We currently have an infuriating intermittent problem with our Trig TT31.
On take off it usually fails to show any squawk at all, but then after about 15 minutes flight, operates normally and completely accurately for mode C readout etc. Then maybe after switching a code it goes u/s again , only to operate normally again after a short while.
We've had two shops look at it only to report "no fault found on test."
Short of renewing the entire installation and unit I've given up hope.
Any bright ideas much appreciated!