User's Manual

TT21 Transponder Installation Manual 19 January 2009
00560-00 Issue AA
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5. Installation
5.1 Unpacking and Inspecting Equipment
Carefully unpack the transponder and make a visual inspection of the unit for evidence of any damage
incurred during shipment. If the unit is damaged, notify the shipping company to file a claim for the
damage. To justify your claim, save the original shipping container and all packaging materials.
5.2 Controller Mounting
The TC20 transponder controller must be mounted rigidly in the aircraft panel. The controller can be
mounted in the ultra compact mounting hole or in a conventional 57mm (2¼ inch) instrument cut-out.
The following installation procedure should be followed, remembering to allow adequate space for
installation of cables and connectors.
 Select a position in the panel that is not too close to any high external heat source. (The
TC20 is not a significant heat source itself and does not need to be kept away from other
devices for this reason).
 Avoid sharp bends and placing the cables too near to the aircraft control cables.
If you are using a 57mm instrument cut-out, you must first clip the two mounting adapters to the
transponder. The controller should then be mounted using the four LONG screws provided. If you are
using the Trig compact cutout, you do not need the mounting adapters. The controller should be
mounted using the four SHORT screws provided. If alternate screws are required, please note that the
mounting thread in each case is 4-40.
5.3 Transponder Main Unit Mounting
The TT21 Mode S transponder is designed to be mounted in any convenient location in the cockpit, the
cabin, or an avionics bay.
The following installation procedure should be followed, remembering to allow adequate space for
installation of cables and connectors.
 Select a position in the aircraft that is not too close to any high external heat source. (The
TT21 is not a significant heat source itself and does not need to be kept away from other
devices for this reason).
 Avoid sharp bends and placing the cables too near to the aircraft control cables.
 Secure the mounting tray (p/n 00667-00) to the aircraft via the three (3) mounting holes in the
tray. The tray should be mounted to a flat surface - it is important that the tray is supported at
the dimples as well as the three mounting points.
 Put the TT21 transponder into the secured mounting tray by hooking the connector end under
the lip on the tray.
 Lock the TT21 transponder into the mounting tray by clipping the retaining wire over the lugs
on the opposite end.
5.4 Cooling Requirements
The TT21 Mode S transponder meets all applicable ETSO requirements without forced air-cooling.
Attention should however be given to the incorporation of cooling provisions to limit the maximum
operating temperature if the TT21 is installed in close proximity to other avionics. The reliability of
equipment operating in close proximity in an avionics bay can be degraded if adequate cooling is not
Trig Avionics Limited Page 7