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Date: Sun, 01 May 2005 23:32:44 -0500
From: Jim Sower <canarder@frontiernet.net>
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To: Rotary motors in aircraft <flyrotary@lancaironline.net>
Subject: Re: [FlyRotary] Re: Ed's new rotor housings
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That would be interesting to delve into.  What is the LG motor rated 
at?  And the CB that tripped?  If the CB was, say, twice the rating of 
the motor, and it still blew (and reset successfully) then I may very 
well have to revisit my premises.  Also if there is evidence that (gawd 
forbid) fuel pumps get hot enough to draw way over their rated current 
and trip breakers while still capable of working.
Let's look into this ... Jim S.

sqpilot@bellsouth.net wrote:

> Hi, Jim....I'm thinking that the landing gear motor is also not a 
> delicate item, but once it overheated, it tripped the circuit breaker. 
> After the motor cooled, the reset circuit breaker allowed the gear to 
> be cycled to the down position.  Can a fuel pump also overheat and 
> trip a breaker or blow a fuse?  I don't know the answer to that 
> question.  Paul Conner
>  
>
>     ----- Original Message -----
>     *From:* Jim Sower <mailto:canarder@frontiernet.net>
>     *To:* Rotary motors in aircraft <mailto:flyrotary@lancaironline.net>
>     *Sent:* Sunday, May 01, 2005 10:46 PM
>     *Subject:* [FlyRotary] Re: Ed's new rotor housings
>
>     I'm not convinced of the utility of Circuit Breakers for flight
>     critical systems.  I would put each of my fuel pumps, the EFIs and
>     what have you on dedicated circuits, each protected with a HEAVY
>     fuse.  My objective is not to protect my fuel pump in case of a
>     surge.  It's a flight critical component, so I'm going to allow it
>     to go while it can.  The fuse is waaaay heavier than the pump (or
>     whatever) draws, and is meant to protect the wire going to the
>     mechanism rather than the mechanism itself.  I do not regard fuel
>     pumps as delicate items, so I don't intend to protect them from
>     transient surges and the like.  I will ride it 'till it drops, and
>     the fuse will blow shortly before the wire melts.
>
>     Delicate avionics I might very well protect with CBs.  These might
>     need to be protected from transient surges/voltage spikes (from
>     whence I cannot say since I have OV protection on my alternator)
>     and the like.
>
>     Heavy duty, robust components like fuel pumps need no such
>     coddling IMO ... Jim S.
>
>
>     WALTER B KERR wrote:
>
>>     John Slade wrote:
>>      
>>     My understanding is that the pumps, at least the ones I'm using
>>     (or at least WAS using when I used to be able to fly this #@#$ing
>>     <mailto:#@#$ing> thing, long ago), are designed to run
>>     continuously. I have one Walbro Inline fuel pump-GSL393 (from
>>     Tracy) and one Walbro Inline fuel pump-GSL394 from Lightning
>>     Motorsports. Both have metal screw in connectors which fit AN
>>     adapters. They're fused at 20 amps.
>>      
>>     ----------------------------------------------------------------------
>>      
>>     OK, I'll stir the pot some more. I am not an electrical engineer,
>>     but I do understand the power of redunancy!
>>      
>>     I will take two separately fused circuits over 1 circuit breaker
>>     every day of the week. If there is a short in my one device or in
>>     the power supply lines, I do not wish to be starting a fire by
>>     resetting circuit breakers while looking for a glider port. I
>>     know there are rotary powered airplanes out there that depend on
>>     one circuit breaker for the entire electrical engine power source
>>     that have many, many more hours of rotary time than me, but I
>>     sleep better have two parallel circuits bringing electrical power
>>     to my fused engine buss and then reduntant pumps on entirely
>>     separate fused circuits. My pumps are both checked during run up
>>     and both on during T/O and landing.
>>      
>>     Bernie
>
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>