Paul A. Franz, P.E.
Joined: 02 Dec 2008
Posts: 280
Location: Bellevue WA
|
 Posted: Tue Mar 31, 2009 3:46 pm Post subject: 912 Fuel pump required |
 |
|
On Tue, March 31, 2009 1:35 pm, Roger Lee wrote:
clippage: clip clip
| Quote: | There should be no pressure regulator on the 912. You should
how ever be at least using the Rotax manual operated pump on the side of the gearbox.
It supplies the correct pressure to the carbs. (2.2 - 5.8 psi). Just a gravity fed
system would have to be tested for delivered pressure, but I would bet it is too low
and because of that during certain flight maneuvers starve the carbs.
|
If 2.2 PSIG is the minimum fuel pressure required, then that requires 81 inches of
static head of gasoline. Our fuel tanks aren't 7 feet above the carbs so that rules
out gravity feed by itself.
| Quote: | If you have a
low feeding tank then a back up Facet fuel pump rated at the proper psi should be
plumbed in parallel as a back up.
|
OK, but then you'd need check valves if the pumps failed open. Maybe you meant to say
configure the fuel pumps in series, rather than parallel.
| Quote: | The manual fuel pump was installed for a reason
|
You say manual but I think you mean "engine driven". I'm not aware of a manual pump on
my Rotax 914. I do certainly have manual pumps on my Caterpillar C-15's though and all
my other Diesel Engines too, for that matter.
| Quote: | and
should not be removed. My FD CT is a high wing and could operate off a gravity feed,
but it should not.
|
What's an "FD CT"? Is that a 912/914 configuration?
| Quote: | When the pump fails it fails open. Plus you are supposed to have a
recirculating line to help prevent vapor lock. The fuel pump is in the system to help
circulate the fuel.
|
You've really got me confused now. If the engine driven pump fails open, a backup
should be placed in series unless there is a check valve. I am not aware of any
recirculation on non-fuel injected engines. And I don't mean throttle body injectors
either.
I'd like to see a flow diagram of what you're talking about. I was going to have an
electric pump in the line which would be used for take-off and landing only. It would
be in series with the existing engine driven pump. I don't see any anything that looks
like a recirculation fuel line on my 914 but I haven't figured out how it all works
yet either. I assume, I'll find this all in the maintenance and service manuals.
--
Paul A. Franz
Registration/Aircraft - N14UW/Merlin GT
Engine/Prop - Rotax 914/NSI CAP
Bellevue WA
425.241.1618 Cell
All bad precedents began as justifiable measures.
-- Gaius Julius Caesar, quoted in "The Conspiracy of
Catiline", by Sallust
Cutting the space budget really restores my faith in humanity. It
eliminates dreams, goals, and ideals and lets us get straight to the
business of hate, debauchery, and self-annihilation."
-- Johnny Hart
Has the great art and mystery of politics no apparent utility? Does it
appear to be unqualifiedly ratty, raffish, sordid, obscene and low down,
and its salient virtuosi a gang of umitigated scoundrels? Then let us
not forget its high capacity to soothe and tickel the midriff, its
incomparable services as a maker of entertainment.
-- H.L. Mencken, "A Carnival of Buncombe"
The avoidance of taxes is the only intellectual pursuit that carries any
reward.
-- John Maynard Keynes
With reasonable men I will reason;
with humane men I will plead;
but to tyrants I will give no quarter.
-- William Lloyd Garrison
| | - The Matronics Kitfox-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?Kitfox-List |
|
_________________
Paul A. Franz, P.E.
Registration/Aircraft - N14UW/Merlin GT
Engine/Prop - Rotax 914/NSI CAP
Bellevue WA
425.241.1618 Cell
425.440.9505 Office |
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
