Today's Message Index:
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1. 07:11 AM - Cont VS Bendix injection systems//auto engine issues (Paul Messinger)
2. 10:46 AM - Re: ND Alternator repair (Steve Sampson)
3. 03:48 PM - Re: Cont VS Bendix injection systems//auto engine issues (George Braly)
Message 1
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| Subject: | Cont VS Bendix injection systems//auto engine issues |
--> AeroElectric-List message posted by: "Paul Messinger" <paulm@olypen.com>
Interesting but I fail to see how the system I had (S-35) COULD do that even
with the hot fuel, is there a real difference to fuel that is in the wings
and heated just from sitting around? Seems either way it can be just as hot
under the right conditions.
The single speed aux pump system I refer to has the same fuel pressure from
the electric pump (as the engine driven pump) that is NOT heated from the
engine.
There apparently can be a problem with either no electric pump or the pump
on LO (what ever that pressure is) during close to the ground ops.
You say the pump on HI did restart the engine so I suggest that if your
system had been designed for full aux pump pressure operation during TO
there would not have been critical Vapor lock (If any at all).
In my opinion the Bendix system would have locked under similar conditions.
Or any system that did not have the aux pump both be able to purge the
system as well as provide sufficent fuel pressure to the engine mounted fuel
pump etc.
Bottom line; with fuel vapor increasing in todays fuel, perhaps some
relooking is needed. Above ground tanks is something I have not considered
as a big concern but I see your point.
Those using todays auto fuel may have problems if the fuel is ever allowed
to be sucked into the pump. The sucking action lowers the pressure and
allows vapor lock.
In fact there have been several accidents in the last year from poorly
designed fuel delivery systems in auto engine conversions. The ones I have
looked into all have a common element, vapor lock due to the design that
allows the pump to suck at the inlet allowing the hi vapor pressure fuel to
vaporize.
The automotive industry solves this problem with intank fuel pumps,
something these auto conversions did not have, nor did they have a header
tank to provide sufficent fuel pressure to prevent pump inlet sucking :-)
Sadly I expect some more accidents, this summer, in experimental auto
conversion powered aircraft from a widely advertised conversion (with a
major fuel delivery system design problem using auto fuel in particular).
But that is a completely different subject and as this one off the lists
purpose.
Thanks for sharing your experience!
Paul
----- Original Message -----
From: "George Braly" <gwbraly@gami.com>
Subject: RE: AeroElectric-List: Re: Cont VS Bendix injection systems
> --> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
>
>
> TCM has a basic system that requires an electric boost pump.
>
> Cessna , Beech and others, at different times have provided either
> single speed boost pumps or two speed boost pumps, depending pretty much
> on which side of the bed some engineer and the FAA got up on the day the
> decision was made.
>
> The two speed pumps are very nice to have and very useful.
>
> I have seen a vapor lock so bad on a normally aspirated IO-550 that took
> off from Bullhead City, Az - - with 100+F new fuel (above ground tanks)
> loaded into the airplane - - that it vapor locked about 120 seconds
> after takeoff.
>
> HARD vapor lock.
>
> LOW boost did not even touch the problem.
>
> It took FULL RICH and HIGH boost to get the engine running again before
> we hit the terrain.
>
> One then current space shuttle mission specialist on board (PIC), me,
> and two teenagers.
>
> It made for some interesting Crew Resource Management.
>
> Regards, George
>
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Paul
> Messinger
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Re: Cont VS Bendix injection systems
>
> --> AeroElectric-List message posted by: "Paul Messinger"
> <paulm@olypen.com>
>
> I think you missed my point.
>
> I agree with much of your comment.
>
> However; My point is that the secret is cooling the mechanical pump with
> cold fuel from the cold electric pump. Something not possible with the
> Bendix system. Fuel from the electric pump is pressurized above vapor
> pressure and does not vaporize at the hot engine pump. Further the cool
> fuel
> is pushed past the pump into the mixture assy where it is also cooled
> and
> exchanged even with the mix control in idle cutoff. Even if there is
> some
> initial vapor produced it is purged back into the tank and is not a
> factor.
> I assume one runs the electric pump long enough to cool things down a
> little. Worked for me at 6,000ft in 110F heat soaked aircraft many times
> when other acft ran the batterys down trying to start.
>
> Once properly cooled enough and considering that need not be much, with
> the
> pressure supplied by the electric pump it eliminates vapor lock during
> the
> critical start. There is always electric pump pressure at the inlet and
> thruout the mech pump and mix assy from the electric pump during its
> operation and thus no possible suction to allow vapor lock at the inlet
> of
> the pump.
>
> I hope you review the Cont system (in the 1971 book) was referring to
> and
> not some later system.
>
> The key to my point is circulation of fuel works and it worked for me
> too
> many times to count and the Bendix system design did not permit this and
> was, in most pilots (I have talked to) experience hard to 'hot' start.
>
> If you have an alternative why there is such a dramatic difference in
> the
> Bendix system VS the Cont system as used in the S35 ( I am specifically
> talking about that system and not other versions) I would be interested.
> I
> found hot starts to be a non event! I have never been able to hot start
> the
> Bendix system with out lots of cranking as one often makes a hot start
> into
> a severely flooded engine start. I have never met a pilot that did not
> have
> problems with the Bendix system and most failed to accept that in the
> S35 it
> could be a non event.
>
> To me as an engineer and mechanic the key is the ability to replace most
> of
> the hot fuel and also cool most of the fuel system prior to any attempt
> to
> crank the engine.
>
> Paul
>
> ----- Original Message -----
> From: "George Braly" <gwbraly@gami.com>
> To: <aeroelectric-list@matronics.com>
> Subject: RE: AeroElectric-List: Re: Cont VS Bendix injection systems
>
>
> > --> AeroElectric-List message posted by: "George Braly"
> <gwbraly@gami.com>
> >
> >
> > Paul,
> >
> > The TCM starting issue has virtually nothing to do with "flushing hot
> > fuel from the system."
> >
> > Rather, it has everything to do with the temperature of the internal
> > components of the mechanical fuel pump that come into contact with new
> > fuel from the tank.
> >
> > If those components are hot enough to flash to vapor a significant
> > portion of the hydrocarbon components of the new incoming fuel stream
> -
> > - then there will be a "bloom" of vapor as the new fuel hits the
> inlet
> > portion of the mechanical fuel pump - - which will then nicely suffer
> a
> > classic vapor lock as the pump inlet "suction" is relieved by the
> bloom
> > of fuel vapor and the pump is no longer able to pull (suck) fuel
> uphill
> > to the inlet of the mechanical pump.
> >
> > It is not helpful to an understanding of the problem to try to deal
> with
> > anything that happens downstream of that point - - as frankly, "HOT"
> > downstream of the mechanical pump is usually helpful to the final
> > result, not harmful.
> >
> > If, during cranking or subsequent operation, a gram of fuel vaporizes
> > in one of the small stainless fuel lines, it is still a gram of fuel
> > that ends up going into the cylinder induction plumbing and eventually
> > into the cylinder and burning just like it would if it were liquid
> when
> > it entered or exited the fuel injector.
> >
> > Regards, George
> >
>
>
> ==
> ==
> ==
> ==
>
>
Message 2
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| Subject: | ND Alternator repair |
--> AeroElectric-List message posted by: "Steve Sampson" <SSampson.SLN21@london.edu>
Bob, interesting that you say failed ND alternators are very rare. Mine is
DOA on arrival from VANS and there is another builder on this list with the
same problem. Now David Chalmers has a problem also. Is it in fact true or
are we justa statistical blip?
Thanks, Steve.
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com]On Behalf Of Robert
L. Nuckolls, III
Subject: Re: AeroElectric-List: ND Alternator repair
--> AeroElectric-List message posted by: "Robert L. Nuckolls, III"
<bob.nuckolls@cox.net>
At 11:07 PM 6/22/2004 -0700, you wrote:
>--> AeroElectric-List message posted by: "David Chalmers"
><David@ChalmersFamily.com>
>
>
>I just removed my failed ND alternator part number 100211-1411. I assume
>the regulator or diodes have failed. Where can I get replacement parts? Is
>this an easy repair or should I take it to a pro? Any advice appreciated.
Achieving the best rework of an alternator assumes you
have the skills, tools and/or the inclination to acquire
them. Given that ND alternator failures are very rare, you
can't depend on your own project offering lots of opportunities
for learning. Further, the price of a new-rebuild from the
car parts stores is so reasonable, it's difficult to justify
a DIY repair for any reason other that academic satisfaction.
Return on investment of time is poor and risks are higher.
However, if working on it yourself is attractive to you,
check for repair parts at http://www.alternatorparts.com
Bob . . .
-----------------------------------------
( Experience and common sense cannot be )
( replaced with policy and procedures. )
( R. L. Nuckolls III )
-----------------------------------------
---
Incoming mail is certified Virus Free.
---
Message 3
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| Subject: | Cont VS Bendix injection systems//auto engine issues |
--> AeroElectric-List message posted by: "George Braly" <gwbraly@gami.com>
Fuel vapor pressure is not increasing in todays 100LL.
That is an old wive's tale.
It is a ASTM D-910 specification - - and all of the aviation gasolines
meet it, with some margin to spare.
Regards, Geoerge
-----Original Message-----
From: owner-aeroelectric-list-server@matronics.com
[mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of Paul
Messinger
Subject: AeroElectric-List: Cont VS Bendix injection systems//auto
engine issues
--> AeroElectric-List message posted by: "Paul Messinger"
<paulm@olypen.com>
Interesting but I fail to see how the system I had (S-35) COULD do that
even
with the hot fuel, is there a real difference to fuel that is in the
wings
and heated just from sitting around? Seems either way it can be just as
hot
under the right conditions.
The single speed aux pump system I refer to has the same fuel pressure
from
the electric pump (as the engine driven pump) that is NOT heated from
the
engine.
There apparently can be a problem with either no electric pump or the
pump
on LO (what ever that pressure is) during close to the ground ops.
You say the pump on HI did restart the engine so I suggest that if your
system had been designed for full aux pump pressure operation during TO
there would not have been critical Vapor lock (If any at all).
In my opinion the Bendix system would have locked under similar
conditions.
Or any system that did not have the aux pump both be able to purge the
system as well as provide sufficent fuel pressure to the engine mounted
fuel
pump etc.
Bottom line; with fuel vapor increasing in todays fuel, perhaps some
relooking is needed. Above ground tanks is something I have not
considered
as a big concern but I see your point.
Those using todays auto fuel may have problems if the fuel is ever
allowed
to be sucked into the pump. The sucking action lowers the pressure and
allows vapor lock.
In fact there have been several accidents in the last year from poorly
designed fuel delivery systems in auto engine conversions. The ones I
have
looked into all have a common element, vapor lock due to the design that
allows the pump to suck at the inlet allowing the hi vapor pressure fuel
to
vaporize.
The automotive industry solves this problem with intank fuel pumps,
something these auto conversions did not have, nor did they have a
header
tank to provide sufficent fuel pressure to prevent pump inlet sucking
:-)
Sadly I expect some more accidents, this summer, in experimental auto
conversion powered aircraft from a widely advertised conversion (with a
major fuel delivery system design problem using auto fuel in
particular).
But that is a completely different subject and as this one off the lists
purpose.
Thanks for sharing your experience!
Paul
----- Original Message -----
From: "George Braly" <gwbraly@gami.com>
Subject: RE: AeroElectric-List: Re: Cont VS Bendix injection systems
> --> AeroElectric-List message posted by: "George Braly"
<gwbraly@gami.com>
>
>
> TCM has a basic system that requires an electric boost pump.
>
> Cessna , Beech and others, at different times have provided either
> single speed boost pumps or two speed boost pumps, depending pretty
much
> on which side of the bed some engineer and the FAA got up on the day
the
> decision was made.
>
> The two speed pumps are very nice to have and very useful.
>
> I have seen a vapor lock so bad on a normally aspirated IO-550 that
took
> off from Bullhead City, Az - - with 100+F new fuel (above ground
tanks)
> loaded into the airplane - - that it vapor locked about 120 seconds
> after takeoff.
>
> HARD vapor lock.
>
> LOW boost did not even touch the problem.
>
> It took FULL RICH and HIGH boost to get the engine running again
before
> we hit the terrain.
>
> One then current space shuttle mission specialist on board (PIC), me,
> and two teenagers.
>
> It made for some interesting Crew Resource Management.
>
> Regards, George
>
>
> -----Original Message-----
> From: owner-aeroelectric-list-server@matronics.com
> [mailto:owner-aeroelectric-list-server@matronics.com] On Behalf Of
Paul
> Messinger
> To: aeroelectric-list@matronics.com
> Subject: Re: AeroElectric-List: Re: Cont VS Bendix injection systems
>
> --> AeroElectric-List message posted by: "Paul Messinger"
> <paulm@olypen.com>
>
> I think you missed my point.
>
> I agree with much of your comment.
>
> However; My point is that the secret is cooling the mechanical pump
with
> cold fuel from the cold electric pump. Something not possible with the
> Bendix system. Fuel from the electric pump is pressurized above vapor
> pressure and does not vaporize at the hot engine pump. Further the
cool
> fuel
> is pushed past the pump into the mixture assy where it is also cooled
> and
> exchanged even with the mix control in idle cutoff. Even if there is
> some
> initial vapor produced it is purged back into the tank and is not a
> factor.
> I assume one runs the electric pump long enough to cool things down a
> little. Worked for me at 6,000ft in 110F heat soaked aircraft many
times
> when other acft ran the batterys down trying to start.
>
> Once properly cooled enough and considering that need not be much,
with
> the
> pressure supplied by the electric pump it eliminates vapor lock during
> the
> critical start. There is always electric pump pressure at the inlet
and
> thruout the mech pump and mix assy from the electric pump during its
> operation and thus no possible suction to allow vapor lock at the
inlet
> of
> the pump.
>
> I hope you review the Cont system (in the 1971 book) was referring to
> and
> not some later system.
>
> The key to my point is circulation of fuel works and it worked for me
> too
> many times to count and the Bendix system design did not permit this
and
> was, in most pilots (I have talked to) experience hard to 'hot' start.
>
> If you have an alternative why there is such a dramatic difference in
> the
> Bendix system VS the Cont system as used in the S35 ( I am
specifically
> talking about that system and not other versions) I would be
interested.
> I
> found hot starts to be a non event! I have never been able to hot
start
> the
> Bendix system with out lots of cranking as one often makes a hot start
> into
> a severely flooded engine start. I have never met a pilot that did not
> have
> problems with the Bendix system and most failed to accept that in the
> S35 it
> could be a non event.
>
> To me as an engineer and mechanic the key is the ability to replace
most
> of
> the hot fuel and also cool most of the fuel system prior to any
attempt
> to
> crank the engine.
>
> Paul
>
> ----- Original Message -----
> From: "George Braly" <gwbraly@gami.com>
> To: <aeroelectric-list@matronics.com>
> Subject: RE: AeroElectric-List: Re: Cont VS Bendix injection systems
>
>
> > --> AeroElectric-List message posted by: "George Braly"
> <gwbraly@gami.com>
> >
> >
> > Paul,
> >
> > The TCM starting issue has virtually nothing to do with "flushing
hot
> > fuel from the system."
> >
> > Rather, it has everything to do with the temperature of the
internal
> > components of the mechanical fuel pump that come into contact with
new
> > fuel from the tank.
> >
> > If those components are hot enough to flash to vapor a significant
> > portion of the hydrocarbon components of the new incoming fuel
stream
> -
> > - then there will be a "bloom" of vapor as the new fuel hits the
> inlet
> > portion of the mechanical fuel pump - - which will then nicely
suffer
> a
> > classic vapor lock as the pump inlet "suction" is relieved by the
> bloom
> > of fuel vapor and the pump is no longer able to pull (suck) fuel
> uphill
> > to the inlet of the mechanical pump.
> >
> > It is not helpful to an understanding of the problem to try to deal
> with
> > anything that happens downstream of that point - - as frankly,
"HOT"
> > downstream of the mechanical pump is usually helpful to the final
> > result, not harmful.
> >
> > If, during cranking or subsequent operation, a gram of fuel
vaporizes
> > in one of the small stainless fuel lines, it is still a gram of
fuel
> > that ends up going into the cylinder induction plumbing and
eventually
> > into the cylinder and burning just like it would if it were liquid
> when
> > it entered or exited the fuel injector.
> >
> > Regards, George
> >
>
>
> ==
> ==
> ==
> ==
>
>
==
==
==
==
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