing engine cylinder as backup control for the fuel injection and ignition timing.

•  Pulse Fuel Injectors – Instead of using the more common “continuous flow” fuel injectors, the FADEC system utilizes “pulse” fuel injectors for each cylinder.  The pulse injector incorporates a fuel injector solenoid on each fuel injector, which is driven directly by the associated ECU control channel.  The control channel actuates the fuel injector by commanding the solenoid-controlled “pulse” fuel injector valve ON or OFF.  The control channel controls the duration of actual fuel injection based on a volumetric “map” of the engine’s breathing characteristics.  The “map” is the baseline mixture for the cylinder at any normal engine condition.  The control channel then compensates the mixture in response to variations in: intake manifold pressure, intake air temperature, fuel pressure, CHT, EGT, system voltage, RPM and power control lever setting.  When FADEC detects the need for more fuel to be injected to a given cylinder, the solenoids are held ON (open) for a longer duration, permitting more fuel to flow to that given cylinder.  The amount of time the injector is held ON determines how much fuel is delivered to the cylinder.
• SSA (Speed Sensor Assembly) –   The SSA consists of two sealed electrical circular connectors installed in the oil sump.  The speed sensor detects camshaft position and top-dead-center.  The signals generated by the SSA are passed to the ECU’s, where they are used to coordinate ignition and fuel injection timing.
• CHT, EGT, MAP, MAT, Fuel Pressure, Fuel Flow Sensor(s) – These sensors are all connected to the FADEC system via the Low Voltage Harness and are used by the ECU’s to control each individual cylinder.

The Malibu M-6 will feature a dual alternator, dual battery electrical system, designed for redundancy and safety.  A unique “bus tie” system will automatically transfer the electrical load and shed non-essential equipment in the event of an alternator failure.  In the very unlikely event of a second alternator failure, the FADEC system is automatically isolated to a single battery for continued operation.

A unique single-lever power control will incorporate throttle (manifold pressure) and propeller (RPM) into a single control.  The system will allow 2600 RPM at full throttle and will reduce smoothly to approximately 2400 RPM throughout the full range of cruise power settings.

This FADEC modification for the Malibu and Mirage aircraft has proven, through rigorous testing, to be smooth, powerful and very reliable.  Please keep an eye on www.malibumods.com for updates on this exciting project.

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