Nose Strut O-Ring Was Bad...

Last week, in -22 temperatures, our nose gear drooped all the way to
the stop. Later, we were able to put some down pressure on the
stabilator (in the hangar) and bring it back up a couple of inches,
but made plans to have our A&P look at it.

Yesterday, since he wasn't coming in the shop till afternoon, we
decided to go flying first. My landing in Oskaloosa, IA (KOOA) was
gingerly -- a text book soft field landing, with the nose gear staying
high in the air till almost stopped. The strut stayed up around three
inches all the way to parking. The temperature was about 5 above
zero, and I thought that perhaps this had been a transient problem
that had "fixed itself". (We always hope, no? :-)

Not. Mary's landing back in Iowa City was fine, but the strut again
collapsed to the stop -- so we taxied straight to the shop. My A&P
told me that he could "service" it (basically, add air), but after
some discussion we decided to replace the seals in the strut. He
said that the O-rings were likely old (we hadn't replaced them in the
5 years we've owned Atlas), stiff, and perhaps "rolled", so that even
though lubricating the strut and adding air might do the trick for a
while, it would be a stop-gap measure, at best.

I helped him do it, and it took about an hour. (Of course, he's done
it a million times -- the job would have taken me all day, with
instructions, and I might have killed myself doing it.) But now, the
strut is sitting tall again, with new fluids, O-rings, and air
pressure.

Total: $65. Not bad at all, in aviation terms...

He says that it's SOP to apply brake fluid to the struts of the DC-9s
he services (at his day job) every, single time they park. It's
messy, as a result, but their strut seals rarely need to be replaced.
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

On Feb 8, 8:32 am, "Jay Honeck" wrote:
Last week, in -22 temperatures, our nose gear drooped all the way to
the stop. Later, we were able to put some down pressure on the
stabilator (in the hangar) and bring it back up a couple of inches,
but made plans to have our A&P look at it.

Yesterday, since he wasn't coming in the shop till afternoon, we
decided to go flying first. My landing in Oskaloosa, IA (KOOA) was
gingerly -- a text book soft field landing, with the nose gear staying
high in the air till almost stopped. The strut stayed up around three
inches all the way to parking. The temperature was about 5 above
zero, and I thought that perhaps this had been a transient problem
that had "fixed itself". (We always hope, no? :-)

Not. Mary's landing back in Iowa City was fine, but the strut again
collapsed to the stop -- so we taxied straight to the shop. My A&P
told me that he could "service" it (basically, add air), but after
some discussion we decided to replace the seals in the strut. He
said that the O-rings were likely old (we hadn't replaced them in the
5 years we've owned Atlas), stiff, and perhaps "rolled", so that even
though lubricating the strut and adding air might do the trick for a
while, it would be a stop-gap measure, at best.

I helped him do it, and it took about an hour. (Of course, he's done
it a million times -- the job would have taken me all day, with
instructions, and I might have killed myself doing it.) But now, the
strut is sitting tall again, with new fluids, O-rings, and air
pressure.

Total: $65. Not bad at all, in aviation terms...

He says that it's SOP to apply brake fluid to the struts of the DC-9s
he services (at his day job) every, single time they park. It's
messy, as a result, but their strut seals rarely need to be replaced.

Problem there is the attraction of dust, which then fouls the
scraper ring and eventually gets under the O-ring and abrades it. We
keep ours just wiped off.
The cold weather makes the O-rings shrink and grab the strut
barrel, and then they roll in the groove and because their flexibility
is gone in the cold, they suffer spiral fractures. It's good practice
to replace them regularly. Granville Strut Seal added to the fluid
will sometimes help by swelling the ring slightly and making it a bit
softer.
There are far better O-rings out there now. I wish someone
like McFarlane would come up with an STC'd oleo kit that used
fluorosilicone or EPDM or some other advanced compound rings. Tougher
and with a better temperature range. There are "quad" O-rings
available, too, that would do a better job. In cross-section they look
like a four-leaf clover, so there's more contact area on two places
and they are more flexible, too. Double the sealing capacity, and
resistant to rolling.

Dan

Jay Honeck wrote:

He says that it's SOP to apply brake fluid to the struts of the DC-9s
he services (at his day job) every, single time they park. It's
messy, as a result, but their strut seals rarely need to be replaced.

Interesting as we did just the opposite with exposed cylinders on the
logging equipment I operated many moons ago. Any oil just collected
dust and formed an abrasive slurry that wass very hard on the seals. I
guess most airplanes probably don't pick up that much dirt normally, but
if I operated from a gravel or dirt strip I'd think twice before
oiling the strut cylinder.


Matt

wrote in message
ups.com...
On Feb 8, 8:32 am, "Jay Honeck" wrote:
Last week, in -22 temperatures, our nose gear drooped all the way to
the stop. Later, we were able to put some down pressure on the
stabilator (in the hangar) and bring it back up a couple of inches,
but made plans to have our A&P look at it.

Yesterday, since he wasn't coming in the shop till afternoon, we
decided to go flying first. My landing in Oskaloosa, IA (KOOA) was
gingerly -- a text book soft field landing, with the nose gear staying
high in the air till almost stopped. The strut stayed up around three
inches all the way to parking. The temperature was about 5 above
zero, and I thought that perhaps this had been a transient problem
that had "fixed itself". (We always hope, no? :-)

Not. Mary's landing back in Iowa City was fine, but the strut again
collapsed to the stop -- so we taxied straight to the shop. My A&P
told me that he could "service" it (basically, add air), but after
some discussion we decided to replace the seals in the strut. He
said that the O-rings were likely old (we hadn't replaced them in the
5 years we've owned Atlas), stiff, and perhaps "rolled", so that even
though lubricating the strut and adding air might do the trick for a
while, it would be a stop-gap measure, at best.

I helped him do it, and it took about an hour. (Of course, he's done
it a million times -- the job would have taken me all day, with
instructions, and I might have killed myself doing it.) But now, the
strut is sitting tall again, with new fluids, O-rings, and air
pressure.

Total: $65. Not bad at all, in aviation terms...

He says that it's SOP to apply brake fluid to the struts of the DC-9s
he services (at his day job) every, single time they park. It's
messy, as a result, but their strut seals rarely need to be replaced.

Problem there is the attraction of dust, which then fouls the
scraper ring and eventually gets under the O-ring and abrades it. We
keep ours just wiped off.
The cold weather makes the O-rings shrink and grab the strut
barrel, and then they roll in the groove and because their flexibility
is gone in the cold, they suffer spiral fractures. It's good practice
to replace them regularly. Granville Strut Seal added to the fluid
will sometimes help by swelling the ring slightly and making it a bit
softer.
There are far better O-rings out there now. I wish someone
like McFarlane would come up with an STC'd oleo kit that used
fluorosilicone or EPDM or some other advanced compound rings. Tougher
and with a better temperature range. There are "quad" O-rings
available, too, that would do a better job. In cross-section they look
like a four-leaf clover, so there's more contact area on two places
and they are more flexible, too. Double the sealing capacity, and
resistant to rolling.

Dan

If I had a certified airplane and knew of better O-rings out there, it
wouldn't surprise me if the hangar elves (elfs?) mysteriously installed a
set of the improved O-rings. I, of course, would never do such a thing on a
certified airplane, but mysterious things sometimes happen behind closed
hangar doors.

Fortunately, I have an experimental aircraft and can install whatever
O-rings I want...

KB

.lots of stuff snipped
There are far better O-rings out there now. I wish someone
like McFarlane would come up with an STC'd oleo kit that used
fluorosilicone or EPDM or some other advanced compound rings. Tougher
and with a better temperature range. There are "quad" O-rings
available, too, that would do a better job. In cross-section they look
like a four-leaf clover, so there's more contact area on two places
and they are more flexible, too. Double the sealing capacity, and
resistant to rolling.

Dan


Cherokee strut seals are quad 0-rings (or at least they are square-ish).
Typically they last 20+ years and start to leak fluid. That can continue
for many years. When I replaced all mine, the nose immediately started
leaking. Took 2-4 days to deflate. After a couple of ounces of
Granville, it stopped. Not sure if we bunged up the install or the ring
had a defect. Still up after a year.

Oddly, I thought the new seals would make the struts move more freely.
That was not the case with mine. They still have a healthy amount of
"stick".

Good luck,
Mike

Well..

That's .065 AMU's....

I have always found that having the "naughts" in FRONT of the real
numbers was better than having the "naughts' (0's) AFTER the real
numbers...



Dave


On 8 Feb 2007 07:32:25 -0800, "Jay Honeck" wrote:

Last week, in -22 temperatures, our nose gear drooped all the way to
the stop. Later, we were able to put some down pressure on the
stabilator (in the hangar) and bring it back up a couple of inches,
but made plans to have our A&P look at it.

Yesterday, since he wasn't coming in the shop till afternoon, we
decided to go flying first. My landing in Oskaloosa, IA (KOOA) was
gingerly -- a text book soft field landing, with the nose gear staying
high in the air till almost stopped. The strut stayed up around three
inches all the way to parking. The temperature was about 5 above
zero, and I thought that perhaps this had been a transient problem
that had "fixed itself". (We always hope, no? :-)

Not. Mary's landing back in Iowa City was fine, but the strut again
collapsed to the stop -- so we taxied straight to the shop. My A&P
told me that he could "service" it (basically, add air), but after
some discussion we decided to replace the seals in the strut. He
said that the O-rings were likely old (we hadn't replaced them in the
5 years we've owned Atlas), stiff, and perhaps "rolled", so that even
though lubricating the strut and adding air might do the trick for a
while, it would be a stop-gap measure, at best.

I helped him do it, and it took about an hour. (Of course, he's done
it a million times -- the job would have taken me all day, with
instructions, and I might have killed myself doing it.) But now, the
strut is sitting tall again, with new fluids, O-rings, and air
pressure.

Total: $65. Not bad at all, in aviation terms...

He says that it's SOP to apply brake fluid to the struts of the DC-9s
he services (at his day job) every, single time they park. It's
messy, as a result, but their strut seals rarely need to be replaced.

On 8 Feb 2007 07:32:25 -0800, "Jay Honeck" wrote:

I helped him do it, and it took about an hour.

And if you hadn't helped him, it might have taken, what? a half-hour?
:-))


--ron

And if you hadn't helped him, it might have taken, what? a half-hour?
:-))

Probably.

Actually, as I've gotten more experience (I'm into my 9th year of
aircraft ownership now -- dang, how did THAT happen?) I've grown more
competent at helping my A&P.

Mostly that means I now know when to stay the hell out of his way...

;-)
--
Jay Honeck
Iowa City, IA
Pathfinder N56993
www.AlexisParkInn.com
"Your Aviation Destination"

"Jay Honeck" wrote in message
ups.com...
And if you hadn't helped him, it might have taken, what? a half-hour?
:-))

Probably.

Actually, as I've gotten more experience (I'm into my 9th year of
aircraft ownership now -- dang, how did THAT happen?) I've grown more
competent at helping my A&P.

Mostly that means I now know when to stay the hell out of his way...

;-)

Mostly that means always. :~o

On 9 Feb 2007 19:36:01 -0800, "Jay Honeck" wrote:

And if you hadn't helped him, it might have taken, what? a half-hour?
:-))

Probably.

Actually, as I've gotten more experience (I'm into my 9th year of
aircraft ownership now -- dang, how did THAT happen?) I've grown more
competent at helping my A&P.

Mostly that means I now know when to stay the hell out of his way...

;-)

I suppose it's a matter of interest and skills in doing that sort of thing.
I've had my airplane since 1976 and try to stay close when it's being
worked on. So I've seen a lot and retained some. But I've not been
interested in picking up tools.

I've changed a tire tube once; and I've also replaced a landing light. I
won't do either again unless the necessity presents itself as it did those
times.



--ron