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By helicopterdcr
#1855925
I'm exploring carburettor inlet temperature levels for an O200 engine - I want to make sure that our carb heat installation is working correctly and have installed a thermistor in the inlet spider just downstream of the carb butterfly.

If you have a carb air inlet temperature gauge fitted, what sort of temperatures are you getting on your gauge? The sort of data I want is related to OAT and inlet temperature before and after application of carb heat. If the gauge is only indicating yellow/green or whatever, information on what those arcs represent in terms of temperature would be helpful.

Alternatively you could tell me what sort of temperatures I should be looking for to ensure no icing - maybe that's a better way to think about it.
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By Rob L
#1855973
helicopterdcr:

I've flown behind many small Continentals (A-40 to O-300); most for many hours and have never used a thermistor or other temperature sensor. Mostly because the aircraft doesn't have an electrical system to drive it. I have always relied upon rpm drop upon carb heat application as an indication.

I'm not knocking your purpose; small Continentals are great ice-making machines; I apply carb heat at regular intervals and (touch wood) have never had an issue with carb ice other than the when I have ice: it stumbles & then cleares.

You can't ensure "no icing" in an O-200 that you have, especially in the summer.

I look forward to replies from others.
By Peter Kelly
#1856043
CS-VLA (which is probabaly the modern certification standard that would be used for most O-200 powered aircraft) says:

Each aeroplane with a sea-level engine using a conventional venturi carburetor has a preheater that can provide a heat rise of 50°C with the engine at 75% of maximum continuous power;

The old CAR-3 standard to which many O-200 powered aeroplanes would have been originally certified called for 90°F at 75% power. My experience is that unless the heat boxes and baffles are in absolute tip-top condition this is rarely achieved in a lot of O-200 powered aircraft.
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By MartinC
#1857425
Jodel Continental 0-200 with Westach carb temp gauge marked in degrees C, like this one:
https://www.aircraftspruce.com/pages/in ... irtemp.php

Yellow 'icing risk' arc from -10 /+10 degrees. Adding heat raises temp by at least 10 degrees but not really kept it on to see how much more it would go..... the idea is simply to keep the temp outside the yellow band. Typically I suppose we see temp settling at around +15 without heat outside the yellow arc., obviously higher on warmer days and potentially within the arc during winter. We carry out regular carb heat checks whatever, but more vigilant when in the yellow band. We have never experienced carb icing with this engine in the Jodel, other than when on the ground in wet conditions.
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By Smaragd
FLYER Club Member  FLYER Club Member
#1857502
Emeraude with C-90. I'm guessing a bit at the numbers but will take a closer look on the next flight. Carb temp normally around 10 deg C lower than ambient. Heat adds, as Martin says, at least 10 deg - I think it's significantly more than that. Only had signs of icing once when airborne, but sometimes when taxiing over damp grass.
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