Grounding of control tubes/cables

I appreciate all of your responses, guys.

Mike, I think your point on controlling static during winch launch
using a wire is the true reason why the previous owner of my ship did
the bonding. I hadn't thought about it, but of course the Tost release
is bonded to the rudder assembly by virtue of the Bowden cable. The
electrical system was probably bonded to the rudder assembly so that
the VHF antenna could discharge static to ground if necessary. So in
my plane only the control column isn't bonded - but perhaps the PTT
switch wiring accomplishes this task.

I've not experienced static discharges like you guys talk about, but
I'd much rather learn from others than do it myself. Assuming that the
rudder assembly, the control column, the Tost release and the
electrical system are bonded, that leaves the spoiler rod (and the
canopy latching rods) as the only metal near me that isn't bonded. Is
this ever done, or is it overkill?

One last question - the bonding in my plane was not done at the
factory. Was the bonding you guys speak of done by the factory?

-John

Mike the Strike wrote:
As one of the lightning guys in this forum, I'm afraid I can't throw
much light on this. I have owned several gliders that had a similar
arrangement - all the metalwork around the pilot was grounded or
bonded, but not the control rods.

The only reason I can think of is to control static electric charges
involved with winch launching with a wire, as this can result in the
flow of significant electric currents, especially under clouds.

Any lightning strike to a non-metallic glider is going to have
significant parts of the discharge path through non-conducting parts
of the structure or across air gaps. Structural damage will depend on
the magnitude and duration of the lightning current. I've seen
everything from small holes to complete destruction. Gliders just
aren't capable of conducting lightning without damage.

Composite aircraft that are required to pass certification for flight
in cloud have to pass the appropriate lightning discharge tests and
the structure is modified with conducting material to enable this. No
glider has been so modified to my knowledge.

As a final remark, I have noted that I get sparks from my tow release
cable to my leg when I fly under electrified clouds. I use this as a
sign that I should be flying somewhere else!

Mike