FADEC

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FADEC

• Full Authority
• Digital Engine Control

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FADEC Overview

• Full Authority Digital Engine Control
• System continuously monitors and controls
  ignition timing, fuel injection timing, and
  fuel-to-air ratio mixture
• Therefore, a FADEC equipped engine does not
  require magnetos and eliminates the need for
  manual fuel/air mixture control.

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Basic components of FADEC

• Two Electronic Control Units (ECUs)
• Health Status Annunciator (HSA)
• FADEC Sensor set
• (1) Speed Sensor Assembly (SSA)
• (4) Cylinder Head Temperature (CHT)
• (4) Exhaust Gas Temperature (EGT)
• (2) Manifold Air Pressure (MAP)
• (2) Manifold Air Temperature (MAT)
• (2) Fuel Pressure Sensors
• (1) Throttle Position Switch (WOT)

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Low Voltage HarnessFigures 3-2 and 3-1 in FADEC
manual

• Connects all essential components of FADEC
• Fuel Injector Coils and all sensors (except SSA,
  Fuel Pressure, Manifold Pressure) are hardwired
  to the low voltage harness
• All information from sensors will flow to the
  Electronic Control Units for data processing and
  analysis

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Electronic Control Unit (ECU)3-7 to 3-9 in FADEC
manual

• Brain of the Engine Control System
• ECU divided into an upper and lower portion
• Lower portion contains the
• Electronic Circuit Board that
• processes all data
• Upper portion contains the
• ignition coils for the spark
• plugs (each ECU has (4) coils)

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ECU contd

• The electronic circuit board (lower portion) of
  each ECU contains (2) independent microprocessor
  controllers which serve as control channels
• (1) control channel is assigned to operate a
  single engine cylinder (thus one ECU per pair of
  cylinders)
• ECU 1 controls opposing cylinders 1 2ECU 2
  controls opposing cylinders 3 4

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ECU contd

• Control channel will receive the sensor inputs
  and monitor any changes
• Control channel will use these inputs to
  precisely trim the fuel to air ratio going into
  each cylinder
• Therefore, the control channels allow each
  cylinder to be individually leaned or enriched

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ECU contd

• If one control channel fails within an ECU the
  other control channel can operate its assigned
  cylinder as well as the opposing cylinder as
  backup control for fuel injection and ignition
  timing
• All critical sensors are redundant with one
  sensor from each type connected to a control
  channel in different ECUs
• Synthetic software default values are also used
  should both sensors of a redundant pair
  failtherefore, FADEC will always have a value to
  work off of so it can inject an average amount of
  fuel to the cylinder

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Health Status Annunciator (HSA)
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HSA contd

• Consists of (5) lights on panel and WOT
• HSA provides information regarding the status of
  the FADEC system
• We have the 2-light system display referenced in
  the manual plus additional indicators as seen on
  the HSA
• HSA will not give you a warning or caution light
  for OIL temp/pressure or ALT FAIL

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HSA lights

• FADEC WARN Engine Failure may be imminent, more
  than (1) cylinder is affectedland ASAP
• FADEC CAUTION 99.99 of installed components are
  working. No immediate action is reqd. Most
  common example is a bad EGT sensorall sensors
  are redundant
• ANYTIME YOU GET A WARNING OR CAUTION REFER TO
  VM1000this is a window into what FADEC sees

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HSA lights contd

• PPWR FAIL Primary Battery is not being charged,
  will be accompanied by EBAT FAILyou will start
  draining both batteries and have at least 60
  minutes to land. Your secondary battery will
  only power FADEC, AI, and Turn Coordinator
• EBAT FAIL Backup Battery not being charged,
  everything can run from Primary Power
  Source/Battery

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HSA Lights contd

• FUEL PUMP illuminates when Fuel Boost Pump Mode
  Switch is in ON or OFF. If this light is
  illuminated it means that you are manually
  controlling the fuel pump or that the fuel
  pressure is out of the 20-40 psi range.
  Illuminates for electric driven fuel pump as well
  as engine driven pump
• WOT below HSA panel. Illuminates when Throttle
  Position Switch (TPS) is contacted (full
  throttle), signal sent to ECU that max power is
  reqd which causes FADEC to set fuel to air ratio
  for Best Power

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FADEC Ignition System

• Consists of high voltage harness and spark plugs
  (2 plugs per cylinder)
• Employs a waste spark ignition system- plugs fire
  once on compression and once on exhaust... this
  keeps plugs clean
• ECU1 fires top and bottom spark plugs for
  cylinders 1 2
• ECU2 fires top and bottom spark plugs for
  cylinders 3 4

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Power Supplies

• Primary Power Source (PPS)-
• 14v 60amp alternator and 12v 25Ah Lead Acid type
  battery (located aft baggage compartment)
• Secondary Power Source (SPS)-
• 12v 7Ah Lead Acid type battery
• PPS and SPS have separate set of breakers and the
  power supply circuits are separated
• Battery condition monitor will illuminate HSA
  with PPWR FAIL or EBAT FAIL to alert pilot of
  possible power supply loss

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Power Supplies contd

• FADEC operates off of primary power source with
  alternator indefinitely
• Alternator fails- FADEC will use primary battery
  until 12v then will cycle between using PPS and
  SPS every volt (FADEC always looking for best
  power source) until batteries are drained
• FADEC can operate on SPS (aka backup or emergency
  battery) for at least 1 hour
• SPS is only to supply power to FADEC (AI and TC
  will also work) and can not be used for starting

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FADEC System Redundancy

• Power Supplies (PPS and SPS)
• If a control channel (CC) has a fault, the other
  CC within the same ECU is capable of operating
  its assigned cylinder as well as the other
  cylinder experiencing the fault
• All sensors are redundant with one sensor from
  each pair connected to channels in different
  ECUs. Synthetic software defaults are used in
  case of sensor failure

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REVIEW

• FADEC utilize a set of redundant sensors linked
  to the respective ECU
• ECU then uses data to analyze and control the
  ignition timing, fuel injection timing and fuel
  to air ratio for each cylinder
• FADEC is powered by 3 sources alternator,
  primary battery, emergency batteryFADEC needs
  only 1 power source to operate
• Reduces a pilots busy work
• 15 more fuel efficiency than correct and
  accurate conventional mixture control

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Low Voltage Harness