Gliding risk....

Many years ago I read an old book that was a collection of self submitted/reported stories from glider pilots that had a good outcome from a potentially disaterous situation. I think it was called "Glider accidents that almost happened".
It's a short book, more of a complication of short stories, but provided experiences of others that all people can learn from.

At 13:48 06 December 2019, rudolph stutzmann wrote:
Many years ago I read an old book that was a collection of self
submitted/reported stories from glider pilots that had a good outcome
from
a potentially disaterous situation. I think it was called "Glider
accidents that almost happened".
It's a short book, more of a complication of short stories, but provided
experiences of others that all people can learn from.


It's called Soaring Accidents That Almost Happened and there happens to be
a
copy listed on ebay

On Friday, December 6, 2019 at 3:15:05 AM UTC-8, Terry Slater wrote:
At 22:33 05 December 2019, 2G wrote:
On Thursday, December 5, 2019 at 11:15:08 AM UTC-8, Dave Walsh wrote:
At 16:14 05 December 2019, 2KA wrote:
Yeah, the entire fleet was inspected and repaired as required=20
(years ago),
and SH paid for the whole thing. Gliders built at the factory=20
in Germany
were found to be affected, as well as those built at=20
contractors.

Lynn Alley
"2KA"
=20
You were lucky! I was in a UK owned DuoDiscus based at=20
Sisteron, France, a few years ago. Wing spar de-bonding was=20
discovered at an annual inspection even though the glider had,=20
in theory, been inspected previously, looking for this specific=20
manufacturing fault. SH DECLINED TO PAY FOR THIS REPAIR;=20
if I recall correctly each of us in the 8 man syndicate had to=20
cough up about =C2=A3700.......
Dave Walsh

This is particularly disturbing, raising the question of the
effectiveness
=
of the original inspection method(s). Do the logbook(s) detail how and
when=
this inspection was done? How did the current annual discover the
de-bondi=
ng?

Tom

The inspections were performed with an endoscope, and the full length of
the spar bonding was inspected visually. SH issued a very comprehensive
guide to the process.

Terry

Yeah, I read their TN 396-08 that covered the process. This required cutting several holes in each wing for access by the endoscope. Of course, these holes had to be repaired and refinished. It would have been so much easier and cheaper to have done this inspection by ultrasonic NDT.

Tom

2G wrote on 12/6/2019 1:53 PM:
On Friday, December 6, 2019 at 3:15:05 AM UTC-8, Terry Slater wrote:

Tom

The inspections were performed with an endoscope, and the full length of
the spar bonding was inspected visually. SH issued a very comprehensive
guide to the process.

Terry

Yeah, I read their TN 396-08 that covered the process. This required cutting several holes in each wing for access by the endoscope. Of course, these holes had to be repaired and refinished. It would have been so much easier and cheaper to have done this inspection by ultrasonic NDT.

If the SH wing is constructed like the ASH26E wing, there is a layer of foam
between the outer skin and inner skin that is glued (hopefully) to spar. I suspect
ultrasound would not be effective, so what would kind of NDT would be used?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Reading this forum, sounds like biggest safety risks in gliding a

- Any glider or radio that has had an AD in it's history
- Rogue thermals
- Mysterious medical symptoms that occur only when flying

Other that that, we are pretty safe.

On Friday, December 6, 2019 at 2:13:13 PM UTC-8, Eric Greenwell wrote:
2G wrote on 12/6/2019 1:53 PM:
On Friday, December 6, 2019 at 3:15:05 AM UTC-8, Terry Slater wrote:

Tom

The inspections were performed with an endoscope, and the full length of
the spar bonding was inspected visually. SH issued a very comprehensive
guide to the process.

Terry

Yeah, I read their TN 396-08 that covered the process. This required cutting several holes in each wing for access by the endoscope. Of course, these holes had to be repaired and refinished. It would have been so much easier and cheaper to have done this inspection by ultrasonic NDT.

If the SH wing is constructed like the ASH26E wing, there is a layer of foam
between the outer skin and inner skin that is glued (hopefully) to spar. I suspect
ultrasound would not be effective, so what would kind of NDT would be used?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Ultrasonic NDT with with sufficient energy to penetrate to the suspect layer.

On Saturday, December 7, 2019 at 2:09:19 AM UTC-8, krasw wrote:
Reading this forum, sounds like biggest safety risks in gliding a

- Any glider or radio that has had an AD in it's history
- Rogue thermals
- Mysterious medical symptoms that occur only when flying

Other that that, we are pretty safe.

The biggest safety risks have been, and continue to be, pilot error.

Tom

On Monday, December 9, 2019 at 1:29:10 AM UTC-5, 2G wrote:
On Friday, December 6, 2019 at 2:13:13 PM UTC-8, Eric Greenwell wrote:
2G wrote on 12/6/2019 1:53 PM:
On Friday, December 6, 2019 at 3:15:05 AM UTC-8, Terry Slater wrote:

Tom

The inspections were performed with an endoscope, and the full length of
the spar bonding was inspected visually. SH issued a very comprehensive
guide to the process.

Terry

Yeah, I read their TN 396-08 that covered the process. This required cutting several holes in each wing for access by the endoscope. Of course, these holes had to be repaired and refinished. It would have been so much easier and cheaper to have done this inspection by ultrasonic NDT.

If the SH wing is constructed like the ASH26E wing, there is a layer of foam
between the outer skin and inner skin that is glued (hopefully) to spar.. I suspect
ultrasound would not be effective, so what would kind of NDT would be used?

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

Ultrasonic NDT with with sufficient energy to penetrate to the suspect layer.

Tom

Ultrasonic will not work through a foam layer.

You were lucky! I was in a UK owned DuoDiscus based at
Sisteron, France, a few years ago. Wing spar de-bonding was
discovered at an annual inspection even though the glider had,
in theory, been inspected previously, looking for this specific
manufacturing fault. SH DECLINED TO PAY FOR THIS REPAIR;
if I recall correctly each of us in the 8 man syndicate had to
cough up about £700.......
Dave Walsh

I inspected this glider in compliance with the AD, and was
accused of
not inspecting it correctly! It was subsequently discovered an
undocumented wing change had taken place. Not all inspectors
or repair
shops are honest!
Terry Slater

I never recall being told that an "undocumented wing change" had
actually taken place; all I heard was a rumour. I was told that
there was no truth in the rumour. The facts remains that SH built
this Duo wing and we, the syndicate partners at the time, ended
up paying for its repair. Who inspected what and whether it was
done competently is not relevant: our wing WAS defective, it had
defective wing spar bonding, we ended up footing the bill. A ****
poor result.
Dave Walsh

On Saturday, December 7, 2019 at 3:09:19 AM UTC-7, krasw wrote:
Reading this forum, sounds like biggest safety risks in gliding a

- Any glider or radio that has had an AD in it's history
- Rogue thermals
- Mysterious medical symptoms that occur only when flying

Other that that, we are pretty safe.

Regarding the rogue thermal comment... they can occur. I came VERY close to becoming a statistic a few years ago while thermalling about 1500 ft. agl and wrote a feature article for SOARING MAGAZINE dealing with it. Rather than stalling an inside wing in a thermal turn (as one would expect if you happened to fly too slowly), while thermalling at about 10-15 kts above stall speed my INSIDE (lower) wing suddenly was pushed up and over, resulting in a steep dive / spiral. Subsequent research showed that some thermals can have strong down cores inside of overall lift, and if a glider happened to hit the sheer boundary, with suddenly one wing in the up air and the other in the down air, your day could quickly end.

See https://www.danlj.org/~danlj/Soaring...b_Thompson.pdf

and Dr. Dan Johnson had a good one, too https://www.danlj.org/~danlj/Soaring...Jan-p12-15.pdf

There are 2 books I referred to in my classes that have some pretty good info, too, although they are mostly intended for business folks:
1. Will Your Next Mistake Be Fatal? by Robert E. Mittelstaedt, Jr. for example - on page 160 - Insight #29 - Culture is powerful - what creates success may kill you. Think about this one seriously, for a long time! What you, or others, have gotten away with for a number of times can lead to complacency... and you becoming a statistic... that you couldn't tell anyone about ... from the grave. I recently attended a "celebration of life" for a friend that I suspect may have either lost his life due to his prior successes or rogue air.
2.Why We Make Mistakes by Joseph T. Hallinan