What could cause extremely high effort to release a Tost CG hook on aTwin Astir?

On Sunday, May 31, 2015 at 7:58:26 PM UTC-6, Frank Whiteley wrote:
On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.

My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?

It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.

BillT

Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.

Bill D

FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.

Has this changed since winch testing and training started, or remained consistent?

Frank W

No change.

Check for the seat pan binding the cable. Look for witness marks on the
under side of the seat pan.

Good luck!

On 5/31/2015 8:12 PM, Bill D wrote:
On Sunday, May 31, 2015 at 7:58:26 PM UTC-6, Frank Whiteley wrote:
On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:
On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:
On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:
I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.

My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?

It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.

BillT
Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.

Bill D
FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.
Has this changed since winch testing and training started, or remained consistent?

Frank W
No change.

--
Dan Marotta

On Sunday, May 31, 2015 at 8:22:40 PM UTC-6, Dan Marotta wrote:
Check for the seat pan binding the cable.* Look for witness marks on
the under side of the seat pan.



Good luck!




On 5/31/2015 8:12 PM, Bill D wrote:



On Sunday, May 31, 2015 at 7:58:26 PM UTC-6, Frank Whiteley wrote:


On Sunday, May 31, 2015 at 7:02:37 PM UTC-6, Bill D wrote:


On Sunday, May 31, 2015 at 6:58:47 PM UTC-6, Bill D wrote:


On Sunday, May 31, 2015 at 6:43:19 PM UTC-6, Bill T wrote:


I believe I remeber a Kestral that had a "stiff release" issue. He removed the seat pan and discovered that the pan was depressing with his weight in it and binding the cable. But you said you have removed the seat pans and checked all of the cables.

My second guess would have been that there was a worn spot or nick in the "jaws" of the TOST release that might be catching on the ring under strain.. But you said the TOST was fairly new. Is the TOST ring in fairly good shape and not one of the imposters that were on the market a few years back?

It would be great if you could have a cable under load at GS=0 to visually watch the release mechanism, but that is not a safe venture without a lot of precautions in set up.

BillT


Both the CG hook and the ring pair are brand new. My only guess (AKA pure speculation) is an improper (and unrecorded) repair left the whole forward fuselage weak so it is deforming under winch launch loads causing the yellow-ball to CG hook cable system to bind. FWIW, I do not suspect the hook itself.

Bill D


FWIW, CS-22 regs say a CG hook operating force can't exceed 140N (31.5 Lbs-F) I'm guessing this one takes 200 Lbs-F or more.


Has this changed since winch testing and training started, or remained consistent?

Frank W


No change.





--

Dan Marotta

The cable runs are well below the bottom of the seats so it's unlikely they could rub the seat.