FLIGHT NO: 1-73-126 DATE OF REPORT: 8/1/67
PILOT: Maj. Knight DATE OF FLIGHT: 6/29/67
CARRIER AIRCRAFT: B-52 #008 LAUNCH LAKE: Mud
ENGINE SERIAL: 108 APU #1 20AN APU #2 18AN
PURPOSE OF FLIGHT: 1. WTR Experiment
2. Horizon Scanner
3. Horizontal Stabilizer Alpha
I. Discussion of Previous Operations
B. An APU H202 relief valve was replaced.
C. Engine S/N 104 was removed for excessive NH3 prop valve leakage & engine S/N 108 was installed.
D. LOX pump discharge transmitter was changed following engine run.
E. New SAS control panel was installed.
B. The aircraft was following a near perfect profile when at approximately 69 seconds of engine burn time the engine shut down and instrument panel warning lights began coming on. Also all T/M, radar, and communications were lost at this time.
C. The sequence of warning lights as ascertained from
the cockpit film was:
2. Three SAS lights and vibration malfunctions (engine)
3. Number two generator out light
4. All lights and cockpit camera went off indicating
complete electrical failure
E. The pilot reported that there was no aircraft response to control inputs and that the side stick would not move full throw indicating a complete loss of hydraulic power, since failure of a hydraulic actuator to move limits stick travel.
F. The pilot tried the BCS controls and verified that they fired but that they did not give complete control at that altitude.
G. Knowing that the APU's cannot be restarted in less than 24 seconds from shutdown, the pilot turned the #2 APU switch to the off position and waited that time period. Then he turned it on but nothing happened.
H. He then turned #l switch to "OFF" position and then remembered that the emergency battery is required for APU re-start. He turned the battery on, then turned #l APU on and heard it wind up.
I. He then made a successful re-entry and landed at Mud Lake.
J. The landing was made without flaps or third skid since they were wired to the main D.C. bus which was dead.
K. Due to the above conditions, landing loads, as indicated by skid marks were extremely high and the slideout measured 9050 feet.
L. The pilot reported that the canopy was difficult to open. Normal opening required that the canopy seal be deflated before the canopy can slide aft. First motion of the canopy opening handle by the pilot unlocks the canopy and vents the seal. Tests in the hangar with X-15-3 show approximately 15 seconds time required to vent the seal completely. During the time the seal is inflated movement of the canopy will be very difficult.
M. The pilot also reported difficulty in disconnecting the suit-to-seat disconnect. Since he had not turned off the suit vent nitrogen system, it is probable that the N2 pressure through the disconnect increased the unlocking force by placing the disconnect halves in tension. (Subsequent tests in the hangar verify that the unlocking force rises significantly when tension is applied to the disconnect halves).
N. At this point the pilot removed his helmet for better visibility and elected to pull the restraint release handle which beside releasing the restraint, fires the head rest deploying the chute.
O. When the head rest fired it struck the raised canopy with enough force to tear the inner skin, crack the left inner windshield and bounce downward striking the pilot a glancing blow on the back of the head.
P. A detailed investigation of components and ship's wiring
has not disclosed any definite cause of the above events.
Perry V. Row Meryl D. DeGeer
X-15 Senior Project Engineer X-15 Project Engineer
ADDENDUM TO X-15 OPERATIONS FLIGHT REPORT 1-73-126
August 17, 1967
Reference: X-15 Operations Flight Report 1-73-126
In the reference report the flight events including shutdown of both APU's and related loss of all electrical power were discussed. Also it was stated that "a detailed investigation of components and ship's wiring has not disclosed any definite cause of the above events." Tests made since that date have uncovered some additional information that may explain the failure. Altitude runs were made in the FRC Altitude Chamber with the experiments that were on the airplane during flight 1-73-126. The WTR experiment was found to have power problems at altitudes of 90,000 feet to 110,000 feet. These problems were manifested in the blowing of two 15-ampere fast-blow fuses in the lab wall power. A fuse was blown in both the Af and Cf Power leads on two separate occasions. Prior to the next run at altitude, a sea-level ambient-temperature run was made to check out proper operation of the experiment. The experiment was found to operate improperly at this time. The decision was made to disassemble the experiment for trouble-shooting at this time.
After the experiment was opened up, the leads leaving the main power plug to the experiment were found burned. Indications were that Af and Cf had been arcing across at altitude and had finally damaged the surrounding wires to cause complete separation of some wires and shorting together of others.
At the time of the fuse blowing, three ten-ampere circuit breakers of an undetermined type which were located in each phase of the power wires did not blow. This is similar to the fact noted following flight 1-73-126 in which the three ten-ampere circuit breakers in the aircraft were not blown. These aircraft breakers were Klixon Toggle type of the 7270-1 series. The corresponding MS number is MS 24509-10.
The shorting together to two phases of generator power with the right conditions in the vehicle power and component grounding system is thought to produce the possibility that a shutdown signal could be passed through the unlatch and shutdown coils of the H202 shutoff solenoids.
Since this condition would require the loss of good grounding paths between several ground posts in the vehicle, it is not felt that the condition can be duplicated during ground-tests in a manner that would prove to be conclusive. Therefore, it is felt that tests beyond loading of the generators and hydraulics with the APU running at simulated altitudes, both steady-state and shock-loading, is not required.
At the present time,
the APU control circuitry, plugs, relays, etc. are being replaced with
careful attention to routing so as to eliminate the possibility of a single
failure affecting both circuits. Further, the experiments are being moved
to the secondary bus so that they will not be transferred to the remaining
APU in event of APU or generator failure. Also, the emergency battery was
replaced with one similar to that used in the F-104 aircraft. The additional
capacity of this battery will allow addition of the flaps and third-skid
circuitry on the emergency bus.
Approve By: Prepared by:
Perry V. Row Meryl D. DeGeer
X-15 Senior Project
Engineer X-15 Project Engineer