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Aircraft integral fuel tank

Aircraft integral fuel tank

Aircraft integral fuel tank

My company is designing a new aircraft trainer whith an integral fuel tank.
The aircraft is completely metallic and I have to give all the necessary information to give a tank which is lightning proof.
I am not sure about what is truly necessary to avoid sparking inside the tank in case of lightning attachment.
(Sealing of bolts, sealing of all the tank internal surface.......and so on.

Is there anybody that could help me.

Ciao e grazie

RE: Aircraft integral fuel tank

As long as the tank is electrically connected to the rest of the fuselage, i.e. bonded correctly, there shoud be no sparking.  Sparking only occures in the absence of a lower resistance path to ground.  Electrical bonding provides the path of least resistace, therefore no sparks.   

Nigel Waterhouse
A licensed aircraft mechanic and graduate engineer. Attended university in England and graduated in 1996.  Currenty,living in British Columbia,Canada, working  as a design engineer responsible for aircraft mods and STC's.

RE: Aircraft integral fuel tank

There is a new SFAR being released related to fuel systems safety, with such requirements as dual bonding jumpers and full electromechanical component isolation to reduce in tank energy to something like 3 microjoules.

RE: Aircraft integral fuel tank

You need special treatment in places where the metal skin forms part of the tank wall. Joins in the skin which are made by sheets butted together, with a metal cover strip over the join and rivetted across them, may flash over during a lightning impulse.  The lightning impulse is a high frequency signal and even though the DC resistance across the join may be close to zero, there is sufficient impedance to cause a voltage drop and form an arc.  

On military aircraft the normal procedure is to seal the whole join with fuel proof polysulphide sealant ensuring coverage of the rivet heads, the edges of the strip and the seam on the inner surface of the tank.  

This isn't a bad thing for fuel sealing either.

RE: Aircraft integral fuel tank

Do you have the following book?
It´s the best I found about lightning protection

Lightning Protection of Aircraft
copyright 1990 Lightning Technology Inc.

RE: Aircraft integral fuel tank

Vittoore... Very good ref follows


down-load the following ACs:

AC 20-53 Protection of Airplane Fuel Systems Against Fuel Vapor Ignition Due to Lightning.

AC 20-136  Protection of Electrical and electronic Systems Against the Indirect Affects of Lightning.

The following can be down loaded at various sites [points to much good data]:

MIL-STD-464 Electromagnetic Environmental Effects Requirements for Systems

Regards, Wil Taylor

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