B. Deterioration of the annulus chill tank end seals has resulted in excessive LN2 leakage into the LN2 bay and CG bay. The resulting cold environment for components located in these bays has produced freezing of the hydraulic systems and minimum temperatures in the ASAS gyro package. Operation of the annulus chill system following flight revealed a new leak which impinged on the No. 2 APU tank cover and was reflected into the vicinity of unprotected hydraulic supply lines. Hydraulic pressure response during the No. 2 APU start lagged the initial turn-on by approximately 30 seconds. The ball nose was inoperative or erratic until 4 minutes before launch.

C. The lower ventral was not recovered for the second consecutive flight because of in-flight recovery chute deployment. The No. 4 .Chase reported a black object (possibly the ventral door or chute) leaving the X-15 at jettison callout. Rigging procedures were reviewed with the crews concerned and found to be consistent with accepted practice. The hook which secures the door appears to have marginal engagement and is positioned by only a spring. Air turbulence at the base of the ventral, especially with speed brake operation, could disengage the hook when rigged to minimum tolerances. Under consideration is the possibility that differential temperatures between the ventral structure and cable actuation system would partially actuate the door latch. Revised rigging procedures to increase door latch engagement and a hook modification will be tested.

D. Corning Glass has inspected the LH windshield which cracked on Flight 1-30-51. Based on the initial report, the cracks were the result of a single heating cycle with temperatures on the glass surface of 1360°F to 1560°F.

B. The CG pressure rake-manometer package was reinstalled.

C. Temperature readout of inertial system stabilizer internal environment and X-15 LN2 injector supply pressure were added to the T/M monitor display for heat and vent system analysis.

B. A ground run with engine S/N 107 was accomplished. During the second engine start (3rd pump operation), a sticking H2O2 metering valve produced excessive manifold pressures of 375 to 400 psi. The engine was not replaced; lt was decided to accept the possibility of an engine shutdown in idle prior to launch because of scheduling factors.

C. Two cameras were inoperative during flight closeout checks. The cockpit GSAP was intermittent due to a control relay, and the lower bugeye was connected to the wrong electrical connector.

D. Extremely cold ASAS gyro temp were again obtained during preflight service due to annulus chill leakage. Discussion presented in Part I (B).

B. Hydraulic system freezing was evident following both APU starts. Discussion included in Part I (B) . Data from the flight indicated the No. 2 hydraulic reservoir sense line may have frozen producing a temporary pump cavitation condition. The No. 1 APU start was normal, however, the ball nose is supplied from the No. 1 hydraulic system through a line which is routed across the LN2 bay, and ball nose action was erratic for an extended period prior to launch.

C. The lower ventral was not recovered as discussed in Part I (B),

D. The No. 2 APU generator tripped out during flight. Reset was accomplished following landing. A faulty generator frequency control relay was found during post flight checks. The generator control relay and protective panel were also changed for the bench check.

E. A rise in cockpit pressure was again experienced during the engine shutdown deceleration. The cockpit regulator was changed.

F. The engine start prior to launch was satisfactory, and subsequent engine operation during flight was normal. Data indicated the H2O2 metering valve duplicated ground operation and manifold pressures in pump idle approached S-30 overpressure situation (447 psi).

G. The pilot reported erratic ball nose indication during flight, Post flight checks failed to reveal a direct cause, however, the sensor cooling system was inoperative and sensor electronic component sensitivity to temperature is under investigation. The sensor was replaced for bench checks.

H. The normal SAS pitch and roll channels tripped out several times during flight. The SAS system has shown extreme sensitivity to both DC bus and SAS circuit generated transients following installation of the notch filter configuration. Complete SAS alignment was accomplished prior to flight. The alignment will be repeated again with additional checks to investigate system transient sensitivity. DC and AC bus transients were significantly increased during a portion of the flight due to single generator operation.

I. The 3 axis ball heading was approximately 3 to 4 degrees in error due to preflight setup procedure or equipment malfunction. The error was constant.

J. The pilot reported below normal suit vent gas temperatures with high heat position of the suit vent heater switch. The heaters were thoroughly checked following flight without deviations. A different procedure was used prior to pilot entry which shocked down the vent system for approximately 5 minutes with heaters off.

K. The ground support crew had difficulty in opening the canopy following flight due to engagement of the canopy forward locating pin. Checks following flight showed fuselage deflection with the aircraft supported on the nose gear could affect the engagement of the locating pin. The pin installed on X-15-1 is 11/32 inches longer than the drawing dimension. The pin will be shortened 1/8 inch to provide clearance.