Today's Message Index:
----------------------
1. 08:16 AM - Bad Fuel (Hans Vander Voort)
2. 05:07 PM - flyin fyi (glich7@juno.com)
3. 07:59 PM - Back in the Air Again! (A-75 bottom overhaul) (kmordecai001@comcast.net)
4. 10:06 PM - Re: Bad Fuel (shad bell)
Message 1
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--> Pietenpol-List message posted by: Hans Vander Voort <hans.vander.voort@alfalaval.com>
Well it's awfully quiet on the list for the last few days
Here is something to get things started:
I went out flying yesterday in the Piet, another hot afternoon but humidity
was for a change below 50%
I took of to the North and made a wide circle around the home field
climbing up to 1200 feet.
Dove hunting season has started in Texas, so low and slow is asking for
trouble. (FLAK)
10 minutes in to the flight my Corvair engine CHT climbed up to 475 F, that
never happened before thus I set up for a landing.
On final temperature dropped again (engine idling), while on the ground I
did another run up, everything checked out OK
Decided to take her up again. During climb out at 500 feet the engine
became erratic and dropped a good 500 RPM.
I decided to land right away, engine ran fine again when power was reduced.
I strongly suspect that my recent fill-up with Mogas was not the octane
level as was advertised, every thing indicated detonation.
It is hard to hear in a open cockpit but I did hear a unusual
pinging/ticking sound coming from the engine.
The three months 10% ethanol is mandatory in Mogas in Texas, this was my
first fresh batch of fuel that would have had Ethanol.
Ethanol would increase the octane level.
But ethanol will also dissolve water.
If it is saturated with water would it lean out a engine enough (water
displacing fuel) to cause detonation ?
Then again water would cool the combustion process.
I will be using Avgas from now on.
Hans
Message 2
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--> Pietenpol-List message posted by: "glich7@juno.com" <glich7@juno.com>
Hey everybody,
As has been mentioned it has been quiet, so I decided to post
something everyone might be interested in. Awhile back, I came across
an airport website for Lee Bottom Flying Field while searching for
info on grass airports. What I found was a far from your ordinary
grass airfield, meant to preserve the look and feel of a vintage
airfield of the 1930s. They have a well groomed grass runway(4100' x
100' I think), old fashioned hangers, and are hard at work on a
vintage aircraft museum. The owners Rich and Ginger work hard to keep
the place looking good (with mostly their own money and a few
donations, along with that of dedicated volunteers). Anyway, what I
wanted to tell the list about is their yearly fly-in, "The Wood,
Fabric, and Tailwheels Fly-in 2006" on September 30th. I think the
Pietenpol would definitely qualify, and I'm sure you would have a
great time. Lee Bottom is in Hanover, Indiana near the Ohio River, so
those living in the Midwest have the shortest trip. All the
information for camping, arrival, and the airport is available on
their website below. I'm doubtful I'll be able to make it but check
it out if you like. Sorry this was long,
http://www.leebottom.com
http://www.airnav.com/airport/64I
Blue Skies,
Tim Hansen in Orient, OH
________________________________________________________________________
Message 3
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| Subject: | Back in the Air Again! (A-75 bottom overhaul) |
Hi Folks,
Well, after about 2 months of downtime we're back in the air again :-) I had
torn down the A-75 back in July to investigate low oil pressure. Found very worn
main and rod bearings and a .010" / .010" under crank with mild scoring and
typical wear. The crank failed magnaflux due to a crack in the front main journal
that would not grind out at .020" under, but I located a good standard
dimension flanged and yellow-tagged crank to replace it. The top end w/ chrome
cylinders was new about 65 hours ago, and all was well up there and within new
assembly tolerances. Likewise for the oil pump. New gears had been installed
with the top end, and they were in excellent shape with good tip clearance.
While looking for a crank I used the extra time to balance the pistons and rods.
Found a total of 10 grams difference between the lightest & heaviest piston
(spec is 13 max), but the two heaviest were within 1 gram of each other, while
the two lightest were within 5. Rods were all within 4 grams, and I was able
to swap cylinders #1 and #4 to achieve less than 1.5 grams total imbalance between
the rear pair of pistons/rods, with about 4 grams total between the front
pair after mixing/matching rods.
I finished the assembly last Friday before the holiday weekend. Used Hylomar along
with the Continental thread to seal the case. If you haven't used Hylomar
before, it's a non-hardening 100% polymer material developed by Rolls years ago
for jet engine applications. Now used by Porsche, BMW, and more recently GM
and Ford for metal to metal non-gasketed joints. I've never had a leak due to
Hylomar on quite a few VW's, BMW motorcycles, a few Porsches, etc.
Completed the ground testing Saturday, no leaks & a clean oil screen, & drained
the oil thru a paint filter with no surprises.
First flight was Sunday, about 1/2 hour above the field, followed by another oil
screen inspection with no "findings".
Now have about 1.5 hours on the engine, not a trace of oil on the exterior, oil
pressure is back in the normal range and oil consumption seems to be low (too
soon to really tell yet) It also looks like the balancing paid off, as it is
much smoother than before.
I think the worn bottom end was allowing too much oil flow thru the main & rod
bearings, resulting in much windage and oil loss thru the breather. I had added
the breather extension tube last year, but it didn't help much. Still lost about
1/2 quart/hour of operation, despite never filling the sump over 3 quarts.
Now the oil level has not visibly changed in the one hour of operation since
the first oil change :-) Oil temperature is running 155-160F, about 20-25F
higher than before. I think this is due to increased oil circulation to the heads
brought about with the higher oil pressure. All indications are good :-)
Looking forward to some good flying this fall with renewed confidence in the old
Continental :-)
Dave Mordecai
Panacea, FL
NX520SF
<html><body>
<P>Hi Folks,</P>
<P>Well, after about 2 months of downtime we're back in the air again :-)
I had torn down the A-75 back in July to investigate low oil pressure.
Found very worn main and rod bearings and a .010" / .010" under
crank with mild scoring and typical wear. The crank failed magnaflux due
to a crack in the front main journal that would not grind out at .020" under, but
I located a good standard dimension flanged and yellow-tagged crank
to replace it. The top end w/ chrome cylinders was new about 65 hours
ago, and all was well up there and within new assembly tolerances.
Likewise for the oil pump. New gears had been installed with the top end, and
they were in excellent shape with good tip clearance.</P>
<P>While looking for a crank I used the extra time to balance the pistons and rods.
Found a total of 10 grams difference between the lightest & heaviest
piston (spec is 13 max), but the two heaviest were within 1 gram of each
other, while the two lightest were within 5. Rods were all within 4 grams, and
I was able to swap cylinders #1 and #4 to achieve less than 1.5 grams total
imbalance between the rear pair of pistons/rods, with about 4 grams total between
the front pair after mixing/matching rods.</P>
<P>I finished the assembly last Friday before the holiday weekend. Used Hylomar
along with the Continental thread to seal the case. If you haven't used Hylomar
before, it's a non-hardening 100% polymer material developed by Rolls years
ago for jet engine applications. Now used by Porsche, BMW, and more recently
GM and Ford for metal to metal non-gasketed joints. I've never
had a leak due to Hylomar on quite a few VW's, BMW motorcycles, a few Porsches,
etc.</P>
<P>Completed the ground testing Saturday, no leaks & a clean oil
screen, & drained the oil thru a paint filter with no surprises.</P>
<P>First flight was Sunday, about 1/2 hour above the field, followed by another
oil screen inspection with no "findings".</P>
<P>Now have about 1.5 hours on the engine, not a trace of oil on the exterior,
oil pressure is back in the normal range and oil consumption seems to be low (too
soon to really tell yet) It also looks like the balancing paid off,
as it is much smoother than before.</P>
<P>I think the worn bottom end was allowing too much oil flow thru the main &
rod bearings, resulting in much windage and oil loss thru the breather. I had
added the breather extension tube last year, but it didn't help much. Still
lost about 1/2 quart/hour of operation, despite never filling the sump over 3
quarts. Now the oil level has not visibly changed in the one hour of operation
since the first oil change :-) Oil temperature is running 155-160F,
about 20-25F higher than before. I think this is due to increased oil circulation
to the heads brought about with the higher oil pressure. All indications
are good :-)</P>
<P>Looking forward to some good flying this fall with renewed confidence in the
old Continental :-)</P>
<P>Dave Mordecai</P>
<P>Panacea, FL</P>
<P>NX520SF</P>
<pre><b><font size=2 color="#000000" face="courier new,courier">
</b></font></pre></body></html>
Message 4
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Man! that sounds all too famillar. We ran only 100LL in our corvair but that sounds
like similar symtoms. Eventually our crank broke and luckly we did not
tear up the airplane. I'm by far no expert on corvairs but what is your static
rpm, climb-out rpm and what prop are you using. We are grounded, probobly untill
next spring when we rebuild another engine. We are using a Heggy 66-30
(I believe) wodden prop and we were getting 3150-3300 static. I'm just currious
about others performance with the corvairs.
Shad
Hans Vander Voort <hans.vander.voort@alfalaval.com> wrote:
--> Pietenpol-List message posted by: Hans Vander Voort
Well it's awfully quiet on the list for the last few days
Here is something to get things started:
I went out flying yesterday in the Piet, another hot afternoon but humidity
was for a change below 50%
I took of to the North and made a wide circle around the home field
climbing up to 1200 feet.
Dove hunting season has started in Texas, so low and slow is asking for
trouble. (FLAK)
10 minutes in to the flight my Corvair engine CHT climbed up to 475 F, that
never happened before thus I set up for a landing.
On final temperature dropped again (engine idling), while on the ground I
did another run up, everything checked out OK
Decided to take her up again. During climb out at 500 feet the engine
became erratic and dropped a good 500 RPM.
I decided to land right away, engine ran fine again when power was reduced.
I strongly suspect that my recent fill-up with Mogas was not the octane
level as was advertised, every thing indicated detonation.
It is hard to hear in a open cockpit but I did hear a unusual
pinging/ticking sound coming from the engine.
The three months 10% ethanol is mandatory in Mogas in Texas, this was my
first fresh batch of fuel that would have had Ethanol.
Ethanol would increase the octane level.
But ethanol will also dissolve water.
If it is saturated with water would it lean out a engine enough (water
displacing fuel) to cause detonation ?
Then again water would cool the combustion process.
I will be using Avgas from now on.
Hans
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