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planejim(at)bellsouth.net
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 Posted: Thu Oct 05, 2006 5:29 pm Post subject: 601 Main Gear |
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Listers,
This is primarily for those operating the OLD type bungee gear on HDs and
HDS'. Mine are 10 years old 531 hours with 730 landings. I have never
operated off of grass, well, some taxiing on grass.
I have been working on one of my R/H Main Gear on my 601HD. I removed the
gear to add some gussets at the strut to fork attach plate juncture since
some folks have had failure at that point. The plates on my main gear are
the small .125" thick ones with just four bolt holes attaching the fork.
Upon disassembly I was shocked to find the bungees in pretty bad shape. The
plate in top of the wing was still riding down tight, flush, like the
bungees were still tight. This was supposed to be an indication that the
bungees were still in good shape. I seem to remember someone saying that
everything is OK until you have a 5/8" gap. I noticed some fraying of the
outer covering at the bottom but it didn't look very bad. Where the bungees
bend over the crosstube ( the tube that slides up and down in the extrusions
inside the gear box ) the outer covering was completely gone and about 25%
of the rubber bands were broken, ( I think this is because the bungees make
a real tight bend there ) if you can believe it with the plate still tight
down on top of the wing.
I didn't find any cracks in the welds. I made four gussets, about 1 1/4"
high of .065 Chromoly ( the same thickness as the strut wall ) and welded
them at 90 degrees to the strut, with two at the forward flange and two at
the aft flange between the bolt holes. I had to slightly open up the top
cutouts of the wheel fairing when I reinstalled the gear to clear the
gussets.
I also added a nylon wear block at the bottom of the strut. The top was
still a snug fit ( even though I couldn't get much grease it there because
the plates was so tight down on the top of the wing ) and there was a few
tousanths wear at the bottom aluminun wear plate. Note that my gear did not
have the nylon wear plates when I built this plane. I had to add one to the
bottom of the nose gear a couple of hundred hours back. That is is the high
wear area. I do keep it well greased too.
The big surprise was when I put the weight of the airplane on the new
bungees. ( Note that I always believed that the original 1080 bungees were
too stiff ). With the new bungees ( 1080 purchased from A/C Spruce last
week ) there is now approx. a 3/16" gap under the plate on top of the wing
on the R/H side. I can grasp the right wing tip and actually make the plate
move up and down. Never could make it do that with the old bungees. Both the
old and new bungee packaging stated 1080, so I don't know what the
difference is.
I can't wait until I get the opportunity to do the left Main Gear so that I
have an airplane that actually taxiis on the bungees rather that one that is
stiff as a board.
So, if you have one of the older 601's you might keep an eye on the gear!
Jim Hoak 601HD - Rotax 912UL - 532 hours - 732 landings.
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webmaster(at)upac.ca
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| Posted: Fri Oct 06, 2006 4:16 am Post subject: 601 Main Gear |
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A friend of mine recently changed one side of his main gear on a 601HD with new 1080 bungies and noticed a gap on the top plate where there was none before. Seems to me that either the new bungies are a bit longer or perhaps softer (stretching) to account for the gap. Maybe a change in the manufacturing process? Who makes these anyways?
Trev Page
C-IDUS 601HD R912
On Oct 5, 2006, at 9:28 PM, <planejim(at)bellsouth.net (planejim(at)bellsouth.net)> <planejim(at)bellsouth.net (planejim(at)bellsouth.net)> wrote:
[quote]--> Zenith-List message posted by: <planejim(at)bellsouth.net (planejim(at)bellsouth.net)>
Listers,
This is primarily for those operating the OLD type bungee gear on HDs and HDS'. Mine are 10 years old 531 hours with 730 landings. I have never operated off of grass, well, some taxiing on grass.
I have been working on one of my R/H Main Gear on my 601HD. I removed the gear to add some gussets at the strut to fork attach plate juncture since some folks have had failure at that point. The plates on my main gear are the small .125" thick ones with just four bolt holes attaching the fork. Upon disassembly I was shocked to find the bungees in pretty bad shape. The plate in top of the wing was still riding down tight, flush, like the bungees were still tight. This was supposed to be an indication that the bungees were still in good shape. I seem to remember someone saying that everything is OK until you have a 5/8" gap. I noticed some fraying of the outer covering at the bottom but it didn't look very bad. Where the bungees bend over the crosstube ( the tube that slides up and down in the extrusions inside the gear box ) the outer covering was completely gone and about 25% of the rubber bands were broken, ( I think this is because the bungees make a real tight bend there ) if you can believe it with the plate still tight down on top of the wing.
I didn't find any cracks in the welds. I made four gussets, about 1 1/4" high of .065 Chromoly ( the same thickness as the strut wall ) and welded them at 90 degrees to the strut, with two at the forward flange and two at the aft flange between the bolt holes. I had to slightly open up the top cutouts of the wheel fairing when I reinstalled the gear to clear the gussets.
I also added a nylon wear block at the bottom of the strut. The top was still a snug fit ( even though I couldn't get much grease it there because the plates was so tight down on the top of the wing ) and there was a few tousanths wear at the bottom aluminun wear plate. Note that my gear did not have the nylon wear plates when I built this plane. I had to add one to the bottom of the nose gear a couple of hundred hours back. That is is the high wear area. I do keep it well greased too.
The big surprise was when I put the weight of the airplane on the new bungees. ( Note that I always believed that the original 1080 bungees were too stiff ). With the new bungees ( 1080 purchased from A/C Spruce last week ) there is now approx. a 3/16" gap under the plate on top of the wing on the R/H side. I can grasp the right wing tip and actually make the plate move up and down. Never could make it do that with the old bungees. Both the old and new bungee packaging stated 1080, so I don't know what the difference is.
I can't wait until I get the opportunity to do the left Main Gear so that I have an airplane that actually taxiis on the bungees rather that one that is stiff as a board.
So, if you have one of the older 601's you might keep an eye on the gear!
Jim Hoak 601HD - Rotax 912UL - 532 hours - 732 landings.
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larry(at)macsmachine.com
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| Posted: Fri Oct 06, 2006 9:14 am Post subject: 601 Main Gear |
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Jim and Trevor,
The added nylon bearing provides considerable relief to the strut
dragging thru the wing aluminum and I'd suppose this freedom of movement
is responsible for the gap seen at the top cap above the wing. I
started with nylon bearings top and bottom and a 3/16" gap. There is a
lot of cushion and slide in the struts when landing too.
Pleased to hear of someone who's found a limit in hours for these
things. (knowing it's an estimate, but still good info)
Larry McFarland - 601HDS at www.macsmachine.com
do not archive
Trevor Page wrote:
| Quote: | A friend of mine recently changed one side of his main gear on a 601HD
with new 1080 bungies and noticed a gap on the top plate where there
was none before. Seems to me that either the new bungies are a bit
longer or perhaps softer (stretching) to account for the gap. Maybe a
change in the manufacturing process? Who makes these anyways?
Trev Page
C-IDUS 601HD R912
>
> The big surprise was when I put the weight of the airplane on the new
> bungees. ( Note that I always believed that the original 1080 bungees
> were too stiff ). With the new bungees ( 1080 purchased from A/C
> Spruce last week ) there is now approx. a 3/16" gap under the plate
> on top of the wing on the R/H side. I can grasp the right wing tip
> and actually make the plate move up and down. Never could make it do
> that with the old bungees. Both the old and new bungee packaging
> stated 1080, so I don't know what the difference is.
>
> I can't wait until I get the opportunity to do the left Main Gear so
> that I have an airplane that actually taxiis on the bungees rather
> that one that is stiff as a board.
>
> So, if you have one of the older 601's you might keep an eye on the gear!
>
> Jim Hoak 601HD - Rotax 912UL - 532 hours - 732 landings.
|
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planejim(at)bellsouth.net
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| Posted: Sun Oct 08, 2006 5:14 am Post subject: 601 Main Gear |
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Trevor and Listers,
This is a follow up to some previous info I sent out. I've done some further investigation on the 601HD main gear ( well the nose gear too ) bungees. The ones received with the kit from ZAC back in 1995 were 1080HD manufactured by Superior. The ones recently received from A/C Spruce ( probably also manufactured by Superior but not confirmed - only Spruces P/N tag on them with no manufactruer identified ) were 1080 only ( no HD after the 1080 ) and the new ones actually measured approximately 1" longer when the loops were laid side by side. I just did that measurement with the other new bungees I have here that I haven't used yet. Don't ask me why I didn't measure them before installing the one's on my right main gear. Too dumb I guess! That probably accounts for the retainer plate now having space under it on top of the wing with the new bungees installed.
Do you supose the 1080 HD's received with the kit were the wrong ones? These bungees are also approved for certified aircraft, thus must meet certain manufacturing standards. Even though the ones I removed at 10 years, 730 landings and 531 hours, were in bad shape, the plate on top of the wing was down tight. I always believed they were too stiff.
I guess what I'm warning you about is, if you have bungees identified as 1080HD I would consider getting the new ones without the HD if you haven't actually installed them yet.
Jim Hoak
[quote] ---
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mfothergill(at)sympatico.
Guest
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| Posted: Sun Oct 08, 2006 10:49 am Post subject: 601 Main Gear |
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Hi;
The spare bungees that I have on hand for my CH-601HDS are Superioring
1080HD, manufactured by SBC Industies Inc. These are the same as
originally supplied with the kit. So far, after 10 years I have only
replaced one bungee on each side. Meanwhile my friend has had to replace
the nosegear bungeee several times.
Mike
CH-601HDS C-FRND 1000hrs+
UHS Spinners
Jim Hoak wrote:
[quote] Trevor and Listers,
This is a follow up to some previous info I sent out. I've done some
further investigation on the 601HD main gear ( well the nose gear too )
bungees. The ones received with the kit from ZAC back in 1995 were
1080HD manufactured by Superior. The ones recently received from A/C
Spruce ( probably also manufactured by Superior but not confirmed - only
Spruces P/N tag on them with no manufactruer identified ) were 1080 only
( no HD after the 1080 ) and the new ones actually measured
approximately 1" longer when the loops were laid side by side. I just
did that measurement with the other new bungees I have here that I
haven't used yet. Don't ask me why I didn't measure them before
installing the one's on my right main gear. Too dumb I guess! That
probably accounts for the retainer plate now having space under it on
top of the wing with the new bungees installed.
Do you supose the 1080 HD's received with the kit were the wrong ones?
These bungees are also approved for certified aircraft, thus must meet
certain manufacturing standards. Even though the ones I removed at 10
years, 730 landings and 531 hours, were in bad shape, the plate on top
of the wing was down tight. I always believed they were too stiff.
I guess what I'm warning you about is, if you have bungees identified as
1080HD I would consider getting the new ones without the HD if you
haven't actually installed them yet.
Jim Hoak
---
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