Rebel - Tail Spring

[Murray Cherkas]

Wayne:

I had to bend my tailspring 14 1/2* in order to make the bolt vertical.I
took it to Alberta Aircraft Overhaul. They said that because the original
radius was a slow bend being no where near the bend radius for this
thickness of aluminum that we could cold bend it. We proceded to put it in a
hydraulic press and bend it.This worked fine. I reviewed this with MAM also
beforehand and they thought that this would be fine. Cold bending because of
the slow bend.

Just a thought
Murray

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Wayne G. O'Shea
Sent: Wednesday, November 19, 2003 3:03 PM
To: murphy-rebel@dcsol.com
Subject: Rebel - Tail Spring


Inspect your aluminum tailsprings closely before installation guys and make
sure they are not cracked anywhere.

I stripped the paint off the one I am working on, before a planned
reinstallation. I noticed that there are small cracks on each edge of the
TOP surface, at the bend where it clamps to the fuselage. I put it in my
press to put a little pressure on it and these opened right up and extended
towards the center of the spring on an angle, and extend down in to the
spring about 3/32 and then go in the same direction as the spring length
like delaminated plywood.

Note that these cracks could not be caused by landing loads. These are
tension cracks in the top outside radius of the bend from manufacturing!
Landing load cracks would be in the lower surface.

I discussed bending of aluminum this thick with Chris Heinz this summer, as
to how they fabricated their landing gear leafs for the CH2000/CH601/701/801
etc. He told me if done "cold", at room temperature of the facility, they
would crack immediately with small outer radius cracks. "The alum needs to
be heated and they bend just fine", he said.. Heating for him is laying the
flat raw material out in the sun, on a hot summer day, for a few hours. Says
you can't pick them up bare handed they get so hot and they bring them in
and immediately bend them without any problems. They try to do their full
years spring leaf run this way, but if they have to do it any other time of
year they have to heat the blanks (and I forget the temp he stated). I don't
know how Murphy does it, but I suspect COLD. Does anyone here know...
GRANT!?!

Cheers,
Wayne




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[Wayne G. O'Shea]

Inspect your aluminum tailsprings closely before installation guys and make
sure they are not cracked anywhere.

I stripped the paint off the one I am working on, before a planned
reinstallation. I noticed that there are small cracks on each edge of the
TOP surface, at the bend where it clamps to the fuselage. I put it in my
press to put a little pressure on it and these opened right up and extended
towards the center of the spring on an angle, and extend down in to the
spring about 3/32 and then go in the same direction as the spring length
like delaminated plywood.

Note that these cracks could not be caused by landing loads. These are
tension cracks in the top outside radius of the bend from manufacturing!
Landing load cracks would be in the lower surface.

I discussed bending of aluminum this thick with Chris Heinz this summer, as
to how they fabricated their landing gear leafs for the CH2000/CH601/701/801
etc. He told me if done "cold", at room temperature of the facility, they
would crack immediately with small outer radius cracks. "The alum needs to
be heated and they bend just fine", he said.. Heating for him is laying the
flat raw material out in the sun, on a hot summer day, for a few hours. Says
you can't pick them up bare handed they get so hot and they bring them in
and immediately bend them without any problems. They try to do their full
years spring leaf run this way, but if they have to do it any other time of
year they have to heat the blanks (and I forget the temp he stated). I don't
know how Murphy does it, but I suspect COLD. Does anyone here know...
GRANT!?!

Cheers,
Wayne




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[Wayne G. O'Shea]

Well this ones cracked in a weird way, exactly as Chris Heinz described 7075
would cracked if you try to cold bend it (There's no sharp radius' on his
Zenair landing gear either). I put the spring in my press to bend it some
more, to get the rake angle right on the tailwheel before reinstallation,
and the little hair line marks at the edges of the outer bend radius opened
right up like delaminated plywood. Instead of installing, it's now going in
the trash and I'll be installing one of my 3 leaf trailer springs to replace
it.

Wayne

----- Original Message -----
From: "Murray Cherkas" <cherkas@shaw.ca>
To: <murphy-rebel@dcsol.com>
Sent: Wednesday, November 19, 2003 8:43 PM
Subject: RE: Rebel - Tail Spring

Wayne:

I had to bend my tailspring 14 1/2* in order to make the bolt vertical.I
took it to Alberta Aircraft Overhaul. They said that because the original
radius was a slow bend being no where near the bend radius for this
thickness of aluminum that we could cold bend it. We proceded to put it in

a

hydraulic press and bend it.This worked fine. I reviewed this with MAM

also

beforehand and they thought that this would be fine. Cold bending because

of

the slow bend.

Just a thought
Murray

-----Original Message-----
From: mike.davis@dcsol.com [mailto:mike.davis@dcsol.com]On Behalf Of
Wayne G. O'Shea
Sent: Wednesday, November 19, 2003 3:03 PM
To: murphy-rebel@dcsol.com
Subject: Rebel - Tail Spring


Inspect your aluminum tailsprings closely before installation guys and

make

sure they are not cracked anywhere.

I stripped the paint off the one I am working on, before a planned
reinstallation. I noticed that there are small cracks on each edge of the
TOP surface, at the bend where it clamps to the fuselage. I put it in my
press to put a little pressure on it and these opened right up and

extended

towards the center of the spring on an angle, and extend down in to the
spring about 3/32 and then go in the same direction as the spring length
like delaminated plywood.

Note that these cracks could not be caused by landing loads. These are
tension cracks in the top outside radius of the bend from manufacturing!
Landing load cracks would be in the lower surface.

I discussed bending of aluminum this thick with Chris Heinz this summer,

as

to how they fabricated their landing gear leafs for the

CH2000/CH601/701/801

etc. He told me if done "cold", at room temperature of the facility, they
would crack immediately with small outer radius cracks. "The alum needs to
be heated and they bend just fine", he said.. Heating for him is laying

the

flat raw material out in the sun, on a hot summer day, for a few hours.

Says

you can't pick them up bare handed they get so hot and they bring them in
and immediately bend them without any problems. They try to do their full
years spring leaf run this way, but if they have to do it any other time

of

year they have to heat the blanks (and I forget the temp he stated). I

don't

know how Murphy does it, but I suspect COLD. Does anyone here know...
GRANT!?!

Cheers,
Wayne

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[BCairboat]

Wayne and group Hello
The springs are cut out of plate cold and sized then sent to Vancouver for
DE-tempering to neutral. They are then shipped back in coolers to prevent fast
temperature changes and bent immediately on the press to the correct angle.
They are then sent back to Vancouver and re-tempered to the correct hardness. The
same procedure is followed with the nose gear forks on the SR and Elite. This
is the first time I have heard of this problem but I believe the plane Wayne
is working on may have had a few bumps in it's day and possibly bent the
spring. If this did indeed occur and someone attempted to rebend it the cracks
would be the natural result. In any event it was a good catch on your part Wayne
to take the extra time and test the part. I know if the springs were ever over
bent they were rejected and not reshaped I have a bunch of them in my shop
that I use for material in pet projects but not as springs again.
Grant



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[Wayne G. O'Shea]

THANKS GRANT!

That's what we needed to hear!

(you say "may have had" with such stealth'ness ) !! )

Cheers, Wayne

----- Original Message -----
From: <BCairboat@aol.com>
To: <murphy-rebel@dcsol.com>
Sent: Thursday, November 20, 2003 3:15 PM
Subject: Re: Rebel - Tail Spring

Wayne and group Hello
The springs are cut out of plate cold and sized then sent to Vancouver for
DE-tempering to neutral. They are then shipped back in coolers to prevent

fast

temperature changes and bent immediately on the press to the correct

angle.

They are then sent back to Vancouver and re-tempered to the correct

hardness. The

same procedure is followed with the nose gear forks on the SR and Elite.

This

is the first time I have heard of this problem but I believe the plane

Wayne

is working on may have had a few bumps in it's day and possibly bent the
spring. If this did indeed occur and someone attempted to rebend it the

cracks

would be the natural result. In any event it was a good catch on your part

Wayne

to take the extra time and test the part. I know if the springs were ever

over

bent they were rejected and not reshaped I have a bunch of them in my shop
that I use for material in pet projects but not as springs again.
Grant

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