08/31/2010. Remarks by Johan Visschedijk: "Development of this tandem aerobatic two-seat trainer to specifications issued by the Fuerza Aerea de Chile (Chilean AF) was started in 1980 by Piper Aircraft Corporation, Lock Haven, Pennsylvania, USA. Using components from the PA-28 Dakota, PA-32 Saratoga, PA-28 Navajo, and PA-31 Cheyenne, two prototypes were completed by Piper. Power plant was a 300 hp Lycoming IO-540-KIK5 engine.

The first of these PA-28R-300 prototypes was marked XBT (experimental basic trainer), and registered N300BT c/n 28R-300-01. It was first flown on March 6, 1981, while the pictured second prototype was first flown on August 31, 1981, marked YBT and registered N40898 c/n 28R-300-02; both aircraft went to Chile in January 1982. Series aircraft were assembled by ENAER in Chile from kits provided by Piper, these were designated T-35 Pillān."