The aircraft had been was impounded at SAT by the US Customs Air Support Unit. From April 1969 to December 1971 the aircraft had been owned by the Sealy Mattress Co. of Ohio, and the significance of the registration was that 593 was Sealy company's PO Box Number, and EW were the initials of Ernest Wuliger, the President and CEO. It was last reported stored in Georgia in 1988 and it was deleted from the US register in April 2013.