Hartzell Propeller’s Top Prop line of STC’d two-, three-, and four-bladed constant-speed propeller conversions reached a milestone of 20,000 sales as of July, 2013.
The Top Prop program was launched in 1991 to offer new, state of the art, alternative replacement propellers for the maturing fleet of piston-engine aircraft, company officials said. The plan was to offer improved 3-blade replacements for original factory installed 2-blade propellers, improving performance, reducing prop diameter and noise, and increasing ground clearance. The program’s Initial offerings were a three-blade conversion for the Mooney M20, Piper Arrow, and Cessna Cardinal RG. These “Original Three” kits are still offered in the current Top Prop catalog.
Over the years, with advances in airfoil design, manufacturing capability, and construction technology, the opportunities to offer improvements have broadened to include scimitar shaped, “blended” airfoils, and the very latest in carbon fibre construction technology, company officials note.
STCs have since been continually added from Hartzell’s archives, and by acquisitions. New kits have been developed using FAA Designees, and by Hartzell’s own engineering department that currently maintains its own FAA STC-ODA, (Organizational Delegation Authority).
Today, the Top Prop catalog has grown to more than 65 company-owned STCs, and more than 170 different conversion kits, company officials said.