Tost release failure

[Bill D]

For the first time in my life I heard a 1st person story of a release failure.
The story follows:

The glider, an ASK-21, was jerked forward by the tug so the front wheel rolled over the rope at the start of an aero tow. The slack was then taken out and the tow was launched without inspecting the hook and release. The working theory is that this somehow cocked the ring set in the hook so it failed to release even with pilot and passenger pulling on the release knobs. The pilot eventually got a successful release by yawing the glider strongly.

AFAIK, the hook in question had not reached it's 2000 tow life limit nor is there any history of repair or maintenance in the hook area. There had been cases where a commercial operator had insisted on providing tows using a chain link instead of a Tost ring set. We think it possible this had damaged the hook in some way.

Operationally, should a roll-over happen again, we will release the rope and re-attach before proceeding with a launch. The release will get special attention in the annual inspection later this month. No chain links will be allowed for any purpose.

[Tim Mara]

There are specific notes on my website and on TOST website warning of
possible damages due to the use of non-approved or badly worn Tost Tow rings
http://www.wingsandwheels.com/page30.htm
tim--
Please visit the Wings & Wheels website at www.wingsandwheels.com


"Bill D" > wrote in message
...
For the first time in my life I heard a 1st person story of a release
failure.
The story follows:

The glider, an ASK-21, was jerked forward by the tug so the front wheel
rolled over the rope at the start of an aero tow. The slack was then taken
out and the tow was launched without inspecting the hook and release. The
working theory is that this somehow cocked the ring set in the hook so it
failed to release even with pilot and passenger pulling on the release
knobs. The pilot eventually got a successful release by yawing the glider
strongly.

AFAIK, the hook in question had not reached it's 2000 tow life limit nor is
there any history of repair or maintenance in the hook area. There had been
cases where a commercial operator had insisted on providing tows using a
chain link instead of a Tost ring set. We think it possible this had
damaged the hook in some way.

Operationally, should a roll-over happen again, we will release the rope and
re-attach before proceeding with a launch. The release will get special
attention in the annual inspection later this month. No chain links will be
allowed for any purpose.

[aerodyne]

Not enough information to form an opinion, but I would suspect a worn/
damaged or improper tost ring substitute was used, as opposed to the
hook being defective. If you can't see the stamp on the ring, it is
no good IMO.

[Darryl Ramm]

On Monday, August 20, 2012 7:18:48 AM UTC-7, Bill D wrote:
> For the first time in my life I heard a 1st person story of a release failure.
>
> The story follows:
>
>
>
> The glider, an ASK-21, was jerked forward by the tug so the front wheel rolled over the rope at the start of an aero tow. The slack was then taken out and the tow was launched without inspecting the hook and release. The working theory is that this somehow cocked the ring set in the hook so it failed to release even with pilot and passenger pulling on the release knobs.. The pilot eventually got a successful release by yawing the glider strongly.
>
>
>
> AFAIK, the hook in question had not reached it's 2000 tow life limit nor is there any history of repair or maintenance in the hook area. There had been cases where a commercial operator had insisted on providing tows using a chain link instead of a Tost ring set. We think it possible this had damaged the hook in some way.
>

BTW I'm also aware of a Tost release failing to release due to corrosion within the release, I believe likely a combination of pee-tube spray and lack of proper care and maintenance. Pee tube spray may not be a factor in typicality ASK-21s but I suspect quite a few tow releases get only a cursory look over pre-flight and during the annual inspection.

And on chain-links just say no. Tim's web site is a great resource for Tost stuff.

Darryl

[Bill D]

On Monday, August 20, 2012 7:42:38 PM UTC-6, Darryl Ramm wrote:
> On Monday, August 20, 2012 7:18:48 AM UTC-7, Bill D wrote:
>
> > For the first time in my life I heard a 1st person story of a release failure.
>
> >
>
> > The story follows:
>
> >
>
> >
>
> >
>
> > The glider, an ASK-21, was jerked forward by the tug so the front wheel rolled over the rope at the start of an aero tow. The slack was then taken out and the tow was launched without inspecting the hook and release. The working theory is that this somehow cocked the ring set in the hook so it failed to release even with pilot and passenger pulling on the release knobs. The pilot eventually got a successful release by yawing the glider strongly.
>
> >
>
> >
>
> >
>
> > AFAIK, the hook in question had not reached it's 2000 tow life limit nor is there any history of repair or maintenance in the hook area. There had been cases where a commercial operator had insisted on providing tows using a chain link instead of a Tost ring set. We think it possible this had damaged the hook in some way.
>
> >
>
>
>
> BTW I'm also aware of a Tost release failing to release due to corrosion within the release, I believe likely a combination of pee-tube spray and lack of proper care and maintenance. Pee tube spray may not be a factor in typicality ASK-21s but I suspect quite a few tow releases get only a cursory look over pre-flight and during the annual inspection.
>
>
>
> And on chain-links just say no. Tim's web site is a great resource for Tost stuff.
>
>
>
> Darryl

The particular ASK-21 is fairly new (2000)and in excellent condition. It has always been stored in it's trailer when not being flown by highly qualified pilots. There is no evidence of corrosion anywhere. Records are being checked but indications are the release life limit has not been exceeded.

I participated in the last annual and while the release was checked, it was not subjected to special scrutiny. (It will be this time.) The ring pair was not checked for authenticity but it will be.

[Darryl Ramm]

On Monday, August 20, 2012 8:08:47 PM UTC-7, Bill D wrote:
> On Monday, August 20, 2012 7:42:38 PM UTC-6, Darryl Ramm wrote:
>
> > On Monday, August 20, 2012 7:18:48 AM UTC-7, Bill D wrote:
>
> >
>
> > > For the first time in my life I heard a 1st person story of a release failure.
>
> >
>
> > >
>
> >
>
> > > The story follows:
>
> >
>
> > >
>
> >
>
> > >
>
> >
>
> > >
>
> >
>
> > > The glider, an ASK-21, was jerked forward by the tug so the front wheel rolled over the rope at the start of an aero tow. The slack was then taken out and the tow was launched without inspecting the hook and release. The working theory is that this somehow cocked the ring set in the hook so it failed to release even with pilot and passenger pulling on the release knobs. The pilot eventually got a successful release by yawing the glider strongly.
>
> >
>
> > >
>
> >
>
> > >
>
> >
>
> > >
>
> >
>
> > > AFAIK, the hook in question had not reached it's 2000 tow life limit nor is there any history of repair or maintenance in the hook area. There had been cases where a commercial operator had insisted on providing tows using a chain link instead of a Tost ring set. We think it possible this had damaged the hook in some way.
>
> >
>
> > >
>
> >
>
> >
>
> >
>
> > BTW I'm also aware of a Tost release failing to release due to corrosion within the release, I believe likely a combination of pee-tube spray and lack of proper care and maintenance. Pee tube spray may not be a factor in typicality ASK-21s but I suspect quite a few tow releases get only a cursory look over pre-flight and during the annual inspection.
>
> >
>
> >
>
> >
>
> > And on chain-links just say no. Tim's web site is a great resource for Tost stuff.
>
> >
>
> >
>
> >
>
> > Darryl
>
>
>
> The particular ASK-21 is fairly new (2000)and in excellent condition. It has always been stored in it's trailer when not being flown by highly qualified pilots. There is no evidence of corrosion anywhere. Records are being checked but indications are the release life limit has not been exceeded..
>
>
>
> I participated in the last annual and while the release was checked, it was not subjected to special scrutiny. (It will be this time.) The ring pair was not checked for authenticity but it will be.

Bill, I did not specifically expect corrosion in this case, I'm much more worried by corrosion where pee tubes are involved with higher performance/XC gliders, including in cases where there may be pee-tube vents into the gear well/on the U/C legs or gear doors and stuff spray around in in unpredictable ways (I don't like some style pee tubes that vent near the gear well) or where the pee tube exit is in front of the (CG) release and just does not poke out far enough.


Darryl

[Muttley]

Hi

The initial message mentiones a rollover - problem there is that the tow rope can wind itself around the main wheel axle and tightens up severly when towed in this way. Nothing to do with Tost or other releases. Any Rollover - rope should be released immediatly and checked that above did not occur. Simple

[Eric Munk]

I've seen a few fail to release. All of them were either the result of
using incorrect (homemade, worn, deformed, etc.) rings (see Tost's website,
which has considerable documentation on this), lack of maintenance
(corrosion related to pee tubes, extremely wet fields, and dirt jamming the
moving parts) and even illegal maintenance (involving readjusting the
overcenter to compensate for beak wear, the owner won't be doing that
again!). Also seen a few broken springs under 2000 launches, but these were
due to operators having a different checklist, using the release 6 times
per flight, and only 10.000 actuations are allowed.

Tost failures other than these are pretty rare, and should be brought to
the attention of the manufacturer.


At 14:18 20 August 2012, Bill D wrote:
>For the first time in my life I heard a 1st person story of a release
>failu=
>re. =20
>The story follows:
> =20
>The glider, an ASK-21, was jerked forward by the tug so the front wheel
>rol=
>led over the rope at the start of an aero tow. The slack was then taken
>ou=
>t and the tow was launched without inspecting the hook and release. The
>wo=
>rking theory is that this somehow cocked the ring set in the hook so it
>fai=
>led to release even with pilot and passenger pulling on the release
knobs.
>=
> The pilot eventually got a successful release by yawing the glider
>strongl=
>y. =20
>
>AFAIK, the hook in question had not reached it's 2000 tow life limit nor
>is=
> there any history of repair or maintenance in the hook area. There had
>be=
>en cases where a commercial operator had insisted on providing tows using
>a=
> chain link instead of a Tost ring set. We think it possible this had
>dama=
>ged the hook in some way.
>
>Operationally, should a roll-over happen again, we will release the rope
>an=
>d re-attach before proceeding with a launch. The release will get
special
>=
>attention in the annual inspection later this month. No chain links will
>b=
>e allowed for any purpose.
>

[GM]

On Monday, August 20, 2012 10:18:48 AM UTC-4, Bill D wrote:
> For the first time in my life I heard a 1st person story of a release failure. The story follows: The glider, an ASK-21, was jerked forward by the tug so the front wheel rolled over the rope at the start of an aero tow. The slack was then taken out and the tow was launched without inspecting the hook and release. The working theory is that this somehow cocked the ring set in the hook so it failed to release even with pilot and passenger pulling on the release knobs. The pilot eventually got a successful release by yawing the glider strongly. AFAIK, the hook in question had not reached it's 2000 tow life limit nor is there any history of repair or maintenance in the hook area. There had been cases where a commercial operator had insisted on providing tows using a chain link instead of a Tost ring set. We think it possible this had damaged the hook in some way. Operationally, should a roll-over happen again, we will release the rope and re-attach before proceeding with a launch. The release will get special attention in the annual inspection later this month. No chain links will be allowed for any purpose.

Lets look at the mechanics of things when the glider gets bumped and rolls over the rope: The rope is pulled with an incredible force down- and backwards. The large ring which is held half way inside the rigid cage of the release is reacting against that cage with a huge force, so it is not unreasonable to assume that the entire housing gets deformed plastically. This could possibly allow the position of the small ring in relation to the moving beak to change and it doesn't take a whole lot to pinch in the ring and lock up the entire mechanism.
We had a release failure on a 2-33 after an new member was allowed to hook up the line using the large Tost ring. The line force was enough to make the ring slide up the wedge shaped release hook and lock itself onto it and not letting go even after the release was pulled. I know that these two mechanisms are completely different but it demonstrated how small deformations combined with wedge shaped bodies can result in very strong connections.
In other countries, the tow ropes are much thicker and stronger than the ones used in the US (following the 80-200% rule, which is total B.S. to begine with) but the manufacturer's stipulated weak-link (part of the POH) is right at the double ring. In the desribed scenario, the weak-link would have broken and the whole episode would have not happened.

GM

[Dan Marotta]

Good post.

I always get funny looks when the line crew says, "Open, close... Check
release", and I say, "No, I just checked it when I opened it for hookup. It
may have only one more operation left and I want it to work when I release
the rope in flight."

It should have occured to me that there's a manufacturer specified life
limit (number of tows) and, while a ground release is not as stressful as an
in-flight release, you're still wearing springs and mating surfaces, cables,
etc. Why wear it out with ridiculous, extra operations? Maybe I should
pull my rip cord before getting into the glider to be sure my parachute will
open when I need it... ;->


"Eric Munk" > wrote in message
.com...
> I've seen a few fail to release. All of them were either the result of
> using incorrect (homemade, worn, deformed, etc.) rings (see Tost's
> website,
> which has considerable documentation on this), lack of maintenance
> (corrosion related to pee tubes, extremely wet fields, and dirt jamming
> the
> moving parts) and even illegal maintenance (involving readjusting the
> overcenter to compensate for beak wear, the owner won't be doing that
> again!). Also seen a few broken springs under 2000 launches, but these
> were
> due to operators having a different checklist, using the release 6 times
> per flight, and only 10.000 actuations are allowed.
>
> Tost failures other than these are pretty rare, and should be brought to
> the attention of the manufacturer.
>
>
> At 14:18 20 August 2012, Bill D wrote:
>>For the first time in my life I heard a 1st person story of a release
>>failu=
>>re. =20
>>The story follows:
>> =20
>>The glider, an ASK-21, was jerked forward by the tug so the front wheel
>>rol=
>>led over the rope at the start of an aero tow. The slack was then taken
>>ou=
>>t and the tow was launched without inspecting the hook and release. The
>>wo=
>>rking theory is that this somehow cocked the ring set in the hook so it
>>fai=
>>led to release even with pilot and passenger pulling on the release
> knobs.
>>=
>> The pilot eventually got a successful release by yawing the glider
>>strongl=
>>y. =20
>>
>>AFAIK, the hook in question had not reached it's 2000 tow life limit nor
>>is=
>> there any history of repair or maintenance in the hook area. There had
>>be=
>>en cases where a commercial operator had insisted on providing tows using
>>a=
>> chain link instead of a Tost ring set. We think it possible this had
>>dama=
>>ged the hook in some way.
>>
>>Operationally, should a roll-over happen again, we will release the rope
>>an=
>>d re-attach before proceeding with a launch. The release will get
> special
>>=
>>attention in the annual inspection later this month. No chain links will
>>b=
>>e allowed for any purpose.
>>
>

[kirk.stant]

Finally! I've been refusing to do release checks for years and get the stink-eye everytime. I've tried explaining that if you can hook up, then you have checked as much as you can, but still get people saying "but what if it fails?".

Maybe one of you smart guys out there can explain the logic of a separate release check?

Kirk
66

[Bart[_4_]]

On Aug 24, 10:25*am, "kirk.stant" > wrote:
> Finally! I've been refusing to do release checks for years and get the stink-eye everytime. *I've tried explaining that if you can hook up, then you have checked as much as you can, but still get people saying "but what if it fails?".
> Maybe one of you smart guys out there can explain the logic of a separate release check?

I thought the reason was to verify that the release works under
tension.

Bart

[BobW]

On 8/24/2012 11:25 AM, kirk.stant wrote:
> Finally! I've been refusing to do release checks for years and get the
> stink-eye everytime. I've tried explaining that if you can hook up, then
> you have checked as much as you can, but still get people saying "but what
> if it fails?".
>
> Maybe one of you smart guys out there can explain the logic of a separate
> release check?
>
> Kirk 66
>

The only rationale I was ever able to generate was that functioning under
tension might somehow reveal a difference compared to "dry firing." (Yeah, I
thought the rationale weak!)

That said, when connecting someone I always offer to perform a release check
"because it's generally expected I do so"...and have no issue with pilots
declining the offer (there are a few!).

Happily, with first an HP-14 and then a Zuni, I had my own built-in
excuse to NOT perform a release check, since both types have Dick Schreder's
(dirt simple) retracting design which generally requires verbal hand-holding
from Joe Pilot in order simply to make the connection, even *after* I'd
pre-positioned the release from its retracted position. My rationale with the
Schreder release is it's safer simply to connect and launch then to increase
exposure time on an active runway fiddling *twice* with "a funky release."

Maybe release checks are like your mother's reminders to always wear clean
underwear in case you have a serious accident. What the heck difference does
it make?!? Can you prove it? :-)

Bob - has never contributed to thread creep! - W.

[Martin Gregorie[_5_]]

On Fri, 24 Aug 2012 10:25:49 -0700, kirk.stant wrote:

> Finally! I've been refusing to do release checks for years and get the
> stink-eye everytime. I've tried explaining that if you can hook up,
> then you have checked as much as you can, but still get people saying
> "but what if it fails?".
>
> Maybe one of you smart guys out there can explain the logic of a
> separate release check?
>
On a CG hook you need to check that back-release works. On the hook types
that I understand mechanically (Tost, Ottfur), the back release has
separate springs and moving parts from the tension release.

Its normal in UK clubs to check back release, free drop (CG hooks) and
tension release (all hooks) before the first flight of the day on that
hook. For subsequent flights its assumed that the hook works since it was
tested by the last flight.


--
martin@ | Martin Gregorie
gregorie. | Essex, UK
org |

[Ken Fixter[_2_]]

why not use the wheel brake at start of launch to reduce the chance of
over running the tow rope, it has been my practice for many years as I had
an unable to releas on a winch launch not a nice experience.
KF

At 17:57 24 August 2012, BobW wrote:
>On 8/24/2012 11:25 AM, kirk.stant wrote:
>> Finally! I've been refusing to do release checks for years and get the
>> stink-eye everytime. I've tried explaining that if you can hook up,
then
>> you have checked as much as you can, but still get people saying "but
>what
>> if it fails?".
>>
>> Maybe one of you smart guys out there can explain the logic of a
separate
>> release check?
>>
>> Kirk 66
>>
>
>The only rationale I was ever able to generate was that functioning under
>tension might somehow reveal a difference compared to "dry firing."
(Yeah,
>I
>thought the rationale weak!)
>
>That said, when connecting someone I always offer to perform a release
>check
>"because it's generally expected I do so"...and have no issue with pilots
>declining the offer (there are a few!).
>
>Happily, with first an HP-14 and then a Zuni, I had my own built-in
>excuse to NOT perform a release check, since both types have Dick
>Schreder's
>(dirt simple) retracting design which generally requires verbal
>hand-holding
>from Joe Pilot in order simply to make the connection, even *after* I'd
>pre-positioned the release from its retracted position. My rationale with
>the
>Schreder release is it's safer simply to connect and launch then to
>increase
>exposure time on an active runway fiddling *twice* with "a funky
release."
>
>Maybe release checks are like your mother's reminders to always wear clean

>underwear in case you have a serious accident. What the heck difference
>does
>it make?!? Can you prove it? :-)
>
>Bob - has never contributed to thread creep! - W.
>

[Andreas Maurer]

On Fri, 24 Aug 2012 10:25:49 -0700 (PDT), "kirk.stant"
> wrote:

>Finally! I've been refusing to do release checks for years and get the stink-eye everytime.
>I've tried explaining that if you can hook up, then you have checked as much as you can, but still get people saying "but what if it fails?".
>
>Maybe one of you smart guys out there can explain the logic of a separate release check?


I can.

1. Three weeks ago we had an accident at an airfield close to us where
the pilot was very, very lucky.

He did a winch tow in an ASW-19. The small ring of the tow cable was
not put into the tow hook, but jammed between the Tost release and its
steel attachement structure, creating an extremely strong and
permanent connection. Mistake of the student pilot who did the hookup.

After the pilot had (thought he had) released at about 1200 ft, he
turned into left downwind. After passing the winch the tow cable went
tense and pulled the ASW-19 into a ballistic arc towards earth - the
emergency cutter on the winch didn't work either.
The pilot estimates that the remaining time till impact was about 5-10
seconds.

Only chance for the pilot was to apply aileron and turn towards the
winch (nose still being pulled into a dive), which fortunately worked.
He flew over the winch at an altitude of about 300 ft and then tried
an extremely tight turn in order to land next to the winch. Just as he
was on final, the tow cable got tangled in some bushes, the ASW-19 got
a nose-down impulse, impacted hard from about 25 ft and was damaged
very badly.
Fortunately, the pilot escaped unhurt - even those old Schleicher
gliders are built incredibly strong.

Time from first inkling of the problem till impact 37 seconds.
Time from noticing the problem (rapide nose-down impulse) till
possible bail-out, estimated by the pilot: None. Bailout not possible.


A release check would have prevented this accident (of course, the
next hookup might have resulted in the same mistake...).


2. I know of a number of incidents where it was possible to hook up
the tow cable, but release failed when it was attempted to release the
cable under tension (on of these cases happened to me in a Ka-8 when I
was a student pilot, fortunately the back release worked). Usual cause
was wrong ring on the tow cable and mechanical prblem in the glider
concerning the control cable to the Tost release.


Lections learned:
If you are the one who's doing the hookup:
- LOOK at the tow release when you put the ring in
- Check the ring if it fits perfectly (it should have just a little
play)
- Check the release mechanism under tension

- Check the emergency release of the winch. Often. We checked ours
imediately after we heard about the accident, and only one of two
emergency cutters worked (the other was stopped by very little dirt
that had collected in the mechanism during the last 6 months). We were
quite surprised how little dirt it takes to block the cutter (ours has
got a force of about one ton to cut our steel cable).

And, of course
- Never, never use rings that are not approved by Tost
- Never, never mess with a Tost release






Cheers
Andreas

[Tom Claffey]

No amount of release checking will avoid a wrongly hooked on rope.
Standard reply is:
"My release was checked yesterday"




10:25:49 -0700 (PDT), "kirk.stant"
> wrote:At 02:14 25 August 2012, Andreas Maurer wrote:
>On Fri, 24 Aug 2012
>
>>Finally! I've been refusing to do release checks for years and get the
>stink-eye everytime.
>>I've tried explaining that if you can hook up, then you have checked as
>much as you can, but still get people saying "but what if it fails?".
>>
>>Maybe one of you smart guys out there can explain the logic of a
separate
>release check?
>
>
>I can.
>
>1. Three weeks ago we had an accident at an airfield close to us where
>the pilot was very, very lucky.
>
>He did a winch tow in an ASW-19. The small ring of the tow cable was
>not put into the tow hook, but jammed between the Tost release and its
>steel attachement structure, creating an extremely strong and
>permanent connection. Mistake of the student pilot who did the hookup.
>
>After the pilot had (thought he had) released at about 1200 ft, he
>turned into left downwind. After passing the winch the tow cable went
>tense and pulled the ASW-19 into a ballistic arc towards earth - the
>emergency cutter on the winch didn't work either.
>The pilot estimates that the remaining time till impact was about 5-10
>seconds.
>
>Only chance for the pilot was to apply aileron and turn towards the
>winch (nose still being pulled into a dive), which fortunately worked.
>He flew over the winch at an altitude of about 300 ft and then tried
>an extremely tight turn in order to land next to the winch. Just as he
>was on final, the tow cable got tangled in some bushes, the ASW-19 got
>a nose-down impulse, impacted hard from about 25 ft and was damaged
>very badly.
>Fortunately, the pilot escaped unhurt - even those old Schleicher
>gliders are built incredibly strong.
>
>Time from first inkling of the problem till impact 37 seconds.
>Time from noticing the problem (rapide nose-down impulse) till
>possible bail-out, estimated by the pilot: None. Bailout not possible.
>
>
>A release check would have prevented this accident (of course, the
>next hookup might have resulted in the same mistake...).
>
>
>2. I know of a number of incidents where it was possible to hook up
>the tow cable, but release failed when it was attempted to release the
>cable under tension (on of these cases happened to me in a Ka-8 when I
>was a student pilot, fortunately the back release worked). Usual cause
>was wrong ring on the tow cable and mechanical prblem in the glider
>concerning the control cable to the Tost release.
>
>
>Lections learned:
>If you are the one who's doing the hookup:
>- LOOK at the tow release when you put the ring in
>- Check the ring if it fits perfectly (it should have just a little
>play)
>- Check the release mechanism under tension
>
>- Check the emergency release of the winch. Often. We checked ours
>imediately after we heard about the accident, and only one of two
>emergency cutters worked (the other was stopped by very little dirt
>that had collected in the mechanism during the last 6 months). We were
>quite surprised how little dirt it takes to block the cutter (ours has
>got a force of about one ton to cut our steel cable).
>
>And, of course
>- Never, never use rings that are not approved by Tost
>- Never, never mess with a Tost release
>
>
>
>
>
>
>Cheers
>Andreas
>
>

[Andy[_1_]]

On Friday, August 24, 2012 10:25:49 AM UTC-7, kirk.stant wrote:
> Finally! I've been refusing to do release checks for years and get the stink-eye everytime. I've tried explaining that if you can hook up, then you have checked as much as you can, but still get people saying "but what if it fails?".
>
>
>
> Maybe one of you smart guys out there can explain the logic of a separate release check?
>
>
>
> Kirk
>
> 66

[Chris Nicholas[_2_]]

‘No amount of release checking will avoid a wrongly hooked on rope.
Standard reply is: "My release was checked yesterday" .’

It can do. If the ring is wrongly inserted, then all three checks are likely to expose it, which ever us done first: free drop, back release, and under tension.

These will also catch other things that may not have applied “yesterday” – different (and now wrong) ring, or damaged ring, or damage to part of the release or the cable mechanism that still allows hook up to some extent but precludes release when needed. There have been examples of all these over the years, hence the development of the three checks. Not doing them is volunteering to have some holes in the Swiss cheese.

Chris N.

[Dan Marotta]

I volunteer.


"Chris Nicholas" > wrote in message
...
‘No amount of release checking will avoid a wrongly hooked on rope.
Standard reply is: "My release was checked yesterday" .’

It can do. If the ring is wrongly inserted, then all three checks are likely
to expose it, which ever us done first: free drop, back release, and under
tension.

These will also catch other things that may not have applied “yesterday” –
different (and now wrong) ring, or damaged ring, or damage to part of the
release or the cable mechanism that still allows hook up to some extent but
precludes release when needed. There have been examples of all these over
the years, hence the development of the three checks. Not doing them is
volunteering to have some holes in the Swiss cheese.

Chris N.

[GC[_2_]]

No.

No matter how many or what sort of test, in the end you take off
attached to a rope whose ability to be released can't been checked.

GC


On 27/08/2012 10:00, Chris Nicholas wrote:
> ‘No amount of release checking will avoid a wrongly hooked on rope.
> Standard reply is: "My release was checked yesterday" .’
>
> It can do. If the ring is wrongly inserted, then all three checks are likely to expose it, which ever us done first: free drop, back release, and under tension.
>
> These will also catch other things that may not have applied “yesterday” – different (and now wrong) ring, or damaged ring, or damage to part of the release or the cable mechanism that still allows hook up to some extent but precludes release when needed. There have been examples of all these over the years, hence the development of the three checks. Not doing them is volunteering to have some holes in the Swiss cheese.
>
> Chris N.
>

[[email protected]]

On Friday, August 24, 2012 1:25:49 PM UTC-4, kirk.stant wrote:
> Finally! I've been refusing to do release checks for years and get the stink-eye everytime. I've tried explaining that if you can hook up, then you have checked as much as you can, but still get people saying "but what if it fails?". Maybe one of you smart guys out there can explain the logic of a separate release check? Kirk 66

Your logic seems fine if you are flying a glider with a Tost hook that you must open in order to connect the tow rope.
But- you may be teaching the line crew not to doa check which may appy to other gliders.
Examples:
1)Tost Hook with back release can be connected by someone who knows how without the pilot pulling the knob. What if the release cable is broken or jammed?
2) Schweizer hooks are easily hooked up without pulling the knob. Same question about cable.
3) Some hooks are externally operated to hook up. 1-35, HP series, others I don't know about. Verifying functionality would seem to be wise.

I happen to tow out to the line on a rope. Releasing acts as my functional test and I don't do another at launch. I encourage our pilots to do the same to save a bit of time at launch, but ask them to tell the line person that the release check has been done.
FWIW
UH

[kirk.stant]

"I encourage our pilots to do the same to save a bit of time at launch, but ask them to tell the line person that the release check has been done. FWIW UH"

Hank, I also usually tow out behind a golf cart, and that hookup/release serves as my release check. On my own ship, with a nose tost, I am comfortable that the hookup process (with rattle check) is sufficient. I will defer to more experienced pilots when it comes to checking CG/back-release hooks. I also tell the line that the check has already been done.

Oddly, my two release failures in over 2000 hrs have both been Schweizers: A PTT in a 2-32 when the release arm didn't seat all the way due to some mud on it and resulted in a surprise PTT at barely 200' - I was in the RCP giving a ride and didn't check the altimeter - but the result was a rapid 180 and return to the launch point for a second (successful) flight; the other was a jammed release when a tost ring was used on a Schweizer hook (2-33) - a practice since discontinued, fortunately - and the little ring somehow jammed the release during the tow. Solved by getting some slack in the line, but the first time I tried to release the knob didn't move at all! On both those occasions a release check was performed and passed. So perhaps my point of view is a bit jaundiced ;^)

Cheers,

Kirk
66

[Dan Marotta]

That's a very good point about hooking up the Tost (belly hook) without
pulling the cable. The line crews where I fly now do not know that you can
do that so the hookup always includes: "Open", "Close", "Check". Since I
know the rope was attached in that fashion, I decline the check. If I'm
hooking up myself before getting strapped in (no line crew) then I'll check.


"kirk.stant" > wrote in message
...
"I encourage our pilots to do the same to save a bit of time at launch, but
ask them to tell the line person that the release check has been done. FWIW
UH"

Hank, I also usually tow out behind a golf cart, and that hookup/release
serves as my release check. On my own ship, with a nose tost, I am
comfortable that the hookup process (with rattle check) is sufficient. I
will defer to more experienced pilots when it comes to checking
CG/back-release hooks. I also tell the line that the check has already been
done.

Oddly, my two release failures in over 2000 hrs have both been Schweizers: A
PTT in a 2-32 when the release arm didn't seat all the way due to some mud
on it and resulted in a surprise PTT at barely 200' - I was in the RCP
giving a ride and didn't check the altimeter - but the result was a rapid
180 and return to the launch point for a second (successful) flight; the
other was a jammed release when a tost ring was used on a Schweizer hook
(2-33) - a practice since discontinued, fortunately - and the little ring
somehow jammed the release during the tow. Solved by getting some slack in
the line, but the first time I tried to release the knob didn't move at all!
On both those occasions a release check was performed and passed. So
perhaps my point of view is a bit jaundiced ;^)

Cheers,

Kirk
66

[Surge]

On Saturday, 25 August 2012 04:14:20 UTC+2, Andreas Maurer wrote:
> On Fri, 24 Aug 2012 10:25:49 -0700 (PDT), "kirk.stant"
> Snip
>
> He did a winch tow in an ASW-19. The small ring of the tow cable was
> not put into the tow hook, but jammed between the Tost release and its
> steel attachement structure, creating an extremely strong and
> permanent connection. Mistake of the student pilot who did the hookup.
>
> Snip
>
> - Check the ring if it fits perfectly (it should have just a little
> play)
>
> Snip
>
> Cheers
>
> Andreas

The club I fly at do the three checks for the CG hook for winch launching and a single tension release check for aero tows on the nose hook.

What I'd like to highlight is that you're the only person in this thread who has mentioned checking for play once the ring is inserted.

We have a standard "rattle check" on hookup.
If the ring does not rattle from side to side once hooked up it is assumed to be jammed from being inserted wrongly and is thus released and reinserted.

Paul