Aircraft integral fuel tank

[vittore]

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

 

[Nigel]

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. >:O>

Nigel Waterhouse
n_a_waterhouse@hotmail.com

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.

 

[swalton]

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.

 

[BrianR]

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.

 

[AlphaJetspecialist]

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

F.A.Fisher/J.A.Plumer
Lightning Protection of Aircraft
copyright 1990 Lightning Technology Inc.

 

[WKTaylor]

Vittoore... Very good ref follows

1. Go to:

http://www2.airweb.faa.gov/REGULATO...CIRCULAR.NSF/MAINFRAMENETSCAPE4X?OpenFrameSet

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