During windshield replacement at NAA Los Angeles, following Flight 1-29-50, a pane drawn from stock showed similar delamination evidence and physical characteristics to the pane removed following flight.

B. Augmented LN2 System Cooling of Inertial System Components

Augmented cooling effectiveness has shown wide variation during postmated inertial checks, pre-taxi, and during flight as well as between B-52 #003 and #008 with X-15-1. It has been necessary to operate both blowers and LN2 at all times to produce a sufficient demand of LN2 to overcome shock-down requirements in the long supply line between B-52 tank and the X-15 injectors. Recently B-52 system changes were made to raise LN2 supply pressure from Nom. 65 psi to 80 psi with some operation improvement.

C. RH Main Gear Up Lock and Roller Misalignment

New hook support brackets were installed in as extreme position as allowed by local A/C structure. Interference was reduced but not eliminated. Gear down operation remained satisfactory. Gear stowage required side load technique. Following flight the roller mount assembly was modified and produced good alignment.

B. A modified side arm control stick with a beep type trim switch replaced the previous trim pot installation. The new switch is wired in parallel with the alternate center stick trim circuit and the normal trim system is deactivated.

C. Engine S/N 109 was replaced with S/N 107, which incorporates an unvectored chamber and gradated Plasmacote with Titanium Oxide overlay.

D. A set of main gear skids were removed which incorporated flame spray coatings of Metcoloy #2 (stainless) end Spraysteel #80 (carbon steel). Six landings were made on these skids prior to replacement due to reduced spray coat thickness. Parent metal was not exposed. A sand blast, recoat attempt will be made and evaluated. Original coatings were .025 thick on a .155 4130 base. An uncoated set of skids with two previous landings was installed.

B. The "Dogleg" total pressure system (previously supplying only pilot instruments) was replumbed to include measurement on a sensitive airspeed recorder cell. The recording instrument is located in a compartment forward of the nose gear well.

C. All impact pressure probes were removed except the BCS compartment station, the station 70 at 20° right of bottom center, and the preston tube rake on the upper ventral.

D. Basic Instrumentation Complement Reduction

B. A cockpit leak check following windshield replacement was 73 CFM. (A post-flight check made following Flight 1-30-51 using the same GSE was 65 CFM.

C. The ground run of engine S/N 109 was outwardly satisfactory except that data indicated a sticky H2O2 metering valve producing a 400 psi manifold pressure in pump idle. Ambient pressure changes between ground and launch altitude would produce a malfunction shutdown due to actuation of the high manifold pressure switch. The engine was replaced with engine S/N 107.

D. During the first ground run of engine S/N 107 three valve malfunction shutdowns were experienced, one in main chamber with an igniter start, one in igniter idle, and one in main chamber with an automatic start. The aircraft was returned to the hangar and investigation revealed an intermittent wire connection in the engine H2O2 safety valve pilot solenoid harness. The harness was replaced and the ground run accomplished the following day.

E. During the second ground run of engine S/N 107, the firex valve actuated without normal cause. A faulty control unit and damaged wire connections on the 'push to test' switch were corrected after the run. With normal operation, a fire condition reduces the resistance of the detector element and the control unit produces a signal to operate the fire light, shutdown the engine, and actuate the firex valve to expel No. 2 helium source into the engine compartment.

F. The No. 1 blower failed during functional operations because of a procedural error where the blower switch was on with only one A. C. phase engaged. The blower will not rotate with one phase and overheat resulted.

G. A three hour delay in the flight takeoff time resulted when excessively cold temperatures were noted on the ASAS gyro ground readout (-75°F) during preflight servicing. A heater malfunction was suspected and the circuit checked. The gyro plug was disconnected, violating the preflight. A bent heater circuit pin at this plug was found and suspected as the cause of an inoperative heater. Accomplishment of the ASAS preflight and in-flight ASAS checks demonstrated the plug reconnection. Removal of the elevator was required to accomplish the preflight of ASAS. Because of excessive leakage from the rear annulus chill seal, reduced usage of annulus was maintained until service closeout to raise the SAS and ASAS gyro environmental temperature (resulting in ASAS gyro temperature of +15 to +35°F).

H. The final temperatures of the APU H2O2 prior closeout was 42°F because of the long cold soak time during ASAS checks.

B. The APU compartment heat indication in the B-52 appeared inoperative during prelaunch activities. Post-flight check of the X-15 thermoswitches was satisfactory.

C. The LH outer windshield exhibited crazing cracks near the rear edge forward of the retainer. These cracks were approximately 1/8" long and .020 deep in a regular pattern parallel to the retainer rear edge. The glass was replaced and sent to NAA Los Angeles for evaluation.

D. A 3 inch crack in the canopy inner skin, forward LH side, occurred during flight. The skin carries pressurization loads and is .022 thick aluminum. A repair patch was installed following flight.

E. Cockpit altitude rose sharply during the engine shutdown transient. Slow recovery was effected, however, data indicated the augmented cockpit pressurization LN2 valve was open for the remainder of the flight above 35,000 feet. The cockpit pressure regulator is suspected of "G" rate effects which produce opening of the valve. The augmented cockpit pressurization system would be required to produce sufficient GN2 to overcome cabin leakage and provide an excess to meet regulator outflow requirements. Since the regulator operation is dependent on a minimum outflow through the valve, closing is sluggish.

F. The augmented cooling LN2 supply failed to maintain normal mixing chamber temperatures from initial turn-on until ram air door was opened at 20 M during the climb-out. The X-15 internal system was demonstrated at 13 minutes prior to launch and produced quick shockdown to normal -40° C temperatures. Ram air cooling produced adequate cooling for inertial components, however, the pilot's suit was pressurized until the X-15 supply was initiated. Following flight, the B-52 pylon LN2 tank jettison indicated a partial loss of LN2 tank vacuum had occurred. (Later operation of this system with the tank replaced during Flight 3-A-ll indicated satisfactory mixing chamber temperatures).

G. The lower ventral was not recovered because the parachute was deployed in flight. The chute door apparently opened during flight; the reason is not known. Ground observers reported that the ventral door and chute were not present when the ventral was jettisoned. Inspection of the drogue gun immediately after impact of the ventral indicated firing on ventral jettison. The chute lanyard was burned off. No evidence of H202 was present on the ventral and no evidence of combustion in the chute box indicated loss of chute was not due to H202 leakage.

H. Normal SAS pitch channel tripped out during the pull-up to max angle of attack during flight. The sequence is as follows: