A balloon number must identify a characteristic unambiguously and connect it to the right inspection record and drawing location. Sequential numbering is common because it is easy to review, but do not assume one starting number, traversal path, gap policy, or sheet-reset convention applies everywhere. Follow the customer’s instructions and your quality management system (QMS) procedure.

What a characteristic number must do

• Distinguish the characteristic from other records in the defined scope.
• Point back to the correct source requirement, sheet, and drawing revision.
• Match the drawing annotation and report entry wherever the process uses balloons.
• Remain controlled when requirements are added, changed, or removed.

For first article inspection (FAI), the applicable AS9102 revision and customer instructions matter. IAQG’s Rev C Form 3 materials use a characteristic number and a reference location to support accountability. That is a traceability purpose; it does not by itself prescribe one visual numbering pattern for every company.

Required, common, or procedure-dependent?

Choose a scheme your team can maintain

For a simple part, a continuous sequence may be enough. For a multi-sheet assembly, a sheet-aware reference can reduce lookup time. The best method is the one that preserves unique identity and traceability through your full report and revision process—not the one that looks most familiar in a screenshot.

Compound callouts need an intentional ID granularity

A single text box can contain multiple requirements. A hole pattern may include quantity, diameter, depth, and a position tolerance. A note may combine a dimensional edge break, deburring, and a coating requirement. Decide whether the accountability record should be one grouped characteristic, multiple related IDs, or a dimensional row plus linked certificate evidence. Make that decision based on the inspection method and customer/QMS rules.

“One printed callout equals one balloon” is not a reliable universal rule. Preserve enough context for a reviewer to understand which physical features and requirements each ID covers.

What happens when the drawing changes?

Suppose Revision B has characteristics 001–018. Revision C adds a requirement between 007 and 008, changes the tolerance at 012, and removes 015. Your procedure may choose to renumber all current characteristics or retain established IDs and append an identifier such as 018A. Either can be workable when allowed. Neither should be selected casually.

1. Compare the controlled revisions and identify new, changed, deleted, and unchanged requirements.
2. Decide whether the characteristic identity persists or whether the change creates a new record.
3. Apply the customer’s and QMS’s numbering rule consistently.
4. Update balloons, report rows, source references, and any downstream forms together.
5. Record the drawing revision in the report and keep the revision comparison auditable.

Stable IDs can make history easier to follow, while renumbering can make a current drawing easier to review. If IDs change, preserve a cross-reference so earlier results are not mistaken for current requirements.

Common numbering failures

• The same ID appears on two sheets but the report does not include a sheet reference.
• A report row keeps the old ID after the balloon is moved to a different requirement.
• A deleted characteristic disappears from the drawing but remains in the current report.
• One balloon points to several unrelated features without defining the grouping.
• A revision renumbers the drawing but leaves customer attachments or prior cross-references unchanged.
• A sequence gap is “fixed” by renumbering records whose history needs to remain stable.

A short numbering procedure to adapt

1. Define the report or inspection scope and the uniqueness boundary.
2. Choose continuous, sheet-prefixed, or another approved ID format.
3. Define how patterns and compound callouts are grouped.
4. Define how new requirements are inserted during revision changes.
5. Define the acceptable treatment of gaps, deleted IDs, and suffixes.
6. Validate duplicates and reconcile IDs against every report row.

BalloonForge can preserve reviewed numbering and offer revision reuse for high-confidence unchanged characteristics, but a reviewer must resolve changed matches and verify the resulting IDs. See the BalloonForge workflow and the complete ballooning process.

Frequently asked questions

Do balloon numbers have to be sequential?

Sequential IDs are a common readability convention. Verify the current standard, customer instructions, and internal procedure before calling them mandatory.

Are gaps in the sequence noncompliant?

Do not infer noncompliance from a gap alone. It may reflect a deleted or reserved identifier. Keep the drawing and report traceable and follow the governing procedure.

Can numbering restart on each sheet?

Only if the numbering system still makes each characteristic unambiguous—for example, when the sheet is part of the identifier or the report reference.

Should IDs stay the same after a revision?

That depends on the customer/QMS convention and whether the requirement remains the same. Keep a revision cross-reference either way.

Further reading

• What the characteristic ID connects
• Deciding which requirements to account for
• IAQG forms and revision control notice