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HELP! C-P HSI NAV FLAG


CRAW
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The CO-pilots HSI displays a to and from Nav flag when either the #2 INS or the #2 TACAN is selected. The INS and TACAN systems work 4.0. We have already swapped HSIs and INUs and have been looking at relays with no luck so far.:confused: Has anyone seen this before?

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Do you get DME when TAC 2 is selected? Two relays in the flight data switching panel relay the INS distance info from the copilots distance relay to the copilots HSI. When deenergized, the NC contact of the copilots distance relay receive TACAN distance info. They both talk to through this distance relay. look in the schematic and See where your Nav flag relay and tac 1 and 2 relays are energized along the path. Has to be a relay.

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I agree sounds like one of your NIS (nav inst switching) relays and they can be a pain in the arse... Check your copilots HSI data relay. Be careful with the screws they break.... They are all the same so you can switch them out and there is a test set but can't remember ever using it...

Hope you do not need to change the cannon plug it sucks!!!

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Update: 28VDC not at NAV SEL switch and not at co-pilots distance relay. Everything else works fine (HSI data from INS/TAC) were just not getting the power to suppress that NAV flag. What i don't understand is, If there is no power at the Distance relay (Where both INS and TAC meet) you would think that when i put coordinates into the INS i would just get default TAC DME and Nav data (since that is how the system is setup). When i select INS 2 on the co-pilots side, I get usable data from the INS 2.

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