Bob
-
On the full power check, with the plane tied down you stated that at 5790 R
PM you had 36 inches MP. Then you stated-when you advanced the throttle
-to past-37.5 inches MP the engine quit... What was the RPM at 37.5 inc
hes MP ? Did the engine RPM exceed 5800 RPM ? to reach the 37.5 Inches MP ?
-
At 5800 RPM you should be seeing 39 to 40 inches MP.
-
When you installed the Airmaster prop, did you set the high RPM "stop" in t
he hub to limit RPM to 5800.???- In order to get full boost of the turbo
you must have the throttle wide open, with the RPM's being goverened by the
prop hub.- This can only be done by setting the prop pitch to limit the
max RPM to 5800.
-
If you did not, the Airmaster-installation manual tells you how to do thi
s. It must be done for proper operation of the engine. And also to prevent
overspeed of the engine on takeoff....
-
Jim Brown
--- On Fri, 9/4/09, Robert Borger <rlborger@mac.com> wrote:
From: Robert Borger <rlborger@mac.com>
Subject: Europa-List: Engine quits at full throttle
Date: Friday, September 4, 2009, 9:29 PM
Fellow Europaphiles:
I'm at 10.5 hrs on my XS Monowheel.- (Just getting the hang of landing it
on pavement)- As you can see from the signature block it has a Rotax 914
and Airmaster C/S prop.- On the last flight the engine developed a surge
and a miss at full throttle at about 500' on takeoff.- When I retarded t
he throttle and surge stopped and miss went away.---After immediate R
TB, pulled the upper cowl and began an inspection.- 1st thing noticed was
that it was not really obtaining full throttle.- Only about 37.5 in MP.
- Full throttle is 39 in MP and- 37 - 38 in MP is in the unstable range
for the turbo controller.- That explained the surging.- Located the re
ason the throttle wasn't going to max and fixed it.- Also checked both fu
el filters.- Secondary was fine.- Main was had considerable crud so it
was replaced.---I can now get full throttle.- Re-synched the carbs.
- Runs nice and smooth.
Now here's what happened today on a full-power, chocks-in, tail tied down,
run-up test.
Engine starts immediately.- I kept the idle at 2000 - 2100 RPM to warm up
.
Engine warmed up, all temps and pressures in the green.- Prop controller
set Auto and T/O.- Main and Boost pumps are both on,
Advance throttle.- Everything is OK up to engine RPM 5790 & MP 36 in.
When the throttle is advanced beyond 37.5 in MP the engine quits.- Like f
uel starved or ignition cuts out.- It just quits.
Retard throttle back below 37.5 in MP and it re-starts and runs smoothly.
Throttled back to 4000 RPM and did a "mag" check.- Left-Off drop is about
275 RPM, Right-Off drop is 305 - 310 RPM.
Throttle back to idle and shut off ignition, the engine stops and after abo
ut 15 seconds there was a large backfire through the exhaust (first time fo
r that!).
Engine has only run on 100LL with appropriate amounts of Decalin TCP & Marv
el Mystery Oil to help with the lead situation.- Oil is still nice and cl
ear.
Do any of you Rotax Gurus have a suggestion as to why the engine cuts out w
hen full throttle is applied?- Any suggestion for things to check and/or
fix?
Thanks in advance for your help,
Bob Borger
Europa Kit #A221 N914XL, XS Mono, Intercooled 914, Airmaster C/S
http://www.europaowners.org/N914XL
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