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The Model
2000 vs. 4000/6000
To start, you actually have 2 EIS
versions suitable for these engines, the model 2000, and the model 4000
(or 6000 for 6-cylinder engines). The Model 2000 provides excellent monitoring
to allow safe operation of the engine. For the additional cost, 95% of
our customers opt for the Model 4000. Many make this choice for the insight
it provides when leaning, but while this is nice, I find the EGT tracking
to be of even greater benefit. It really makes it easy to diagnose the
source of a rough running engine, and provides great reassurance that the
roughness you feel when flying over water is in your head, and not in the
engine. The 6 auxiliary inputs and programmable screens are additional
reasons for choosing this instrument also.Since
the Model 4000/6000 is the overwhelming most popular choice, it is described
here.
The Typical
Starting Package
For low wing airplanes, such as the
RV’s, you would begin with the Model 4000 package ($995), which includes
the instrument, pre-wired cables, oil temp and oil pressure sensors, 4
EGT probes and 4 bayonet type CHT probes with adapters. For RV's, you would
add a fuel pressure sensor ($35), manifold pressure sensor ($60), and you
would use two auxiliary inputs for the 2 fuel levels. You can use the float
type sensors(Van's includes these
with many kits), or your can purchase the Princeton Electronics capacitive
fuel level probe ($95 each). The capacitive probes have damping features
that allow more accurate measurements than the float type, and no moving
parts to wear out,but both provide
repeatable readings.I would say
95% of EIS users on RVs start with this list. High wing airplanes may not
require the fuel pressure sensor.
Why Manifold Pressure for Fixed Pitch Props?
Many would think that the manifold
pressure sensor is most suited for constant speed prop equipped airplanes.
While this may be feasible with production airplanes which include power
setting charts, kitplanes typically do not have this information, if for
no other reason than the vast combinations of engines, props, and factors
affecting drag. This leaves the fixed pitch propeller user with the need
to determine engine power when cruising at altitudes below about 8-9000
feet. Above this altitude, wide open throttle produces less than 75% power,
making leaning safe. Below this altitude, the manifold pressure is necessary
for accurate determination of the power setting to allow for safe leaning.
The Remaining Aux inputs and the Electric Airplane
The Model 4000 now has 6 aux inputs,
leaveing 2 of them unused. For all electric airplanes,one
of these aux inputs can be used to measure alternator output (ampmeter),
and the other as a second voltmeter for the second battery.
The Remaining Aux inputs and the
Vacuum Airplane
Since the Model 4000/6000 has
6 aux inputs, one of the remaining two can be used for instrument suction.
The sensor for this function is $60, and best of all, the EIS will generate
an alarm the moment suction is lost. I find it absolutely amazing that
most IFR airplanes do not have such warning. Vacuum pumps must be the most
unreliable, and most important element of an IFR airplane.
This leaves you with one aux input.
Often time it is not used, but it has been used by our customers for everything
from elevator trim to cowl temperatures, and you name it. One customer
even used it to measure the temperature of the water for his floatplane
(lake water, that is!)
The Options – Fuel Flow, Altimeter/VSI,
Airspeed
Is fuel flow essential?
Fuel flow has the potential to offer
some safety benefits, but its cost/benefit ratio, at least with respect
to safety, is not as high as other EIS functions. If money IS an object,
then this feature could be deferred. (About half our customers order fuel
flow with the EIS, and about¼
order it later.)
One ofthe
safety features that fuel flow offers is the detection of leaking fuel
lines, although this benefit is probably only significant with fuel injected
engines due to their higher fuel pressures.
For pilots who often fly near
the limits of the airplane’s endurance, the accuracy of the fuel flow totalizer
offers an additional safety benefit.
When using the EIS with the EFIS graphical
engine monitoring page, the concentric fuel flow and power “gauges” on
the EFIS allow easy comparison of fuel flow, and percent power.The
relative difference between these two displays represents the engine efficiency.
Since practically any engine problem reduces its efficiency, this is a
very simple, yet comprehensive indicator of engine health.
Still…considering the $375 cost for
this option, safety is rarely the motivating factor for ordering fuel flow.
The benefit that motivates the purchase of this function is the endurance
display, and the reassurance provided by the accurate totalizer. The endurance
display ends the mental calculations necessary to estimate the endurance
of the airplane, and makes the land now/continue to the next airport decisions
dramatically easier.
When coupled with the EFIS moving map,
reserve fuel (in time or fuel) at each airport can be displayed.The
reserve can be displayed assuming an immediate change to that airport as
the destination, or via the planned destination.You
can begin to imagine how this could be a convenience you can’t live without.Airline
pilot customers almost always order fuel flow, as they have grown accustomed
to this convenience at work.
Adding up all of these benefits, you
can begin to see why 75% of our customers choose fuel flow sooner or later.
Altimeter/VSI and Airspeed
The EIS can be equipped with airspeed
and altimeter/VSI options also. In an airplane with dual electrical buses,
the probability of loss of both buses should be very remote, making this
a viable alternative to mechanical instruments as backups.The
obvious benefit here is cost compared with mechanical instruments ($149
for the altimeter, and $195 for the airspeed option), reliability (we have
had no airspeed or altimeter failures in the 12 years we have been producing
the EIS), and panel space savings, and accuracy.
Practically speaking, flying with
reference to a purely digital altimeter has its trade-offs compared with
analog altimeters. On the plus side, you never are a thousand feet off
because you read the altimeter wrong (I’m not the only one that makes that
mistake am I?). On the negative side, it take a little more effort
to use the digital altimeter when attempting to fly a constant altitude…an
analog altimeter has the edge there.
Surprisingly, I find flying with a
digital airspeed effortless. I actually prefer it to analog airspeed gauges.While
it is true you might see an airspeed trend more easily with an analog airspeed,
I didn’t miss this when I switched to digital airspeed. I assume I was
getting a sense of the airspeed trend via the rate of change of the digital
speed.
As a sidenote, the EFIS Horizion displays
airspeed and altitude with both digital displays (they make accurte readings
very easy) and graphical tapes, to make holding a constant altitude or
speed, easy. I find it suprising that some flat panel displays of
altitude overlay the digital altimeter on the altitude tape, relegating
the tape to little more than a trend indicator (and not a good one at that).
Further enhancing the pilot's knowledge of the airplane's state, the EFIS
Horizon includes trend indicators on these readings also.
The accuracy of these features is excellent.
The altimeter can be adjusted by the user to meet IFR accuracy requirements.
The airspeed measurement never requires adjustment.
When used with and EFIS Horizion, the
EFIS will perform an automatic cross-check between the EIS airspeed and
altimeter, and its own sensors. This provides full time monitoring, and
instant alerting to failed or inaccurate sensors. This is clearly a significant
advantage over mechanical instruments.
Still Not Sure….
Feel free to give us a call. We would
be happy to assist you with your instrumentation decisions. After all,
that is our job!
Order
Green Sky Adventures, Inc. Toll
free 888 887-5625 cell 352 318-5625
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