Outside Air Temperature

[GAdams]

My 337D OAT gauge consistently reports the temperature lower than it actually is. Can anyone point me towards a previous thread that deals with this subject? Or can anyone tell me where to start to troubleshoot the problem? The Probe or the Gauge?

[Learjetter]

Relevant pages from non-current G and H model service manual attached. Perhaps they’ll be of some help in determining what the problem is?

—edit: added OAT mechanical gauge page to attachment

[JimC]

The D uses just a basic stick thermometer, right? No electronics?

[GAdams]

Yes just a stick. No electronics. Old school.

[JimC]

I'm not sure that the probe & gauge are separable. There's a bimetallic spring inside. If someone were to remove the cover and overload the spring in one direction, the temperature indicator would probably consistently show several degrees higher in the direction of the overload.

[GAdams]

The documents Learjetter sent me of the maintenance manual appear to be the same system I have. The probe and the gauge are not one in the same. I wish it was.

[JAG]

Anyone else confused?

Learjetter included attachments for two different style OAT:
1) electronic panel mounted (separate Gauge and probe)
2) old style "meat thermometer" one-piece unit that screws through the windscreen.

If you have #2 above, it is indeed one piece unit by design. If it is off by more than 5 degrees, it needs to be replaced with a new one. No adjusting or troubleshooting...it is DOA. New ones available at Aircraft Spruce.

I am not sure how accurate mine is, but I have OAT with my engine monitor and also my Garmin GAD13.

Jeff

[GAdams]

Sorry for the confusion. I have the probe separate from the gauge. The probe is on the left strut brace and of course the gauge is on the panel.