Post by Jason ScottCurrently operating 3 tow planes, all with Schweizer hooks installed.
would love to get access to some concrete information on the issues wit
the Schweizer hooks, comparison between the two, and any concerns wit
the TOST system. My goal is to likely switch over the fleet, havin
personally experienced a situation with a glider losing directiona
control on tow, and causing momentary upset to the towplane. In m
opinion, the TOST system is superior, and tangible information is th
best way to present this opinion to the other parties involved in ou
operation.
In the FAA Advisory Circular, Date 3/3/08 AC No 43.13-2b, Page 76, Pa
808 states as follows:
WHEN THE GLIDER UNDER TOW OPERATES ABOVE A CERTAIN ANGLE TO TH
TOW PLANE, THE RING MAY SLIDE UPWARDS ON THE HOOK, CAUSING EXCESSIV
LOAD ON THE HOOK AND DIFFICULTY IN RELEASING THE TOW ROPE RING.
The Soaring Society of America thru their Soaring Safety Foundation, To
Pilot Training Course additionally acknowledge IN RED as follows:
If at any time the nose of the tow plane is pulled uncontrollabl
by the glider to a dangerously high or low pitch attitude, - PULL TH
RELEASE!
It goes on to say:
Depending on the installation of the tow hitch, it may be possibl
for the release mechanism to become jammed due to the excessively hig
position of the glider, (American style hook).
Here we have two "authorities" acknowledging the problem which has bee
a contributing factor to the death of tow pilots in the past. Thi
condition has existed for a few decades at least with knowledge of and
lack of interest in correcting the matter. If this is not 'concrete
enough then I don't know what would be.
Every report I have read notes a "delay in releasing" on the part of th
tow pilot. I would submit that there was no delay in the attempt
rather a mechanism which is meant to release but will not as noted i
the above documents.
My letter to the FAA recommended at a MINIMUM that there be blanke
permission for a qualified A&P IA to invert the Schweizer hook AND t
allow for the increase in the length of the release handle, increasin
the mechanical advantage and allowing for access to the tow pilot in th
upright and seated position. It is absurd to have it down on the floo
and with a 5-1 mechanical advantage which has been shown to b
inadequate to affect a release. The TOST system would be preferabl
especially if you consider that you may not tow any glider with a ma
gross weight of 1500 lbs with the Schweizer hook as this system i
limited to a 1200 lb rope.
The push back will be the cost of the Tost system and while you're at i
don't forget to improve the position and mechanical advantage of th
release handle. But If you don't value the life of your tow pilots...
Walt Connelly
Former tow pilot (7K tows)
Now happily flying helicopter
--
Walt Connelly