We recently purchased a used DA42 NG, all using adapted templates from AOPA US (they are generic and fit for EASA-land):
- Bill of Sale (had it verified by Swiss CAA that it was sufficient)
- Purchase Agreement
Worked out beautifully!
The escrow agent was simply a normal notary of our choosing (and accepted by the seller) without aviation experience. IMHO aviation experience is irrelevant for the escrow agent, as he simply ensures the holding and transfer of money vs. bill-of-sale between two parties, a generic transaction for a notary. It is also the notary that establishes the “Escrow Agreement” between himself and the parties.