Manual Number 9019161
Revision A, September 9, 2020
13
PNEUMATIC PRESSURE CONNECTIONS
For the MD23 versions with pneumatic inputs, the connector kit supplied with the unit contains two
(2) pneumatic quick disconnect fittings. These fittings are specific to the connections on the rear of
the unit and are required for proper operation. The two fittings are marked with “S” and “P” on the
case. The “S” fitting, or Static, is for absolute pressure. The “P” fitting, or Pitot, is for positive
pressure and provides a differential pressure in relation to the Static input.
Aircraft tubing that connects to the unit must be ¼” OD with an approximate 0.17” ID. When
determining tubing length, be sure to include sufficient service length for insertion and removal
without stressing the tubing.
NOTE: It is helpful to identify/label each tube (pitot or static) so that it can be connected to the
correct port on the back of the unit during installation and so they do not get switched during
maintenance or reconnection in the future.
WARNING: Engage the Lock by pressing the metal tab on the quick disconnect before connecting
to the unit to avoid damaging the o-rings. The connectors will ‘snap’/lock into place once they are
fully engaged.
MOUNTING
The MD23 FLEX
is designed primarily to be rear mounted in an aircraft instrument panel. Refer to
Section 2.2 for Equipment Location information. To install the unit in the instrument panel, follow the
instructions below and refer to Figure 3.3 and Figure 3.4.
Notes:
If using flat-head screws, minimum panel thickness is 0.050 inches (1.3mm). Thinner
panels require a pan-head screw, or a spacer/washer between the unit and the rear surface
of the panel to properly secure the unit.
If using screws other than those provided, ensure that they do not protrude more than ½-
inch into the unit.
Remove burrs around the cutout and holes to allow the unit to mount flush with the panel.
Electrical bonding between the aircraft and the unit chassis is NOT required.
1. Once a location is selected, cut the panel per the dimensions in Figure 3.4.
Either through-holes for pan-head or cap screws, or countersink holes for flat-head
screws can be used. The installation kit includes flat-head screws.
2. Route the prepared cable harness and pneumatic tubing (if applicable) behind the panel
and to the panel cutout.
3. VERIFY THAT AIRCRAFT POWER IS TURNED OFF.
4. Connect the cable harness and pneumatic fittings (if applicable) to the rear of the unit.
5. Insert the unit into the panel cutout and secure with four (4) #6-32 screws (provided).
