Replacing TOST release at 10K activations

[150flivver]

Those of you with TOST hooks, how do you track the number of times the release is activated? As I understand it, the mechanism has to be rebuilt when it's been exercised 10,000 times due to the main spring getting worn out.

[Kevin Neave[_2_]]

Pretty sure it's in the manual.
(Not sure if it's manual for hook or glider!)

For a club glider assumption is 4 activations per launch, once to hook on
to tow to launchpoint, once to release when at launchpoint, once at start
of launch, once at top of launch.

So hook should be overhauled every 2500 launches or so.

Overhaul of our hooks normally costs 150-200 Euro, so about 0.16 Euro a
launch (2-hooks)

If you don't tow the glider around on the hooks you may be able to make a
case for only 2 activations per launch so saving yourself the vast sum of
0.08 per launch

KN


At 16:23 28 January 2014, 150flivver wrote:
>Those of you with TOST hooks, how do you track the number of times the
>release is activated? As I understand it, the mechanism has to be
rebuilt
>when it's been exercised 10,000 times due to the main spring getting worn
>out.
>

[Dan Marotta]

Another reason why I don't "check" the release before takeoff. I checked it
when I opened and closed it during hookup and will check it again at the top
of the launch. Checking it again before takeoff will probably be the last
time it functions properly and it will fail during the launch and I'll have
to land on tow (because the tug's release will also fail that day). At
today's rate, that's a savings of $1.09/launch!


"Kevin Neave" > wrote in message
...
> Pretty sure it's in the manual.
> (Not sure if it's manual for hook or glider!)
>
> For a club glider assumption is 4 activations per launch, once to hook on
> to tow to launchpoint, once to release when at launchpoint, once at start
> of launch, once at top of launch.
>
> So hook should be overhauled every 2500 launches or so.
>
> Overhaul of our hooks normally costs 150-200 Euro, so about 0.16 Euro a
> launch (2-hooks)
>
> If you don't tow the glider around on the hooks you may be able to make a
> case for only 2 activations per launch so saving yourself the vast sum of
> 0.08 per launch
>
> KN
>
>
> At 16:23 28 January 2014, 150flivver wrote:
>>Those of you with TOST hooks, how do you track the number of times the
>>release is activated? As I understand it, the mechanism has to be
> rebuilt
>>when it's been exercised 10,000 times due to the main spring getting worn
>>out.
>>
>

[K]

On Tuesday, January 28, 2014 9:23:47 AM UTC-7, 150flivver wrote:
> Those of you with TOST hooks, how do you track the number of times the release is activated? As I understand it, the mechanism has to be rebuilt when it's been exercised 10,000 times due to the main spring getting worn out..

Most Flight Manuals will defer to the Manufacturers recommendation for a particular component (Look at your seatbelts). You understand correctly that it is 10,000 actuation,s or 2000 launches (which most of us will never get to) . The manufacturer also recommends the release be sent in every 4 years.. There is also an Advisory Circular that addresses this. Many of the well known glider maintenance shops in the US like to see no more than 10 years in service before replacement. I tend to agree with this. In many ships they are a pain to get to and do not get cleaned or lubed very often. Also, there is some preload on the main spring so frequent service/replacement is not a bad call. I just bought a late model ship with less than 200 flights on it and I am in the process of replacing all the life limit parts. The release (CG only) was packed with dirt and corroded. While exchanging the release I also had access to the forward gear pivot which is another area that is not usually serviced due to the difficult access. Keep track of your cycles but also take a good look at the release every chance you get.

[Eric Munk]

We've used Tost's previous recommendation to overhaul at 2,000 launches as
a guide and have put this in our maintenance program. We've had a spring
failure on a release that inadvertently did 2,300 launches.

[Bob Kuykendall]

On Tuesday, January 28, 2014 9:16:06 AM UTC-8, Dan Marotta wrote:
> ...Checking it again before takeoff will probably be the last
> time it functions properly and it will fail during the launch and I'll have
> to land on tow ...

Dan, the vast majority of Tost E85 nose hook failures are caused by failure of the torsion spring that keeps the hook closed. The result is that the hook will open just fine, it just won't close properly.

Thanks, Bob K.

[Dan Marotta]

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?


"Bob Kuykendall" > wrote in message
...
> On Tuesday, January 28, 2014 9:16:06 AM UTC-8, Dan Marotta wrote:
>> ...Checking it again before takeoff will probably be the last
>> time it functions properly and it will fail during the launch and I'll
>> have
>> to land on tow ...
>
> Dan, the vast majority of Tost E85 nose hook failures are caused by
> failure of the torsion spring that keeps the hook closed. The result is
> that the hook will open just fine, it just won't close properly.
>
> Thanks, Bob K.

[Bob Kuykendall]

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.

[Alan[_6_]]

In article > 150flivver > writes:
>Those of you with TOST hooks, how do you track the number of times the
>release is activated? As I understand it, the mechanism has to be rebuilt
>when it's been exercised 10,000 times due to the main spring getting worn
>out.

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.

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

If I thought that a component in my car (say a spring in the brake system)
had that sort of limited lifetime, I would have bought a different car.

Alan

[Frank Whiteley]

On Wednesday, January 29, 2014 6:17:11 PM UTC-7, Bob Kuykendall wrote:
> 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.

Same thing on CG hook, at least with two up. Pull on rope was not enough for the release to open. On another CG hook, release failure, but this was attributed to wear on one of the shafts. CG hooks get a lot of dirt, water (in come regions), and probably an annual cleaning.

Frank W.

[Dan Marotta]

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.

[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.

[son_of_flubber]

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.

[Eric Munk]

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.
>
>

[Dan Marotta]

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.
>>
>>
>

[[email protected]]

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

[Eric Munk]

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.

[[email protected]]

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.

[Dan Marotta]

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.

[Eric Munk]

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.

[Dan Marotta]

It doesn't look standard to me. It folds up flush when no ring is attached.


"Eric Munk" > wrote in message
...
> 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.
>

[Dan Marotta]

"...and *hopefully* come back safely."

Sheesh!


"Eric Munk" > wrote in message
...
> 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.
>

[Dan Marotta]

Meant for the Aviators segment.

"Dan Marotta" > wrote in message
...
> "...and *hopefully* come back safely."
>
> Sheesh!
>
>
> "Eric Munk" > wrote in message
> ...
>> 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.
>>
>

[[email protected]]

We do offer an exchange program as UH mentioned. If you mail us your release, we will ship you an overhauled release if in stock. We have most in stock and can turn around in a day. Feel free to call and we can tell you current inventory...

http://wingsandwheels.com/page30.htm

Everything is explained on the link above, so you may not even miss a weekend of flying.

Garret Willat
Wings and Wheels