Is it as simple as a drop in?

the400kid

the400kid

Pre-takeoff checklist
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My KT76-C transponder is in the fritz and the repair station doesn't think it's worth repairing. He has one he can sell me but for $1,700. I see these units all over the place for less than $500.

Can I buy a cheap, yellow tagged unit and simply slip it in, or does it need the Mode S code entered?
 
Simply slide a serviceable one in. There is no Mode S code to deal with because it’s not a Mode S transponder.

On side side not you could also use a KT76A transponder as its tray compatible.
 
the400kid said:
Can I buy a cheap, yellow tagged unit and simply slip it in
Click to expand...
and get it checked by an avionics guy?
Yes.
Transponders are excluded from "preventative maintenance" slide in replacement. Part 43, appendix A, (c) (31).
 
+1 on above... grab a pito-static check while at it
 
It does not need yellow tag since you have to get the transponder test anyway. You can also get a King KT-74 or Trig 31 and those are a slide in replacement but has Mode S and is solid state for more reliability. You should be able to find one of those used for $1700 or new for $2300 or so.
 
the400kid said:
Can I buy a cheap, yellow tagged unit and simply slip it in, or does it need the Mode S code entered?
Click to expand...
FYI: to add to the above, the KT76C is not mode S, only an AP can slip it in, and the replacement xspndr will require a 91.413 check by a CRS.
 
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Capt. Geoffrey Thorpe said:
Transponders are excluded from "preventative maintenance" slide in replacement. Part 43, appendix A, (c) (31).
Click to expand...

<thread drift> So if it were say perhaps a rack mount COM radio like an KY197A, could an owner slide in a KY197 or an ICOM A220 as "preventive maintenance"?
 
asicer said:
If it were a KY197-A220 swap,
Click to expand...
Different scenario. Is the the A220 an approved drop-in replacement for a KY197? If not, it doesn't fit the definition of "replacement" so becomes an alteration which requires an AP.

As to any EW W&B computations this also requires an AP unless the weight difference is 1lb or less for 5000lb EGW aircraft, 2 lbs or less for 5000-50000lbs EGW, etc.
 
the400kid said:
My KT76-C transponder is in the fritz and the repair station doesn't think it's worth repairing. He has one he can sell me but for $1,700. I see these units all over the place for less than $500.

Can I buy a cheap, yellow tagged unit and simply slip it in, or does it need the Mode S code entered?
Click to expand...
You can buy a used unit. It may last 6 months or 6 years. I would upgrade to mode S now rather than tossing money at an obsolete transponder.
 
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