Shocking windshield a sign you need static wicks?

[Ben Jackson]

While in solid IMC last Sunday I reached toward the windscreen to see how
warm the defroster was and I got a quick series of static shocks without
actually touching anything. Under the same conditions I was still
receiving the VORs for the airway I was on and communicating with ATC with
no noticable drop in radio quality.

Is that a sign I need static wicks? If I'd been in the same conditions
for a longer period of time would my radio performance have degraded?

--
Ben Jackson
>
http://www.ben.com/

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Ben Jackson wrote:
<snip>
> Is that a sign I need static wicks? If I'd been in the same conditions
> for a longer period of time would my radio performance have degraded?
>
Airframe static usually shows up as a break in squelch and steadily
building static noise on your comm radio. The static will build until
it reaches the point of discharge, then everything goes quiet again
until the cycle repeats. It doesn't sound like you had enough of a
buildup to affect your radios, so I wouldn't worry about it. All
airframes build up some static in flight. Apparently, your airframe
was discharging the static before it became a problem.

John Galban=====>N4BQ (PA28-180)

[Don Hammer]

On Thu, 09 Jun 2005 00:55:11 -0500, Ben Jackson > wrote:

>While in solid IMC last Sunday I reached toward the windscreen to see how
>warm the defroster was and I got a quick series of static shocks without
>actually touching anything. Under the same conditions I was still
>receiving the VORs for the airway I was on and communicating with ATC with
>no noticable drop in radio quality.
>
>Is that a sign I need static wicks? If I'd been in the same conditions
>for a longer period of time would my radio performance have degraded?

Two qualifiers - I'm not and avionics guy and my experience is with
large aircraft.

The windshields are bonded to the airframe, but plastic is a poor
conductor. A Ven Degraff generator is made by causing friction on
plastic. The plastic windshield of a Challenger, even though they
have dischargers on them, will build up a charge heavy enough to knock
you off the ladder when you try to clean it. We always discharged
them with water before touching them.

A static charge building up on the airframe is looking for a sharp
path to exit, like the tip of an antenna. We could usually tell we
needed to replace the wicks when you could hear the roar in the ADF
audio. I've personally never had it effect the comms or navs enough
to make them unusable.

My guess is unless it is causing an operational problem, the airframe
static is discharging fine. Also, a plastic window will build up a
charge and there is nothing you can do about it anyway. It's very
normal to see St. Elmo's on even a glass windshield on a jet and it
doesn't seem to do anything except provide you something beautiful to
marvel at.