Military & defense
Military depot hydraulic leak root-cause workflow
A depot reconditioning line saw hydraulic fitting leaks climb on a shared vehicle sub-assembly after a surface-prep procedure change. The team had days — not weeks — to contain, isolate cause, and restore line confidence.
Challenge
Leak-test failures rose from 3% to 9% across two reconditioning cells. Mission-support schedules made extended line downtime unacceptable without data-backed direction.
How they worked it
Scoped the leak spike with 5W2H, issued a quality alert, held a depot stand-down, and signed off containment training.
Verified leak-test and torque data with variable Gage R&R before comparing reconditioning cells.
Mapped leak failures by reconditioning cell and fitting zone so the team could see where escapes concentrated.
Ran Exploration Cascade and narrowed the contrast to the two cells running the updated surface-prep sequence.
Chi-Square confirmed a statistically significant difference in leak rates between the two reconditioning cells.
Swapped the surface-prep tooling kit between cells; leak failures followed the kit, not the operators or shift.
Screened prep-tool wear features to confirm abrasion depth drift — the swap study had already isolated the kit.
Segregated recent reconditioned lots and held outgoing assemblies while the worn prep tooling was replaced.
Put torque and leak-test results on SPC under the restored prep procedure and updated control limits.
Updated PFMEA, control plan, and special process assessment with prep-tool replacement intervals and in-process SPC requirements.
Closed the readiness review in an 8D with defect maps and corrective-action evidence for government QA.
Outcome
Root cause traced to worn surface-prep tooling on one cell. Containment, tooling replacement, and PFMEA updates closed the readiness review with traceable evidence — leak rate returned to baseline within one production week.
Illustrative workflow based on typical military depot and defense supplier quality patterns — not a specific government engagement or named program.
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