Building Tips
Got a sure fire-way to tackle one of those "challenging" tasks on
your project or flying RV? Drop us a note and we'll post it here.
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Pitot-static
line installation (Doug Weiler)
I am finally to
one of the more enjoyable (but challenging) parts of my RV-7
project: the instrument panel. Finally it seems here things begin
to come together and all of that planning and dreaming of a panel
full of goodies starts to take shape. Recently I had SteinAir cut
out my panel and now I was able to start to put some of the cool
electronic doo-dads in place at least temporarily.
After getting some of the preliminaries of the electrical system
laid out, I thought now would be a good time to get the
pitot-static lines hooked up to the various EFIS boxes and
instruments. SteinAir sells those intriguing plastic air lines and
fittings, which seemed like a vastly improved method of installing
the pitot static system. Yes, I could be an “old
school” guy like my mentor Tom Berge and install a system of
aluminum tubing and AN fittings. But my skill level in cutting and
bending aluminum tubing is sub-standard and the plastic air lines
seemed cutting edge and MUCH quicker.
My panel requires pitot inputs to one AFS EFIS box, the Tru Trak
autopilot controller, the standby airspeed, and the Tru Trak ADI-2
standby attitude indicator. I also need to provide static inputs to
the all of these items plus the standby altimeter. So lots of
branching of the lines was needed.
I sat down and selected all the air fittings that would work
including:
several T fittings,
a Y fitting,
a three-port manifold fitting,
and several straight connectors that comprise a ¼” NPT
fitting that screws into the back of the instruments.
I installed the straight connectors first and everything went well.
Tom Berge warned to be sure to wrap additional Teflon tape around
the threads to provide additional sealing capability. Screwing
these fittings to the brass receptacles of the AFS EFIS box and the
UMA standby instruments was no problem.
But the both the Tru Trak autopilot controller and the ADI-2 have
plastic fitting receptacles which just didn’t seem to tighten
up very well. And just to prove how incompetent I am, I twisted the
pitot fitting into the ADI-2 just a little too far and it
CRACKED!!! UGH!! How could I be so dumb??? I quickly took it out of
the panel, boxed it all up and sent it off to Tru Trak to get it
fixed.
With that screw-up behind me, I throttled-back and looked at this
differently and decided to approach the pitot-static installation
in a more logical manner. Tom B and I had heard of several RVs
nearly ready to fly with big-time pitot static leaks. Once the
airplane is all together it is REAL hard to find out where the leak
is. THUS… I decided I was going to check the system as I
assembled it. I highly suggest checking all of the integrity of the
system right at the panel while everything is wide open.
So first you need a source of pressure and suction. Nothing works
better than a BIG syringe hooked up to plastic tubing. Mine was a
leftover from a TCP fuel additive kit that I bought long ago and
worked perfect.
The P501 connectors installed into the Tru Trak autopilot
controller with Tite Seal
So basically I just checked the fittings into each of the
instruments once by one and then the integrity of the system as I
added various lines and connectors. One BIG tip that Stein helped
be with was how to install the P-501 into the plastic receptacle
blocks on the Tru Trak instruments: wrap a couple layers of Teflon
tape around the fitting and then a thin “smear” of Tite
Seal. Tighten the fitting into the block up to about a 1/16”
of reaching the flange of the fitting. There should be a nice
shoulder of Tite Seal around the fitting flange. That’s
it…. Don’t let the fitting bottom out or you may hear
the discourage “crack’!
After getting everything all hooked up (still not the permanent
installation), I did a static leak test and everything was rock
solid:
Now you have determined the integrity of the pitot static system
behind the instrument panel. Now when you do the final assembly of
your airplane you can hook up the wing pitot line and the fuselage
static lines with confidence that any leaks that then show up will
be outside of the panel.
The end product will route the green pitot lines and the white
static lines to the various instruments on the
panel.
RV
Fuel Tank Repair
Hello to all! My name is Paul Beck, and I have been working as an
A&P mechanic for Willmar Air Service for 15 years now. We work
primarily on the Mooney fleet of aircraft. As some or most of you
know, Mooney's are famous for leaking fuel tanks! My former
employer here in Willmar and I knew something had to be done to
address the problem as it was compromising the value of the Mooney
fleet.
During the last 9 years, with the help from my former employer,
Bruce Jaeger, we developed a system of removing all the poly
sulfide sealer from inside the fuel tanks, without the nasty task
of having to hand scrape it out! The result of this process is a
truly clean tank, ready to accept new sealer. I personally have
completed around 300 Mooney aircraft, one Vultee BT-13, and one
Thrush crop sprayer this way. I also have developed a process for
the Piper fleet of aircraft with removable aluminum fuel tanks. I
am currently looking into working with the Grumman fleet that also
incorporate the wet wing style of fuel tank.
I had the opportunity on Tuesday, March 23rd, 2010 to isolate and
repair a leak on Mark Kenworthy's RV-9A. The construction of tanks
on the RV aircraft are very similar to the Piper and somewhat the
Mooney tanks. Talking with Mark I developed a real interest in the
aircraft and especially the fuel tanks. I could see a real value in
assisting owners of the RV's in finding leaks or constructing new
tanks for their planes, should they choose not to.
So that's my ideas! If any one needs help or knows anyone I could
call to get into helping assemble the tanks for new owners, I would
greatly appreciate it!
You can see a brief article on what I do at www.willmarairservice.com and click on fuel tank repair.
Paul Beck
Weep No More
Willmar Air Service
Cell-320-295-1671
Work- 320-235-4844
Personal email-vair73@yahoo.com
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Alex Peterson’s Tire Balancer
My
plane has always had a little vibration around 22 to 24 knots. This
has been true with several sets of tires, from Van's cheapies to
Michelin to my current favorite, retreads from Desser. I've never
worried too much about it, since that speed is a bit faster than
typical taxi speeds, and during takeoff and landing, one passes
through those speeds fairly quickly. However, after the last
annual, during which I rotated the tires inside to out, the
vibration showed up a fair bit more noticeable. In fact, it was
quite noticeable right after landing as well, probably picking up
the 2x excitation speed of 46 knots.
I built the balancer shown in the pictures below. I used a couple
very small ball bearings for minimal friction, a precision 1.25"
shaft, and a couple collars to clamp the wheel bearings snugly. I
put the first wheel on, and it lazily found a preferred position.
It didn't seem like a lot of imbalance, but it took a fairly
sizable piece of lead (don't tell California) to bring it to
balance (the small wheel diameter). The other wheel took a piece
perhaps 1/4 the size of the one in the picture. I used some 3m
double sticky pads to attach the lead.
I went out flying, with some taxiing up to 28 knots, and no
vibration at all! On landing, I held the speed up down the runway,
exploring the whole range of speeds, and not the slightest sign of
any vibration.
What was quite a surprise is how little imbalance there seemed to
be when I first put the wheel on the balancer. I really would not
have thought it to be a problem, until I saw how much lead it
took.
The small bearings, without seals, are key, as anything larger
probably would have had too much friction.
__________________
Alex Peterson
RV6A N66AP 1100+ hours
Maple Grove, MN
www.n66ap.alexap.com
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Tom
Berge's Tire Removal Contraption
So, it’s
time to replace your tires. Sounds simple, doesn’t it? First,
let the air out. Very important! Second, loosen the three bolts
holding the wheel halves together. Then take out the bolts and set
the brake disc aside. Third, pull the wheel halves away from the
tire…….wait a minute. This part just took all the fun
out of a simple process. The darn tires are stuck to the wheels.
Seems nothing will pry them free without damaging the wheel halves.
Put the hammer and pry bar, a.k.a. screw driver away.
After years of struggling with the dreaded tire removal job, I
finally decided that a simple, cheap solution could be had. I know
there are tools you can buy to do the task, but why spend lots of
money for something that is done so infrequently? So here
goes.
One 5/8 threaded rod / 12” - $3.29
Two 5/8 fender washers - $.45 each
Two 5/8 nuts - $.45 each
24” 2 x 4 – Free in most workshops
30” 1 x 4 – Free in most workshops
Couple of adjustable wrenches – Better be in your workshop
already!
1. Cut the 2 x 4 to about 10 inches and drill a ¾ inch hole in the
middle. Need two.
2. Cut the 1 x 4 to about 7 or 8 inches long and cut a curve on the
side a bit bigger than the wheel. I used the hub cap that came with
the wheel kit as a template. Need four.
3. Attach one 1 x 4 to each end of the 2 x 4 using 2” screws
with the curved edges facing each other and spaced a bit wider than
the wheel.
4. Put one 2 x 4 on each side of the tire, being careful to center
the wheel inside the curves.
5. Put a nut and washer on one end of the threaded rod, slide it
through the 2 x 4’s and put a washer and nut on the other
end.
6. Tighten the nuts, keeping the wheel centered
Popping the tire off without all the fuss, Priceless!
I timed myself starting with the removal of the valve stem and had
the wheel halves off in 6 ½ minutes. Not bad for about $6 in parts
and a half an hour of planning/construction.
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Tom
Berge's Brake Bleeder Contraption
OK, I just love
coming up with contraptions. It’s a great way to be both
clever and cheap. Besides, there’s a job to be accomplished.
Over the years, I have always used a pump style oil can to fill the
brake systems on RV’s from the bleeder valve. This involved
hooking up the can with a plastic line to the brake bleeder valve
under the wheel cylinder and adding brake fluid without introducing
air. It’s sometimes tough to find an oil can that can pump
just fluid without air.
Peter Fruehling and I had just finished installing his brake system
and needed to fill it. I decided this time to find another method.
Buying a pressure bleeder was out of the question due to my
cheapness. Eighty-five bucks was too much. I thought, “Why
not roll my own?” After much searching, I found the perfect
container. A small Vlasic Sweet Relish jar in my fridge would fit
the bill fine. Now I’m sure a regular relish jar would work
just as good, but I have my standards. After dumping the contents
into a convenient Tupperware container and thoroughly cleaning the
jar, I started the actual construction.
Now I know that most RV builders will, by this stage of
construction, have a few extra parts lying around. I scrounged up
two -3 bulkhead fittings with the associated B-nuts and sleeves
from my excess stuff drawer. I then drilled two 3/8 holes into the
jar lid and installed the bulkhead fittings. On fitting #1, I
attached a 3/16 aluminum tube that extended to the bottom of the
jar with just a bit of clearance off the bottom then added a piece
of aluminum tubing to the top side. On fitting #2, I attached a
short piece of aluminum tubing just to the top. I then attached a
3/16 plastic line from fitting #1 to the brake bleeder valve.
The way a pressure bleeder works is applying air to the
“can” from one line which will force the fluid out the
other line. Pretty simple. The risky part for me was how to add the
pressurized air. Putting a twist type valve inline would have
worked great, but I didn’t have one of those in my junk
drawer. Cheapness prevailed. I stuck a piece of the milky white
tubing that is included in the RV kit onto the inlet side of the
jar to act as an interconnect for a regular air sprayer. These
sprayers are not known for their precise metering of air, but what
the heck. The worse that would happen is I over pressurized the jar
and brake fluid would spray all over Peters fuselage and the hangar
floor. I was OK with that since it wasn’t my fuselage or
hangar floor!
The moment came, Peter and I set up. I practiced controlling the
air flow and then gave it a whirl. It worked like a charm. The
fittings and related parts are about $9 if you don’t have
any. The Vlasic Sweet Relish jar was about $1.69 at your local
grocer and you still get the relish. Pretty darn sweet.