J.P. Instruments EDM 960 Twin Primary Installation Manual - Manual (Page 12)

FAA Approved Installation Manual for the EDM-960 system Report No 909
Primary Engine Data Management System Page 12 of 46 Rev D
Date 2-6-2014
When the installation is complete all wires should be secured using ties and carefully checked for interference, rubbing
or chafing with flight control cables or other moving parts.
14. Pressurized Aircraft wire Routing
Pressurized twin Engine Aircraft have a factory installed pressure bulkhead pass thru boot or connector at each wing
root where all electrical wires from the engine pass through to the cockpit. If you can not find the opening follow the
wires from the engine to the pressure vessel. If a boot with sealant is used remove the sealant, pass the three RS-
232 signal wires from the Data Acquisition Unit mounted in the engine compartment to the Display. Upon
accomplishing this reseal the hole with factory recommended sealant.
An alternate method for a cannon connector is to use existing wires in the aircraft going thru the pressure bulkhead.
The EDM-960 replaces the RPM, MAP, Oil Temperature, Oil Pressure and TIT gauges which have wires going thru
the pressure bulkhead. Any combination of three wires can be used to transmit signal to the cockpit display. Making a
new hole in the pressure bulkhead is beyond the scope of this document and will require a DER or other FAA
approval
.
15. Power Connection
The EDM-960 automatically accommodates either a 14 or a 28-volt electrical system. Master Bus power must be
individually provided, via three 5 amp circuit breakers, to the two DAU units and the EDM-960 head.
IMPORTANT: Insure the DAU ground wires are connected to the engine block. Any wiring extensions or additions
beyond JPI supplied wiring must be MIL-W-32759/16 or equivalent. The EDM-960 has a 8-second warm-up. No
connection to the aircraft dimmer system is required because the instrument dims automatically with reductions in
ambient light. The instrument is designed to reset at less than 10 vdc bus power, therefore the instrument may reset
on engine start (typical for 14 vdc systems). This is normal due to the starter loading down the battery output to below
10 vdc.
16. Probe Wiring
When cutting the pair of leads to the proper length to connect to the probes, leave enough slack in the wiring so that
probe may be interchanged to an adjacent cylinder if necessary for trouble-shooting and servicing. Thermocouple wire
length is not critical and should be trimmed to any length as required for a clean installation.
The Temperature probe must be wired with the correct polarity. The temperature probe connects to its temperature
indicator with yellow jacket Teflon Chromel-Alumel wire supplied. Strip the wires as shown below—observing color-
coding.
1/4" 1 1/2"
Fold back wire
double before
crimping terminals
2 1/4"
Thermocouple wire harness
red
yellow
Terminate each wire with a crimp-on ring terminal, provided. The ring terminals may be crimped with a “service-type”
tool, however AMP part number 48518 crimp tool is recommended. Verify the quality of each crimp with a sharp tug on
the wire. The terminal should be impossible to pull off when crimped correctly.
shrink tubing
ring terminal
Place a ¼ x 4-inch sleeve over each pair of wires in the wiring. Connect the wire ring lug to the probe ring lug using the
supplied number 4 screws and nuts, placing the star washer between the ring lugs, not against the nut.
Important: place star waster between two ring
terminals and tighten nut and bolt as
necessary
to instrument
to probe