In most aerospace and defense environments, the terms are related but not identical:
Baseline: Full vs partial FAI
Under AS9102, the starting point is a full FAI: all drawing, model, and specification characteristics, all operations, and all notes are verified and documented for a configuration (part number, revision, and manufacturing method).
A partial FAI is any FAI that does not repeat the entire original full FAI. Instead, it covers only a defined subset of characteristics or operations. Partial FAIs are typically triggered by:
- Design changes affecting some characteristics
- Process changes (e.g., new machine, new NC program, new fixture)
- Changes in source or location (e.g., new supplier, new facility)
- Significant lapse in production, depending on your procedure
AS9102 recognizes this approach, but the exact triggers, scope, and documentation method must be defined in your internal procedures and contract reviews.
What is a delta FAI?
A delta FAI is a specific form of partial FAI that focuses only on the delta: the items changed since the last approved full FAI (or previous partial FAI) and any characteristics that are impacted by those changes.
In practice, a delta FAI usually means:
- You start from a prior approved FAI as the baseline (full or partial).
- You identify the configuration change (e.g., new drawing revision, NC program revision, process router change).
- You determine which characteristics or operations are affected by that change.
- You inspect and document only those affected characteristics and operations, plus any that are indirectly impacted.
Because a delta FAI is scoped to the change, it must clearly reference the baseline FAI and the specific change documentation (e.g., ECN/ECR, drawing revision, router change order) to maintain traceability.
Key differences in intent and usage
- Scope definition
Partial FAI: Any subset of characteristics, for any allowed trigger, as defined by your procedure.
Delta FAI: A partial FAI whose scope is defined explicitly by the difference between configurations (old vs new).
- Relationship to baseline
Partial FAI: May or may not be tightly framed as a change from a specific prior FAI, depending on how your process is written.
Delta FAI: Always anchored to a prior FAI and a documented change. It is conceptually “baseline FAI + evaluated changes.”
- Change traceability
Partial FAI: Can be used for broader requalification (e.g., after long lapse or process drift) where the scope is not strictly limited to documented deltas.
Delta FAI: Requires explicit traceability to the change record and clear linkage showing which characteristics were impacted and reverified.
- Terminology risk
Some organizations and suppliers use “partial” and “delta” as synonyms. Others distinguish them exactly as above. Auditors will look for internal consistency between your procedures, records, and actual practice.
Practical considerations in regulated, brownfield environments
In mixed legacy environments with paper FAI forms, spreadsheets, and newer digital tools, the distinction matters operationally:
- System behavior: Some AS9102 / FAI software explicitly supports “delta FAI” workflows (e.g., revision compare, carry-forward of unchanged characteristics). Older systems may only have a generic “partial FAI” flag, so the delta concept must be enforced via work instructions.
- Traceability: You need a clear link between the baseline FAI and any delta/partial FAI in your MES, PLM, QMS, or document control. If these systems are not well integrated, that linkage may rely on disciplined naming, cross-references, and manual checks.
- Change control: Delta FAIs depend heavily on robust ECN/ECR and router change processes. If your change impact analysis is weak, a delta FAI can mistakenly omit affected characteristics, creating risk during audits or field issues.
- Lifetime of qualifications: In long-lifecycle aerospace programs, you rarely redo full FAIs unless forced by major changes. Delta/partial FAIs, grounded in controlled changes, are usually the only practical way to maintain FAI currency over many years.
How to decide what to call and use in your plant
The AS9102 standard does not rigidly define the everyday shop-floor usage of “delta FAI.” What matters most is:
- Your procedures clearly define:
- When a full FAI is required
- When a partial FAI is allowed
- How a delta FAI (if you use the term) is scoped and documented
- Your forms, templates, and digital tools support that distinction.
- Operators, programmers, inspectors, and supplier quality engineers are trained to apply it consistently, including for suppliers.
If your current systems or suppliers blur the terms, it is safer to define “partial FAI” in your QMS as the umbrella concept and then define “delta FAI” explicitly as a partial FAI based on a documented configuration change and impact analysis.
