Transcript FADEC - Orange County Flight Center

FADEC
Full Authority
Digital Engine Control
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.
Basic components of FADEC
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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)
Low Voltage Harness
Figures 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
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 cont’d
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& 2…ECU
#2 controls opposing cylinders 3 & 4
ECU cont’d
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
ECU cont’d
If one control channel fails within an ECU the other
control channel can operate it’s 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 fail…therefore, FADEC
will always have a value to work off of so it can inject an
average amount of fuel to the cylinder
Health Status Annunciator (HSA)
HSA cont’d
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
HSA lights
FADEC WARN: Engine Failure may be
imminent, more than (1) cylinder is
affected…land ASAP
FADEC CAUTION: 99.99% of installed
components are working. No immediate action
is req’d. Most common example is a bad EGT
sensor…all sensors are redundant
ANYTIME YOU GET A WARNING OR
CAUTION REFER TO VM1000…this is a
window into what FADEC sees
HSA lights cont’d
PPWR FAIL: Primary Battery is not being
charged, will be accompanied by EBAT
FAIL…you 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
HSA Lights cont’d
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
req’d which causes FADEC to set fuel to air ratio
for Best Power
FADEC Ignition System
Consists of high voltage harness and
spark plugs (2 plugs per cylinder)
Employs a waste spark ignition systemplugs fire once on compression and once
on exhaust... this keeps plugs clean
ECU#1 fires top and bottom spark plugs
for cylinders 1 & 2
ECU#2 fires top and bottom spark plugs
for cylinders 3 & 4
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
Power Supplies cont’d
FADEC operates off of primary power source
with alternator indefinitely
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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
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SPS is only to supply power to FADEC (AI and TC will
also work) and can not be used for starting
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
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 battery…FADEC
needs only 1 power source to operate
Reduces a pilot’s “busy work”
15% more fuel efficiency than correct and
accurate conventional mixture control
Low Voltage Harness