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SV: Fuel tank - bulges and leakage.

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arno-k(at)online.no
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Posted: Fri May 02, 2008 11:03 pm Post subject: SV: Fuel tank - bulges and leakage.

Gary Leinberger,  

   

Sorry that I have overlooked your questions amongst the great number of comments following my message to the list.  

   

My tank was delivered in 2000 and there has been fuel in it since August 2005.  

   

Then some comments to your eventual aluminium tank.  

   

I have maid some design calculations for a new TIG welded tank made of aluminium which is 70 mm higher than the original.  With a stiffener spacing of 135 mm and 250 mm, the minimum thickness required for an internal pressure of 3.5 psi (FAR 23) using a 5052 quality came out at 1.74 mm. So I will use 2 mm. At the present stage the horizontal stiffeners on the forward and aft walls are corrugations and the vertical stiffeners are 3 longitudinal bulkheads. The weight is calculated to 11.3 kilogram. I learned last night that Graham had used magnesium in his tank weighing 7.8 kilogram. I think the density of magnesium is around 1.7 compared to 2.7 for aluminium. I have some experience applying aluminium in high speed crafts, but no experience with magnesium. So I think I will pay the weight penalty and stick to aluminium. The volume with a simplified geometry in the lower part is 83 litres. As soon as I obtain more information about the space available in that area, I intend to increase the volume somewhat.  

   

Regards  

Arnold  

   

-----Opprinnelig melding-----

 Fra: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] På vegne av Gary Leinberger

 Sendt: 29. april 2008 22:58

 Til: europa-list(at)matronics.com

 Emne: RE: Fuel tank - bulges and leakage.  

   

How old is your tank and how long have you had fuel in it? I had to replace mine - it was my fault in the sense that I pressure tested it with too much air pressure and ended up with stress cracks on the outer edges where the wing comes in - but the real problem seems to be it is not a very flexible material and over time I am afraid I will need to replace it again - if I do I guess I will get an aluminium tank welded up - pictures of land Rovers running over the tank may not be the best approach to judging the long term ability of the tank to accept stress -  

   

   

Gary Leinberger  

A237  

       

  

From: owner-europa-list-server(at)matronics.com [mailto:owner-europa-list-server(at)matronics.com] On Behalf Of Arnold Kr. Hansen

 Sent: Tuesday,  April 29, 2008 1:52  PM

 To: europa-list(at)matronics.com

 Subject: Fuel tank - bulges and leakage.    

   

  

Hi,  

   

Shortlybefore start of taxiing, it was discovered that fuel was coming out of the fuselage on my Europa XS trigear (LN-ABM), through the access holes below the tank. Draining of the tank was started and the leakage stopped when 20 - 25 litres were remaining in the tank.  

   

Two daysbefore I had drained the tank completely since the aircraft had been stationary (in a heated hangar) since 1. july 2006 with app. 35 litres of mogas in the tank. The day of start up I filled 18 litres and checked all hose connections. Started the engine and runned it for 5 minutes to check hose connections to the recently installed oil thermostat. Then filled another 36 litres of mogas and started the engine for the local flight.  

   

Removing the wings, it was revealed that the tank front facing the wing spars, had great bulges, bulges inwards and outwards, and the centre one touching the aileron cross tube, see attached picture. I have not yet localized the crack, but I suspect the saddle section just ahead of the fibreglass bracket. To me the in and out shape of the bulges indicate compression stresses due to material expansion (caused by the fuel applied, 95 octane mogas?). And I think the crack is caused by shear stresses just forward of the bracket mentioned.  

   

I will appreciate comments and advice. At present I do not trust the material, polyethylene, used in the tank. Has anybody applied metal tanks?  

   

Regards  

Arnold Kr. Hansen  

Europa XS trigear, Kit No.381  [quote]  _-=          - The Europa-List Email Forum -more:_-=   --> http://www.matronics.com/Navigator?Europa-List_-=               - MATRONICS WEB FORUMS -_-=   --> http://forums.matronics.com_-=             - List Contribution Web Site -_-=  Thank you for your generous support!_-=                              -Matt Dralle, List Admin._-=   --> http://www.matronics.com/contribution [b]

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