v4p369

Report of the PRESIDENTIAL COMMISSION on the Space Shuttle Challenger Accident

Volume 4 Index

Hearings of the Presidential Commission on the Space Shuttle Challenger Accident: February 6, 1986 to February 25, 1986

FEBRUARY 11, 1986 SESSION

[370] [Ref. 2/11-12] O-RING HISTORY.

PRIOR TO STS 51-L......11 STATIC TEST MOTORS, 48 FLIGHT MOTORS.
FIELD AND NOZZLE JOINTS OF 57 MOTORS HAVE BEEN EXAMINED REPRESENTING 228 JOINTS WITH 456 O-RINGS.
OBSERVATIONS
- 6 OF THE 171 FIELD JOINTS EXHIBITED SOME EROSION OF THE PRIMARY O-RING.

- 2 OF THE 171 FIELD JOINTS EXHIBITED SOME SOOT BEHIND THE PRIMARY O-RING.

- 16 OF THE 57 NOZZLE JOINTS EXHIBITED SOME EROSION OF THE PRIMARY O-RING.

- 8 OF THE 57 NOZZLE JOINTS EXHIBITED SOME SOOT BEHIND OF THE PRIMARY O-RING.

- NO FIELD-JOINT SECONDARY O-RINGS HAVE BEEN ERODED.

- 1 NOZZLE-JOINT SECONDARY O-RING HAS BEEN ERODED (ONLY 1/4 OF THE ESTIMATED SAFE DEPTH)

CONCLUSIONS
- IN ALL OF THE FIELD JOINTS EXAMINED, THE PRIMARY O-RING SEALED EFFECTIVELY EVEN WITH EROSION.

- IN ONE NOZZLE JOINT, THE PRIMARY O-RING FAILED TO SEAL, BUT THE SECONDARY O-RING SEALED EFFECTIVELY EVEN WITH EROSION.

[Ref. 2/11-13] SRM FIELD JOINT.