of about 0.64:1. Designed by a team under Frederick Morley, the first versions of what had become the 'Spey' entered service in 1964, powering both the BAC One-Eleven and Hawker Siddeley Trident. Several versions with higher power ratings were delivered through the 1960s, but development was ended nearing the 1970s due to the introduction of engines with much higher bypass ratios, and thus better fuel economy.

In 1980, Turbomecanica Bucharest