Chris,
I'm surprised, as the Rotax with the Europa supplied CKT muffler is quite q
uiet with the 912S.
N12AY is a trigear. With the sealed tunnel and 914 it is very quiet. Most
passengers in it are amazed at how quiet and smooth it is.
That said, the Mono tends to be noisier due to the wheel well and airflow t
hrough the tunnel.
The 912S is not that much noisier than the 914. Turbos with a muffler real
ly quiets it.
The 912S is a bit rougher of an engine than the 914. But it is smoother th
an a Lycoming.
The RV and Zenith Rotax powered aircraft are noisy in my opinion (I've flow
n a lot of Zeniths). The metal tends to reflect the noise in the cockpit
The LSA metal aircraft are not terribly noisy with an interior and properly
fitted canopy.
A properly built composite aircraft is very solid sounding. Free from oil
canning noises common in metal aircraft.
In my articles on my website and other places I give some typical causes of
vibration. Word doc attached of an old one.
In my Rotax troubleshooting guide I make mention of the carb balance tuning
. I normally can balance a Rotax by ear and visual inspection.
If the mag drop (ignition check) is at the limit or a touch higher, you hav
e carb balance and or ignition issues.
Here are some tips for smoothness some folks don't realize:
Run up the engine and if your calves begin to vibrate, it is the propeller.
Your calf muscle is about the 1/4 harmonic of the prop.
If the prop has one blade out by a 1/2 degree the vibration is awful. Make
sure the prop blade angles are as close as possible to one another. If yo
u didn't static balance your prop with the spinner. You must.
Trying to find noise and vibration is straight forward:
On the ground: Tied down.
Pull the cowl and run the engine and note the ignition modules. They shoul
d be steady from idle to full power. I mean you should be able to read the
serial number at idle and fuzzy up to 4000. After 4000 the uncowled engin
e is hard to read.
Check the exhaust and look for any broken springs, down pipes and make sure
the reflector shield is secure and doesn't rattle. The muffler and pipes
should not contact the cowl or engine frame.
Check the Binx nuts are tight and the frame is tight.
Check the propeller tracking while its running. (Safely abeam the prop arc
at low power and well clear.) I know that's odd, but it happens that blad
es have been known to flex. One poorly seated blade can be seen.
Check the spinner tracks. Europa classic spinners are tough to get precise
ly smooth. And they are long and heavy.
Have the propeller dynamically balanced. (The Europa is a very light aircr
aft and the whole airframe shakes from the prop blast sometimes making a pr
op balance difficult.) It may need to be done in flight.
I've flown hard and soft mounts. Neither had a noise difference or vibrati
on.
Listen to your exhaust note. If very loud you probably have a modified muf
fler or its blown out a baffle. The Rotax can sound like one of those rice
burner cars the kids run around in if the muffler is not either a Rotax or
the even quieter CKT muffler.
There are a number of mufflers for the Rotax. Some are awful. I'm prejudi
ced in that the CKT is the nicest note. That's why it is used by most of t
he manufacturers in Europe as it meets the DB level.
Look for engine to cowl rub marks.
Ground Airframe Checks:
Run the engine at various RPMs (roughest point preferably) and listen to th
e airframe. Put your ear next to the wing, the stabs, the fuselage.
Ground Rattle checks:
Doors without any seals will rattle a bit.
Access panels that are loose especially the cockpit ones are noisy, heavy w
ires rattle if not tied.
Rudder cables that are not properly guided and clearance and vibrate agains
t bulkheads, and fuselage unless properly supported.
The panel starboard side is often only secured at the top and will vibrate
against the fiberglass firewall.
Climb in the aircraft:
The Europa is like being in a Thermos insulated bottle. Pretty well solidl
y glued and therefore like wood in that it is devoid of skin rattles and no
ises. If you hear rattles and noises, you have components that are vibrati
ng in the structure.
Case in point: If a control rod in the wing is just barely clearing a rib,
if there is vibration, it will be transmitted to the airframe.
Feel the airframe at different RPMs. Relax your legs and feel the movement
of your butt, legs, and arms.
Observe your instrument panel. A shallow clear cup of water that is splash
ing is your first sign of serious vibration issues.
Check your instrument panel is not vibrating blurring the analogue instrume
nts.
The mono wheel well can be rather noisy from air flow. This depends on man
y factors:
The gaps in the gear and brake handle and any other holes. Gear frame arm
to fuselage cutout clearance.
Door seals are important. If the door seals are leaky, there is a suction
in the cockpit formed and the air is pulled through the slots in the cockpi
t module.
Wing gap seals are necessary also as the air between the fuselage and wing
root as the air smacks into the spar then rumbles into the cockpit.
Finally, interior finish choices are important. Paint is light, but the fa
bric / padded leather interior is very quiet.
At 100 knots or less you can casually talk in 12AY. Over 120 knots indicat
ed, the wind noise outside the canopy is quite loud in any aircraft.
I've never needed ANR headsets in any of the aircraft I have built.
I'm interested in your rebuilt engine. Did they tinker with anything or is
it stock? A difference in timing makes a difference in smoothness. Like
I said before, if the muffler is one of those "Performance" mufflers. They
are loud.
Finally, paint and finish tightens up the aircraft, smooths the airflow al
so. It is like a washed car is quieter.
My test is:
If my wife can go 2000 miles in 6 hops without complaining about noise, sea
ts, or anything other than our bladders, I know my plane is comfortable and
quiet. She can't go that far in our Honda Accord. She prefers my F150 wh
en we travel.
Hopefully, you find your issues and enjoy a very quiet, comfortable aircraf
t.
Best Regards,
Bud Yerly
-----Original Message-----
From: owner-europa-list-server@matronics.com <owner-europa-list-server@matr
onics.com> On Behalf Of n7188u
Sent: Monday, November 15, 2021 8:57 PM
Subject: Europa-List: Noisy cockpit
Dear Europa Friends,
First let me say I am really enjoying my Monowheel. This last weekend I too
k my wife on a trip to Miami (first x-country on the Europa for her) and it
was a total success. She really loved it and we had a great weekend.
With that said I have a question about something that has been bothering me
for a while. Although the airplane has been great, I am trying to gain con
fidence on my engine. Let me explain: My engine is a 912ULS rebuild by an i
RMT Repair Center. Not quite an overhaul though (no crankshaft change but e
ngine was torn down, inspected and were necessary new parts installed). The
engine runs quite nice but I did have some issue with it that have been ad
dressed. I am having a little difficulty fully trusting this engine as I th
ink it feels a little rough and noisy.
I have been told that the engine sounds great and smooth from outside the a
irplane (some people thought it was an electric airplane since it is so qui
et) but I find it quite noisy inside and feels a little rough. Maybe its me
being picky since it is really not bad but I am so used to after almost 40
years of flying behind Lycosaurus and Continentals engines that I find tha
t my engine seems to scream inside the Europa cockpit. Vibration is not hig
h but I do feel what I can only describe as a high frequency short amplitud
e harsh vibration in the panel and I can hear it contributing to some level
of fatigue after an hour or so of flying. It's a bit gritty and makes me f
eel as if the gearbox is grinding itself to pieces. But oil looks fine, no
metal in the filter or magnetic plug and the gearbox clutch torque check pa
sses fine. I have balanced the carbs multiple times. I have dynamically bal
anced the prop and replaced the rubber mounts with Europa supplied ones. I
have to reiter!
ate, it's not bad and my Lycoming on the LongEZ vibrates more but in the R
otax it feels a bit harsh and I am not used to it. I did fly in an RV-12 wi
th the same engine and it felt smoother. So a few questions:
1.- Is the Europa a little noisier and transmits more vibration from the en
gine than say an RV-12?
2.- My aviasport tach needle vibrates quite a bit. Like a high frequency bu
zz. My altimeter also tends to wobble a bit at certain power settings. is t
his normal?
3.- I just installed new mounts from Europa but do you guys think that thes
e mounts may be a little hard and allow a bit of vibration to pass through
to the airframe. They do feel hard.
4.- Could it be just me not used to the Rotax? maybe this is perfectly norm
al in the Europa and the RV-12 just happens to be a little smoother. my air
plane has not interior covering, just painted. the RV-12 I flew was covered
inside.
If I just knew that it is normal for the Europa to be a little noisier than
the RV-12 inside I would relax. Just no way to know since the only Europa
I have ever flown is mine.
Best Regards and Thanks.
Chris
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