Replacing TOST release at 10K activations

I guess I could also examine one closely and try to figure it out!


"Bob Kuykendall" wrote in message
...
On Wednesday, January 29, 2014 3:36:56 PM UTC-8, Dan Marotta wrote:

So, what's the real test, Bob? Would simply giving it a good tug after
hookup disclose a failure? Or would it simply not close over the ring,
once
installed by the wing runner? I have only a CG hook - wouldn't it suffer
the same failure mode?

I'm sorry, I don't know the answer to that one.

The one failure I was directly involved with was where one side of the
spring had broken, but the other side was intact. The result was that the
hook appeared to function correctly, but it sprung open as soon as the
towplane powered up. JJ can probably tell you more about this.

Bob K.

On Thursday, January 30, 2014 12:02:14 AM UTC-7, Alan wrote:


Somewhat in jest, one is tempted to ask if hooking the release handle out

when you release, so it stays pulled until you are ready to hook up next time

would save the operating cycle of the spring.
Alan,
I hope this is in jest. If you hold the release open you are increasing the load on the spring. It has some preload when it when closed.

On Thursday, January 30, 2014 2:02:14 AM UTC-5, Alan wrote:

it does seem like a rather severely limited lifetime. They
should be using better parts to make their releases last longer - a lot longer.


10,000 is obviously a NICE ROUND NUMBER that some engineer picked based on the limited facts at hand at the time. It does not mean that the release will fail at 10,001 cycles, or even 20,000 cycles. 10,000 accounts for the inability to foresee the effects of the worse case abuse experienced by the TOST release in the field.

When the service person takes a look at the release after 10,000 cycles, they might as well replace the parts that might someday fail especially if that makes the customer feel that they got something of value for the expense of sending the release in for renewal.

Does anyone know what happens to the old springs? Do they get sent back to TOST and are a random sampling of them then tested until failure? The results of that testing would confirm that 10,000 was a sufficiently short service life. I doubt that TOST makes that evaluation based on uncontrolled failures in the field.

The vast amount of Tost releases get overhauled by Tost themselves, as it
is the only authorized facility to do so in most of Europe. I'd suggest
Tost has a more than fair amount of experience in judging wear and tear on
their releases, also judging by their online publications on release wear,
use and maintenance.

Also, spring failure is not the only limiting factor in lifetime. Spring
tension is too. Compare with Cair, who specifically state spring tension is
to be measured on a yearly basis.

At 23:41 30 January 2014, son_of_flubber wrote:
On Thursday, January 30, 2014 2:02:14 AM UTC-5, Alan wrote:

it does seem like a rather severely limited lifetime. They
should be using better parts to make their releases last longer - a lot
l=
onger.


10,000 is obviously a NICE ROUND NUMBER that some engineer picked based
on
=
the limited facts at hand at the time. It does not mean that the release
wi=
ll fail at 10,001 cycles, or even 20,000 cycles. 10,000 accounts for the
i=
nability to foresee the effects of the worse case abuse experienced by
the
=
TOST release in the field. =20

When the service person takes a look at the release after 10,000 cycles,
th=
ey might as well replace the parts that might someday fail especially if
th=
at makes the customer feel that they got something of value for the
expense=
of sending the release in for renewal.

Does anyone know what happens to the old springs? Do they get sent back
to=
TOST and are a random sampling of them then tested until failure? The
res=
ults of that testing would confirm that 10,000 was a sufficiently short
ser=
vice life. I doubt that TOST makes that evaluation based on uncontrolled
f=
ailures in the field.

Does Tost have an exchange program?


"Eric Munk" wrote in message
...
The vast amount of Tost releases get overhauled by Tost themselves, as it
is the only authorized facility to do so in most of Europe. I'd suggest
Tost has a more than fair amount of experience in judging wear and tear on
their releases, also judging by their online publications on release wear,
use and maintenance.

Also, spring failure is not the only limiting factor in lifetime. Spring
tension is too. Compare with Cair, who specifically state spring tension
is
to be measured on a yearly basis.

At 23:41 30 January 2014, son_of_flubber wrote:
On Thursday, January 30, 2014 2:02:14 AM UTC-5, Alan wrote:

it does seem like a rather severely limited lifetime. They
should be using better parts to make their releases last longer - a lot
l=
onger.


10,000 is obviously a NICE ROUND NUMBER that some engineer picked based
on
=
the limited facts at hand at the time. It does not mean that the release
wi=
ll fail at 10,001 cycles, or even 20,000 cycles. 10,000 accounts for the
i=
nability to foresee the effects of the worse case abuse experienced by
the
=
TOST release in the field. =20

When the service person takes a look at the release after 10,000 cycles,
th=
ey might as well replace the parts that might someday fail especially if
th=
at makes the customer feel that they got something of value for the
expense=
of sending the release in for renewal.

Does anyone know what happens to the old springs? Do they get sent back
to=
TOST and are a random sampling of them then tested until failure? The
res=
ults of that testing would confirm that 10,000 was a sufficiently short
ser=
vice life. I doubt that TOST makes that evaluation based on uncontrolled
f=
ailures in the field.

On Monday, February 3, 2014 10:03:02 AM UTC-5, Dan Marotta wrote:
Does Tost have an exchange program? "Eric Munk" wrote in message ... The vast amount of Tost releases get overhauled by Tost themselves, as it is the only authorized facility to do so in most of Europe. I'd suggest Tost has a more than fair amount of experience in judging wear and tear on their releases, also judging by their online publications on release wear, use and maintenance. Also, spring failure is not the only limiting factor in lifetime. Spring tension is too. Compare with Cair, who specifically state spring tension is to be measured on a yearly basis. At 23:41 30 January 2014, son_of_flubber wrote: On Thursday, January 30, 2014 2:02:14 AM UTC-5, Alan wrote: it does seem like a rather severely limited lifetime. They should be using better parts to make their releases last longer - a lot l= onger. 10,000 is obviously a NICE ROUND NUMBER that some engineer picked based on = the limited facts at hand at the time. It does not mean that the release wi= ll fail at 10,001 cycles, or even 20,000 cycles. 10,000 accounts for the i= nability to foresee the effects of the worse case abuse experienced by the = TOST release in the field. =20 When the service person takes a look at the release after 10,000 cycles, th= ey might as well replace the parts that might someday fail especially if th= at makes the customer feel that they got something of value for the expense= of sending the release in for renewal. Does anyone know what happens to the old springs? Do they get sent back to= TOST and are a random sampling of them then tested until failure? The res= ults of that testing would confirm that 10,000 was a sufficiently short ser= vice life. I doubt that TOST makes that evaluation based on uncontrolled f= ailures in the field..

Yes- quite reasonable. One US supplier maintains some stock of common releases for exchange.
UH

At 15:03 03 February 2014, Dan Marotta wrote:
Does Tost have an exchange program?

Yes. Either opt for having your release itself overhauled (new bolts,
bushings, spings, paint, on-condition replacement of cage or hook), or if
in a hurry opt for an exchange release and get a different one in return
for your old one. Costs a fraction more, but nice if in a hurry. See
www.tost.aero.

The Tost T/N and manual state 10,000 actuations, approximately 2000 launches. In Canada the service overhaul period is enforced as an AD so it's legally required. It should also be noted that this is a longer period than the original one and only applies to hooks that comply with the the T/N. If you have a 1972 Standard Cirrus which has the original hook(s), never overhauled but with only 1700 launches on it the hooks need to be overhauled because they won't conform to the T/N.

For our club gliders we go with the 2000 launches guideline. Overhaul isn't expensive, nor does it take long.

As for buying a different product because you don't like the limited lifetime, in North America that pretty much means going for a Schweizer or Schreder glider.

Hey Mike C,

Isn't that a Schreder release under the nose of your Mini Nimbus?

wrote in message
...
The Tost T/N and manual state 10,000 actuations, approximately 2000
launches. In Canada the service overhaul period is enforced as an AD so it's
legally required. It should also be noted that this is a longer period than
the original one and only applies to hooks that comply with the the T/N. If
you have a 1972 Standard Cirrus which has the original hook(s), never
overhauled but with only 1700 launches on it the hooks need to be overhauled
because they won't conform to the T/N.

For our club gliders we go with the 2000 launches guideline. Overhaul isn't
expensive, nor does it take long.

As for buying a different product because you don't like the limited
lifetime, in North America that pretty much means going for a Schweizer or
Schreder glider.

At 18:03 05 February 2014, Dan Marotta wrote:

Isn't that a Schreder release under the nose of your Mini Nimbus?

I'd say a Tost S72 or SH72 as standard on most early Schempp-Hirth
glassfibre ships.