<<Looks like a great case for including your tie-down rings/hard points in
the
ground path with internal grounding straps...

> On looking at the unlucky Glasair, I wonder if the original path was down
> the rudder hinge line, through the control and then the tie-down chain.>>
Bob:  Notice in the photographs sent earlier that steel chains anchor the
Glasair to the ramp thus providing a dense grounding pathway for lightning
strike.  Such a well-defined pathway doesn't exist for an aircraft in
flight---or does it?  I'm not an engineer but I'd sure like to hear more
about this from those of you out there who are engineers.

It is my guess that a flying glass airplane is more of a "target of
opportunity" than it is a target for lightening, i.e.., if you happen to be
in the pathway, it may drill you but otherwise lightening shouldn't
recognize that you are simply nearby.>>

I'm not a lightning expert, but I wonder if the aircraft didn't sit there in
the highly "electric" atmosphere and gradually build up a static charge.
Tires are normally conductive enough to dissipate this charge even if the
chains didn't - except that the airframe is almost a perfect insulator.
finally something internal was close enough to arc, let's say between the
rudder control cable or hinge and the tie-down.  This arc actually created
the field and the "chain" reaction that triggered the lightning.  The
aircraft itself could have caused the lightning strike, not merely been a
victim of it.  More confirmation that electrically connecting all the
available metal parts of the plane is a good idea.  My tie-downs are already
buried, so nylon tie-down straps might be the only solution for that
particular scenario.  We need to keep in mind that, even though the event
was certainly devestating to the owner, no one got hurt - the event
hopefully produced information we can use to make the planes safer in
flight.



Gary Casey
ES project