Aerospace Key Characteristics Worksheet
Key characteristics are the features whose variation most affects fit, form, function, performance or service life. AS9103 asks suppliers to manage that variation deliberately. This worksheet keeps the list, the risk rating, the control method and the capability gap in one place.
| KC ID | Part number | Feature and requirement | Designated by | Severity (1-10) | Occurrence (1-10) | Detection (1-10) | Risk priority number | Control method | Cpk target | Cpk actual | Cpk gap to target | Owner | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
72 | 0.15 | ||||||||||||
128 | -0.12 | ||||||||||||
60 | 0.12 | ||||||||||||
135 | 0.17 | ||||||||||||
84 | 0.05 |
A negative Cpk gap means the process does not yet meet the target and needs improvement or 100% inspection until it does. Capability targets here (1.33 and 1.67) are common examples; use the value your customer or AS9103-based procedure specifies. RPN is a prioritization aid, not a replacement for judgment.
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How to use the worksheet
Start from the characteristics the customer or design authority designates. Add features your own risk analysis identifies, then rate severity, occurrence and detection. Choose a control method for each and record the Cpk target and the latest actual value. The gap column shows where capability falls short. Export to Excel for your control plan or for customer review.
- Link each KC to the drawing characteristic number used in the FAI
- Update Cpk actual from real SPC data, not an estimate
- Review the list when drawings or processes change
- Assign an owner for every row
What AS9103 requires
AS9103 covers variation management of key characteristics. The flow is to identify the KCs, determine the process and its sources of variation, collect data, assess capability, and improve or control the process where capability is insufficient. Customers specify their own thresholds, and the standard gives guidance on sampling and on actions when capability is not demonstrated, such as interim 100% inspection.
Reading the table
Sort by RPN to see where risk concentrates, then look at the capability gap. A high-severity feature with a negative gap needs immediate containment. A high Cpk with a poor detection score may justify reducing inspection effort. In the example, KC-02 has a gap of minus 0.12, so the position tolerance needs setup improvement or full inspection until capability reaches the target.
Common mistakes
Teams often designate too many characteristics, which dilutes attention, or compute Cpk from too few parts or from a non-normal distribution. Record how Cpk was calculated and over what period. In SAP QM, SyteLine or Epicor, flag KC characteristics in the inspection plan so results feed the same SPC history every time.
Frequently Asked Questions
What is a key characteristic?
A key characteristic is a feature of a material, process or part whose variation has a significant influence on product fit, performance, service life or manufacturability. It is designated by the customer or design authority, or identified by the supplier's own risk analysis, and managed with extra controls.
What Cpk is required for key characteristics?
It depends on your customer. Values such as 1.33 and 1.67 are widely used as targets, but the contract or customer procedure sets the actual requirement. When capability is not shown, many customers require 100% inspection as a temporary measure until it is.
How do key characteristics relate to the FAI?
Key characteristics appear on the first article Form 3 with a designator, and later in production they are controlled through SPC or other methods. Keeping a single ID across FAI, control plan and inspection plan avoids mismatches during audits.
Is RPN required by AS9103?
No. RPN is a common FMEA scoring method used here for prioritization. AS9103 does not mandate it. If your FMEA uses action priority instead, replace the columns to match your procedure.
If you need key characteristic results pulled from your ERP inspection data into capability reports, we can help build that on your own servers.
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