Date: Sun, 07 Mar 2004 22:53:20 -0600
From: Perry Casson <pcasson@sasktel.net>
Subject: Re: [FlyRotary] Re: Cooling System Dynamics
In-reply-to: <list-3068225@logan.com>
To: Rotary motors in aircraft <flyrotary@lancaironline.net>
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Hi All,

I had a bit of excitment today that was cooling system related.  Flew 
this AM for about 1.4 hours (6.5 hours total) with no problems and was 
delighted to see I'd finally got the heavy left wing resolved.  This 
afternoon under a warm spring sun I took off, had just climbed to 4500' 
and found it was actually warm enough to turn the cab heat off for the 
first time this year.  About 10 seconds after turning off the flow of 
coolant to my heater core I could smell something and a slight white 
smoke came up from under panel.  Pulled the power back, radioed the 
tower I could smell something and headed back to the circuit.  Smell and 
smoke appear to have cleared  while decending and I made a normal 
landing with the emergency trucks there to greet me at the taxi way.  
When I got to the hangar I first started to look under the panel for 
something that was heat damaged but everything looked fine so I removed 
the cowl and really could not see much wrong there either untill I 
noticed a bit of moisture on the overflow line from the coolant 
expansion tank.

So what I think happened is, turning off the flow to the heater core 
caused a pressure increase in cooling system which burped a bit of extra 
coolant into the expansion tank which was enough to cause it to overflow 
the tank which had a too short of hose on it so it dripped a bit of 
coolant on the header pipes which caused the smoke.  Before I fly again 
I'm going to switch over to the pressurized recovery tank and move the 
location over to the cool side of the engine as I prefer not seeing 
trucks with flashing lights waiting for me to land.

Perry Casson