Today's Message Index:
----------------------
1. 03:21 AM - Re: Too high fuel pressure (Hans J. Danielsen)
2. 06:42 AM - Re: Too high fuel pressure (Robert C Harrison)
3. 10:07 AM - Speak (mike gamble)
4. 10:13 AM - Fuel Pressure Indication (Hans J. Danielsen)
5. 11:05 AM - Congrats (mike gamble)
6. 01:27 PM - Re: Fuel Pressure Indication (Robert Borger)
7. 01:41 PM - Re: Fuel Pressure Indication (Bud Yerly)
Message 1
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| Subject: | Re: Too high fuel pressure |
Thank you Jan for your good advice! I'll lokk into the problem on Monday.
Ragards
Hans
----- Original Message -----
From: "Jan de Jong" <jan_de_jong@casema.nl>
Sent: Sunday, October 17, 2010 2:39 AM
Subject: Re: Europa-List: Too high fuel pressure
>
> From your description I would still suspect the return line. Is there a
> 1-way valve in there?
> A way to test it would be to connect the forward line (from the pumps)
> directly to the return line using a T-piece with the differential
> pressure measurement moved to between the 3rd leg of the T and the
> airbox. Run a pump, then both pumps, and see the lowest differential
> pressure the regulator can be expected to provide. If it is over 5 psi
> it is out of Rotax spec and the return line needs repair.
> It could be a very improvised connection - it should only have to deal
> with a gauge pressure of 5 psi.
> On the other hand, with a completely closed return line a pump delivers
> 1.8 bar (26 psi). And both in series 3.6 bar (53 psi).
> In that case you can make it a very short test.
> At zero pressure the pumps are rated to supply 120 l/h. I have heard
> that the pumps tend to get better with use. Maybe the improvement to
> your current 160 l/h is making it apparent that the return line is too
> restrictive.
>
> Regards,
> Jan de Jong
>
>
>
>
>
>
>
>
Message 2
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| Subject: | Too high fuel pressure |
Hi! Hans.
Early Rotax/912 Europa aircraft instructions were to fit a restrictor in the
return line. This was a simple plug with a fine bore hole in it, they even
provided the plug.
I don't know the origin of your aircraft or fuel system but I do know that
this restrictor is not required in the 914 system.
Check out your installation as to if it has the restrictor in it? They were
simply held in place by a jubilee clip clamping it in place. I have heard of
such restrictors just buggering off down the line after the clips have
relaxed.
Check that out too.
Regards
Bob Harrison. G-PTAG
-----Original Message-----
From: owner-europa-list-server@matronics.com
[mailto:owner-europa-list-server@matronics.com] On Behalf Of Hans J.
Danielsen
Sent: 17 October 2010 11:18
Subject: Re: Europa-List: Too high fuel pressure
Thank you Jan for your good advice! I'll lokk into the problem on Monday.
Ragards
Hans
----- Original Message -----
From: "Jan de Jong" <jan_de_jong@casema.nl>
Sent: Sunday, October 17, 2010 2:39 AM
Subject: Re: Europa-List: Too high fuel pressure
>
> From your description I would still suspect the return line. Is there a
> 1-way valve in there?
> A way to test it would be to connect the forward line (from the pumps)
> directly to the return line using a T-piece with the differential
> pressure measurement moved to between the 3rd leg of the T and the
> airbox. Run a pump, then both pumps, and see the lowest differential
> pressure the regulator can be expected to provide. If it is over 5 psi
> it is out of Rotax spec and the return line needs repair.
> It could be a very improvised connection - it should only have to deal
> with a gauge pressure of 5 psi.
> On the other hand, with a completely closed return line a pump delivers
> 1.8 bar (26 psi). And both in series 3.6 bar (53 psi).
> In that case you can make it a very short test.
> At zero pressure the pumps are rated to supply 120 l/h. I have heard
> that the pumps tend to get better with use. Maybe the improvement to
> your current 160 l/h is making it apparent that the return line is too
> restrictive.
>
> Regards,
> Jan de Jong
>
>
>
>
>
>
>
>
Message 3
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Apologies for any irritation. I have been having problems sending text to
the list for the past week. The odd test message gets through but the more
serious/important stuff does not. I have re-registered so maybe I am back in
business.
Mike
G-CFMP
XS mono
Test flying complete. Paperwork with LAA.
Message 4
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| Subject: | Fuel Pressure Indication |
During my studying in order to rectify my too high fuel pressure
indication (which for my 914 installation most probably is caused by a
restriction - one way or another - in the fuel return line), I'm
astonished to (re)learn that there is no requirement from Rotax to
install a fuel pressure instrument.
The Installations Manual states: "There is no standard connection
provided to measure the fuel pressure. For general observation and at
engine troubles fuel pressure readings would be helpful". The text
further describes how to go about fitting of an extra banjo bolt etc.
In other words: It's entirely up to the builder - or to follow local
country requirements - to install such an indicator.
Nevertheless: The Rotax Operations Manual issue a warning (page 2-4)
which says: "Exceeding the max admissible fuel pressure will override
the float valve of the carburetor and to engine failure".
I would say that a check of the pressure would be damned "helpful" in
this respect! Or, how would I know at all of any ill funktion before the
donkey elects to stop over the biggest lake in Norway???
Now, can someone explain to me why the Rotax factory has such an
indifferent approach to this issue in the Installations Manual, while
the Operations Manual "paints the devil on the wall" in pointing out the
dangers. And, there is no follow up whatsoever in procedures or check
lists for high fuel pressure, as with other abnormalities. In other
words: Rotax issue a Warning based on an abnormality you wouldn't stand
a chance to know - if you didn't find it "helpful" to install the
indicator system!
This can't be right!
Hans
LN-HJD, #334
Message 5
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Paul,
After annoying forum access problems - a special, rather delayed, message of
congratulation on your first flight.
I hope we will meet up before long on a doth or other fly in.
Regards
Mike
G-CFMP
Message 6
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| Subject: | Re: Fuel Pressure Indication |
Hans,
Tried to find the documentation from Rotax requiring the installation and use of
the "Fuel/AirBox Differential Pressure Gauge" but can't find it right now.
In any case, Rotax now requires that a gauge and sensor system be installed to
monitor the differential between fuel pressure and airbox pressure to ensure there
is always sufficient fuel pressure to overcome airbox pressure in the carbs
preventing fuel starvation issues. It also allows detection of excess fuel
pressure which can cause the problems you already described.
UMA makes the system. I know that it is available from Aircraft Spruce:
http://www.aircraftspruce.com/catalog/inpages/umafuelairbox.php
And is probably available from other vendors as well.
Good luck in solving your fuel pressure problems. As you previously stated, there
is probably some restriction in your fuel return.
Check six,
Bob Borger
Europa Kit #A221 N914XL, XS Tri-Gear, Intercooled 914, Airmaster C/S Prop
http://www.europaowners.org/forums/gallery2.php?g2_itemId=60232
http://www.biplaneforumgallery.com/index.php?cat=10046
Europa Flying!
3705 Lynchburg Dr.
Corinth, TX 76208
Home: 940-497-2123
Cel: 817-992-1117
On Oct 17, 2010, at 12:10, Hans J. Danielsen wrote:
> During my studying in order to rectify my too high fuel pressure indication (which
for my 914 installation most probably is caused by a restriction - one way
or another - in the fuel return line), I'm astonished to (re)learn that there
is no requirement from Rotax to install a fuel pressure instrument.
>
> The Installations Manual states: "There is no standard connection provided to
measure the fuel pressure. For general observation and at engine troubles fuel
pressure readings would be helpful". The text further describes how to go about
fitting of an extra banjo bolt etc.
>
> In other words: It's entirely up to the builder - or to follow local country
requirements - to install such an indicator.
>
> Nevertheless: The Rotax Operations Manual issue a warning (page 2-4) which says:
"Exceeding the max admissible fuel pressure will override the float valve
of the carburetor and to engine failure".
>
> I would say that a check of the pressure would be damned "helpful" in this respect!
Or, how would I know at all of any ill funktion before the donkey elects
to stop over the biggest lake in Norway???
>
> Now, can someone explain to me why the Rotax factory has such an indifferent
approach to this issue in the Installations Manual, while the Operations Manual
"paints the devil on the wall" in pointing out the dangers. And, there is no
follow up whatsoever in procedures or check lists for high fuel pressure, as
with other abnormalities. In other words: Rotax issue a Warning based on an abnormality
you wouldn't stand a chance to know - if you didn't find it "helpful"
to install the indicator system!
>
> This can't be right!
>
> Hans
> LN-HJD, #334
Message 7
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| Subject: | Re: Fuel Pressure Indication |
Hans,
You are right that they do not have a requirement, spelled out, but it
is implied. Rotax does have parts for it and information is in the new
Rotax installation manual. Copy attached (check currency), page 69.
I follow their instruction requirements very closely. Part numbers are
in the parts catalogue.
UMA does make a pressure differential gauge to measure airbox vs. fuel
pressure. I can do the math so I just use the raw fuel pressure and
manifold pressure.
Explanation: My normal fuel pressure is 4-5psi. When I go to boost I
glance at it to see if the pressure rose IAW the boost.
We know that 29.92 in HG is 14.7 psi so 2 inches of Hg is about 1 psi.
ISH OK.
Example: On takeoff, at a boost pressure of 40 inches, that is 10
inches over atmosphere (that's 5 psi ish) so the fuel pressure must be
above 2.3 ish min plus 5 psi or a min of 7.3 to keep the fuel going to
the carbs to prevent fuel starvation as the operations and installation
manuals state..
If I cruise at a fuel pressure of 5 psi at 30 inches MP at low altitude,
that is OK, if I climb at 34 inches I'm looking for 6 ish and on
takeoff, 8.
I don't cruise at high altitude normally, but as you climb, the outside
pressure decreases and that lowers the fuel pump inlet head a bit, so as
you climb your MP or outside pressure is around 17 inches HG at 15,000
MSL. (Remember, you loose 1 in HG per 1000 or so.) That means outside
air pressure is 8-9 psi or so in round numbers below sea level pressure
of 29.92 inches or 14.7 PSI. If you push the MP above 30 inches then,
the engine may start to see some fuel starvation, so turn on the other
pump when going above 10,000 and you can run max continuous power up to
15000 or so. Above 15,000 I haven't gone, but I imagine that one has to
pay attention. Let's see. MP gauge reads 34 inches at 15,000 feet,
minus 17 is 17 inches HG and that is about 8 psi, so 2.3 plus 8 is 10.3
at the fuel pressure meter... That needs both pumps to do, and it does
it well.
So install a good MP gauge and a descent fuel pressure gauge or buy one
of the UMA differential gauges and press on. I prefer to know my raw
pressure. It is a preference for troubleshooting. When my math skills
go, I'll buy the other gauge I guess.
Hope this wasn't too confusing. Check my math, I am getting older.
Bud Yerly
Custom Flight Creations, Inc.
----- Original Message -----
From: Hans J. Danielsen<mailto:hansjd@online.no>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Sunday, October 17, 2010 1:10 PM
Subject: Europa-List: Fuel Pressure Indication
During my studying in order to rectify my too high fuel pressure
indication (which for my 914 installation most probably is caused by a
restriction - one way or another - in the fuel return line), I'm
astonished to (re)learn that there is no requirement from Rotax to
install a fuel pressure instrument.
The Installations Manual states: "There is no standard connection
provided to measure the fuel pressure. For general observation and at
engine troubles fuel pressure readings would be helpful". The text
further describes how to go about fitting of an extra banjo bolt etc.
In other words: It's entirely up to the builder - or to follow local
country requirements - to install such an indicator.
Nevertheless: The Rotax Operations Manual issue a warning (page 2-4)
which says: "Exceeding the max admissible fuel pressure will override
the float valve of the carburetor and to engine failure".
I would say that a check of the pressure would be damned "helpful" in
this respect! Or, how would I know at all of any ill funktion before the
donkey elects to stop over the biggest lake in Norway???
Now, can someone explain to me why the Rotax factory has such an
indifferent approach to this issue in the Installations Manual, while
the Operations Manual "paints the devil on the wall" in pointing out the
dangers. And, there is no follow up whatsoever in procedures or check
lists for high fuel pressure, as with other abnormalities. In other
words: Rotax issue a Warning based on an abnormality you wouldn't stand
a chance to know - if you didn't find it "helpful" to install the
indicator system!
This can't be right!
Hans
LN-HJD, #334
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