Prerequisites
98-152675-A
Chapter 3: Installation
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Cobham Public
3.4
Prerequisites
Before you start to install the antenna, read the following sections carefully:
•
Antenna location and mounting considerations
•
Structural modifications and sealing
•
•
Alignment and installation limitations
Refer to [2] for an outline drawing of the LGA-5005.
3.4.1
Antenna location and mounting considerations
This section provides information on the mounting of the LGA-5005 hardware and the
installation of the antenna.
Make sure that the installation is in accordance with the following mounting considerations:
• Mount the LGA-5005 antenna on top of the fuselage.
• In some instances a mounting plate may be used to install the LGA-5005 onto the
aircraft fuselage. This document can also be followed when the LGA-5005 is installed
onto a mounting plate. Contact the antenna manufacturer for the relevant mounting
plate installation instructions in order to install a mounting plate onto the aircraft
fuselage.
• The antenna base is profiled with a radius of 3.25 m [127.95"].
If the fuselage radius is less than 1.8 m, contact the antenna manufacturer for a suitable
solution (adaptor plate).
• Mount the LGA-5005 antenna in a position with a clear view of the sky.
• Make sure that the mounting location is interference free, refer to
For a detailed step-by-step installation procedure see
3.4.2
Structural modifications and sealing
Structural loads
The effect of the installed antenna on the fuselage is airframe specific. A structural analysis
must be performed to determine what structural modifications to the airframe are required
before installing the antenna. This is the responsibility of the installation designer.
Sealing of the antenna
Sealing of the gap between antenna and fuselage skin is an aspect that is determined by
customer preference. Cobham does not require the underside of the antenna to be sealed
since there is no unprotected metal prone to corrosion.
Many years’ experience on a similar installation concept has proven this. If, however, the
customer has a requirement for fuselage skin protection, he should consider the use of an
in-situ injectable sealant or a gasket to afford the necessary protection against corrosion.
Use of a gasket is not straightforward and will require the installer to determine if adequate
compression can be supplied by the 4 mounting bolts to still attain sealing around the