| Selected
            by Boeing to power the 747, the JT9D helped open a new era in
            commercial aviation, the high-bypass engine to power wide-body
            aircraft. Production of the JT9D ended in 1990 to be
            replaced by the PW4000.  There are still well over 2,000 JT9Ds
            powering 600 commercial aircraft world-wide. |  | 
              |  | Turbofan |  |  | Fan: 1-stage |  |  | Compressor: 3-stage LP, 11-stage HP |  |  | Turbine: 2 + 4 |  |  | bypass ratio: 4.8 |  |  | pressure ratio: 26.7 |  |  | mass flow: 1,510 lbs/sec |  |