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1. 12:53 PM - Flight Test Update - N776PM (Paul Mulwitz)
2. 07:17 PM - Re: Flight Test Update - N776PM (Michel Therrien)
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| Subject: | Flight Test Update - N776PM |
It's been a little over two months since my Zodiac XL got its
airworthiness certificate. Yesterday I had my first flight with no
squawks. I figured it is time to spread the word on the things I
found. Current flight time is around 17 hours. My typical test flight
was just over one half hour with just one landing. This might have been
a bit shorter if I didn't have to get out from under a class C terminal
area before climbing to a reasonable test altitude.
Yesterday the air was reasonably cool - around 60 on the ground so it
must have been around 45 at 5000 MSL where I did my testing. At full
throttle the engine ran smoothly and the plane indicated around 120
knots. I have not calibrated the airspeed yet, but casual comparison
with GPS ground speed suggests it is pretty close to correct. I have a
Jabiru 3300A with wood Sensenich 64ZK49 propeller (standard stuff when
you buy the FWF package from Pete at USA Jabiru). Cylinder head
temperatures were all green with the highest around 320. Oil
temperature was around 170. At WOT engine RPM was just over 3000 RPM at
5000 MSL. CHTs in full throttle climb were around 1100 and in high
cruise around 1300.
I am sure I can't remember all the problems I fixed in the first two
months of phase I flight test, but I'll try to recount as many as I can.
1. Engine cooling was a big problem. My first attempt at adding rubber
seals at the front of the cooing ducts was not correct. I should have
fitted the rubber seals carefully to the inlets in the cowl. I also
needed to adjust the air dams in the right duct (cylinders 1,3,5) but
the other one never needed any adjustment.
2. Nose gear bearings were too tight. The plastic bearings at both the
top and bottom of the nose gear column restricted movement instead of
just guiding it. The nose should move up and down easily when you put
your weight on the propeller drive shaft. The plastic bearings as
delivered from ZAC were much too tight. I loosened them on original
installation but that wasn't enough.
3. Rudder does not return to center when you remove pressure from the
pedals. This problem is unresolved. It doesn't present too much of a
problem but it is difficult to keep the ball centered unless you give
the left rudder pedal a good kick after maneuvering. A related
unresolved problem is the nose tends to wander in yaw - especially in
turbulence. I am thinking nice thoughts of adding some sort of fixed
vertical stabilizer fin - probably on the bottom of the fuselage to
correct this. It is not a big problem but makes flying a bit uncomfortable.
4. I had a few electronic problems with my Dynon and Garmin avionics.
The Dynon tachometer needed to have a resistor installed in line with
the connection to the alternator (through a fuse). Before adding the
resistor the tachometer went nuts in mid range power settings but worked
fine above 2200 RPM and below 1700.
The only problem with the Garmin stuff was I needed to attach a pin to
ground to enable the built-in intercom on my SL-30. I also had issues
setting the squelch, but that was just an operator issue.
5. Several times I had the quick drains in the fuel tanks turn into
slow leaks. This was caused by tiny pieces of aluminum getting caught
in the tiny O-ring that seals the quick drain. I got an extra quick
drain valve and learned how to replace a faulty one with a pail under
the stream of fuel to collect that fuel that escapes between the time I
remove one and install the other one. Then it is a relatively simple
task to clean out the defective seal and put it aside for the next
occurrence of this problem.
6. At one point I discovered the carburetor was barely attached to the
engine. It was held in place by the air intake hose but this was still
a bit scary. It was easy to loosen both hose clamps that hold the
carburetor and push it firmly in place before tightening the clamps again.
7. Another carburetor problem -- the small hose connecting the
carburetor to the air box came off. This caused the engine to drop out
randomly with RPM dropping about 500 revs in turbulence when I reduced
power for descent. The engine ran more smoothly when I added power to
cruise levels. The original hose had a 3/16 ID and was quite loose on
the carburetor nipple. I got some vinyl hose with .170 ID at the
hardware store and it holds on and works just fine.
8. Elevator trim was not powerful enough to trim pitch when any flaps
were employed. I added an extra fixed tab to the rear of the original
one and found improvement but I was still unable to get neutral trim
with full flaps. A bigger tab fixed this. I think the final extra tab
was around 20 square inches to neutralize 20 degrees of flaps.
9. I had a lot of trouble getting the rudder into a neutral position in
flight. The nose gear centers when there is no weight on the gear and
the connections through the pedals and rudder cables pulls the rudder
one way or the other until you get this properly adjusted. This took me
many small changes. At one point I didn't like the number of exposed
threads in one of the turnbuckles and learned you can get forks that are
about a half inch longer than the normal ones to give you more
adjustment room. I only needed one of these extra length forks to allow
more "Left" rudder in the cable setup. (I am getting really good at
installing safety wire in turnbuckles.)
In all my experience at being a test pilot for an amateur (me) built
aircraft has been quite an experience. The only time I felt at all
scared was when the engine was cutting out. Mostly it has been a matter
of getting all the little adjustments made to make the plane fly
properly. Now, I am looking forward to spending some time in the
pattern learning how to do really nice approaches and landings.
Paul
Camas, WA
Message 2
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| Subject: | Re: Flight Test Update - N776PM |
Thanks for sharing Paul. Now you should start to really enjoy your toy.
Do not archive
Sent from my iPad
On Sep 20, 2011, at 15:50, Paul Mulwitz <psm@att.net> wrote:
>
> It's been a little over two months since my Zodiac XL got its airworthiness certificate.
Yesterday I had my first flight with no squawks. I figured it is
time to spread the word on the things I found. Current flight time is around
17 hours. My typical test flight was just over one half hour with just one landing.
This might have been a bit shorter if I didn't have to get out from under
a class C terminal area before climbing to a reasonable test altitude.
>
> Yesterday the air was reasonably cool - around 60 on the ground so it must have
been around 45 at 5000 MSL where I did my testing. At full throttle the engine
ran smoothly and the plane indicated around 120 knots. I have not calibrated
the airspeed yet, but casual comparison with GPS ground speed suggests it
is pretty close to correct. I have a Jabiru 3300A with wood Sensenich 64ZK49
propeller (standard stuff when you buy the FWF package from Pete at USA Jabiru).
Cylinder head temperatures were all green with the highest around 320. Oil
temperature was around 170. At WOT engine RPM was just over 3000 RPM at 5000
MSL. CHTs in full throttle climb were around 1100 and in high cruise around
1300.
>
> I am sure I can't remember all the problems I fixed in the first two months of
phase I flight test, but I'll try to recount as many as I can.
>
> 1. Engine cooling was a big problem. My first attempt at adding rubber seals
at the front of the cooing ducts was not correct. I should have fitted the
rubber seals carefully to the inlets in the cowl. I also needed to adjust the
air dams in the right duct (cylinders 1,3,5) but the other one never needed any
adjustment.
>
> 2. Nose gear bearings were too tight. The plastic bearings at both the top
and bottom of the nose gear column restricted movement instead of just guiding
it. The nose should move up and down easily when you put your weight on the
propeller drive shaft. The plastic bearings as delivered from ZAC were much too
tight. I loosened them on original installation but that wasn't enough.
>
> 3. Rudder does not return to center when you remove pressure from the pedals.
This problem is unresolved. It doesn't present too much of a problem but it
is difficult to keep the ball centered unless you give the left rudder pedal
a good kick after maneuvering. A related unresolved problem is the nose tends
to wander in yaw - especially in turbulence. I am thinking nice thoughts of
adding some sort of fixed vertical stabilizer fin - probably on the bottom of
the fuselage to correct this. It is not a big problem but makes flying a bit
uncomfortable.
>
> 4. I had a few electronic problems with my Dynon and Garmin avionics. The Dynon
tachometer needed to have a resistor installed in line with the connection
to the alternator (through a fuse). Before adding the resistor the tachometer
went nuts in mid range power settings but worked fine above 2200 RPM and below
1700.
>
> The only problem with the Garmin stuff was I needed to attach a pin to ground
to enable the built-in intercom on my SL-30. I also had issues setting the squelch,
but that was just an operator issue.
>
> 5. Several times I had the quick drains in the fuel tanks turn into slow leaks.
This was caused by tiny pieces of aluminum getting caught in the tiny O-ring
that seals the quick drain. I got an extra quick drain valve and learned
how to replace a faulty one with a pail under the stream of fuel to collect that
fuel that escapes between the time I remove one and install the other one.
Then it is a relatively simple task to clean out the defective seal and put it
aside for the next occurrence of this problem.
>
> 6. At one point I discovered the carburetor was barely attached to the engine.
It was held in place by the air intake hose but this was still a bit scary.
It was easy to loosen both hose clamps that hold the carburetor and push it
firmly in place before tightening the clamps again.
>
> 7. Another carburetor problem -- the small hose connecting the carburetor to
the air box came off. This caused the engine to drop out randomly with RPM dropping
about 500 revs in turbulence when I reduced power for descent. The engine
ran more smoothly when I added power to cruise levels. The original hose
had a 3/16 ID and was quite loose on the carburetor nipple. I got some vinyl
hose with .170 ID at the hardware store and it holds on and works just fine.
>
> 8. Elevator trim was not powerful enough to trim pitch when any flaps were employed.
I added an extra fixed tab to the rear of the original one and found
improvement but I was still unable to get neutral trim with full flaps. A bigger
tab fixed this. I think the final extra tab was around 20 square inches
to neutralize 20 degrees of flaps.
>
> 9. I had a lot of trouble getting the rudder into a neutral position in flight.
The nose gear centers when there is no weight on the gear and the connections
through the pedals and rudder cables pulls the rudder one way or the other
until you get this properly adjusted. This took me many small changes. At
one point I didn't like the number of exposed threads in one of the turnbuckles
and learned you can get forks that are about a half inch longer than the normal
ones to give you more adjustment room. I only needed one of these extra
length forks to allow more "Left" rudder in the cable setup. (I am getting really
good at installing safety wire in turnbuckles.)
>
> In all my experience at being a test pilot for an amateur (me) built aircraft
has been quite an experience. The only time I felt at all scared was when the
engine was cutting out. Mostly it has been a matter of getting all the little
adjustments made to make the plane fly properly. Now, I am looking forward
to spending some time in the pattern learning how to do really nice approaches
and landings.
>
> Paul
> Camas, WA
>
>
>
>
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