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Carb Heat

ABS Full Member
Posts: 59

Looking at purchasing a 35R Bonanza. A previous A&P removed the carb heat handle many years ago, so there is no way to check carb heat. Current owner says that it is not necessary because of the Pressure Carb. on the E-series engines. I don't think he is right, as I have owned two E-series Bonanzas and each had the carb heat handle. Does the fact that this 35R does not have the carb heat handle essentially make it "unairworthy" ? Thanks John Farrell

Model: Bonanza 35R
Posted 4/10/2019 - 7 months ago
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Replies

ABS Full Member
Posts: 993

Although the pressure carburetor is essentially single-point fuel injection and much less likely to form internal icing than a float-type carburetor, the carburetor heat system is part of the type design and a required airworthiness item unless there is an approved major alteration in the engine logbook. Have the owner or mechanic contact the ABS Technical advisors here or by calling 316-945-1700 with any questions.

Posted 4/11/2019 - 7 months ago
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ABS Full Member
Posts: 230

The main purpose of the "carb heat" hardware is not to provide heat as is required in a float type carburetor but as an alternate engine induction air source should the air cleaner plug from icing or other means. In all of the years I have owned my E powered G-35 I have never pulled the "carb heat" control for operational purposes. The only times I have done so was to gain some data on the affect on MP and perceived HP. If you take a good look at the routing and restriction of the induction air when the alternate air door is open you will see why it is a bad idea to use that system except for providing needed alternate induction air.

I have a section in my book on checking the alternate air door tension (page 137) for beginning of the door opening point so it does not begin to open during the takeoff roll at WOT and high RPM. If the door opens any there is a HP loss resulting as well as unfiltered air being ingested by the engine.

Regards, Lew Gage

Posted 4/19/2019 - 7 months ago
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Carb Heat