Using the following part number from Spruce: W31X2M1G10 .  Have been using these for 30+ hours to date.

These bi-metallic single pole breakers weigh less than 2 oz. and are especially suitable for homebuilt aircraft. Used as original equipment in Beech, Cessna and Piper aircraft. Maximum operating voltages: 32 VDC and 250 VAC (to 400 Hz).

Toggle Thermal Circuit Breaker
• 0.5 amp to 50 amp ratings may be used as on/off switch.
• Cannot be reset against overload.
• Screw termination.
• Trip-free operation.

… will double-check my pumps but don’t recall seeing “20 Amp fuse” anywhere on them.

 

Jeff

 

From: Charlie England <flyrotary@lancaironline.net> Subject: Re: [FlyRotary] Re: Fuel Pump and Regulator Date: Fri, 17 Mar 2017 07:40:16 -0500 To: Rotary motors in aircraft <flyrotary@lancaironline.net>

As Andrew says, my Walbro GSL393 pumps (from Tracy, before he retired) say '20 Amp Fuse' right on the pump. If you don't already know this, an automotive blade fuse is a relatively fast blow device; it will blow at the slightest provocation. 'Aircraft quality' circuit breakers, on the other hand, are basically 'extremely slow blow' devices. They can take seconds to trip, unless the overload is extreme. The nature of blade fuses is probably why Walbro specs 20 amp fuses; the load on the positive displacement pump is going to be changing constantly with injectors opening/closing, fuel lines expanding/contracting, mechanical regulator opening/closing, etc. If you're using a different pump, the equation might change. I've got some little in-tank turbine pumps I'm playing with that only draw about 6 amps at full load. BTW, there's a recent thread on the VAF forum about electrical architecture surrounding the new (to Lyc drivers) automotive style injection, where one of the really smart contributors, who's done both Lyc and alt engine installs, makes the case that 'switchology' would be safer it it's as close as possible to conventional a/c techniques. He advocates that the primary pump have protection, but come up with the engine controller automatically, and only the backup pump get a separate switch. (Different subject; may start a new thread...) Charlie

 

 

From: Jeff Whaley
Sent: Friday, March 17, 2017 8:11 AM
To: 'Rotary motors in aircraft'
Subject: Re: [FlyRotary] Fuel Pump and Regulator

 

Steve, I have two pumps in parallel - one pump usually indicates 35-36psi, when the second pump is on about 40 psi.

Both umps use 10 amp switched breakers.

Jeff

 

Jeff Whaley
Manager, Test and Repair

International Datacasting Corp.

Tele: 613-596-4120 (ext: 2295)
www.datacast.com

 

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