Really baffling set of test results Kevin. I am sort of curious
what the actual fuel flow is at 1500 rpm where the engine will run. It
should be a low number like maybe 3 gph or less. The power to turn a
fixed pitch prop is a *cube* function of rpm, not linear. These tests
were with prop on I assume.
Also surprised at the temps still going up at 1500 but that may
be normal for rebuilt Lycs. What was CHT at 1500 before overhaul?
Back from Osh (great trip, 7 rotaries there) after an eventful
return flight. Entire state of Georgia was under a big dome of
clouds with MVFR conditions below. I made the decision to go on top
which was at around 12,500 ft when I reached edge of cloud cover at
north end of Ga. Had grand view of weather and could easily navigate
around thunderstorms that had buildups into FL 40. Bad news was
that top of cloud cover kept rising as I flew across Georgia
and eventually reached 18,000 ft by the time I reached the southern
edge of cloud cover near Florida border. Did I mention that I have no
Oxygen on board?
Had one exciting moment when I encountered one of those very
thin gauzy looking cloud layers at 18,000. Not wanting to break into
Class A airspace I descended through it figuring I would fly in the 200
foot gap between it and the cloud layer below for the few minutes it
would take to get past it. The canopy (and wing too I
suspect) immediately started accumulating ice. Class A here I come,
I'll deal with FAA if I have to. By the time I spiraled down through
closely spaced thunderstorms in Florida I had spent about 2 hours
between 16 and 18 thousand feet. It was a fairly high stress period.
Shady Bend was under a thunderstorm by this time so I diverted
to Lake City and landed. It was hot, I was dehydrated from not
drinking enough water and the 3 G spiral down through the clouds added
to the discomfort level. Nevertheless, I felt OK at touch down but by
the time I taxied to the FBO I felt violently ill. I assumed it was the
hypoxia and heat exhaustion (had that back in Army days) but Laura was
concerned that the symptoms could be heart attack. Went to hospital
and blood tests showed slightly elevated enzyme that indicates possible
heart attack. Great. Now I am obligated to go through the whole drill
(cardiac catheterization) to prove it was not a heart problem if I
wanted to keep my pilots license. Test came out good (cardiac guy said
arteries clean as a whistle and hopes his heart looks that good at 57).
The plane was magnificent the whole trip and did anything I
asked of it. Still had respectable rate of climb at 18,500 (who needs
a turbo?), engine never skipped a beat, burned 101 gallons in 17.1
hours of flight (includes taxi time) so fuel burn averaged about 6
gph. Glad to be home.
Tracy (belatedly ordering Oxygen system)
-----
Original Message -----
Sent:
Wednesday, August 03, 2005 7:15 PM
Subject:
[FlyRotary] further testing - -lycoming O-320
my engine continues to
baffle me and everyone else on the airport. I would send it to a
mechanic, but I've spoken with all of them and they have no ideas
either. it continues to look like fuel starvation, but no gauges
support this theory. it runs at 2150rpm, burning 11.5-12.3 gals per
hr, 3 lbs fuel pressure, for about 2 minutes then stumbles(and will die
unless I reduce the throttle to 1500rpm. )the stumbling occurs when
cht's are hitting 375 - 410. continued running at 1500 allows the
cht's to climb, so I have to shut things down. the same behavior
occurred when I flew the plane the first two times (until I realized I
could duplicate the problem on the ground) I have a new carb(ma4spa)
and 4 rebuilt cyls (on which I am attempting to set the rings,
unfortunately) if I run the engine at less than full rich the engine
won't stumble before temps hit 400+ and I have to pull power.
I bypassed my fuel filters
with no difference. I installed new filters that have a core of little
brass balls stuck together and seemingly much better flow than the
other filter(no angles either, just straight flow)
I cleaned and backflushed
the fuel pickups and vents, ran with the gas caps off(no diff). my
fuel flow is not changing(until it sputters back to 1500rpm), so my
idea that the carb bowl was slowly not being refilled doesn't show up.
the same problem existed before I had the cyls rebuilt and welded, so I
doubt that stuck valves/weak springs are to blame. also, that would
show problems from the start, not a few minutes later.
everyone wants to blame
the electronic ig. switching between mag and elec. during the first
minute shows no diff. switching after it starts to falter shows no
diff. pulling back to 1500rpm after falter shows no diff. I can't
believe I have a spark or timing problem because there are no times
when one works and the other doesn't. my slick mag is brand new also.
I haven't tried new plugs yet, the current ones are new, although I've
heard many stories of bad new plugs (hey, what do you want for $20?)
my 1" dia. cheapy van's
fuel pressure meter is now showing 3 lbs. I removed the pressure
regulator. in the past it used to show 8lbs pressure (hence I
installed the regulator)and my carb showed signs of leakage which is
one reason I replaced it. I have no idea why it shows only 3 lbs now.
I tried plumbing the carb directly from a gas can. I forgot to switch
the fuel line off and shot fuel clear out on the wing when the engine
started. I would guess that the mech. fuel pump is working correctly.
the facet elec pump will pump about 1 gallon in 2 minutes when pumping
into a gas can thru the mechanical pump. it makes no diff. if I run
the facet or not. I have bypassed the mech. pump and run just with the
facet, no diff., in fact, when I shut off the facet the engine still
runs until the bowl burns down, maybe 30 sec.?
it is hard to believe that
both the auto plugs and aero plugs are simultaneously failing due to
heat. I could fly the plane at less than full rich to see how long it
would fly I suppose, but that seems unnecessarily risky. I've had two
"lucky" flights so far.
I checked for induction
leaks(pressurized and soap solution) and found nothing.
I am out of ideas.
this problem is just kicking my butt. hopefully one of you guys will
spark an new idea or theory for me.