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CFM56-7B T25 probe question

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CFM56-7B T25 probe question

Old 10th May 2016, 06:03
  #1 (permalink)  
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Join Date: Mar 2007
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CFM56-7B T25 probe question


there has been a number issues of the CFM56-7B having throttle roll backs due to erroneous signals to FADEC due to icing of the T25 probes. I had this discussion with another chap who said that the probe wasn't heated i.e. there is no heating element. It was my understanding that there is and there is a corresponding circuit breaker to match. does anyone have a schematic to show the probe is heated. I do not recall it was heated by engine bleed.

look forward to the responses from the brains trusts!
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Old 7th Jun 2016, 08:36
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Bit late, but are you sure is it T25 problem? This sensor is located btw. booster and high pressure compresor inlet, too hot place for icing IMHO.
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Old 7th Jun 2016, 08:56
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As it's a combined temp/pressure sensor surely heating it would be a problem
here's the URL link.


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Old 7th Jun 2016, 12:16
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Join Date: Mar 2009
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Just checked possible ∆T trough LP section and I am really surprised how low is on idle N1. Table is from 56-3, which is bit different, but with same number of stages. PT25 is used for fuel metering and HPTACC schedule. Presure sensing at this station is optional, for engine trend monitoring only. The temperature for both channels is sensed by heated platinium wires with no extra anti-ice.

Last edited by LEVEL600; 7th Jun 2016 at 12:37.
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