Bill,
Flying with no engine monitoring of the CHT is not only not recommended it
violates government regulations on required engine monitoring.
I can=92t emphasize enough to read the GRT EIS manual.
Any info is there on the operation. The EIS always is the input to the GRT
displays (Horizon, Mini, etc.).
Opinions are like butt holes, everyone has one. 2nd hand owners who choose
to do their own maintenance must become familiar, in fact, pro=92s at the
installation and maintenance of each system. Flying is fun, improper maint
enance or lack of it can and will lead to mishaps. Download your manuals f
or the aircraft. (I have mine on the cloud and can refer to them off my cel
l phone) Study the system, and for sure ask questions. We all had questio
ns on installation. If the previous builder did not provide wiring documen
tation, you will have to make up your own to understand how things work. T
hat is why I have my 2nd hand owners spend a week in doing a nose to tail o
n the plane so they know where to look and I can tell what their maintenanc
e limitations are. Even certified airplane mechanics that have no experime
ntal aircraft experience are often times put into questionable airworthines
s decisions without proper documentation.
The GRT EIS is designed not to use CHT ring terminals of the J type. Do no
t use the Rotax cylinder probes as the CHT input on the EIS 25 pin CHT/EGT
D sub.
Facts on GRT CHT is it is a thermocouple ring terminal not a resistive type
. Do not operate the EIS without the ring terminal CHT probe. Inspect and
test the CHT ring terminal at least annually. Normally any failure in a r
ing terminal CHT is either age and the nichrome wire at the crimp point has
failed (or was cut by an improper crimp). Buy a new one. The next proble
m is simply a connection error. The EIS sends out 5 volts to the CHT ring
via a thermistor wire. That wire (normally a red for the +5 and white for
the return signal on a J type thermocouple) is somewhat fragile. GRT and
other manuals say any extension also has to be the same type wire. Not rea
lly over a short distance.
In my observations of many aircraft I=92ve inspected and assisted on, any e
rror in reading is usually wear, owner operator installation or programing.
I have had one bad EIS box in 20 years of installs.
Don=92ts:
Wrap your CHT wires all around the heads or exhaust pipes.
Cut or trim your CHT wires shorter. Changing the connector at the end is b
asically OK but normally use a Spade connector connecting your CHT J wires
to extend them into the panel.
Allow the CHT wires to be routed directly above exhaust pipe connection as
leaks have a huge affect on readings.
Reliability of H2O probes in the coolant line is not a primary source of in
formation due to poor grounding unless tested and properly grounded.
Crimp or severely kink the thermocouple wires.
Do=92s:
>From the CHT ring, use standoffs and hang the wires away from other heat so
urces to the transition plug or instrument itself.
Use proper spade connectors from the termination to any firewall transition
plug. GRT recommends using CHT Thermocouple extensions for the wire if ne
cessary to the EIS plug.
Protect your Thermocouple wires as the nylon wound insulation is easily dam
aged. Heat shrink works fine.
Coil excess wire rather than cutting it.
Use quality connectors and proper sized wires in completing your wiring.
Check your EIS output on the 25 pin CHT/EGT connector is putting out 5 volt
s.
I recommend you use the H2O input for the #3 CHT input as a cross reference
to CHT.
Note: The #3 cylinder is in close proximity to the exhaust pipe and oil ta
nk. Probes on #3 tend to run high because of this.
See Cooling 101 on my website www.customflightcreations.com<http://www.cust
omflightcreations.com> Techniques section.
Enjoy your reading. If you need one I have copies of the older GRT EIS Mod
el 4000 I can send you.
Best Regards,
Bud Yerly
Custom Flight Creations
Sent from Mail<https://go.microsoft.com/fwlink/?LinkId=550986> for Window
s 10
|