Slip slidin' away.

"...both rudder pedals went to the floor..."

Sounds to me like one cable broke, the rudder went hard over due to
unbalanced cable tension, and there was no way to center the rudder.
Knowing both the accident pilot and the owner of the other JS-1 which had
the failure on the ground, I believe them. And neither I, nor the factory,
nor the NTSB were in the cockpit.

I also believe that the factory fix will take care of the problem.


"John Galloway" wrote in message
...
I too would like to see a full report into the US accident but I
doubt that JS1 pilots will be at all disturbed now when they are
flying:

If the US accident was the result of the rudder cable fraying
(which clearly was a design issue) and then breaking in flight
then that should be fixed by the modification to the rudder
pedal S tube design by adding bell ends and sleeve inserts to
protect the cables (Technical Note TN.JS-010 06 July 2012).

If it was due to misinterpretation of the rudder over-locking in a
side slip then that aspect has been highlighted in the flight
manual.

John Galloway


At 07:51 31 August 2013, Ramy wrote:
I find it disturbing that no follow up that I am aware off was
published
ye=
t about the cause of this incident by the pilot or anyone else
who knows
ab=
out it. If I was flying a JS1 I would be even more disturbed.
Now we all
kn=
ow we can't trust the NTSB to teach us anything about the
cause of glider
a=
ccidents, but one would hope that at least we will be sharing
information
a=
mong ourselves, so we don't have yet another one of those
"too bad he
wasn'=
t aware of this".

Ramy

The right hand rudder cable on Angel Paula’s JS-1 was cut through; the rudder then went full left. There is no quick obvious way to get control of the rudder when that happens. The glider was about 3,000 ft. AGL then.

The cable was cut by the sharp end of the S tube through which the cable passes. The end of the S tube is normally flared out, or bell shaped. Some manufacturers also run a plastic tube through the S tube and have the cable routed in the plastic. The JS-1 that Angel bailed out of and a sister ship owned by Barton Tate, also at Moriarty, had S tubes with no plastic tube and no flare on the end. The end was apparently cut with some kind of rotary cutter, probably an abrasive disk and the sharp end that resulted was not dressed smooth. I have cut steel tube this way and the end is so sharp you can almost shave with it. It will cut your flesh quite easily.

That sharp end is at the bottom of the tube where the cable exits and goes forward to an anchor point on a bulkhead. Each time the rudder pedal was pressed forward the sharp end of the steel tube cut into the cable. The cable is made of many small diameter wires bundled together. The sharp end of the steel tube simply cut, over many applications of right pedal, the cable one small strand at a time. Soon there were not enough strands to withstand the tension loads and the remaining strands, probably already nicked a bit, broke under that load. The tension spring on the LH rudder pedal then pulled the rudder to full left deflection.

The rudder did not lock out nor did the cable break, it was cut. The breaking strength of stainless steel 7x19 aircraft cable is 1760 lbs, galvanized is 2,000 lbs. The forward anchor point of the cable would fail before the cable reached its breaking point. The pictures of the wreckage show the forward anchor point to be intact. The glider hit almost level, almost no forward movement; the cable did not break during impact. Pictures do show the cut cable.

Jonkers so much admitted the correctness of this description when they sent Barton Tate new rudder pedals with a plastic tube in the S tube. After Angel’s accident Barton sat in his glider and cycled the rudder pedals from stop to stop, his already frayed cable was cut through even further.
This was a sobering moment for Barton.

I have designed and built and flown a rudder pedal assembly, Genesis prototype and production units, I know the critical design points. Those pedals have proven to be trouble free, they have a flared end and a plastic tube. I have pictures of Angle’s cut cable and Barton’s almost severed cable. I have felt the sharp end of the S tube. There is no other scenario that is viable.

Robert Mudd
Composite Aircraft Repair LLC
Moriarty, New Mexico USA

On Saturday, August 31, 2013 2:46:04 PM UTC-4, wrote:

The cable was cut by the sharp end of the S tube through which the cable passes.
..
..
..
The [ed. S-tube] end was apparently cut with some kind of rotary cutter, probably an abrasive disk and the sharp end that resulted was not dressed smooth.

The sheer incompetence and/or disregard for human life that this implies is appalling.

Excellent explanation, Robert. Thanks for clarifying this. Fred

In article ,
"kirk.stant" wrote:

On Friday, August 30, 2013 9:45:29 AM UTC-7, WB wrote:

If there is one good thing about training in Schweizers, it's that one

learns to slip for glidepath control.



WB (who has also slipped Cezznas with full flaps).

In glass, it's not the slip that is the problem - it's trying to land
afterwards without using dive brakes that can be really interesting (and
expensive)!

Unfortunately, that is not a problem in a Schweizer, so bad habits can (and
have) transfer - and lead to broken gliders.

Kirk (who has also tried the dreaded Cezzna full flap slip)
66

Yeah, I definitely had to augment my Schweizer training with some 2-seat
glass time. Most of my 2-seat glass time has been in Grob trucks. Great
for initial teaching of energy management in the pattern.

The instructor who does my flight review always wants to see a
no-divebrake pattern and landing. I have done no divebrake landings in
my 301. Slip as low as I dare and very careful airspeed control. Still,
the float is very long. If I had to out-land without divebrakes (very
unlikely in my 301 as it has a tail chute as a backup) and the field was
too short, I'd just have to land in a slip as slowly as possible and
ride out the ground loop.

I agree. This makes me wonder what else was overlooked.

Ramy

Jonkers so much admitted the correctness of this description when they sent Barton Tate new rudder pedals with a plastic tube in the S tube.

So did Jonkers compensate him for the loss of his very expensive glider or is Angel suing them to get it back? Nice that he survived.

Uncle Fuzzy: Instead of just wondering about the integrity of the 30+ year old cables why not put a new set in? It's not that complicated or expensive a job. With lots of gliders there is a calendar or flight hour limit on the cables anyways.

I recall Derek Piggott writing that the DG-100 rudder locks over and that the Janus does too so a Janus flight was a good way of experiencing the effect with an instructor if you had purchased or were considering purchasing a 100.

My 15B slips very steeply and effectively and behaves well in a full slip but the incident with the JS-1 also had me wondering about what would happen if a cable broke. When I disconnected the left cable at the turnbuckle aft of the pedals in the process of replacing my cables I noticed that the rudder was only deflected about ten degrees by the spring on the side that was still hooked up. Of course this doesn't tell me what it would do with a 50 knot or more airflow over it. Since I frequently fly barefoot I suppose I could do a test in flight by simply grabbing one pedal with my toes and pulling it backwards putting slack in the cable while not touching the other pedal.

On Wednesday, September 4, 2013 1:17:24 AM UTC-7, wrote:
Uncle Fuzzy: Instead of just wondering about the integrity of the 30+ year old cables why not put a new set in? It's not that complicated or expensive a job. With lots of gliders there is a calendar or flight hour limit on the cables anyways.



I recall Derek Piggott writing that the DG-100 rudder locks over and that the Janus does too so a Janus flight was a good way of experiencing the effect with an instructor if you had purchased or were considering purchasing a 100.



My 15B slips very steeply and effectively and behaves well in a full slip but the incident with the JS-1 also had me wondering about what would happen if a cable broke. When I disconnected the left cable at the turnbuckle aft of the pedals in the process of replacing my cables I noticed that the rudder was only deflected about ten degrees by the spring on the side that was still hooked up. Of course this doesn't tell me what it would do with a 50 knot or more airflow over it. Since I frequently fly barefoot I suppose I could do a test in flight by simply grabbing one pedal with my toes and pulling it backwards putting slack in the cable while not touching the other pedal.

The cables are fine. I just like to 'what if' when I have the time, and this was one of those times. I found I can make it go generally where I want, with or without rudder input, with or without aileron input, but I do need ONE of them. Kinda' OBE now that my only 'rating' is "Ballast" (maybe 'honorable ballast'

snip...Since I frequently fly barefoot ...

Not in New Mexico, I'd wager!


wrote in message
...
Uncle Fuzzy: Instead of just wondering about the integrity of the 30+ year
old cables why not put a new set in? It's not that complicated or expensive
a job. With lots of gliders there is a calendar or flight hour limit on the
cables anyways.

I recall Derek Piggott writing that the DG-100 rudder locks over and that
the Janus does too so a Janus flight was a good way of experiencing the
effect with an instructor if you had purchased or were considering
purchasing a 100.

My 15B slips very steeply and effectively and behaves well in a full slip
but the incident with the JS-1 also had me wondering about what would happen
if a cable broke. When I disconnected the left cable at the turnbuckle aft
of the pedals in the process of replacing my cables I noticed that the
rudder was only deflected about ten degrees by the spring on the side that
was still hooked up. Of course this doesn't tell me what it would do with a
50 knot or more airflow over it. Since I frequently fly barefoot I suppose I
could do a test in flight by simply grabbing one pedal with my toes and
pulling it backwards putting slack in the cable while not touching the other
pedal.