Garmin GRA 5500 Installation Manual

Contents

Garmin GRA 5500 Installation Manual Manual pdf 25 page image

GRA 5500 Installation Manual 190-01277-00Page 2-10 Rev. A2.3.4 Antenna Installation ConsiderationsThe following guidelines should be observed when implementing the antenna installation:1. Antenna and airframe surfaces should be prepared and bonded according to guidance given inSection 2.4.2. A visual inspection should be performed to verify that all coaxial cables are connected properlybefore attempting to operate the equipment.3. Always refer to the antenna manufacturer’s provided installation material for any additionalinstallation guidance specific to the antenna type being used.2.4 Electrical BondingAll electrical equipment, supporting brackets, racks, and antennas should be electrically bonded to theaircraft’s main structure. Refer to SAE ARP 1870 Section 5 when surface preparation is required toachieve electrical bond. The electrical bond should achieve direct current (DC) resistance less than orequal to 2.5 milliohms to the local structure to where the equipment is mounted. Compliance should beverified by inspection using a calibrated milliohm meter. An equivalent OEM procedure may also besubstituted. There may be OEM specific reasons for electrically isolating equipment or having a higherbond resistance. These reasons should be rationalized upon installation approval. In general, Garminrecommends that all GRA 5500 equipment be electrically bonded.2.5 Cabling and WiringRefer to the interconnect examples in Appendix C for wire gauge guidance. Use only wire, coaxial cable,and installation methods that are compliant with governing aviation regulations and standards.Any bend radius applied to a cable must not exceed the minimum bend radius specification as prescribedby the cable manufacturer for the specific cable type. It is recommended that the bend radius applied to acoaxial cable is minimized when in close proximity to the connector ferrule or compression housing inorder to decrease side loading of the cable at the crimp or compression area. Whenever possible, it isrecommended that no clearly visible bending exists within 1/2 inch of each coaxial cable assemblyconnector ferrule or compression housing. All cables should be secured in a manner that minimizes anypotential back and forth side loading of the cable at the connector crimp or compression area. Whenrouting the wire and cable, the installing agency should observe the following important precautions:• Route all wiring and coaxial cables in a manner that maintains a minimal length of cable needed tocomplete the required connections, while avoiding, (as much as possible) routing near noisyenvironments such as power sources and circuits that carry or generate heavy current, 400 Hzgenerators, trim motors, pulse transmitting equipment, or fluorescent lighting power sources.• For all wiring and coaxial cables, do not exceed the specified minimum bend radius and eliminateany potential of sharp bends that exceed the minimum bend radius (refer to preceding paragraphfor additional cable recommendations).• Ensure that all wiring and coaxial cables are properly secured while avoiding the potential ofdeteriorating the integrity of the insulation and jackets because of rubbing against the aircraftstructure, other installed equipment, or excessively tight cable ties.• Prior to connecting the fabricated wiring harness to the GRA 5500, verify correct routing ofaircraft power and aircraft power ground to the assigned pins and verify that aircraft power isavailable at the assigned pins after routing verification.DRAFT