A Lawyer Writes...
Guys
This is almost certainly not a partnership as that word is understood in English law.
A partnership is the relation which subsists between persons carrying on a business in common with a view of profit. Section 1 Partnership Act 1890.
This is probably simple co-ownership. Just possibly a trust.
So the right to dissolve a partnership, which usually involves the sale of its assets, is irrelevant.
That's why you need a clear agreement as to what happens if you want to "dissolve" the group (to use a neutral word).
Ignoring land, which has its own special rules, there is no automatic right to force a sale of co-owned property or for one party to acquire the other's share. You can sell your own share to someone else without the other's consent, and so can he. But you can't force your co-owner to join in a sale of the asset or to sell his own share against his will, unless of course you've some form of agreement to that effect.
So the facts (including oral agreements and understandings) have to be trawled through in fine detail to see if something can be used to support the existence of an agreement (or possibly even a trust) for a sale.
If you can't settle it amicably, this could cost you a lot in fees. Settle it amicably if you possibly can, but if you can't, do find a competent solicitor who does aviation work and has seen this area before. If you pay peanuts, you WILL get advice from a monkey.
ALEXA