The International Cessna^® 170 Association

Hi Guys and Gals,

Proud new pilot/owner of a 48 ragwing here. I searched the forums looking for a similar issue but found almost the opposite as what I'm experiencing so I had to be that newb that starts a new thread. lol

This is my first plane so forgive me if I'm uneducated here but my current center tunnel and footwell gets extremely hot while in use. Cabin Heat Knob on and off! Its to the point where it burnt my ankle and the fuel selector is almost too hot to touch. Again I have no knowledge other than commonsense to make me think that this is something I need to figure out. Super hot and fuel in the area is starting to concern me. I mentioned it during my annual and my AME seemed like it wasn't anything to worry about and said the system was functioning properly, but I was curious if the experts on the board have had similar experiences. After searching the forums it seems most need more heat and I'm trying to find a way to cool mine. lol

Kyle

Hot air flowing when the valve is "closed" is a big freakin' deal. If you develop an exhaust leak you will be unable to stop carbon monoxide getting into the cabin. It needs to be fixed.

Once it's fixed, you will probably still notice that the trim wheel gets warm when the heat is on. The majority of '48s (serials prior to 18574) use a sheet metal duct that runs from the foot vents to the rear seat vent. It is inevitable that it will leak some hot air into the tunnel. In my plane I stuffed some insulation into the duct aft of the foot vents. My trim wheel no longer gets warm and all of the hot air comes out in the front of the cabin. I never have back seat passengers so that's what I prefer.

Also check the entire heat system to damage or leaks. It's kind of a pain to get to, so it is often overlooked. I have seen more than one plane (not just 170s) where a scat tube in a difficult-to-inspect location was completely disconnected.

Kyle,
Congratulations on your "new" 170! I'm impressed that you, as a new owner, are being proactive in resolving this heater issue rather than just taking your AME's word that all is fine. (Burning feet might add to your resolve to get this fixed! ) As this FAASTeam bulletin explains, your aircraft airworthiness is primarily the owner/operator's responsibility.

I agree with Brian as to the critical nature of this valve. That valve needs to work not only to block carbon monoxide but also, in the event of an engine fire, to isolate the flames to the front side of the firewall. Do you have any gap between the heater valve control knob and the instrument panel when the control is fully closed? There should be around an 1/8" space there so that you know the valve is hitting the fully closed position. If the control knob touches the the panel the cable needs to be adjusted. You might also want to remove duct (#2) and visually confirm the flapper valve is shutting completely. I'd also suggest getting a CO detector if you don't already have one.

Thanks fellas,

@gary - the knob has that 1/8-1/4" gap which is good because I thought that might be the problem in thinking it isn't fully closed. I'll have to get in there to see what this flapper valve looks like and figure out if it is working properly.