Transponder problem

If you’ve been following the transponder saga, you know that recently I have had Approach A tell me they’ve lost my transponder (as they slip to the airplane’s 3 or 4 o’clock position), and yet have Approach B (still ahead) see it just fine.

Happened again yesterday, with my home base airport BLM, in site; i.e. I was low, 2,000 feet, when McGuire Approach - at my 3 o’clock - lost my transponder. I requested a 360 and asked them to advise if they picked it up… partway through my turn, when I was headed more or less toward McGuire, they did.

Add to this others’ experiences - so far, I know of two who have had the same thing happen. I am now reasonably satisfied that this problem has some sort of directional nature to it; also satisfied that whatever it is, it’s very borderline, considering that some owners never (or hardly ever) experience it. Stay tuned.

  • Mike.

Mike,

Your reports are very thoughtful, analytical, and enlightening. I only hope that you are sharing this info with CD so that they can address the problem before SR22 #111 hits the ground!

We all appreciate your efforts.

Greg

If you’ve been following the transponder saga, you know that recently I have had Approach A tell me they’ve lost my transponder (as they slip to the airplane’s 3 or 4 o’clock position), and yet have Approach B (still ahead) see it just fine.

Happened again yesterday, with my home base airport BLM, in site; i.e. I was low, 2,000 feet, when McGuire Approach - at my 3 o’clock - lost my transponder. I requested a 360 and asked them to advise if they picked it up… partway through my turn, when I was headed more or less toward McGuire, they did.

Add to this others’ experiences - so far, I know of two who have had the same thing happen. I am now reasonably satisfied that this problem has some sort of directional nature to it; also satisfied that whatever it is, it’s very borderline, considering that some owners never (or hardly ever) experience it. Stay tuned.

  • Mike.

Mike,

Your reports are very thoughtful, analytical, and enlightening. I only hope that you are sharing this info with CD so that they can address the problem before SR22 #111 hits the ground!

We all appreciate your efforts.

Greg

Greg,

I have indeed been talking with CD; they’ve also concluded that the exhaust pipes may be the problem. They are being very supportive and cooperative (same experience as I’ve had with all issues so far).

The likely culprit is the “hang” of my exhaust pipes; apparently, the top of the ends should be no more than 2 inches from the undersurface of the lower cowling; mine are more like 6 inches away. The theory is that when the pipes are correctly positioned, they don’t disturb the transponder radiation pattern.

CD sent me Service Bulletin 20-78-01 (19 May 2000), applicable to serial numbers 1005 through 1035. The SB describes the procedure for adjusting the tension of the exhaust ball joint flanges correctly. Although N84MR is serial 1118, it would seem that I need to have this done.

I’ll post again after the work has been done and I’ve had a chance to fly in the system a bit more.

  • Mike.