PITOT Annunciator panel is always illuminated but pitot probe heat works

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Redkin
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PITOT Annunciator panel is always illuminated but pitot probe heat works

Post by Redkin »

Hello Diamond pilots,
Flying DA40 2003 of my fried. Still believe that I am pretty new to this plane, only about 30 hours flown.
A few days ago during the flight I noticed that when I switch Pitot heat ON the annunciator light does not extinguish. On the ground I turned it ON again and made sure that pitot probe becomes hot. The AMP load also rises. But the light was still there. According to the POH it should die out when the switch is in ON position.
Did anybody of you encounter something like that?

As we fly VFR only normally we don't use it. But now I started my IFR training and that might be a problem when it comes to real IMC (now fly under the hood and it's still kinda warm outside here in Canada).
Curious what might be the problem. Also, am I legal to fly IFR with faulty annunciator if I physically check the probe before each flight and verify it's on by AMP load change?
Thanks in advance!
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Rich
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Re: PITOT Annunciator panel is always illuminated but pitot probe heat works

Post by Rich »

The warning light is triggered by a current sensor that detects the total current to the two pitot heat elements. It could be a problem with the current sensor itself or maybe one of the heating elements or the high-temperature switch to it has failed, so that the current level is insufficient to make the sensor happy, even though the pitot blade is warm.

Note: It is normal for this condition to happen when stationary on the ground, as the temperature sensors will trigger if there is not airflow over the blade.
2002 DA40-180: MT, PowerFlow, 530W/430W, KAP140, ext. baggage, 1090 ES out, 2646 MTOW, 40gal., Surefly, Flightstream 210, Orion 600 LED, XeVision, Aspen E5
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Charles K
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Re: PITOT Annunciator panel is always illuminated but pitot probe heat works

Post by Charles K »

There are two heating elements so if one is out it will cause this due to drawing less current.

Important note - when this happened to me - you do not need a new pitot tube mast - you can get the elements separately and replace one or both of them. Some shops are not aware of this.
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Redkin
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Re: PITOT Annunciator panel is always illuminated but pitot probe heat works

Post by Redkin »

Thanks for your replies. So far I noticed it works intermittently - one day it's fine, another day the light does not disappear. The AMP load always reacts to the pitot switch.
I think I am still safe to fly, probably will show it to mechanic the next time I go there.
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