FADEC & Diesel Engines in General Aviation

FADEC and Diesel Engines in General Aviation
Mathew Cussen
Purdue University

FADEC andDiesel EnginesinGeneral Aviation
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Abstract
In this research paper, I focus on the use of FADEC systems on aircraft with piston engines and
also on the use of diesel engines in aviation. I explain the advantages and disadvantages of
these two subjects. With the FADEC system, I give examples of engine companies with this
technology available and aircraft manufacturers who offer this. I also highlight the
specifications of the system, the general theory of operation, the controls in comparison to
those used in traditional spark ignition engines and the overall cost of the FADEC system. With
the diesel engines section, I give examples of engine companies with this technology available
and the airframes which are approved for these engines. I also give information regarding the
weight of diesel versus gasoline engines, the fuel required and approved for use, the operation
of the engine including controls, the general theory of operation of diesel engines in
comparison to gasoline engines, fuel consumption qualities with a focus on brake specific fuel
consumption of diesel versus gasoline engines, overhaul time and reliability compared to spark
ignition engines, and the overall cost of diesel engines in comparison to gasoline engines.

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FADEC
FADEC, which is short for Full Authority Digital Engine (or Electronics) Control, is a systemthat
controls all aspects of an engines performance and the propeller (Aircraft Systems, 2006). This
is accomplished with the use of a digital computer systemcalled an Electronic Engine Controller
(EEC) or an Engine Control Unit (ECU) and other ancillary components. In a reciprocating engine
that uses spark ignition, the FADEC system uses sensors to monitor the status of the cylinders
individually. The systemuses temperature, speed and pressure sensors in this monitoring
process. The digital computer in the FADEC systemcalculates what the ideal pulse is for each of
the injectors, and it will adjust the timing of the ignition accordingly to accomplish the optimal
engine performance.
Engines using FADEC systems do not have the need for magnetos, mixture controls,
carburetor heat, and engine priming. Aircraft using the FADEC systemwill simply have a single
throttle lever. A decrease in fuel consumption and an increase in horsepower are a result of this
precise control of the combustion process.
Although these systems were initially designed and manufactured for use in turbine engines
and military use, they are becoming increasingly popular for use among civilian aircraft with
piston engines as well. This technology applied to piston engines has now been around for over
a decade. The engine manufacturers which offer these FADEC systems for spark ignition
reciprocating engines include Continental and Lycoming. Lycoming uses its iE2 FADEC
technology on the TO-450, TIO-540-NXT, TSIO-550, and the TEO-540-A1A engines. These are
used on aircraft such as the Lancair Evolution and the Northrop Grumman Firebird. Continental

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uses its PowerLink FADEC system on their IO-240, IO-360, IO-550, IO-F240, IOF-550, and TSIOF-
550 engines. These are used on aircraft such as the Piper PA-46, the Liberty XL-2 and the Cirrus
SR22.
FADEC technology offers many advantages over a traditional spark ignition piston engine. Two
of the main benefits of this system that I mentioned earlier are the improved performance and
efficiency of the engine when this systemis used. There are, however, other advantages that
this system offers. With the use of a single throttle lever as opposed to the traditional prop and
mix levers, the pilot essentially doesn’t have to think as much about engine parameters while
flying. He or she is allowed more mental room to spend on flying itself. “It’s especially helpful in
bad weather and high traffic situations. The pilot can focus on flying the airplane instead of
continually having to manage the fuel control and manifold pressure,” according to Guido
Defever who is the vice president of research, development and engineering for Lycoming
Engines (FADEC, 2011). The throttle lever has detents in the lever for “Start”, “Idle”, “Cruise
Power” and “Max Power”. The pilot simply sets the lever to these positions, and the FADEC
system takes care of the rest. Another huge benefit is the ability of the system to give the pilot
real-time engine diagnostics. This allows a pilot to know exactly what issues the engine may be
having. The system also adjusts itself to correct these issues, if possible.
One advantage that goes hand in hand with the real-time diagnostics is the ability for a
technician to hook up a computer to the system and see fault codes that translate into
potential problems that the engine had on a particular flight. I personally feel that this is one of
the most beneficial aspects of this system. As a certified engine mechanic on the F-16/F-15’s

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Pratt & Whitney F100-220, I’ve seen the advantages of this first hand. The P/W F100-220 uses a
Digital Electronic Engine Control (DEEC) and an Engine Diagnostic Unit (EDU). After every flight,
we would go out to the flight line and download the fault codes from the EDU. We would then
bring them back to our shop and upload the codes into our computer. The software would
show us what the fault code meant, and it saved us a lot of time troubleshooting. This would
ensure a timelier fix so we could get the particular aircraft back in service quicker.
Fuel efficiency increase with FADEC is a huge benefit. With the TCM PowerLink FADEC system,
each cylinder in the engine is individually monitored. This allows for a continuous optimization
of fuel efficiency on an independent basis (Smith, 2007).
FADEC systems vary in price. A system for a turbine engine can cost in excess of $100,000
(Smith, 2007). However, Continental estimates that retrofitting a piston engine with their
FADEC system will cost anywhere from $2500 to $7500 depending on the particular engine on
which it is being installed (Cox, 2010)
.Diesel Engines
Diesel engines are rare in the aviation world. However, they do exist, and there is a major
push for advancement in this technology. This push is driven by the fuel efficiency qualities and
availability of the fuel. Although there have been multiple major engine companies report that
diesel technology will soon be available, the only six companies that have stuck to that
commitment are Thielert, DeltaHawk, Wilksch, Centurion, SMA and Austro (Goyer, 2012).
Although Lycoming has claimed to be a competitor in this race, they have yet to put their
money where their mouth is. Continental is still in the development stages of there GAP diesel

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engine (Small Aircraft Propulsion, 2004). They have teamed up with NASA in this development
process.
There are a few aircraft whose airframes are equipped for diesel engines. Some of these
include the Diamond DA52, the Cessna 172, the Cessna 182 NXT, the Robin Ecoflyer, the Van’s
RV9, the Diamond Star DA40 TDI, and others (Diesel Air Newsletter, 2012). This being said,
there are more and more manufacturers trying to get into the playing field for diesel because of
the benefits.
There are quite a few advantages to running a diesel engine. One of the greatest benefits of
diesel engines are their desirable fuel type. Diesel engines are equipped to use diesel fuel or
Jet-A, which is not only widely available, but also considered to have low flammability
characteristics (DeltaHawk Engines, 2012). This fuel is much more available than Avgas in the
worldwide spectrum. Secondly, since Avgas is leaded, it will soon be illegal to use. Therefore,
these gasoline fueled engines will become unusable (DeltaHawk Engines, 2012).
Another desirable aspect of diesel engines is their fuel efficiency. For example, we will use the
DeltaHawk diesel engine. This engine has a brake specific fuel consumption of .35 lb/hp/hr
(DeltaHawk Engines, 2012). Compare this to an Avgas engine which has a brake specific fuel
consumption of .59 lb/hp/hr at 75% power and above (DeltaHawk Engines, 2012). So as you can
see by the numbers, the diesel engine burns fuel at a slower rate.
One thing that goes hand in hand with fuel economy is the lower overall fuel cost. Since diesel
engines get 30%-40% more range per gallon, the fuel cost is naturally much less (DeltaHawk

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Engines, 2012). Another factor that plays into this is the fact that on average, Jet-A is about 9¢
more per gallon than Avgas (DeltaHawk Engines, 2012).
Similar to the cockpit setup of an aircraft with FADEC, an aircraft with a diesel engine will only
have one power lever. A mixture control lever is not used (DeltaHawk Engines, 2012). When the
lever is pushed forward, fuel flow increases and the engine speeds up. Like the FADEC setup,
this is one less thing that a pilot has to worry about while flying.
Although diesel engines and gasoline engines are both internal combustion engines, they
have some important differences. The main difference between gasoline and diesel engines is
the way in which combustion is accomplished in the engine. In a gasoline engine, fuel and air
are mixed. This mixture is then compressed and ignited by a spark from the spark plugs. The
spark plugs receive a pulse of current from the magnetos. A diesel engine accomplishes this in a
different way. First and foremost, diesel engines do not use spark plugs and magnetos. In diesel
engines, air is compressed first. Then the fuel is injected into the cylinder. The fuel ignites
because air heats up when it is compressed (Brain, 2012). The compression ratios of diesel
engines are also higher than in gasoline engines. This means that diesel engines generate more
power. A diesel engine can have a compression ratio of 14:1 to 25:1, where a gasoline engine
will be between 8:1 and 12:1 (Brain, 2012).
One of the major disadvantages of diesel engines is the weight in comparison to gasoline
engines. For example, although the DeltaHawk engine has smaller dimensions than the
Lycoming O-360, the DeltaHawk weighs in at 330 lbs where the Lycoming O-360 weighs 282 lbs

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(DeltaHawk Engines, 2012). In the aviation world, weight is the enemy. So, this is obviously a big
factor that manufacturers are trying to cut down on.
Diesel engines tend to have shorter overhaul times than gasoline engines. This is considered a
disadvantage by some. An example of this would be the Thielert 1.7 liter diesel used in the
Diamond DA42. Initially, this engine had a TBO or Time Before Overhaul of only 600-hrs (Kern,
2012). That number later moved up to 1000-hrs TBO, but that is still low. In comparison, the
gasoline fueled Lycoming O-360 has a TBO of 2000-hrs (Bertorelli, 2012). So, that is a significant
difference. Another issue with the Thielert diesel was that the clutch and gearbox had to be
rebuilt every 300-hrs (Kern, 2012). The second generation version of this engine has improved
to a TBO of 1500-hrs and the clutch and gearbox must be rebuilt every 600-hrs (Kern, 2012).
Diesel engines can most definitely be more affordable than gasoline engines. For example, I
will compare the cost of the DeltaHawk Turbo-Diesel engine to that of a Lycoming IO-360-A1B6
gasoline engine. For a non-assembled Lycoming IO-360-A1B6, the price tag comes in at $84,933
(DeltaHawk Engines, 2012). For the DeltaHawk pre-assembled fast build kit, you would be
looking at a price of $69,500 (DeltaHawk Engines, 2012).
As the previous examples have illustrated, diesel engines are most likely the wave of the
future. With increased efficiency and a lower initial price tag, don’t be surprised to see an influx
of this technology in years to come.

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References
Aircraft Systems, Chapter 6. (2006). Pilots Handbook of Aeronautical Knowledge. Retrieved
from the FAA online
http://www.faa.gov/library/manuals/aviation/pilot_handbook/media/PHAK%20-
%20Chapter%2006.pdf
FADEC. The Future of Piston Engine Management. (2011). Aviation Maintenance Magazine.
Retrieved from Aviation Maintenance Magazine online http://www.avm-
mag.com/news/fadec-the-future-of-piston-engine-management
Smith, D. (2007, July). General Aviation: FADEC: Making a Piston Engine Act Like A Turbine.
Aviation Today. Retrieved from
http://www.aviationtoday.com/am/categories/bga/General-Aviation-FADEC-Making-
%09a-Piston-Engine-Act-Like-a-Turbine_13506.html#.UKAFleQ80ih
Cox, B. (2010, February). FADEC Comes of Age. Plane & Pilot. Retrieved from
http://www.planeandpilotmag.com/aircraft/modifications/fadec-comes-of-
age.html?start=1
Goyer, R. (2012, June). Diesel Economics. FLYING. Retrieved from
http://www.flyingmag.com/blogs/going-direct/diesel-economics
DeltaHawk Engines. (2012). Why Aero DIESEL. Retrieved from the DeltaHawk Engines website
http://www.deltahawkengines.com/
Diesel Air Newsletter.(2012).Home. Retrieved from the Diesel Air Newsletter website
http://www.dieselair.com
Small Aircraft Propulsion: The Future Is Here. (2004). NASA. Retrieved from NASA online
http://www.nasa.gov/centers/glenn/about/fs01grc.html
Brain, M. (2011, October). How Diesel Engines Work. How Stuff Works. Retrieved from
http://www.howstuffworks.com/diesel1.htm
Bertorelli, P. (2012, May). Diesel vs. Mogas. AvWeb. Retrieved from
http://www.avweb.com/blogs/insider/AvWebInsider_DieselMogas_206680-1.html
Kern, T. (2012, July). What About Those Deisels? Pt. 2. AviationPros. Retrieved from
http://www.aviationpros.com/article/10731435/recip-technology-what-about-those-
diesels-part-2

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