FAA
Aviaon Safety
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General Aviaon
Joint Steering Commiee
Safety Enhancement Topic
Full Authority Digital Engine Control (FADEC)
The General Aviaon Joint Steering Commiee (GAJSC) idenes electronic engine control (EEC), which
ranges from electronic ignion through full authority digital engine control (FADEC), as a safety enhancement
to GA aircra. These systems can decrease pilot workload and provide engine monitoring capability that can
alert operators of certain mechanical problems.
Electronic Ignition & Engine Control
Whether we realize it or not, most cars
today benet from electronic ignion and electronic
engine control (EEC) technology. If you press a
buon to start and stop your car, you have an EEC
on board. The EEC keeps
your engine running at
peak eciency for your
operaonal environment
by evaluang input from
engine and environment
sensors hundreds of
mes per second. Those
same sensors can
provide valuable input as
to the health of your
powerplant. If problems
are detected, a service
light on your panel will indicate the issue.
Fewer mechanical parts means longer
service intervals and reduced maintenance expense.
AFS-920 17-12
Electronic Ignition for Aircraft
As with automobiles, fewer mechanical parts
on aircra equals increased reliability which, in turn,
increases maintenance intervals and reduces
maintenance expense. You may also see an increase
in fuel eciency.
But, to get all the benets from digital
technology, you’ll have to cede at least some engine
control to computers. There are a couple of ways to
do that.
The rst way is through EEC. With EEC, we get
electronic ignion and some computer control such
as ignion ming and air/fuel mixture. EEC is also
more reliable than magnetos.
Connued on Next Page
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Digital Electronic Control System
Full Authority Digital Engine Control (FADEC)
means just that. There is no direct pilot control over
the engine or manual control mode. If the FADEC
fails, the engine fails. However, system redundancy
makes it much less likely for a FADEC system to fail
than a tradional magneto system. In fact, a double
magneto failure is stascally more likely than a
FADEC failure.
FADEC systems are:
autonomous,
self-monitoring,
self-operang, and
redundant.
FADEC Advantages
FADEC shares advantages with electronic
ignion and EEC systems, but it takes power
management several steps further. FADEC
combines throle, prop, and mixture controls into a
single control. Every throle seng at any altude
results in the opmum power/prop RPM/mixture
combinaon. This enables pilots to realize fuel
economy that would only have been dreamed of
previously.
Automac engine performance monitoring
constantly provides over-speed and over-boost
protecon throughout the operaonal range. Pilots
can command maximum power and the system will
deliver just that and no more. There is no possibility
of exceeding limitaons. FADEC also features
diagnosc processes that constantly monitor the
health and well-being of the aircra powerplant.
The diagnoscs are very good at dening small
problems before they become big problems. It’s not
surprising that FADEC delivers big returns in
increased fuel eciency and reduced maintenance
expense.
FADEC Disadvantages
Pilots, accustomed to managing their
engines directly, may inially view FADEC exclusive
engine control with suspicion, but with experience,
will learn to trust the system. The hardest fact for
most to get accustomed to is that the system
provides no reversion to manual control.
Occasionally, pilots have run engines beyond
operaonal limits in order to get out of ght
situaons. That can’t happen with FADEC.
Maximum allowable power for any ight level is
always available, but no more than that. Also,
sucient electrical power to start and run the
engine is needed. Hand propping denitely won’t
work with FADEC.
Although just a few GA manufacturers are
using FADEC now, we can expect to see many more
in the future.
Resources
FAA Advisory Circular 33.28-1, Compliance
Criteria for 14 CFR secon 33.28, Aircra
Engines, Electrical and Electronic Engine Control
Systems: hps://go.usa.gov/xn89k