REFLECTOR: N173VS RPM

Tue Feb 21 15:29:58 CST 2012

Big smiles here.

You're not supposed to be focusing in on the cylinder temps now.  You're
supposed to be grinning and driving that thing around the airport.  You've
earned it.

The temps will tell you if all the sparklers and squirt guns are working.
If you have a cold cylinder, then you'll need to address it.

If it is stumbling at high RPM then I would look to the mixture.

You have a Lycoming IO-360 200 HP; or it looks like you do.

The servo will control the metered fuel to the cylinders.  Since that would
have to be adjusted at a shop, I would take care of the simple stuff first
and see how many problems are left.

This is just another step along the building path.  Keep working the problem
and you'll get it.

Andy

==========================

Andy Millin

amillin at sbcglobal.net

From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Geoff Gerhardt
Sent: Tuesday, February 21, 2012 12:01 PM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: N173VS RPM

Andy,

Thanks for all the good suggestions.  I'm typically only able to get out to
the hangar on weekends, but its supposed to be in the 50's here this week,
so I'll probably sneak out there a couple evenings this week to check on a
few of the things you've mentioned.

While I have the great Dynon Skyview system that tracks all the engine
parameters, I'm kicking myself now for not taking note of more
temperatures/pressures.  I was so excited to be taxiing around, I was
looking outside to be sure I didn't hit something more than looking at the
panel.  Even when I was just standing still doing the static runup, I was
listening to the engine and adjusting the mixture and things and not paying
enough attention to all the sensor readings other than making sure the oil
temp/press was coming up.  I will probably connect my laptop to the skyview
for the next start and log everything so I can look back on it.

Anyway, there's a number of issues that I need to resolve before I try
again.  

*	I need to figure out why my fuel pressure reading is so low.  I
checked the sensor, and it responds to pressure changes, is getting fuel and
has good grounding.   Oil pressure sensor mounted beside it works fine
(indicating good ground to the block their both mounted on).  My feeling is
that the low pressure is real, but I'm going to connect an analog dial gauge
and check it.  
*	There's still a problem with my LightSpeed EI.  The disable switch
does not work.  Only when I turn power off to the EI unit does it stop
working.  Also, the RPM output from the LightSpeed unit is not working/being
seen by the Dynon Skyview.  I have it connected to the low-voltage Tach
input of the Dynon EMS, but when I switch off the Mag, RPM drops to zero
when only running on EI (the Dynon allows two RPM inputs and should switch
intelligently b/w them).  The EI unit seems to be functioning well and
providing good spark aside from these issues, tho.

Once I resolve these issues, I'll give it another go...

One other thing - when I go to full throttle, the engine starts to sputter
and I need to lean it out (~ half way) to achieve maximum power.  Is that
consistent with a fuel flow problem?

Thanks again for the help.

Geoff

On Tue, Feb 21, 2012 at 9:57 AM, Andy Millin <amillin at sbcglobal.net> wrote:

Geoff,

Congrats on the taxi.  It looked great.

If you are looking for some help on the low static RPM.

You said you were getting low fuel pressure readings.  What fuel flow do you
get?

It looks like you have a Lightspeed EI.  Are you running 1 and 1?  What is
the "mag" check like.  Are both systems firing.

Do you have an engine monitor?  What are the EGTs and CHTs looking like when
running on either ignition system.

How much time have you spent on leaning the engine.  When I started my
engine on the plane, it was running very rich.  The Catto prop is very light
and will not be much of a flywheel.  So, you're keeping the RPM up just to
keep it running.

I have a Prince prop.  It was a challenge to get it to idle below 800 RPM.
It wasn't until Terry Brokaw helped me get the idle settings right that I
could get it to 600 RPM.

Where is your fuel pressure sensor located?

If you are running both the mechanical and electric fuel pumps, there is a
pretty good chance you can make the pressure you need.  The pressure to the
spider will be controlled by the Servo.

If the EGTs and CHTs are in the same ball park for all cylinders, then the
blockage (if any) would be before the spider.  Fuel Filter, Fuel Shutoff
Valve, lines, etc. 

It is also possible your prop is over pitched.  Craig has been known to do
that.

Andy

==========================

Andy Millin

amillin at sbcglobal.net

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