"oh, that's common practice"

Escrow is not necessarily a good idea.

If the buyer has the power to withdraw the funds, then the seller is not
protected. If the escrow provides that the buyer and seller together must
agree on funds withdrawal, then the seller can just refuse to allow the
funds to be disbursed. In that case, the bank will hire a lawyer to
protect themselves and that will eat up the entire escrowed amount, since
the bank's attorney fees will come from the escrowed money.

If the airplane was not of special interest, I would walk away. If I
thought it was the perfect airplane, I might offer the seller a $500 earnest
money agreement, which would state that if it passed an inspection made by a
reputable A & P mechanic, with no significant defects, then I would agree to
purchase the aircraft. If there were defects, then I would not have to
purchase the aircraft and have my $500 refunded.

If he is not willing to do that, I would not want to buy an airplane from
him.

Colin