Snappy Starts on the JT9D
1969 was the year the 747 was to be delivered to Pan Am. I was in the
first group to go to school in SFO. To save money, Pan Am decided to
use the "specific behavioral objective" system of training.
It was the first time we weren't thoroughly trained. They gave us a
little extra because we would have to help the mechanics. Starting the
JT9D engine was an ongoing problem. As the engines deteriorated, starting
became increasingly difficult. We used many tricks but the Maintenance
dept insisted we use
only one ignition system. I soon found out starting was much better
using both ignition systems. The start switches were located high on
the ceiling and no one could know where your fingers were. I received
many compliments on my quick starts. I had no interest in starting a
crusade to change the checklist. Many mechanics told me they could tell
by the sound if an engine start would be successful. I solicited their
opinions during start and used the remainder of the bag of tricks if
necessary. After retirement I taught Engines at San Jose State Univ.
and found out that the first two starters, the first turbine and the
burner cans operated above the melting temperatures of these parts.
Cooling air bathed these parts through a series of holes in the hollow
blades with high pressure air. The other surprise was the 25:1 compression
ratio. Diesels use 18:1!