A Critical Supplier's Operator-Error 8D, a Deviation Request, and a Skip-Lot Plan

'Operator error' is a stopping point, not a root cause. ISO 9001:2015 clause 10.2 expects reaction, evaluation of the need for action to eliminate the cause, implementation, and review of effectiveness. Retraining plus a checklist is containment and detection, not cause elimination.

Missing elements.

• Why the operator was there. A new night-shift operator on a critical bore operation implies a competency/qualification system failure. Who authorized assignment, what training record existed, how was competence verified?
• Escape analysis. Bore oversize of 0.026-0.031 mm should be caught by PTC's final inspection if it gauges 100% or by in-process SPC. Why did it reach Bracken? The two-part answer is normally detection (gauging frequency, gauge capability) and process (tool wear, thermal drift on night shift).
• Measurement system. Was the bore measured with a gauge with acceptable GR&R? Confirm before attributing parts to a person.
• Scope. One operator, one shift, or systemic? Data from other lots and shifts either supports or kills the hypothesis.
• Effectiveness verification. Three consecutive lots with capability data, not a signed retraining sheet.

Decision. Reject the 8D as incomplete; return it with the specific questions. Accept the interim containment (retrain, checklist) as temporary while root cause work continues, and require a revised 8D with data within a stated period. A supplier's on-time delivery record is irrelevant to whether a corrective action closes.

Start with the characteristic, not the quantity. The bore is an actuator housing fit; oversize bore reduces interference or changes clearance, and true position affects assembly alignment. That is form, fit and function territory.

Decision logic.

1. Is the drawing customer-controlled? Bracken's customer requires full traceability and FAI for new parts, which suggests a customer-owned design. Where a deviation affects a customer-specified or key characteristic, Bracken normally cannot self-approve; the request goes to the customer with supporting analysis.
2. What analysis supports use-as-is? Worst-case fit and clearance calculation using 25.031 mm and 0.08 mm true position, plus functional test data on parts at the extremes. A statement that the assembly is 'non-critical' is not analysis.
3. What happens if it fails in service? An actuator housing with an out-of-spec fit can produce binding, lost motion, or premature wear, with warranty and safety implications.
4. Alternatives first. 100% sort and gauge the lot, segregate conforming pieces, and quantify how many are truly usable; check whether rework is technically feasible and approved. Deviation should be the last option, not the first.

Supplier's stock position. Three days of cover is a supply continuity problem, not a quality justification. In parallel, push for expedited replacement, authorize overtime at an approved alternative source, and give the customer a recovery plan.

Who owns the decision. Material review with quality, engineering and the customer's supplier quality function where the characteristic is customer-designated. The quality function holds a veto; commercial pressure does not vote.

New part approval. On-time delivery is a delivery metric and does not substitute for process capability evidence. Require, before approval:

• Process FMEA and control plan for the new part, plus a process flow diagram.
• MSA for each inspection method, and capability studies on critical characteristics from a stable process, typically Ppk at or above 1.67 for a new part on safety-related features.
• Full first article inspection to the customer's requirement, with ballooned drawing and material/process certificates.
• A closed, verified corrective action history on the existing part, not a plan.

Approval should be conditional and staged: trial lots with first-article and capability data, then production approval after demonstrated performance.

Skip-lot. The premise of skip-lot is a demonstrated stable process with a quality history. Five pieces revealing two out-of-tolerance bores is a high defect rate in that sample, which invalidates the premise. Therefore:

1. Return to tightened inspection immediately - increased sample, or 100% verification of critical characteristics for a defined number of lots.
2. Assess the three skipped lots retrospectively: pull retained samples or returned stock and check the same characteristics. Skipped lots are unverified, not known good.
3. Define exit criteria in writing: for example, ten consecutive conforming lots, 100% critical-characteristic verification, and verified corrective action effectiveness, with the supplier quality function approving the return to normal inspection.
4. Treat this as a supplier risk rating change and record it; the deviation request should not influence the inspection decision.