From: [email protected] <[email protected]> on behalf of Michael Coates <mcoates@...>
Sent: Friday, April 15, 2022 7:20:24 PM
To: [email protected] <[email protected]>
Subject: Re: [XAIR] X Air Hawk fuel tank 'shedding' particles into fuel

Agreed, it is nothing to do with the engine it is to do with fibreglass, vinyl ester resins, epoxy resins and their weaknesses to current aviation and/or car fuels.

This issue is simply, fuels or additives in fuels leach into the resins and dissolve them therefore leaving exposed fibres from the fibreglass which eventually get broken off from the fuel sloshing around and then they end up in the fuel lines and the fuel filters eventually causing fuel supply issues, engine stoppages etc.

It is only the bottom end of aviation that uses fibreglass fuel tanks, every other industry knows their weaknesses and has moved on to other products. Most cars 25 years ago used steal for their fuel tanks but almost unanimously they have all now change to polyethylene because it does not rust, it is much superior in an accident and it does not get affected by the fuels we are currently using.

The problem in the aviation industry is fibreglass is easy to manufacture and fairly cheap, you can make round shapes very easily like the corners of the fuel tank, it does not rust and most importantly for us, it is lightweight, the downside is it is not durable when it comes to different fuels.

Polyethylene is used for aviation fuel tanks in some aircraft but it is about 10 times the weight.....??

There are a number of "sloshing compounds" that can be used which you mix up and pour into a fibreglass fuel tank and then turn it around in all directions so that the surfaces are coated and when it dries it provides a barrier between the fuel and the fibreglass.

The problem with these is that they are not always successful in bonding with the fibreglass material even when you use the proper primer and it is because the inside of the fuel tank is nice and smooth because this is the inside of the mould when it is made and the material doesn't stick so well....

Something else which is worth looking at is a fuel bladder but these are also heavy and are quite expensive....

The current alternative seems to be, remove the fuel tanks once every 12 months, throw a chain inside and move it around breaking off all the fibres and put the fuel tank back into service.? Clean fuel system regularly, use a good quality fuel filter that can capture the fibres and the problems are solved, or mitigated at least.

This issue has nothing to do with different type of engines
----- Upprunalegt skeyti -----
Frá: Brian Ellis via groups.io <bellis2uk@...>
Til: [email protected]
Sent: Fri, 15 Apr 2022 16:52:50 -0000 (GMT)
Efni: Re: [XAIR] X Air Hawk fuel tank 'shedding' particles into fuel

Thanks
Just reading that I am glad we chose a Rotax

On 15 Apr 2022, at 14:02, Justin Gregoris <jgregoris789@...> wrote:

?fuel tank sealant colours- see Jabiru website: "JSL007-7" service bulletin for all who are interested. lots of great information there,

-- 
With regards,    Michael Coates

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USA +1 213 984 1237


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