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Message-ID: <4D1934EC.5000607@gmail.com>
Date: Mon, 27 Dec 2010 18:53:00 -0600
From: Dave <david.staten@gmail.com>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Chris - Update needed
References: <list-4655921@logan.com>
In-Reply-To: <list-4655921@logan.com>
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Doug..
     heat soak is a well known problem with aircraft fuel systems, 
especially fuel injected factory opposed piston engines.

     When you shut the engine down, all cooling airflow stops. Heat 
remains. Everything under the cowl heat soaks before gradually cooling 
off. Fuel injection systems usually have fuel returns, so any excess 
pressure due to fuel vaporization in the rail is vented back to the fuel 
tank, so no dangerous overpressure results. The vaporization only occurs 
after shutdown, after cooling airflow ceases to a hot engine, as the 
fuel rail heat soaks due to conduction and radiation.

     The technique I described a few posts ago has worked like a charm 
for me in Bonanzas, Mooneys and Arrows (all fuel injected engines in 
those particular models of airframe).

Dave

On 12/27/2010 3:50 PM, Doug Carter wrote:
> Also remember that when you are starting the engine you are starting 
> it under a load.  This is different then in a car config where in a 
> car you are starting it with no load attached to the crankshaft.  If 
> the fuel rails are getting so hot that they are vaporizing I would 
> think this would cause an excess pressure in the fuel system and be 
> very dangerous.