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.