B. Both experiments, the KC-l and KS-25, incorporate a vacuum system using a sense line routed from the experiment to ambient pressure in the aircraft LN2 bay. Sporadic malfunctions have occurred resulting in loss of vacuum and loss of data. Moisture collection in the sense line had been suspected, and a dry nitrogen purge was accomplished at closeout following the first malfunction. A resume of vacuum conditions follows:

B. A satisfactory engine run with S/N 107 was accomplished on July 11, 1963

C. The No. 1 APU (S/N 25AN) gearbox pressure decreased to approximately (l) psi during both APU shutdown sequences of the ground run. The pressure recovered slowly as the unit cooled down following the run and a leak check was made at 10 psid without indication of leakage. The pressure relief valve was changed because the reseat pressure was only slightly above the regulated pressure. Gas leakage from the cooling-gas vent was noted following each shutdown and indicated leakage from the case through the turbine-shaft upper seal. Since the seal did not leak while cold, distortion of the seal with temperature is suspected. Pressurization of the case during the operation of the unit was adequate, therefore, the unit was accepted for flight.

D. Flight l-A-60 was accomplished on July 17, 1963. The flight was terminated after B-52 takeoff because the pilot's oxygen disconnect (B-52 to X-15) became disengaged. Propellant jettison was completed, and the flight terminated as soon as possible since the pilot was breathing from the more limited X-15 internal supply. Pilot usage was 1300 psid in 30 minutes.

Post-flight investigations indicated tolerance differences among several disconnect combinations, resulting in variable degrees of engagement. An incomplete disconnect engagement was tolerant to an axial load, however, side loads or vibration resulted in eventual disengagement. All parts will eventually be reinspected and tolerances altered if required.

E. Due to the modifications of the inertial platform 28V DC power supply as part of circuit changes to computer S/N 1A, the power change-over after B-52 engine start resulted in a power break and platform upset. (see V-A).

B. The engine was shutdown by the pilot after 83.5 seconds of 100% operation. The engine reverted to normal prime mode for 15 seconds, then a malfunction occurred. Review of data after flight indicated an unexplained actuation of the K-39 relay (second-stage-igniter start) producing the malfunction. Functional tests of the lube oil system and an electrical function after flight did not reproduce the in-flight operation. No evidence of moisture was noted in the igniter pressure sense line during purge checks.