The Avro Type 621 Tutor was a two-seat British radial-engined biplane from the interwar period. It was a simple but rugged basic trainer that was used by the Royal Air Force as well as many other air arms worldwide.
The Avro Model 621 was designed by Roy Chadwick as an Avro private venture metal replacement for the Avro 504. Conceived as a light initial pilot trainer, the biplane design featured heavily staggered equal-span, single-bay wings; the construction was based on steel tubing (with some wooden components in the wing ribs) with doped linen covering. A conventional, fixed divided main undercarriage with tailskid was used in all but the latest aircraft, which had a tailwheel.
The Model 621 was powered either by a 155 hp (116 kW) Armstrong Siddeley Mongoose or Armstrong Siddeley Lynx IV (180 hp/130 kW) or IVC (240 hp/179 kW) engine; later Lynx-powered models had the engine enclosed in a Townend ring cowling. The Mongoose-powered version was called the 621 Trainer and the more numerous Lynx-engined aircraft the Tutor. The Tutor also differed by having a more rounded rudder.
The first flight of the prototype G-AAKT was in September 1929, piloted by Avro chief test pilot Captain Harry Albert "Sam" Brown.
The Royal Canadian Air Force operated six aircraft. Wikipedia