XTF Program Initiated: March 1964
First TF39 Engine to Test: December 1965
YTF Flight Test Program: June 1968 - June 1969
A-Model Production Engine Deliveries: October 1968 - December 1971
C-5A Aircraft Deliveries to USAF (81 Total): June 1969 - May 1973
1-C Engine Upgrade Program: August 1978 - November 1986
B-Model Production Engine Deliveries: February 1985 - November 1988
C-5B Aircraft Deliveries to USAF (50 Total): December 1985 - December 1989
HT90 Modification: April 1998 - Present
Thrust Reverser Overhaul: January 1992 - Present