Garmin GRA 55 Maintenance Manual - Page 12

2 SYSTEM DESCRIPTION 2.1 Description of Alteration This STC upgrades the existing functionality of the Bell 206B, 206L series aircraft avionics system as summarized below. The GRA 55/5500 radar altimeter system features: two antenna architecture for transmitting and receiving radio waves for altitude quantities, remote mounted LRU transceiver for quantifying Above Ground Level (AGL) altitude information, and interface capabilities to the existing aircraft G500H Flight Deck System (FDS) for pilot display of aircraft altitude and system degraded warnings. The GRA 55/5500 radar altimeter may also integrate with an installed Garmin GTN 6XX/7XX for the purpose of providing the optional 50 ft callout as part of optional HTAWS functionality. The GRA 55/5500 LRU which is 3.99"x3.02"x11.62" mounted, is located on the supplied mounting rack that is electrically bonded to the avionics shelf. The two approved radar altimeter antennas are optimally located on the underside of the tailboom, separated by a minimum distance of 20" on center using approved antenna mounts installed via STC SR09598RC, STC SR02162LA or other mounting provisions that are compatible with the approved radar altimeter antennas. The system requires a 5 Amp minimum circuit breaker installed on the overhead panel to supply power. 2.2 Block Diagram $5,1& *71;;;; *71 $5,1&&RQWURO'LVSOD\8QLW *+ 3)' &RORU 'LVSOD\ .QREV %XWWRQV 7; 190-01277-A3 Rev. 1 0DLQ 3URFHVVLQJ 8QLW 5; .(< *5$ /58 $5,1& 0LFURSURFHVVRU EDVHGVXEV\VWHP Figure 2-1. GRA 55/5500 Block Diagram System Maintenance Manual GRA 55/5500 Bell 206 STC Page 2-1