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Electrically grounding an aircraft parked in the open?

Posted By:
Dov Elyada
4
Posts
1
#1 Posted: 4/1/2011 00:56:09

Considering its effects on corrosion and lightning attraction, is it a good, bad or nonsense idea to electrically ground an aircraft normally parked outside, in the weather?

what I mean is adding a conductor wire alongside one of the tying lines and electrically connecting it to the airframe on one side and to the ground peg on the other.

Does anybody do that?

 



Nick Myers
96
Posts
11
#2 Posted: 4/1/2011 09:33:04

 

In my limited exposure, I can't envision many environments where the aircraft is the tallest object around.  Even at the most desolate unimproved desert strips around here, there was at least a saguaro that would more likely attract the lightning.

That said, the aircraft themselves are probably pretty well insolated from the ground, and without doing all of the math, I would imagine the path of least resistance for the lightning is not generally going to be through the aircraft...even in an open field...but I could be wrong on that.

On the flip side, grounding the aircraft is probably going to do more in the way to promote electrical conductivity to the ground, and that would likely have negative affects in the way of corrosions.

Now...all of that said, my last point makes everything I said above moot.  When you tie down your airplane with chains, and even rope, you are doing a pretty good job of grounding your aircraft anyway.  Rope may not be ideal...or even good in some cases, but probably sufficient.

What ever the real answer is, I highly doubt that adding another thing to the ramp area or any tie down that can potentially get wrapped up in a prop, or neglected in the pre-flight is worth the effort and potential problems.

Just my $0.02

 



Robert Dingley
Homebuilder or Craftsman
161
Posts
38
#3 Posted: 4/1/2011 11:58:03

Oh yes! I have seen two examples where aircraft were parked on concrete with steel re-bar in it. Not grounded. Both  were Bell 206 helicopters.  First indications the morning after the storm were fist size divots in the concrete under the fuselages. Detailed inspection turned up 1/8 inch hole buned through the skin over the gouge in the concrete. In the hangar, a lot of bearings in a lot of components were found to be fused. BIG $$$. I had thought that the skid cross tubes were electicaly bonded to the airframe, but found out the hard way that they were not.

Once apon a time, I skirted a T'storm cell less than a mile from an oil & gas platform in the Gulf of Mexico. After landing, I heard a lot of electrical arcing going on. When standing on the steel deck, I got shocked when I touched the A/C skin. The noise was comming from arcs jumping from deck to skids and skid cross tubes to air frame. I dragged a fuel grounding wire to the bird and after grounding, the zapping stopped. The Sikorsky 76 that I also flew has a pencil sized silicone rubber ground strap on the left main wheel. (Helos hover left side low and the L.M. touches down first) When the L.M. touches down, you can sometime hear static go away in your head set. The tires do prevent grounding. 

Concrete for parking is now poured with fiberglass reenforcement instead of re-bar. Compass roses especialy. I have a length of scrap braided wire with aligator clips that I stow in the junk bag for grounding. For FW, I ground like the fuel truck drivers do. Engine exhaust. A lot of small planes do not have those little braided bonding straps to bond wings to airframe, but the engine does.

Bob



Justin Daugherty
52
Posts
5
#4 Posted: 4/3/2011 13:34:43

FWIW:


Working at an FBO with upwards of $50million dollar airplanes: Never grounded, inside or out. Only when fueling, the ground would go from the truck to the aircraft. Never saw problems.


Working with the military now: Everything is grounded, inside and out of hangars. When fueling the truck is grounded, the airplane is grounded and the truck is grounded to the airplane....such over kill. Never seen any problems.


Personal opinion: I wouldn't worry about it, chances are nothing will happen. If something does happen, you are just one unlucky SOB. 

And as stated before, chains are more then efficient means of having the aircraft grounded.



Robert Dingley
Homebuilder or Craftsman
161
Posts
38
#5 Posted: 4/3/2011 20:22:49

I hear what you are saying Justin.  I too was "the man" with 50 mil worth of comm turb a/c (more or less) and dozen & half pilots. Unlike my previous military exp, grounding was not req. The repairs were just overhead.

Bob  



Richard Shankland
Homebuilder or Craftsman
7
Posts
0
#6 Posted: 4/8/2011 19:02:11

Built a wood airplane. No problem. But, believe it or not, a little bit of rain and I cannot reach out with a handheld com. I might as well be in a Farady cage!



Steve Ruse
20
Posts
5
#7 Posted: 4/14/2011 23:13:06

Grounding the plane will not increase it's likely hood of being struck by lightning.  The tires and air gap from the fuselage or wheels to the ground present virtually no impedance to a lightning strike.  Think of it this way...if lightning can travel through 2,000' to 6,000' of air, will the 6" gap from the tire to the ground somehow stop this strike?  It won't have any effect.  This is a common misconception...that "rubber shoes" or tires will somehow stop a lighting strike.  It simply isn't true.

Also, corrosion is not generally caused by static electricity so grounding again would have no effect.



Dov Elyada
4
Posts
1
#8 Posted: 4/15/2011 03:44:04

Thank you people for your answers and discussion.

Thank you Steve Ruse, in particular -- I find your answer to-the-point and illuminating.

As far as I'm concerned, the subject has been exhausted. I suggest we turn to other matters.

 



Doug Schleifer
6
Posts
0
#9 Posted: 4/17/2011 18:57:36

Just a little nit picking here. The rubber in the tires is a lot like the locks on the door of your house - it hopefully encourages the lightening or intruder to take the easier path of another object or house if one is available. It won't won't stop a thing if the plane or house door is still the easier path. When I was in the airforce decades ago they drilled into us that the wire from the truck to the aircraft was a bonding wire and did nothing to "ground" the aircraft. The wire from the truck or aircraft to the approved and tested grounding rod burried in the pavement was a ground and completed the electrical circuit. Of course the three wires had to be placed in the proper order to minimize any trouble. Cheers!