AC-DC,
Leather is a fine dressing - don't get me wrong.
But be aware that there are different flame standards - as in horses for courses. I see that you are in the old country so your rules may be a little different to the US standards with which I usually work.
Consider that
(a) most of the usually encountered civil commercial flame Standards are not of much use in, or relevance to, the aircraft situation
(b) light aircraft of the FAR23 variety only require a flame resistant performance which usually is demonstrated by a simple bunsen burner test with the test specimens held horizontally
(c) heavy aircraft have a requirement for a similar test but with the specimen held vertically. This is rather more demanding of the specimen.
(d) larger aircraft have a comparatively involved flamethrower type of test requirement which is very demanding - leathers can have some considerable difficulty with this test in particular, as we have experienced with some recent jobs.
I would presume that the hides to which you refer are supplied to the horizontal test Standard. Consider that you might prefer to have a better chance of post prang evacuation if you spec a vertical burn test performance, as is your option for all fabrics in the interior refurb.
While not speaking to leather specifically in the following comment, be aware that many (especially "ordinary" commercially sourced fabrics) may perform nicely on the horizontal test, but burn with a most impressive display on the vertical. Additionally, many commercial fabrics, some with commercial flammability certification, burn like a bonfire even with the horizontal test.
This is a sufficient problem that the manufacturer with which I was involved over many years adopted a policy that we would use only vertical performance fabrics unless the customer insisted on a fabric which passed the horizontal but not the vertical test requirement.
So far as the foams go, there are many fire retardant foams in the marketplace.
Presuming that your aircraft is a lightie, I suggest that you consider making your refurb a FAR 25 vertical burn standard. It ought not cost you much more, if at all, but is worth a degree of peace of mind .....
I know what my approach would be if I owned the aircraft ....
[This message has been edited by john_tullamarine (edited 04 June 2001).]