FAQs
1.) Why should
I choose Plasma CDI over good old magnetos?
2.)
What is the difference between the Plasma II Plus
and the Plasma III system?
3.)
Can I use one Plasma CDI and one mag? How do
they work together?
4.) How does
the Plasma CD system advance the timing?
5.) Will my
engine temperatures change when I install a Plasma
CDI?
6.)
What are the power requirements for
the Plasma CD systems?
7.) Back-up battery?
8.)
I have an older Lycoming engine with a small
generator pulley, does that work with the Direct
Crank Sensor system?
9.)
My engine has a single drive dual magneto in place of two
magnetos. How can I adapt my engine to run
with Plasma ignition?
10.) How should I
feed the wires through the firewall?
11.)
Can the supplied coax cable be replaced with any
other wire?
12.)
Which spark plug location do you recommend for a
single Plasma CDI installation?
13.)
Can I use my key switch with the Plasma CD ignition
system?
14.) Does
the Plasma CDI work with my electronic tachometer?
15.)
Are the Plasma CD ignition systems FAA approved?
1.)
Why should I choose Plasma CDI over the good old
magnetos?
-
Aside
from the significant performance and efficiency
gain, electronic ignitions are significantly
more reliable and do not require regular
overhauls, inspections, or repairs.
In the excellent 1992 book "The Magneto
Ignition System", author John Schwaner
says the following about magneto repair:
"Since 1985, the
National Transportation Safety Board has cited
magnetos as a cause or factor in 92 accidents
involving 22 fatalities and 21 serious
injuries. This is surprising in that only
one magneto is required to operate the
engine."
"Magnetos are
reliable and provide a redundant safety factor,
but they have the potential of causing engine
failure if they are not inspected and
serviced. When the magneto bearings
fail on one obsolete magneto model, the
rotor seizes causing the gear teeth inside the
engine to break. The broken gear uncouples
both magnetos causing instant engine
shutdown. Worn impulse-coupling rivets can
cause engine failure when the impulse coupling
engages in flight. The adage "...if
it's not broke don't fix it." translates to
"...operate it until it fails and hope it
doesn't take the engine (and us) when it
does."
"Low voltage and
hard starting can be caused by shorted secondary
turns within the magneto coil."
"Any time the
magneto is "fired" without the
secondary circuit attached to spark plugs or
ground, the full secondary voltage stresses the
winding insulation. Eventually the
insulation breaks down and the windings
short."
"Shorting of a
secondary winding may create an open circuit as
the winding burns."
In writing of impulse coupling failure, the
author states, "The flyweight moves outward
until the heal(sic) of the flyweight strikes the
stop pin. At first, the heal(sic) just
grazes the stop pin causing a telltale mark on
the flyweight. Eventually, the heal(sic)
strikes the stop pin with enough force that it
pivots the flyweight outward where it engages
the stop pin. When this happens during
engine cruise, there is enough force that the
flyweight disintegrates into the accessory gear
train. Pieces of the impulse coupling then
lodge into the engine gearing, breaking off gear
teeth and decoupling both magnetos from the
engine. The engine quits."
Other failure mechanisms have to do with arcing
of the distributor block, oil or moisture in the
magneto, especially on super-charged engines,
heat failures of the capacitor, weak armature
magnets, incorrect timing of the "E"
gap, and incorrect impulse coupling lag-angle
when faster or slower starters are installed
which can cause kick-back.
2.)
What is the difference between the Plasma II Plus and the
Plasma III system?
3.)
Can I use one Plasma CDI and one mag? How do
they work together?
-
Under
high power conditions the Plasma CDI fires at
about the same ignition timing as the mag.
Only when MP is reduced will the Plasma CDI
advance its ignition timing accordingly.
While this is not as ideal as advancing the
timing on both spark plugs, it is much better
than not advancing the timing at all, as is the
case with magnetos.
4.)
How does the system advance the timing?
-
The
Plasma CDI adjusts the timing based on manifold
pressure (MAP) and rpm. Most of the change
is based on MAP, and only a few degrees of
change are based on rpm.
Optimized timing means more advance at lower
manifold pressures and less timing advance at
high power. During start, the systems fire
at TDC, independent of manifold pressure.
The ignition timing is at an optimum when the
engine produces peak torque. At peak
torque the highest amount of energy is used for
work and the least amount of energy is absorbed
by the cylinder head (too much advance) or
wasted in the exhaust (too much retard).
5.)
Will my engine temperatures change when I install a
Plasma CDI?
-
As
mentioned in question 3, optimizing the timing
means less heat is lost into the cylinder head,
piston, cylinder, and exhaust and more heat is
used to make power. This applies to all
power settings including idle. At altitude you
should see a 75F- 150F lower EGT when the Plasma
CDI is used.
Since heat is a byproduct of power, and since
the spark characteristics and timing of the
Plasma CDI increase max power, the associated
heat can also be slightly higher at the new
power output.
6.)
What are the power requirements for
the Plasma CD systems?
-
The
current versions of Plasma CDI systems need a
minimum of 6.2 volts to start operation.
This is more than 2 volts less than the minimum
voltage needed by the starter solenoid, thereby
eliminating the possibility of kick-backs during
starter operation.
Plasma systems shipped before December 20 of
2004, need 8.5 volts to start operation.
This higher "on" voltage can cause a
misfire if the starter current drain is high
and/or the battery is weak and the voltage
collapses below this threshold during
cranking. Systems shipped before 2005, can
be upgraded to have the lower voltage
capability.
Once the engine is running, all systems operate
down to less than 5 volts, should you lose your
charging system.
7.)
Back-up battery?
Any
aircraft with a starter has excess energy stored
in the battery for starting. In flight, this
large capacity is not needed. In case of an
alternator failure, 17ah or more should be
available. If this is only used for the
ignition (2ah at 13.8v), the airplane will
probably run out of fuel before the battery
does. It should be standard procedure to
land ASAP if there is a charging problem on an
all-electric plane. Also, one of the Plasma
systems can be switched off to minimize current
consumption since the power is nearly the same,
especially when the interconnect feature is used.
8.)
I have an older Lycoming engine with a small
generator pulley, does that work with the Direct
Crank sensor system?
9.)
My engine has a single drive dual magneto instead of two
magnetos. How can I adapt my engine to run
with Plasma ignition?
Most
pilots with these engines replace the dual mag
completely and use a dual Plasma CDI with Direct
Crank Sensor or DCmini Sensor triggering. This installation
eliminates the failure points of a dual mag set-up, significantly reduces weight, and is less
expensive than other options.
Hall Effect Modules are not used on engines with
single drive dual magneto configurations.
10.)
How should I feed the wires through the firewall?
-
It
is important that the sensor wires (connecting
the Hall Effect Module, Direct Crank Sensor, or
DCmini Sensor to
the Plasma CD box) are routed through the
firewall by themselves or only with other low-voltage "sensor"
wires. All "sensor" wires should
be well separated from high power wires.
The RG-400 primary ignition wires (connecting
the ignition coils to the Plasma CD box) are
high power wires and should only be by
themselves or with other high power wires
(starter cable, alternator cable...).
For best reliability, do not splice or otherwise
modify the supplied cables.
11.)
Can the supplied coax cable be replaced with any
other wire?
12.)
Which spark plug location do you recommend for a
single Plasma CDI installation?
-
A
single Plasma CD system keeps the entire
combustion chamber clean so it does not matter
much if the Plasma CDI is on the top or the
bottom. It is best if you use your first
system on the top and the second on the bottom
plugs. Since even a single Plasma CDI will
keep the spark plugs clean, the systems should
not be crossed. Use either all top or all
bottom plugs for each system.
13.)
Can I use my key switch with the Plasma CD ignition
system?
-
Yes,
all Plasma II Plus and Plasma III CDI systems
can be operated with a standard aircraft key
switch. A "P"-Lead (wired to the
output connector) is provided and should be
connected to the key switch in the same way as
the magneto "P"-Lead. There is no current
drain on your battery when power is supplied via
the input connector and the key switch is in the
off position. A pull-able circuit breaker
should still be installed in the positive power
wire.
The older Plasma II does not have this feature
and must be turned on and off with a quality
toggle switch.
14.)
Does the Plasma CDI work with my electronic
tachometer?
-
All
Plasma CD Ignitions have a pulse output (on the
input connector) for an electronic
tachometer. The pulse characteristics are
shown in the manual and most tachometers will
respond to that signal. If you have two
Plasma systems and you want to have a tach
reading from either Plasma CDI, you need to run
the signals through a selector
switch.
If you are using Plasma III versions
"A" or later (available after 12/05), you can
connect the tach pulses from two systems
together to one tach terminal.
Plasma III and Plasma II Plus CD ignitions also
have a built in tach which provides a voltage
output for a millivolt meter on the output
connector. See the wiring diagrams for
details.
15.)
Are Plasma CD ignition systems FAA approved?
-
We
do not have FAA approval for the Plasma CDI. In order to install the ignition
system on your certified aircraft, you will need
to get a field approval or a STC. Several
have been applied for. News regarding a
field approval will be published here.
On December 10th 2007, Helicopteres Guimbal received a
Supplemental Type Certificate from EASA*
for the Light Speed Engineering Plasma
CDI as standard equipment on their new
Helicopter, the Cabri G2.
Reciprocal
agreements between the FAA and EASA can
facilitate further applications on
certified aircraft in the future.
*
The European Aviation Safety Agency is
the European equivalent of the FAA.
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