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.