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Great Carb Mike, do you know what venturi were you using ? Also
did you have a full filter on the carb intake / heat box ?
On 19/10/2022 00:33, Mike Dwyer wrote:
I used to operate my Q200 at 12 to 14,500 feet,
probably density altitudes at least 2000 feet higher than that
with no issue seen. Typically using no ethanol auto gas. I had
500 fpm climb rate left at 14,000 ft. MA3SPA carb.
Mike Dwyer xQ200
On Tue, Oct 18, 2022, 14:25
Kidd, Robert L [US] (IS) <robert.kidd@...
I found your post to be very
Sunday afternoon I was returning to
Logan Utah from Halfway Oregon, in a Cessna 150. Was
cruising along at 9,500 MSL, leaned and throttled back
slightly. I attempted to climb higher to clear some
terrain and at about 10k’ my engine stumbled and began
to run rough. I pulled the carb heat on and it cleaned
up momentarily before it continued to run rough, so full
rich mixture added kept it stumbling along. I have
experienced this before when running Mogas, and thought
I had cured the problem with a replacement fuel line
between my gascolator and the carb, and installing
firesleeve over that fuel line. I’ve been able to fly
to 10,500 without issues, and this time I had a mix of
Mogas and Avgas (about a 5:8 ratio), and was surprised
to once again experience symptoms of vapor locking. I
was almost over Idaho City (U98) and debated landing but
opted to turn south to lower terrain. Full carb heat,
full rich carb mix, and occasionally having to pump the
throttle to keep it running, I descended to about 6700’,
skirting the east corner of Boise’s airspace, before it
started to run reasonably. I was able to adjust the
mixture, but still had to maintain the carb heat setting
as I made my way to Gooding for a fuel stop. As I
closed in on Gooding, I was able to adjust the carb heat
off. After I landed at Gooding and fueled up, the rest
of the flight home was uneventful, even when I climbed
back up to 9,500’.
I’ve never had an issue when I’ve run
straight Avgas, and thought I had enough Avgas that I
couldn’t have any issues with the mixture of Mogas I was
running, but maybe somebody’s chemistry changed, or some
other reason that I haven’t worked out yet. I’ve
wondered about installing a fuel pump somewhere in the
system, to turn on when this event happens. I don’t
suppose most of the Cessna 150’s are operating at these
altitudes. Perhaps something similar happened to the Q2
that went down in Wyoming…
Thanks for sharing your insights.
Not to get too far over my skis here,
but when I did the comprehensive summary of Q accident
Type Aircraft Accident Analysis.pdf ), I found
that the number one cause of engine failure was actually
a failure in fuel delivery (Fuel starvation due to fuel
delivery problem or fuel exhaustion). This is not unlike
the statistics in homebuilts in general, so is
important even if not building a Q.
I have tested my fuel delivery
system’s reliability from near sea level to 18,000 feet.
I find that my system does behave differently depending
on altitude. By this, I mean not just mixture and
carburetion, but flow through fuel lines, pumps,
induction air and regulator all behave differently. If
you have not tested your fuel system for robust
reliability at all altitudes within your altitude
envelope, then caution is warranted as you expand the
envelope, because the fuel flow may suddenly become
So indirectly, going to your original
question, your engine-altitude performance may be a
complicating issue, because in high terrain, you may not
be able to maintain sufficient AGL to glide to a safe
landing area if an engine problem develops.
Jay I agree we are just curious
what happens to learn from that! In my case I'm
still rebuilding my Quickie and never flew one before
and want to learn!
On Tue, Oct 18, 2022 at 10:21 AM
Jay Scheevel <jay@...>
Looks like the engine was
not running, so I don’t think it was a
What I am saying, since the
airplane is based in Vancouver, so that the
pilot would have a lot to handle, first with
the engine out, next with the density altitude
that was likely over 11,000’, then with wind
and possibly gusty wind. Was a good landing,
all of that considered.
My thought is that she went
for the pavement, but probably broke the
canard on the road and then veered off into
the sage brush. Not a bad strategy, actually,
given those conditions!
Also looks like new
blacktop with a huge shoulder drop off.
Jay- are saying it was
maybe above it’s max ceiling at 10,000MSL?
And that may have caused the engine out? What
is the max ceiling for a VW engine powered Q2
On Oct 17,
2022, at 10:40 PM, Jay Scheevel <jay@...>