During the early-1960s, the Brazilian Air Force was on the hunt for a successor to its aging stock of American-made T-6 'Texan' and Dutch-originated Fokker S-11/S-12 basic trainers (the pair held roots in the 1930s and 1940s, respectively). A modern, local solution was selected for the basic training / ground attack role in the Neiva N621 'Universal', a single-engine, two/three-seat monoplane form built of all-metal construction. Some 189 total units were ultimately realized and these went on to stock the inventories of the Brazilian Air Force as well as the air services of Bolivia, Chile, and Paraguay.
The series began in the YT-25A prototype of largely conventional design. The monoplane wing members were fitted ahead of midships and low against the sides of the fuselage. The fuselage itself was widened to include the two cockpit seats in a side-by-side arrangement, offering excellent communications between student and instructor. The engine was installed in the usual way in the nose, the powerplant becoming the American-made Lycoming IO-540-K1D5 series 6-cylinder air-cooled piston engine offering 300 horsepower. This was used to drive a simple, two-bladed propeller at the nose.
The tail section was just as traditional, incorporating a single vertical with slightly raised horizontal planes. For ground-running, there was a wholly-modern wheeled tricycle arrangement that was completed retractable into the design - preserving the aircraft's aerodynamic efficiency.
A first-flight in prototype form was recorded on April 29th, 1966 and led to a 150-strong order by the Brazilian Air Force, which adopted the design formally as the T-25 'Universal'. By the end of the 1970s, the service returned with an order for another 28 units.
The Universal was given a running length of 28.2 feet with a wingspan measuring 36 feet and a height of 9.9 feet. Empty weight was rated at 2,535lb against an MTOW of 3,750lb. Performance specs included a maximum speed of 190 miles-per-hour, a cruising speed of 177 mph, a range out to 930 miles, and a service ceiling of 20,000 feet. Rate-of-climb reached 1,315 feet-per-minute.
If armed, the T-25 was cleared to carry 2 x 7.62mm machine gun pods on two external hardpoints.
The T-25 went on to lead a healthy and long service life in the Brazilian Air Force. The service even thought enough about their homegrown product to operate it as a COunter-INsurgency (COIN) platform and armed it for the low-level role. Beyond its basic training role, this sort of modification showcased the T-25's inherent versatility.
It was the Chilean Army, not Air Force, that took an interest in the T-25 and ordered ten examples. These later fell to the Chilean Air Force before ending their journey with Paraguay. With the arrival of the Embraer EMB-312 'Tucano' trainer-light strike platform in the early 1980s, the T-25's time in the air was numbered. In 2005, the Brazilian Air Force, already having committed to the Tucano in 1983, delivered to Bolivia and Paraguay and six T-25 aircraft apiece.
The YT-25B ('Universal II') was proposed as a suitable successor for the original T-25A but was not followed-up on. This prototype recorded its first-flight on October 2nd, 1978.