From: marv@lancair.net
Subject: Re: [LML] Re: Fuel tank camera for inspection of Lancair fuel
 tanks
To: <lml@lancaironline.net>
Date: Fri, 23 Feb 2007 13:56:14 -0500
Message-ID: <web-1858375@logan.com>
In-Reply-To: <00ce01c7577a$55ecaff0$0400a8c0@mountain0676a7>
References: <00ce01c7577a$55ecaff0$0400a8c0@mountain0676a7>
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Posted for "Bryan Burr" <bjburr@mwheli.com>:

  What you have to realize is that the Lancair ES that had the explosion
  problem also was parked on top of a blue plastic tarp.  There was
  absolutely no contact with the ground and the tarp acted as an
  additional insulator.  While there are still risks associated with
  static creating activities if you make efforts to create a grounding
  event such as touching the airplane, connecting the airplane to a ground
  when fueling, wiping it with a damp rag frequently when waxing, buffing,
  polishing, the risk is minimized.  Also, the explosive event happened by
  blowing the wing off using an air nozzle over an open fuel filler inlet.
  And the tank had fuel or fuel vapors escaping.  All of the factors lead
  up to the explosive event.  Blue tarp, long period of sanding, blowing
  off the wing using an air nozzle, open fuel port, no frequent attempt to
  discharge the static.
  
  During the painting of my airplane (I had flown 250 hours so fuel had
  been introduced to the system) I made absolutely sure the painter
  touched the wings frequently.  I made sure he hosed down the floor and
  used water and wet sanded during the sanding process.  I made sure
  during polishing that he did not go for long periods of using an
  electric polisher/buffer.  We always had safety wire or something
  touching the ground and the airplane surface he was working on.
  
  During fueling I make sure the grounding cable is attached either to the
  exhaust or to the tow bar plate and I also make sure that the refueling
  nozzle is contacting the metal ring that seats the fuel cap.  Refueling
  trucks that use certified aircraft refueling hose has a ground wire
  embedded in the rubber hose that connects to the nozzle..  By touching
  the nozzle to the fuel cap seating ring another grounding is being made
  in addition to the regular static grounding cable.
  
  Remember that in non carbon fiber airplanes (IE Lancair normal ES) there
  is no conductivity.  E glass does not conduct.  So there is no way to
  fully discharge static.  That is why static wicks don't work on an ES.
  They only discharge the static created by the wick itself.  They do
  nothing for the wing surfaces.  Perhaps there is another topic of
  discussion for using metal based primer during painting and then
  installing static wicks.
  
  You may say that the rubber tires touching the ground are also an
  insulator.  This is true.  When I asked the same question the answer was
  that there is enough dirt, grime, moisture etc. on the tires that static
  is discharged.  This is also why using a grounding cable when refueling
  is necessary.  I also prop my tow bar against the wing being refueled as
  added measure of safety.
  
  Man what a Pandora's box this static thing is in non-carbon plastic
  airplanes!
  
  Bryan
  N132BB
  

[Jim Frantz put it best a long time ago... our glass airplanes are flying 
di-electrics.   Think capacitor with wings <g>.   <marv>    ]