Description of Driving Event:
A K-Seal drawing and manufacturing instruction specified measurement of inner and outer diameters, but no measurement of the K-Seal legs. Following the failure of a batch of seals during an Acceptance Test Procedure (ATP), an investigation revealed that they had all yielded and provided insufficient sealing forces. The yielding was caused by thin leg sections that occurred due to no direct measurement of leg thickness during manufacturing. Failure of this K-Seal could result in hot high pressure oxygen leakage during the orbiter launch phase with its associated hazards and also a lack of sufficient oxygen for external tank autogenous pressurization. Note: A drawing of the subject seal is available with the source documentation.
Lesson(s) Learned:
Critical dimensions, measured indirectly during inspection, may allow for excessively thin material, resulting in permanent yielding and component failure.
Recommendation(s):
For this component, the manufacturing and tooling process was revised to add direct measurements of critical dimensions during inspection.
Evidence of Recurrence Control Effectiveness:
N/A
Documents Related to Lesson:
N/A
Mission Directorate(s):
N/A
Additional Key Phrase(s):
- Flight Equipment
- Ground Operations
- Hardware
- Safety & Mission Assurance
Additional Info:
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