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Bob Jenneson
Guest
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 Posted: Sat Feb 07, 2009 2:06 pm Post subject: Grob 109 wing pins |
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Hi,
I am seeking advise on the replacement of the wing pins fitted in the
end of the spars on Grob 109 and 109B.
This also applies to the Grob Twin Astir.
A brief history.
These pins are welded to a plate that is glassed into the wing spar end
during manufacture. It was found out at a later time that some of these
assemblies were prone to cracking around the welds and required replacement
if found to be cracked.
In Australia we are required to "ultrasonic " test these pins every 500
hours ( AD 370 )
If tested 'OK' we keep flying.
We now have two aircraft that have 3000 hours each ( Life extension time )
and no cracks found.
Do we need to change the pins?
This is serious and expensive surgery and I am seeking advise as to how
other countries have dealt with this problem.
I understand that Australia in the only country that uses the ultrasonic
test.
Grob are happy to supply the new pin assemblies, but is it really necessary
if the old ones have a 3000 hour safe history.
Any help appreciated, Bob. |
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JJ Sinclair
Guest
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| Posted: Sat Feb 07, 2009 2:06 pm Post subject: Re: Grob 109 wing pins |
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I don't believe there has ever been a failure on any Grob spar
fitting. The British air academy cadets tested a G-103 with 50,000
simulated winch launches and got one weld to crack. To my knowledge
that is it, an AD was issued and a few cracks were found, but nothing
ever came apart due to spar fitting failure. I'd say to keep on with
the ultrasonic testing every 500 hours if your national aviation
authority allows this, the US doesn't, but how often have we been
right on anything recently?
JJ |
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Gilbert Smith
Guest
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| Posted: Sat Feb 07, 2009 6:05 pm Post subject: Re: Grob 109 wing pins |
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In the UK we replace them on the G109B at 3000 hours irrespective,
together with a few other mods which come up at that time. The new
pins have a better taper, handy if you rig frequently as I do, and are
replaceable without the major surgery reuired on the first occasion.
- Colin.
"Bob Jenneson" <bobj (AT) adam (DOT) com.au> wrote:
| Quote: | Hi,
I am seeking advise on the replacement of the wing pins fitted in the
end of the spars on Grob 109 and 109B.
This also applies to the Grob Twin Astir.
A brief history.
These pins are welded to a plate that is glassed into the wing spar end
during manufacture. It was found out at a later time that some of these
assemblies were prone to cracking around the welds and required replacement
if found to be cracked.
In Australia we are required to "ultrasonic " test these pins every 500
hours ( AD 370 )
If tested 'OK' we keep flying.
We now have two aircraft that have 3000 hours each ( Life extension time )
and no cracks found.
Do we need to change the pins?
This is serious and expensive surgery and I am seeking advise as to how
other countries have dealt with this problem.
I understand that Australia in the only country that uses the ultrasonic
test.
Grob are happy to supply the new pin assemblies, but is it really necessary
if the old ones have a 3000 hour safe history.
Any help appreciated, Bob.
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Rod Swallow
Guest
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| Posted: Mon Mar 23, 2009 1:06 am Post subject: Re: Grob 109 wing pins |
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Dear Gilbert
I am a Grob 109b owner in Australia. Currently I am trying to assemble a
trolley to make wing folding easier as I want to be able to rig it on my
own. Do you have any suggestions?
Thanking you
Rod Swallow
At 16:13 07 February 2009, Gilbert Smith wrote:
| Quote: | In the UK we replace them on the G109B at 3000 hours irrespective,
together with a few other mods which come up at that time. The new
pins have a better taper, handy if you rig frequently as I do, and are
replaceable without the major surgery reuired on the first occasion.
- Colin.
"Bob Jenneson" wrote:
Hi,
I am seeking advise on the replacement of the wing pins fitted in
the
end of the spars on Grob 109 and 109B.
This also applies to the Grob Twin Astir.
A brief history.
These pins are welded to a plate that is glassed into the wing spar end
during manufacture. It was found out at a later time that some of these
assemblies were prone to cracking around the welds and required
replacement
if found to be cracked.
In Australia we are required to "ultrasonic " test these pins
every
500
hours ( AD 370 )
If tested 'OK' we keep flying.
We now have two aircraft that have 3000 hours each ( Life extension
time
)
and no cracks found.
Do we need to change the pins?
This is serious and expensive surgery and I am seeking advise as to how
other countries have dealt with this problem.
I understand that Australia in the only country that uses the ultrasonic
test.
Grob are happy to supply the new pin assemblies, but is it really
necessary
if the old ones have a 3000 hour safe history.
Any help appreciated, Bob.
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Gilbert Smith
Guest
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| Posted: Wed Mar 25, 2009 1:06 am Post subject: Re: Grob 109 wing pins |
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Hello Rod,
I use a home-spun device which clamps to the wingtip just outboard of
the aileron. I have fitted two small wheels to this so that the wing
can be moved into position while vertical. When rigging you then have
to lift the tip with the device still fitted, go flat, and push it
home. A fold-down prop then supports the tip while I engage the main
and leading edge pins.
It also has an extension of about a foot out from the trailing edge to
help with the aft c of g at the tip. I rig and derig alone every day,
and the device has been in use for 25 years.
My attempt at a trolley and hydraulic jack was a failure because I
lost the "feel" required to locate the spar pin.
If you like I can email photos of both.
Regards,
"Gilbert"
Rod Swallow <rsswallow (AT) bigpond (DOT) com> wrote:
| Quote: | Dear Gilbert
I am a Grob 109b owner in Australia. Currently I am trying to assemble a
trolley to make wing folding easier as I want to be able to rig it on my
own. Do you have any suggestions?
Thanking you
Rod Swallow
At 16:13 07 February 2009, Gilbert Smith wrote:
In the UK we replace them on the G109B at 3000 hours irrespective,
together with a few other mods which come up at that time. The new
pins have a better taper, handy if you rig frequently as I do, and are
replaceable without the major surgery reuired on the first occasion.
- Colin.
"Bob Jenneson" wrote:
Hi,
I am seeking advise on the replacement of the wing pins fitted in
the
end of the spars on Grob 109 and 109B.
This also applies to the Grob Twin Astir.
A brief history.
These pins are welded to a plate that is glassed into the wing spar end
during manufacture. It was found out at a later time that some of these
assemblies were prone to cracking around the welds and required
replacement
if found to be cracked.
In Australia we are required to "ultrasonic " test these pins
every
500
hours ( AD 370 )
If tested 'OK' we keep flying.
We now have two aircraft that have 3000 hours each ( Life extension
time
)
and no cracks found.
Do we need to change the pins?
This is serious and expensive surgery and I am seeking advise as to how
other countries have dealt with this problem.
I understand that Australia in the only country that uses the ultrasonic
test.
Grob are happy to supply the new pin assemblies, but is it really
necessary
if the old ones have a 3000 hour safe history.
Any help appreciated, Bob.
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Guest
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| Posted: Wed Mar 25, 2009 11:59 am Post subject: Re: Grob 109 wing pins |
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On Mar 25, 9:18 am, Gilbert Smith <nos...@nospam.com> wrote:
| Quote: | Hello Rod,
I use a home-spun device which clamps to the wingtip just outboard of
the aileron. I have fitted two small wheels to this so that the wing
can be moved into position while vertical. When rigging you then have
to lift the tip with the device still fitted, go flat, and push it
home. A fold-down prop then supports the tip while I engage the main
and leading edge pins.
It also has an extension of about a foot out from the trailing edge to
help with the aft c of g at the tip. I rig and derig alone every day,
and the device has been in use for 25 years.
My attempt at a trolley and hydraulic jack was a failure because I
lost the "feel" required to locate the spar pin.
If you like I can email photos of both.
Regards,
"Gilbert"
Rod Swallow <rsswal...@bigpond.com> wrote:
Dear Gilbert
I am a Grob 109b owner in Australia. Currently I am trying to assemble a
trolley to make wing folding easier as I want to be able to rig it on my
own. Do you have any suggestions?
Thanking you
Rod Swallow
At 16:13 07 February 2009, Gilbert Smith wrote:
In the UK we replace them on the G109B at 3000 hours irrespective,
together with a few other mods which come up at that time. The new
pins have a better taper, handy if you rig frequently as I do, and are
replaceable without the major surgery reuired on the first occasion.
- Colin.
"Bob Jenneson" wrote:
Hi,
I am seeking advise on the replacement of the wing pins fitted in
the
end of the spars on Grob 109 and 109B.
This also applies to the Grob Twin Astir.
A brief history.
These pins are welded to a plate that is glassed into the wing spar end
during manufacture. It was found out at a later time that some of these
assemblies were prone to cracking around the welds and required
replacement
if found to be cracked.
In Australia we are required to "ultrasonic " test these pins
every
500
hours ( AD 370 )
If tested 'OK' we keep flying.
We now have two aircraft that have 3000 hours each ( Life extension
time
)
and no cracks found.
Do we need to change the pins?
This is serious and expensive surgery and I am seeking advise as to how
other countries have dealt with this problem.
I understand that Australia in the only country that uses the ultrasonic
test.
Grob are happy to supply the new pin assemblies, but is it really
necessary
if the old ones have a 3000 hour safe history.
Any help appreciated, Bob.- Hide quoted text -
- Show quoted text -
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Dear Gilbert
I would really appreciate the photos as it sounds like a much simpler
system than the one I was considering.
Thanking you
Rod Swallow |
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