|
Wow. Lots of good design features.
When analyzing designs like this, it's important for me to remember that we
already know exactly what's going to fail. Dozens of guys have discovered the
failures before us. So I just review how your design responds to known failures.
So let's see. Number one most common failure is clogged filter. At least
that's true with canards. Not sure about other aircraft. Oh, oh. Major design
oversight there. You are using design that will allow clogged inlet filter to
affect flow. Fortunately, when that happens, you've done superb job of flagging
the operator. With that large header tank, you'll have tons of advance notice.
Proactive low fuel sensor! Brilliant!
Many times safer to have separate fuel inlet to each facet. Series plumbing
is almost always dramatically more dangerous than parallel. Particularly true
with fuel designs. You should be using automotive filter bag inside tank instead
of inline filter. Way safer. Way.
2nd highest risk historical failure is fuel management oversight. Like you
are flying on wrong tank, running low on fuel and don't know. Wow, have you
handled that right. Overflow from header goes back into mains. So if you leave
facet on too long, no biggie. Fuel level sense and proactive again. Wonderful.
Unporting. Total non risk for you, as you would need to be unported for
around an hour to have problem.
Those are the three most common failures. You've done real well, but should
take further action. Thanks for sharing it!
-al wick
----- Original Message -----
Sent: Wednesday, May 29, 2013 8:32
AM
Subject: [FlyRotary] Re: Intermittent
fuel pressure loss
Thanks Al
I agree on the automotive angle.
Could you comment on design attached for our Glasair SII RG.
Steve
<I'm fabricating our fuel system now
Perfect. Encourage you to follow the same approach that every single
car mfg now uses. In the last decade they have arrived at design that
dramatically reduces all fuel risks. Unporting can't affect flow, vapor lock
risk driven to near zero. No matter how much debris you have, flow is
unaffected. It's just brilliant. You can prove this all by bench
testing.
Unfortunately it's different from traditional airplane approach, so
going to be a long time until it's adopted by planes.
-al wick
----- Original Message -----
Sent: Wednesday, May 29, 2013 7:46
AM
Subject: [FlyRotary] Re: Intermittent fuel
pressure loss
Another example of why I appreciate this list.
Thanks al, I'm fabricating our fuel system now and appreciate the
wise sober advice.
Steve Izett
Perth Western Australia
Hey Bill. A whole bunch of tests you can do without flying. I'd
sure encourage that. Highly unlikely it's a fuel pump unless you
routinely operate them without fuel. As Jeff suggests, fuel is important
pump lubricant, should resist urge to run sys dry.
If you shared pics, it would help. Particularly gascolator, pump,
plumbing.
Since you get consistent good results from turning on second pump,
that points to flow restriction as likely cause. So a good test
would be to undo fitting at engine and pump fuel into bucket. Measure
volume with ruler and stopwatch. Pump 1, pump 2. This will also disprove
pump theory. You could repeat test by disconnecting fuel return line.
This is more severe test as now pump has to achieve 40 psi. Bad pump
would not flow much volume at 40 psi.
Methodically go thru sys looking for debris, kink. Not just
gascolator, but other areas too. It's possible to have gascolator leak
air and lean sys.
For that matter, you may have engine running lean due to intake
leak (other?), 2nd pump adds touch more fuel per injector pulse. Thus
masking true cause. So I'd do the propane test (or other) for intake
leak. Something loosen during flight and allow leak. Poke and push on
components. Review o2 sensor values. By chance do you record these
things during flight? Do you have other data that can prove it was or
was not lean?
Verify each pump has independent grounds, power supply. Verify sys
voltage. Recalibrate fuel pressure sender.
We have natural tendency to say "aha, I bet that's it". Forgetting
that there are some simple tests to prove it. This is important time to
be conservative and methodical.
Good luck.
-al wick
----- Original Message -----
Sent: Monday, May 27, 2013 7:09
AM
Subject: [FlyRotary] Intermittent fuel
pressure loss
Has anyone had an instance of intermittent failure of
the fuel pumps? A
couple of days ago the engine started to
intermittently lose power and
changed tanks. (both tanks were low,
about 5 gal in right and 10 or so in
left) The problem
stopped so I thought I had unported the right tank.
Several minutes
later it started again on the left tank and I turned on the
other
fuel pump. That seemed to stop it again. I still suspected
that I
had unported the tanks.
A couple of days later, I
took off with about 45 gal and after about a 30
min flight, the
engine lost power again twice. I turned the other fuel
pump
on and the problem stopped.
My fuel system goes thru a
Gascolator then to the two pumps, then to a fuel
filter. I
assume that the Gascolator or the fuel filter could be
getting
clogged, but I don't think that the other pump would bring
the pressure back
if that were the case. I only have about 70
flight hours on the pump and
maybe about 100 hours total including
ground runs.
Also on the flight back, I had both pumps on and
showing 40 lbs of pressure.
I then turned the secondary pump off
and the pressure held at 40 lbs. This
strikes me that it is
an intermittent pump failure. I plan to clean the
Gascolator,
replace the fuel filter, and replace the pump.
Any thoughts,
suggestions, experiences?
My wife was with me
on the last incident and I don't think she is interested
in trying
to join Ed's glider club!
Bill
B
--
Homepage: http://www.flyrotary.com/
Archive
and UnSub: http://mail.lancaironline.net:81/lists/flyrotary/List.html
<steve_pastor_esig.jpeg>
Thanks Al
I agree on the automotive angle.
Could you comment on
design attached for our Glasair SII RG.
Steve
On 29/05/2013, at
11:08 PM, Al Wick <alwick@juno.com> wrote:
> <I'm
fabricating our fuel system now
>
> Perfect. Encourage you
to follow the same approach that every single car mfg now uses. In the last
decade they have arrived at design that dramatically reduces all fuel risks.
Unporting can't affect flow, vapor lock risk driven to near zero. No matter
how much debris you have, flow is unaffected. It's just brilliant. You can
prove this all by bench testing.
>
> Unfortunately it's
different from traditional airplane approach, so going to be a long time until
it's adopted by planes.
>
> -al wick
>
>
> ----- Original Message -----
> From: Stephen
Izett
> To: Rotary motors in aircraft
> Sent: Wednesday, May 29,
2013 7:46 AM
> Subject: [FlyRotary] Re: Intermittent fuel pressure
loss
>
> Another example of why I appreciate this list.
>
Thanks al, I'm fabricating our fuel system now and appreciate the wise sober
advice.
> Steve Izett
> Perth Western Australia
> On
29/05/2013, at 9:59 PM, Al Wick <alwick@juno.com> wrote:
>
>> Hey Bill. A whole bunch of tests you can do without flying. I'd
sure encourage that. Highly unlikely it's a fuel pump unless you routinely
operate them without fuel. As Jeff suggests, fuel is important pump lubricant,
should resist urge to run sys dry.
>>
>> If you
shared pics, it would help. Particularly gascolator, pump,
plumbing.
>>
>> Since you get consistent good results
from turning on second pump, that points to flow restriction as likely cause.
So a good test would be to undo fitting at engine and pump fuel into bucket.
Measure volume with ruler and stopwatch. Pump 1, pump 2. This will also
disprove pump theory. You could repeat test by disconnecting fuel return line.
This is more severe test as now pump has to achieve 40 psi. Bad pump would not
flow much volume at 40 psi.
>>
>> Methodically go
thru sys looking for debris, kink. Not just gascolator, but other areas too.
It's possible to have gascolator leak air and lean sys.
>>
>> For that matter, you may have engine running lean due to intake
leak (other?), 2nd pump adds touch more fuel per injector pulse. Thus masking
true cause. So I'd do the propane test (or other) for intake leak. Something
loosen during flight and allow leak. Poke and push on components. Review o2
sensor values. By chance do you record these things during flight? Do you have
other data that can prove it was or was not lean?
>>
>> Verify each pump has independent grounds, power supply. Verify
sys voltage. Recalibrate fuel pressure sender.
>>
>>
We have natural tendency to say "aha, I bet that's it". Forgetting that there
are some simple tests to prove it. This is important time to be conservative
and methodical.
>>
>> Good luck.
>>
>> -al wick
>>
>>
>>
>> ----- Original Message -----
>> From: Bill
Bradburry
>> To: Rotary motors in aircraft
>> Sent: Monday,
May 27, 2013 7:09 AM
>> Subject: [FlyRotary] Intermittent fuel
pressure loss
>>
>> Has anyone had an instance of
intermittent failure of the fuel pumps? A
>> couple of days ago
the engine started to intermittently lose power and
>> changed tanks.
(both tanks were low, about 5 gal in right and 10 or so in
>>
left) The problem stopped so I thought I had unported the right
tank.
>> Several minutes later it started again on the left tank and
I turned on the
>> other fuel pump. That seemed to stop it
again. I still suspected that I
>> had unported the
tanks.
>>
>> A couple of days later, I took off with about
45 gal and after about a 30
>> min flight, the engine lost power
again twice. I turned the other fuel pump
>> on and the problem
stopped.
>>
>> My fuel system goes thru a Gascolator then
to the two pumps, then to a fuel
>> filter. I assume that the
Gascolator or the fuel filter could be getting
>> clogged, but I
don't think that the other pump would bring the pressure back
>> if
that were the case. I only have about 70 flight hours on the pump
and
>> maybe about 100 hours total including ground runs.
>>
>> Also on the flight back, I had both pumps on and showing 40 lbs
of pressure.
>> I then turned the secondary pump off and the pressure
held at 40 lbs. This
>> strikes me that it is an intermittent
pump failure. I plan to clean the
>> Gascolator, replace the
fuel filter, and replace the pump.
>>
>> Any thoughts,
suggestions, experiences?
>>
>> My wife was with me
on the last incident and I don't think she is interested
>> in trying
to join Ed's glider club!
>>
>> Bill B
>>
>>
>> --
>> Homepage:
http://www.flyrotary.com/
>> Archive and UnSub:
http://mail.lancaironline.net:81/lists/flyrotary/List.html
>
>
<steve_pastor_esig.jpeg>
>
>
|