In addition to selling the plane as 'unairworthy' if you obtained a Hold Harmless and Indemnification Agreement from the Purchaser, then the Purchaser would be (nearly) excluded from suing the seller.  Other people that may be harmed would have to sue the Purchaser first, before they could come back on the Seller.  Even then, the Purchaser would have to make you whole to the full extent of his financial capabilities before they got into your pockets.  

All legal barriers can be penetrated, but given the low level, or non-existent successful suits, and the additional barriers of Hold Harmless and Indemnification, the true risks shrinks to one of insignificance.  After all, we live in a risky world but if we wish to live and function, we must accept a certainly level of quantified risk...this seems to be one of the small ones and the financial gain from a sale is outsized to the small legal risk.

Chuck Jensen