Carb Ht or Alt air

[Doug Johnson]

Induction air

While going through FAA files I ran into the basic changes Helio was making in the H-391B to H-395 model.



Something that caught my eye was the reference to a change from “alternate air to Heated air” in the induction system. My Helio was an H-295 when I renewed the markings on my panel, I had a knob marked carb heat but I already knew it was different from comparing it to my carburetted Cessna there was no scoop on the manifold to direct heated air into the carb, it just had a flap that closed the outside ram air and allowed warm air from inside the cowling to enter the carb much like my fuel injected Cessna . I remarked my helio “Alternate air/Carb heat”.

I also had an extra heat muff on the left side but didn't know why. My intent was to use this muff as cabin heatt to the rear seat. I didn't know that the 1400 series Helios did have a duct to the rear seat although they don't use an exta heat muff.

I have since seen a mod where the muff on the left exhaust pipe is used for auxillary heat it is referred to as the heat muff provided for the Rajay turbocharger installation. But I just figured out in the parts book that this muff was originally for carb heat on the H-395. 

I suspect most H-395's no longer use this carb heat muff and has probably been removed, Also the conversion from 395 to 295 air induction look mostly like converting from carb heat to alternate air by removing the extra air filter and ducting.

H-395/U-10B


H-295/U-10D


Back seat heat was discussed here as well           http://flyhelio.com/smf/index.php?topic=343.msg1605#msg1605

The last thumbnail is a 337.pdf that you can download.

Doug