I've got a FlightDek 180 in my RV7 that's been flying for 10 years. I regularly get a minus number reading on one CHT when at low throttle openings (the other three cylinders are normal). I've replaced the probe but it hasn't made any difference. This sometimes happens with EGTs but changing a probe usually fixes it. Any ideas? It's not flight critical but annoying to have to keep cancelling a low CHT warning.
Flightdek 180 CHT odd reading
- Thread starter Coling955
- Start date
jakej
Well-Known Member
A minus number eg -99 indicates a disconnect somewhere & maybe at the D25 end - when installing the thermocouples/wires I usually
Remove the backshell & the blackheatshrink near it
Carefully bend the harness to the shape needed when it's installed so the pins do not retract back from the fully home position
(note - if you hold the dsub connector, close your other hand around the loom, & wiggle the loom at that end while looking at the end tip of the pins - you'll then see them moving in/out & in come case will actually be recessed far enough to cause a disconnect - try it & you'll see they move like pistons) the egt/cht wires are much stiffer than standard wiring & the movement of the harness can/will result in disconnects.
After the harness is bent (especially the ones further out from the center of the D25) to the shape of it's final resting place you should then use lacing cord to better 'hold' the wiring in place. Then use self amalgamating tap for where the backshell clamps around the harness.
FWIW - I also use electrical contact cleaner on those connectors & at the probe end. No worries
Remove the backshell & the blackheatshrink near it
Carefully bend the harness to the shape needed when it's installed so the pins do not retract back from the fully home position
(note - if you hold the dsub connector, close your other hand around the loom, & wiggle the loom at that end while looking at the end tip of the pins - you'll then see them moving in/out & in come case will actually be recessed far enough to cause a disconnect - try it & you'll see they move like pistons) the egt/cht wires are much stiffer than standard wiring & the movement of the harness can/will result in disconnects.
After the harness is bent (especially the ones further out from the center of the D25) to the shape of it's final resting place you should then use lacing cord to better 'hold' the wiring in place. Then use self amalgamating tap for where the backshell clamps around the harness.
FWIW - I also use electrical contact cleaner on those connectors & at the probe end. No worries
Many thanks Jake. I'm on it.A minus number eg -99 indicates a disconnect somewhere & maybe at the D25 end - when installing the thermocouples/wires I usually
Remove the backshell & the blackheatshrink near it
Carefully bend the harness to the shape needed when it's installed so the pins do not retract back from the fully home position
(note - if you hold the dsub connector, close your other hand around the loom, & wiggle the loom at that end while looking at the end tip of the pins - you'll then see them moving in/out & in come case will actually be recessed far enough to cause a disconnect - try it & you'll see they move like pistons) the egt/cht wires are much stiffer than standard wiring & the movement of the harness can/will result in disconnects.
After the harness is bent (especially the ones further out from the center of the D25) to the shape of it's final resting place you should then use lacing cord to better 'hold' the wiring in place. Then use self amalgamating tap for where the backshell clamps around the harness.
FWIW - I also use electrical contact cleaner on those connectors & at the probe end. No worries