[4] According to Cassagneres, "The main landing gear, in fact, was the most noticeable external change from the STA in that the wheels were mounted outboard of the shock struts rather than the fork type of the earlier STs and STMs.

Each cockpit included an airspeed indicator, altimeter, oil temperature and pressure gauges, tachometer and compass.

[3] In order to simplify maintenance, the wheel spats and landing gear fairings were deleted in the production examples The PT-22 was developed in 1941 from the civilian Ryan ST series.

The rapid expansion of wartime aircrew training required new trainers, and the Ryan PT-22 was ordered in large numbers.

[5] Named the "Recruit", it entered operational service with the U.S. Orders also were placed by the Netherlands, but were never realized as the nation capitulated to Axis forces.