Tost release failure

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

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

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.

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 |

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.

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

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

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

‘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.

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.