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

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?

Yes, factory on the '27.

Steve, Mike,

Again, I appreciate your answers. It's strange, though - the grounding
in my 1984 ASW19 is clearly home-made. I wonder why Schleicher would
do the -20s, and not the -19s.

-John

On Mar 1, 11:51 pm, Steve Koerner wrote:
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?

Yes, factory on the '27.

On Mar 2, 7:23 pm, Mike the Strike wrote:
John:

Both my present glider (2001 Discus 2) and the previous one (1980
ASW20) had similar factory-installed grounding straps.

Mike

jcarlyle wrote:

On Mar 1, 11:51 pm, Steve Koerner wrote:
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?
Yes, factory on the '27.

On Mar 2, 7:23 pm, Mike the Strike wrote:
John:

Both my present glider (2001 Discus 2) and the previous one (1980
ASW20) had similar factory-installed grounding straps.

Steve, Mike,

Again, I appreciate your answers. It's strange, though - the grounding
in my 1984 ASW19 is clearly home-made. I wonder why Schleicher would
do the -20s, and not the -19s.

Is it possible that the ASW 20 with the bonding straps was built for a
country in Europe where cloud flying was common? I don't recall bonding
straps on my ASW 20 C. Our Blanik had them, though.

--
Eric Greenwell - Washington State, USA
* Change "netto" to "net" to email me directly

* Updated! "Transponders in Sailplanes" http://tinyurl.com/y739x4
* New Jan '08 - sections on Mode S, TPAS, ADS-B, Flarm, more

* "A Guide to Self-launching Sailplane Operation" at www.motorglider.org

On Mar 2, 8:38*pm, jcarlyle wrote:
Steve, Mike,

Again, I appreciate your answers. It's strange, though - the grounding
in my 1984 ASW19 is clearly home-made. I wonder why Schleicher would
do the -20s, and not the -19s.

I have no reason to think the bonding in my 19b (19356) was not
factory original. The bonding on my 28 certainly is. Some Schleicher
factory stuff looks home made. Don't let that make you think it's
not factory original. Glider manufacture is a cottage industry. Didn't
you notice the German garden hose fittings in the water ballast
system?

How Schleicher got away with joining ballast valve control cables
with electrical terminal blocks in the 28 is beyond me.

I may have some photos that show the bonding in 19356. I'll check
tonight.

Andy

On Mar 5, 3:53*pm, Andy wrote:
On Mar 2, 8:38*pm, jcarlyle wrote:

Steve, Mike,

Again, I appreciate your answers. It's strange, though - the grounding
in my 1984 ASW19 is clearly home-made. I wonder why Schleicher would
do the -20s, and not the -19s.

I have no reason to think the bonding in my 19b (19356) was not
factory original. *The bonding on my 28 certainly is. *Some Schleicher
factory stuff looks home made. * Don't let that make you think it's
not factory original. Glider manufacture is a cottage industry. Didn't
you notice the German garden hose fittings in the water ballast
system?

How Schleicher got away with joining ballast valve control cables
with *electrical terminal blocks in the 28 is beyond me.

I may have some photos that show the bonding in 19356. *I'll check
tonight.

Andy

I have a photo of 19356 rudder cable bonding. Email me and I'll send
it to you.

Andy

Hi, Andy,

My 19b is 19397, so if yours was bonded by the factory then mine
probably was, too. I appreciate the offer of a photo, I'll write you
off-line about that issue.

Reiterating, I'm talking about a wire that leads from the battery
negative side bus bar to the rudder assembly. This is probably not the
bonding that you and others are talking about. Now, I know for a fact
that the battery was put in by the previous owner. And the reason I
think the bonding was homemade is because the ring connector to wire
junction has been made the the mother of all cold solder joints! We're
talking ugly, dull and lumpy, to the nth degree.

-John

On Mar 5, 5:53 pm, Andy wrote:
I have no reason to think the bonding in my 19b (19356) was not
factory original. The bonding on my 28 certainly is. Some Schleicher
factory stuff looks home made. Don't let that make you think it's
not factory original. Glider manufacture is a cottage industry. Didn't
you notice the German garden hose fittings in the water ballast
system?

Andy

On Mar 6, 12:39*pm, jcarlyle wrote:
We're talking ugly, dull and lumpy, to the nth degree.

-John


Awww John, you're not THAT bad...

P3

Is it GCup season yet?

Oh, thanks, Erik! Thanks very much. My seconds will call upon your
seconds. Or......you can let me fly your LS-8 once....8-)

-John


On Mar 6, 10:52 pm, Papa3 wrote:
On Mar 6, 12:39 pm, jcarlyle wrote:

We're talking ugly, dull and lumpy, to the nth degree.

-John

Awww John, you're not THAT bad...

P3

Is it GCup season yet?

John:

Both my present glider (2001 Discus 2) and the previous one (1980
ASW20) had similar factory-installed grounding straps.

Mike


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