Garmin GDL 69/69A, Installation Manual

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Appendix C – Construction and Validation of Structures
GDL 69/69A Installation Manual Page C-1
190-00355-02 Revision E
Appendix C - Construction and Validation of Structures
This appendix includes information necessary for testing load-carrying capabilities of equipment
mounting structures, such as shelves, mounting plates and mounting brackets, used to mount the GDL
69/69A remote rack.
Baggage compartments and cabins or cockpit floors are good mounting platforms providing the floor
attachments meet the strength requirements. If support racks, brackets or shelves need to be fabricated,
they should be fabricated and attached to the aircraft structure in accordance with the methods outlined in
AC 43.13-2A Chapter 2. After the structure is installed, it should be tested as outlined in AC43.13-2A
Chapter 1 to verify that it is capable of supporting the required loads.
The GDL69/69A installation must be capable of withstanding the Ultimate Load Factors listed in Table
C-1 for at least 3 seconds in each direction specified without damage or permanent deformation. Note that
these required loads differ somewhat from those normally required for equipment installations. The
following tables, C-1 and C-2, show the static test loads for the GDL 69/69A with both types of racks.
The combined weight of the
GDL 69 and the remote rack
is 2.69 lbs, the static loads which must be
applied (Load Factor x 2.69 lbs.) will be the following:
Table C-1. Static Test Load (GDL 69 with Remote Rack)
Direction of
Force
Load Factor
Static Test Load
(Load Factor x (GDL 69 + Rack
Weight))
Downward 6.6 g (6.6 x 2.69) = 17.75 lbs
Upward 6.0 g (6.0 x 2.69) = 16.14 lbs
Sideward 4.5 g (4.5 x 2.69) = 12.11 lbs
Forward 18.0 g (18.0 x 2.69) = 48.42 lbs
The combined weight of the
GDL 69A and the remote rack
is 2.83 lbs, the static loads which must be
applied (Load Factor x 2.83 lbs.) will be the following:
Table C-2. Static Test Load (GDL 69A with Remote Rack)
Direction of
Force
Load Factor
Static Test Load
(Load Factor x (GDL 69A + Rack
Weight)
Downward 6.6 g (6.6 x 2.83) = 18.68 lbs
Upward 6.0 g (6.0 x 2.83) = 16.98 lbs
Sideward 4.5 g (4.5 x 2.83) = 12.74 lbs
Forward 18.0 g (18.0 x 2.83) = 50.94 lbs
One method of determining the static load capability is as follows:
1. Mark and drill the holes where the GDL 69/69A equipment rack will be mounted.
2. Install four 8-32 machine screws (MS35206, AN526 or equivalent) in the four holes which will
be used to mount the GDL 69/69A remote rack.
NOTE
Some means of a locking fastener must be used, such as lock nuts and lock washers.
3. For testing downward loading, place shot bags or other suitable weights totaling the weight of
your equipment plus the rack (See Tables C-1 and C-2) within the footprint outlined by the four
screw holes (assuming the mounting surface is horizontal) or use a calibrated force gauge at the
location of the center of gravity when the unit is mounted.
4. Verify there is no damage or permanent deformation of the structure after 3 seconds.