Corvair conversion engines

Richard Lamb wrote:

Cal Vanize wrote:


The issue us addressed in this page:

http://www.flycorvair.com/crankissues.html

The date on the page is 15 January 2006 - just released information.



Ron Webb wrote:

Do you have a link for the broken cranks? I cannot find anything
about broken cranks on the "Corvair authority" site.

http://www.flycorvair.com/

I did find the following statement:

"I have never seen a cracked head, cylinder, case, crank or rod in
the hundreds of Corvair engines I have inspected. It is a very strong
engine."

The Corvair engine has been flying since the early 1960's. Seems odd
that ANY flaw would only now be being discovered.





that dose seem like a lot of broken cranks...

Three out of five cranks cracked. All with 200 or less hours. That's a
small sampling, but not very good results.

The article does indicate that the cranks were from engines in planes
that were flying. That's the good news. But does that also mean that
the engines need a teardown and inspection as part of every oil change?

"Cal Vanize" wrote

The article does indicate that the cranks were from engines in planes that
were flying. That's the good news. But does that also mean that the
engines need a teardown and inspection as part of every oil change?

If you are running a conversion that is different from William's
conversions, it could be a good idea. g

If people take the time (yeah, lots of it) to read the whole article, you
will notice a few things, and I will attempt to point out some of the more
significant (to me) points.

Biggest point. Do not use corvair engines outside of the recommended
operating parameters. Some sub points.

Biggest one, don't use longer prop extensions. Big time no-no.

Others include, don't use heavy props, or hand carved props. Don't
overstress the prop with some aerobatic maneuvers, or hard landings. Make
sure the crank is properly ground. Oil systems must provide for consistent
oil flow to all parts, at all times; stay away from two line cooler and
filter systems. Use low RPMs and big props, rather than smaller props and
higher RPMs. Avoid detonation, which is easy to let happen, if treated like
an aircraft engine.

Obey all points of his conversion manual. Nitrated cranks are a good way to
add an extra margin of safety, when obeying the conversion manual, but the
other examples that have followed the manual have been OK for long
operational periods, even without the nitrated cranks.

Avoid other's add ons, like extra bearing hubs, as they have not been
tested.

I am sure I missed some points, or miss stated some, but if you are using
corvair power, it would be wise to investigate what this man has to say, and
not take my word on it.

I remember saying a long time ago, that I would feel better (or something
like that) if a redrive was used to take the stress off of the crank. I
think I will still stand by those words. Of course, It would need to be a
properly researched and tested redrive, which at this time, does not exist.
--
Jim in NC

Morgans wrote:


"Cal Vanize" wrote


The article does indicate that the cranks were from engines in planes
that were flying. That's the good news. But does that also mean that
the engines need a teardown and inspection as part of every oil change?


If you are running a conversion that is different from William's
conversions, it could be a good idea. g

If people take the time (yeah, lots of it) to read the whole article,
you will notice a few things, and I will attempt to point out some of
the more significant (to me) points.

Biggest point. Do not use corvair engines outside of the recommended
operating parameters. Some sub points.

Biggest one, don't use longer prop extensions. Big time no-no.

Others include, don't use heavy props, or hand carved props. Don't
overstress the prop with some aerobatic maneuvers, or hard landings.
Make sure the crank is properly ground. Oil systems must provide for
consistent oil flow to all parts, at all times; stay away from two line
cooler and filter systems. Use low RPMs and big props, rather than
smaller props and higher RPMs. Avoid detonation, which is easy to let
happen, if treated like an aircraft engine.

Obey all points of his conversion manual. Nitrated cranks are a good
way to add an extra margin of safety, when obeying the conversion
manual, but the other examples that have followed the manual have been
OK for long operational periods, even without the nitrated cranks.

Avoid other's add ons, like extra bearing hubs, as they have not been
tested.

I am sure I missed some points, or miss stated some, but if you are
using corvair power, it would be wise to investigate what this man has
to say, and not take my word on it.

I remember saying a long time ago, that I would feel better (or
something like that) if a redrive was used to take the stress off of the
crank. I think I will still stand by those words. Of course, It would
need to be a properly researched and tested redrive, which at this time,
does not exist.

Good points all.

The point that stood out most for me was the part about the crank from
the engine that William built for his own demo 601. From the article:
"This engine represents a standard installation, albeit one that was
flown at its limits by Gus"... "showed stress fractures on both sides of
the area in question." at 200 hours. "no nitride"

Note with particuclar interest the phrase "represents a standard
installation" regardless of how his pilot flew the plane (it was HIS
pilot after all). The statement goes on to say that the engine "was
flown at its limits" not beyond its limits.

What William wrote is that an engine he purposefully built himself for
his own 601 demo plane had a not insignificant crank issue. If he was
following his own recommendations, why did he use a crank that wasn't
treated?

He may be the Corvair conversion expert, but I'd like to read an
explanation as to why he wasn't following his own specs.

I have read every word on William's web site. It would appear that he
has done his homework and research. He may be the most credible source
for Corvair conversion aircraft engines. But yet, this discrepency
sticks out sorely.

"Cal Vanize" wrote

Good points all.

The point that stood out most for me was the part about the crank from the
engine that William built for his own demo 601. From the article: "This
engine represents a standard installation, albeit one that was flown at
its limits by Gus"... "showed stress fractures on both sides of the area
in question." at 200 hours. "no nitride"
\
Yes, that paragraph does seem to run contrary to the rest of the _long_
website's information. So what gives, others in the know?
--
Jim in NC

Morgans wrote:

"Cal Vanize" wrote

Good points all.

\
Yes, that paragraph does seem to run contrary to the rest of the _long_
website's information. So what gives, others in the know?

Or could it be that it's just taken a few years to rack up 200 hours?

I didn't catch a time span reference on any of the example engines.
But I thought it has been years?

Richard Lamb wrote:
Morgans wrote:


"Cal Vanize" wrote

Good points all.

\

Yes, that paragraph does seem to run contrary to the rest of the
_long_ website's information. So what gives, others in the know?


Or could it be that it's just taken a few years to rack up 200 hours?

I didn't catch a time span reference on any of the example engines.
But I thought it has been years?

First flight of William's 601 was 13 May 2004. That engine had 200 hours.

The article implies that all the engines were torn down at about the
same time. It must have been fairly recently because one of the engines
was a 2005 engine with 71 hours. The previous "crank update" was 15 August.

On Thu, 19 Jan 2006 09:05:51 GMT, Richard Lamb
wrote:

Morgans wrote:

"Cal Vanize" wrote

Good points all.

\
Yes, that paragraph does seem to run contrary to the rest of the _long_
website's information. So what gives, others in the know?

Or could it be that it's just taken a few years to rack up 200 hours?

I didn't catch a time span reference on any of the example engines.
But I thought it has been years?

About one year of flying - MAX.

Morgans wrote:

"Cal Vanize" wrote

Good points all.

The point that stood out most for me was the part about the crank from
the engine that William built for his own demo 601. From the article:
"This engine represents a standard installation, albeit one that was
flown at its limits by Gus"... "showed stress fractures on both sides
of the area in question." at 200 hours. "no nitride"

\
Yes, that paragraph does seem to run contrary to the rest of the _long_
website's information. So what gives, others in the know?

My read was that he was updating his policy based on new data. He even
mentioned one of his customers reminding him of a sentence in his
conversion manual saying something like "I reserve the right to get
smarter."

"Morgans" wrote in
:


"Cal Vanize" wrote

Good points all.

The point that stood out most for me was the part about the crank
from the engine that William built for his own demo 601. From the
article: "This engine represents a standard installation, albeit one
that was flown at its limits by Gus"... "showed stress fractures on
both sides of the area in question." at 200 hours. "no nitride"
\
Yes, that paragraph does seem to run contrary to the rest of the
_long_ website's information. So what gives, others in the know?

His recomendation of nitriding every corvair crank is NEW based on this
data and the several KR crank issues in the recent past. In other words,
nitriding was considered optional until the last week or so....

--
-- ET :-)

"A common mistake people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools."---- Douglas Adams

On Wed, 18 Jan 2006 22:49:19 -0600, Cal Vanize
wrote:



Morgans wrote:


"Cal Vanize" wrote


The article does indicate that the cranks were from engines in planes
that were flying. That's the good news. But does that also mean that
the engines need a teardown and inspection as part of every oil change?


If you are running a conversion that is different from William's
conversions, it could be a good idea. g

If people take the time (yeah, lots of it) to read the whole article,
you will notice a few things, and I will attempt to point out some of
the more significant (to me) points.

Biggest point. Do not use corvair engines outside of the recommended
operating parameters. Some sub points.

Biggest one, don't use longer prop extensions. Big time no-no.

Others include, don't use heavy props, or hand carved props. Don't
overstress the prop with some aerobatic maneuvers, or hard landings.
Make sure the crank is properly ground. Oil systems must provide for
consistent oil flow to all parts, at all times; stay away from two line
cooler and filter systems. Use low RPMs and big props, rather than
smaller props and higher RPMs. Avoid detonation, which is easy to let
happen, if treated like an aircraft engine.

Obey all points of his conversion manual. Nitrated cranks are a good
way to add an extra margin of safety, when obeying the conversion
manual, but the other examples that have followed the manual have been
OK for long operational periods, even without the nitrated cranks.

Avoid other's add ons, like extra bearing hubs, as they have not been
tested.

I am sure I missed some points, or miss stated some, but if you are
using corvair power, it would be wise to investigate what this man has
to say, and not take my word on it.

I remember saying a long time ago, that I would feel better (or
something like that) if a redrive was used to take the stress off of the
crank. I think I will still stand by those words. Of course, It would
need to be a properly researched and tested redrive, which at this time,
does not exist.

Good points all.

The point that stood out most for me was the part about the crank from
the engine that William built for his own demo 601. From the article:
"This engine represents a standard installation, albeit one that was
flown at its limits by Gus"... "showed stress fractures on both sides of
the area in question." at 200 hours. "no nitride"

Note with particuclar interest the phrase "represents a standard
installation" regardless of how his pilot flew the plane (it was HIS
pilot after all). The statement goes on to say that the engine "was
flown at its limits" not beyond its limits.

What William wrote is that an engine he purposefully built himself for
his own 601 demo plane had a not insignificant crank issue. If he was
following his own recommendations, why did he use a crank that wasn't
treated?

He may be the Corvair conversion expert, but I'd like to read an
explanation as to why he wasn't following his own specs.

I have read every word on William's web site. It would appear that he
has done his homework and research. He may be the most credible source
for Corvair conversion aircraft engines. But yet, this discrepency
sticks out sorely.


It was built BEFORE the crack issue came up and BEFORE the
recommendation to use a nitrided crank. VERY simple.