Bill Schertz
KIS Cruiser # 4045

----- Original Message -----

= From: Finn Lassen

Sent: 5/27/200= 4 7:36:59 AM

To: flyrotary@lancaironline=2Enet

Subject: [FlyRotary] Re: Fuel Pump Desig= n

2nd fuel filter should be before the T ?

If this is a low wing aircraft, you do NOT want direct connection between left and right tanks: you could be sucking air when one wing is lower than the other (with no fuel)=2E Not an issue if the common pickup point is substantially lower then the lowest point of each tank, as in a high wing aircraft=2E

Finn

Bob Perkinson wrote:

The attached drawing is my idea of a simple fuel system for the 9a that I am building, with Aux fuel tanks akin to Berne Kerr=92s Project=2E I would like some feed back as to what problems this arrangement might pose, and what the remedy would be for such problems=2E The plan is to use large diameter pipe between the main fuel tanks so as to allow the fuel to equalize

Bob Perkinson=2E=

-----Original Message-----
From: Rotary motors in aircraft [mailto:flyrotary@lancaironline=2Enet]On Behalf Of= Mark Steitle
Sent: Tuesday, May 25, 2004 3:06 PM
To: Rotary motors in aircraft
Subject: [FlyRotary] Fuel Pump Design

Fuel system design hasn't come up in quite a while=2E But since a large portion of accidents are fuel related, I thought this would be worthy of discussion=2E

I have experienced a failure mode during ground runs on my Lancair ES with 20B that seems to be a problem with other types of installations as well=2E I recently read a first flight report by a professional test pilot, David Allen, that almost had to set a Lancair ES, N711RG, down on I-70 due to the inability to restart the engine after running a tank dry=2E (See www=2Ege= ocities=2Ecom/daveandjj for the full story=2E) This was a certified fuel-injected engine installation=2E Also, the Subaru guys (I have been lurking on the Eggenfelder Subie site today) had a similar situation, resulting in some glider time and a dead-stick landing=2E

The problem is that after exhausting the fuel in one tank an airlock forms between the fuel pump(s) and the fuel pressure regulator that the efi pump cannot overcome due to lack of fuel in the supply line=2E This is what I have experienced with my installation on ground runs=2E I can't get the efi pumps to re-prime unless I momentarily break a line loose between the pump outlet and the pressure regulator=2E As soon as I do that the pump will re-prime and all is well=2E

For the record, I have two of Tracy's efi pumps, with two efi filters, hooked in parallel=2E They are mounted low on the fire wall=2E Upstream is a gascolator and an Andair 6-port selector valve=2E Downstream of the pumps/filters is a map sensing pressure regulator=2E There is a -6AN going to the fuel rail, and a -4 return line back to the Andair valve/tank=2E

I was curious if anyone else has had this happen and what they did to resolve the issue=2E I have come up with two possible solutions=2E

1=2E Tee off the pump output and put an electric solenoid valve in the line and tee the outlet of the solenoid to the fuel return line, past the regulator=2E Push-button switch on panel would activate the solenoid=2E If needed, a second or two of activation should relieve the air-lock and allow the pumps to re-prime=2E

2=2E Install a bleed line around the pressure regulator with a small metering orifice (=2E020-=2E030") that would bleed off any air that might get trapped=2E (This appears to be the solution the Subaru group is focusing on)=2E This would be a full time bypass=2E This seems to be the simpler solution=2E

3=2E Install a low pressure, high volume fuel pump in one, or both, of the wing tanks=2E Procedure would be to always keep reserve fuel in this tank=2E

Any comments from seasoned flyers would be welcomed=2E

Mark S=2E

Homepage: http://www=2Eflyrotary=2Eco= m/ Archive: http://lancaironline=2Ene= t/lists/flyrotary/List=2Ehtml

------=_NextPart_84815C5ABAF209EF376268C8 Content-type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable A second problem where the tanks are connected together as shown is that as = fuel is removed and returned to the tank(s) the fuel flow back to the tanks may s= urprise you as to where it goes=2E It is very difficult to get it to feed equally fr= om both tanks, and return equally to both tanks=2E any difference in pressure drop d= ue to vagaries of plumbing can cause one of the tanks to preferentially lose fuel,= and the other to fill enough to overflow, and if I understand your drawing corre= ctly, there is no way to force the fuel to come from a *specific* tank, therefore = if one draws down sufficiently, you will suck air and have a fuel starvation incide= nt with gas on board=2E =20 Bill Schertz KIS Cruiser # 4045=20 ----- Original Message ----- From: Finn Lassen Sent: 5/27/2004 7:36:59 AM To= : flyrotary@lancaironline=2Enet Subject: [FlyRotary] Re: Fuel Pump Design=20 2nd fuel filter should be before the T ? If this is a low wing aircraft, you do NOT want direct connection between left and right tanks: you could be sucking air when one wing is lower than the other (with no fuel)=2E Not an issue if the common pickup point is substantially lower then the lowest point of each tank, as in a high wing aircraft=2E Finn Bob Perkinson wrote: =09The attached drawing is my idea of a simple fuel system for the 9a that I am building, with Aux fuel tanks akin to Berne Kerr=92s Project=2E I would like some feed back as to what problems this arrangement might pose, and what the remedy would be for such problems=2E The plan is to use large diameter pipe between the main fuel tanks so as to allow the fuel to equalize=20 =09Bob Perkinson =2E -----Original Message----- From: Rotary motors in aircraft [ [mailto:flyrotary@lancaironline=2Enet] mailto:flyrotary@lancaironline=2Enet= ] On Behalf Of Mark Steitle Sent: Tuesday, May 25, 2004 3:06 PM To: Rotary motors in aircraft Subject: [FlyRotary] Fuel Pump Design Fuel system design hasn't come up in quite a while=2E But since a large portion of accidents are fuel related, I thought this would be worthy of discussion=2E I have experienced a failure mode during ground runs on my Lancair ES with 20B that seems to be a problem with other types of installations as well=2E I recently read a first flight report by a professional test pilot, David Allen, that almost had to set a Lancair ES, N711RG, down on I-70 due to the inability to restart the engine after running a tank dry=2E (See [http://www=2Egeocities=2Ecom/daveandjj]www=2Egeocities=2Ecom/d= aveandjj for the full story=2E) This was a certified fuel-injected engine installation=2E Also, the Subaru guys (I have been lurking on the Eggenfelder Subie site today) had a similar situation, resulting in some glider time and a dead-stick landing=2E=20 The problem is that after exhausting the fuel in one tank an airlock forms between the fuel pump(s) and the fuel pressure regulator that the efi pump cannot overcome due to lack of fuel in the supply line=2E This is what I have experienced with my installation on ground runs=2E I can't get the efi pumps to re-prime unless I momentarily break a line loose between the pump outlet and the pressure regulator=2E As soon as I do that the pump will re-prime and all is well=2E=20 For the record, I have two of Tracy's efi pumps, with two efi filters, hooked in parallel=2E They are mounted low on the fire wall=2E Upstream is a gascolator and an Andair 6-port selector valve=2E Downstream of the pumps/filters is a map sensing pressure regulator=2E There is a -6AN going to the fuel rail, and a -4 return line back to the Andair valve/tank=2E I was curious if anyone else has had this happen and what they did to resolve the issue=2E I have come up with two possible solutions=2E=20 1=2E Tee off the pump output and put an electric solenoid valve in the line and tee the outlet of the solenoid to the fuel return line, past the regulator=2E Push-button switch on panel would activate the solenoid=2E If needed, a second or two of activation should relieve the air-lock and allow the pumps to re-prime=2E 2=2E Install a bleed line around the pressure regulator with a small metering orifice (=2E020-=2E030") that would bleed off any air that might get trapped=2E (This appears to be the solution the Subaru group is focusing on)=2E This would be a full time bypass=2E This seems to be the simpler solution=2E 3=2E Install a low pressure, high volume fuel pump in one, or both, of the wing tanks=2E Procedure would be to always keep reserve fuel in this tank=2E=20 Any comments from seasoned flyers would be welcomed=2E Mark S=2E=20 ----------------------------------------------------------------------------= ---- ----------------------------------------------------------------------------= ---- Homepage: [http://www=2Eflyrotary=2Ecom/]http://www=2Eflyrotary=2Ecom/ Arch= ive: [http://lancaironline=2Enet/lists/flyrotary/List=2Ehtml]http://lancair= online=2Enet/lists/flyrotary/List=2Ehtml ------=_NextPart_84815C5ABAF209EF376268C8--