Stapled “NASA Technical Memorandum” (TM-X0-53761) entitled “Investigation and Resolution of J-2 Engine System Malfunctions during Flight of AS-502,” by C. R. Smith o the Propulsion and Vehicle Engineering Laboratory, dated July 25, 1968. Published by the Marshall Space Flight Center (MSFC) in Huntsville, Alabama, the 25-page booklet contains various sections and illustrations that describe the J-2 engine system failures occurring during second and third stage operation of the AS-502 flight and the investigative efforts to determine the cause of the failures and to duplicate the failures in ground testing. In fine condition. Apollo 6, also known as AS-502, was the third and final uncrewed flight in the United States' Apollo Program and the second test of the Saturn V launch vehicle. AS-502 served as a test vehicle for the Command and Service Module and for the S-IVB stage J-2 Engine re-start capability. The main problem that arose was pogo oscillation, an intense vibration that developed after liftoff and well along the flight path.
