|
Re: N420HP Fuel Selector, Fuel Return, "Fuel
Log"
to: "SEMLOH Aviation Services Corp"
<semlohav@juno.com>
Suggestion:
Regarding the fuel selector and single tank return, an alternate
fix would be to insert a "fuel log" into the return between
the fuel selector and the engine, which gets connected back into the
fuel to the engine after the fuel selector and beofre the fuel pumps.
The "fuel log" is cylindrical and basically acts as a volume
buffer, plus has a 45 micro internal filter (good for the injectors
and water). In this way, your fuel flow sensors (before the fuel
log insertion before the pump after the fuel selector) will only sip
fuel from the tank that it needs to keep the system replenished (no
subtration calculation needed). No fuel is returned to either
tank. This would save on fuel selector replacement and plumbing
upgrade back out to tank. Fuel temperature doesn't cool as much
as when returned to the tank.
http://www.petersonfluidsys.com/fuelfilt.html
Your fuel pump probably sends a nearly constant 35 GPH through
the system, only part of which is used by the engine, the rest being
returned to the tank.
Curiosity: what is your fuel pressure setting?
I know of one airplane LIVP doing this.
Just a thought.
Jeff L
Listers,
Just an update for today.
N420HP completed 2.25 hours of flying
today. We had a slight delay getting going this morning as we
need to replace the Gear Box temp sensor. We had four hops of
just over 40 minutes each and found that we did indeed solve the high
oil temp problem. All other systems are working very well.
Pulled the chip detector from the gear box this evening and showed no
metal at all, at least none to be seen with the naked eye. We
took an oil sample that will go out tomorrow. I shot some really
fun air to air stuff which is about nine minutes long. I have
that down loaded to my computer but have no idea how to get it up
where people can see it, anyone help in that department. The
file is about 23MB. Anyhoo, the engine continues to sing.
One alteration that we are making tomorrow is to install a fuel
selector that has a return to both tanks. This comes about as
the owner had selected one that only had a return to one tank.
Initially this was thought to be ok but we find that the twin fuel
pumps produce much more return than we expected. The left tank
was used up fast as more fuel was being returned to the right tank
than what the engine was using, so basically we were just pumping fuel
to the engine and the right tank. Not a hard problem to fix.
As a note we used a Cirrus SR22 as a chase plane for our testing and
it has worked out well. We have taken the aircraft to 8000 feet
so far and just up to 180KTS IAS. No stall work has even been
considered yet. The owner made his first solo this evening and
that is where my video comes from.
Content-Type: image/pjpeg
Content-Description: air2air420pm 024_0001.jpg
Content-Disposition: attachment; filename="air2air420pm
024_0001.jpg"
Attachment converted: Macintosh HD:air2air420pm 024_0001.jpg
(xxxx/«IC») (000FB08B)
Content-Type: image/pjpeg
Content-Description: air2air420pm 022_0001.jpg
Content-Disposition: attachment; filename="air2air420pm
022_0001.jpg"
Attachment converted: Macintosh HD:air2air420pm 022_0001.jpg
(xxxx/«IC») (000FB08C)
Content-Type: image/pjpeg
Content-Description: air2air420pm 022_0002.jpg
Content-Disposition: attachment; filename="air2air420pm
022_0002.jpg"
Attachment converted: Macintosh HD:air2air420pm 022_0002.jpg
(xxxx/«IC») (000FB08D)
|