The 421 uses geared Continental MotorsContinental GTSIO-520-D
engines. The gearing means that rather than the drive shaft being
directly connected to the propeller, it drives through a set of
The geared engines operate at a similar speed to a typical direct
drive engine however the gear-reduction drive slows the propeller RPM
down. This lower prop speed of 1600-1900RPM in cruise greatly reduces
cabin noise which is the greatest benefit of the gear reduction drive.
These engines have proven to be extremely reliable.
The 421 was first produced in 1968. It was redesigned in 1970 and marketed as the 421B.
In 1976 the 421C appeared which featured wet wings
and the absence of wing tip fuel tanks. In 1980 the 421C's landing gear
was changed from straight-leg to a trailing-link design.
Production ended in 1985 due to product liability concerns, along with all other piston-powered Cessna aircraft.
The aircraft remains a popular high-performance pressurized personal
aircraft and commands high prices in the used aircraft market.
Some 421s have been modified to accept turboprop engines, making them very similar to the Cessna 425, which itself is a turboprop development of the 421.