Stewart Kissel wrote:

At 17:54 10 September 2006, 588 wrote:
*Does your glider operation use a weak link at the
tow plane end of the
rope, as required by 91.309 a (3) ii?

Nope....1,000lb rope used for Standards, 15 and 18
meter ships, ergo no weak link required on either end.

Poorly presented question on my part -- sorry.

What I should have said was: _when_ FAR 91.309.a.(3) requires the weak
link, do you use two or just one at the glider end?

The question is really about interpretation of (3) i and ii. Some
(many?) glider operations use only one weak link. I read the reg as
requiring two weak links, one at each end. To me, ii references the weak
link required by i in such a way that I can't see it as an either/or
situation -- both are required. I wondered whether anyone has a cite for
a ruling or other definitive interpretation beyond what is set forth in
the reg. quoted below.

---

§ 91.309 Towing: Gliders and unpowered ultralight vehicles.

http://tinyurl.com/fllgz

(a) No person may operate a civil aircraft towing a glider or unpowered
ultralight vehicle unless—

[....]

(3) The towline used has breaking strength not less than 80 percent of
the maximum certificated operating weight of the glider or unpowered
ultralight vehicle and not more than twice this operating weight.
However, the towline used may have a breaking strength more than twice
the maximum certificated operating weight of the glider or unpowered
ultralight vehicle if—

(i) A safety link is installed at the point of attachment of the towline
to the glider or unpowered ultralight vehicle with a breaking strength
not less than 80 percent of the maximum certificated operating weight of
the glider or unpowered ultralight vehicle and not greater than twice
this operating weight;

(ii) A safety link is installed at the point of attachment of the
towline to the towing aircraft with a breaking strength greater, but not
more than 25 percent greater, than that of the safety link at the towed
glider or unpowered ultralight vehicle end of the towline and not
greater than twice the maximum certificated operating weight of the
glider or unpowered ultralight vehicle;

[....]

---

Just out of curiousity...the breaking strength of the
rope is for brand new, unused rope. I wonder what
the actual strength of most rope being used is?

Less. But that's OK since the FAR's are not concerned with weakening of
the rope as long as its breaking strength remains no less than 80% of
the max weight of the glider -- which we can all assess just be looking
at it.


Jack