Aerospace
Aerospace supplier root-cause analysis workflow
A machining supplier received a source-inspection alert on bore diameter for a flight-critical bracket. The team had 48 hours to contain, isolate cause, and propose corrective action.
Challenge
Two CNC cells produced the part. Customer data showed a tail on undersized bores, but incoming inspection had not flagged the same pattern consistently.
How they worked it
- Built a quality-issue plan capturing the bore escape, both cells, and the 48-hour customer containment window. (Paynter Chart)
- Used Exploration Cascade to separate measurement drift from machining variation, then Chi-Square on undersize rates by cell and shift. (Exploration Cascade, Chi-Square Test)
- Ran variable Gage R&R on the bore mic so incoming and in-process readings could be compared with confidence. (Variable Gage R&R)
- Updated PFMEA for fixture bushing wear and completed a special-process review for the machining cell. (PFMEA / DFMEA Lite, Special Process Review)
Approach
- Compared capability by cell and shift to confirm the escape was cell-specific.
- Ran a swap study exchanging tooling, fixture, and coolant between cells.
- Used SPC on in-process bore checks to catch drift earlier than final inspection.
- Opened an 8D record with defect maps, disposition logic, and corrective-action evidence.
Tools used
Outcome
Root cause traced to a worn fixture bushing on one cell. Containment, replacement, and PFMEA updates closed the customer alert with traceable evidence.
Illustrative workflow — represents typical aerospace supplier quality practice, not a named customer case.
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