Not to be argumentative, and altho I agree with Fred that internal
grounding of the tank may be a bad idea in the case of a
lightning-strike, plastic planes (without any embedded
charge-distributing protective mesh) can and do indeed 'explode' when
hit by lightning anyway - the UK glider as an example. Hmmmm.... I
wonder how they would have faired if it were a Motorglider with fuel on
board ;-)
If the lancair accident was indeed a lightning strike, they should
easily identify all those melted/burned pieces. I wonder if the new
Lancairs have mesh.
Cheers,
Pete
A239
-----Original Message-----
From: Fred Fillinger [mailto:fillinger@ameritech.net]
Subject: Re: Europa-List: Static Charges and how to avoid them
<fillinger@ameritech.net>
> Fred,
>
> I agree with you that bonding other metal parts in the fuel
> system to the filler cap is probably less safe rather than
> more so. However if fuel drains are fitted, I think it's a
> good idea to ground them independently. Although it's a fairly
> remote possibility the last thing you need is a spark when you
> are lying on the ground draining fuel!
>
> Best regards,
> Nick
If a remote possibility, it's because static inside the tank dissipates
by itself shortly after refueling, and pre-flight fuel samples aren't
static producers. Nevertheless, note that merely tying it to A/C ground
does not remove any charge. The A/C ground has to be earthed also to be
effective.
Regarding anything metal exposed to the fuel tank innards which is tied
via a run of wire to A/C ground, there may be no good statistical answer
comparing the lightning hazard vs. that of static charges. I have only
one such item, the fuel sender, and it has a 2-pin connector accessible
inside the headrest. Theory is if caught near a storm, pull the thing
to at least feel better.
Recently a Lancair IV "exploded" in cruise, deviating around
thunderstorms, in apparent VMC on top. The preliminary report suggests
either G-load induced separation of both wings simultaneously - a rare
event...or a lightning strike. At least worrisome until NTSB says what
happened:
www.ntsb.gov/NTSB/brief.asp?ev_id=20030520X00696&key=1
Regards,
Fred F.
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