Bailey Moyes 912 Dragonfly, Maintenance Manual

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3) Do not use the same ground lead for the instrument, and the ignition kill switch(es). Be sure these
separate ground leads do not connect to the engine in such a way that they could become disconnected
from the engine, but remain connected together.
4) The remainder of the signals are now connected. Accuracy of these sensors is not affected by the
length of the leads. Refer to figure 5a & 5b for an illustration of these connections.
5.2.1 Outside Air Temperature Sensor
The sensor for this unit is mounted using the plastic clip. This clip is attached to the airplane, and the
sensor snaps into it. To assure maximum accuracy, do not install the sensor such that it is in the path of
engine exhaust gases or cooling air outputs. Also avoid attaching it to aircraft structure that is warmed
by the sun. The ideal location is under the wing, or under the fuselage for pusher-engine installations.
It is very easy for the probe to get warmed by the engine if it is installed behind the engine, usually
resulting in readings that are 5-10 deg F too high. Avoid routing the wires to this sensor near radios,
ignition systems, or other electronic devices as much as practical. Ground the sensor near then
instrument To help prevent electrical noise from affecting the sensor, twist the entire length of leads
from the instrument to the OAT probe.
The outside air temperature is displayed in degrees Fahrenheit and Celsius as shown on figure 1.
5.2.2 Water Coolant/Oil Temperature Sensor
Start by installing the sensor in the engine according to the recommendations of the engine
manufacturer. After installation, route the wires through engine compartment, making certain the wire
is supported so that it will not be chaffed. A connector or terminal strip may be used between the
aircraft wiring and the sensor to enhance maintainability if desired. Single-wire type sensors, (those
which have a one electrical connection to them) require that their cases be connected to ground. For
these sensors pipe thread compound should be used to seal the sensor. Teflon tape should be avoided
because it may electrically insulate the case of the sensor from ground. If practical, connect the ground
wire to the same point where the instrument is grounded to minimize differences in ground voltages.
5.2.3 Voltmeter
The voltmeter senses its voltage through the power input to the instrument, and thus does not require a
separate connection.
5.2.4 Oil Pressure Sender
The oil pressure sender should first be installed on the engine. This sender uses an 1/8-27 NPT pipe
thread fitting, but may be adapted to any engine with the appropriate pipe fitting adapters. The sender
may also be mounted remotely, using suitable hose connections. This is necessary with some engines,
especially Lycoming.
The electrical connections are made through the case of the sender (ground) and the electrical terminal
opposite the pipe thread fitting. Ground is normally provided by the engine when the sensor is
mounted directly to it, but a separate ground wire may be necessary for remote installations.
5.2.5 Magnetic Tachometer Sensor
See instructions with this sensor for installation recommendations.