Gazelle Transponder
Dear All.
Please dont flame me if this is the wrong area;
A friend of mine operates a Miltary Gazelle Helicopter SA341 and has been told that the transponder is intermittant by ATC. The first time this failed he was charged nearing £380 to change one of the selectors on the control box for a part that costs less than a fiver from RS components - Had the RS part number printed on the selector which we found when a second selctor failed, it was an easy (and cheap) part replacement (also the soldering done during the previous repair was shoddy) , third time the transponder failed he was charged nearing the same to have the upper/lower antenna relay pulled out(behind the P2 seat, next to the switch in the rear), sprayed with switch clean and reinserted, he was later told that the relay is a common failure and most just operate in the lower position anyway to avoid the problem. The transponder has failed again, whilst it sounds as though its unreliable this is over a period of four so not too bad really for nearing a thirty year old piece of equipment.
The question; is it possible to test these on the ground without specialised equipment? any suggestions of what/where to check before it goes back in for another potentially expensive repair for a simple job?