To illustrate the view that it is operating costs (both fixed and hourly), not capital costs, that must be equally shared, how about this - is there any rule that actually requires the owner of an aircraft to even be a pilot? For example I bet there are one or two pilots whose planes are in their (non-PPL) spouses name.....
Take this example: doting Aunt, doesn't fly, would never go up in one of those things - but she knows her favourite nephew does, and is a very discerning type of pilot so she buys a PFA Permit plane (naturally, he's a discerning pilot!) which she will let him fly, but owns it herself as, say, she has already used her tax-free gift allowance or maybe just likes telling her friends that she owns her own aeroplane!
Nephew pays 100% of the hangarage and insurance, all the fuel etc for the hourly costs, and charges himself £X per hour with the balance over the consumables going to an engine replacement fund. Legal? Yes, imho.
OK, bring in said-nephew's PPL cousin; with Aunt's permission they share the hangarage and insurance costs 50/50, and each pay the same £X per P1 hour. Still legal? Again, yes imho. And no capital ownership.
So if the above example is right, it should not matter who is the owner, as long as all the operating costs are split equally, and there is no suggestion of profit / hire / subsidy etc
Or am I missing something?
Slip