Balloon numbers and ballooned drawings
“Ballooning” means marking up a drawing so that every requirement has a number. Those numbers are what Form 3 is keyed to. Without them, a measured value has nothing to attach to.
What ballooning is
You take the controlled drawing or model and assign a sequential number to every requirement on it. Each number gets a balloon — a circle or similar marker — placed next to the thing it identifies.
The result is a drawing on which every requirement is addressable. That is the entire point: a row in Form 3 can say “characteristic 47” and everyone reading the package can find exactly what number 47 refers to.
What gets a balloon
Not just dimensions. Ballooning covers everything the drawing or specification requires:
- Dimensional callouts — lengths, diameters, radii, angles, positions.
- Geometric tolerances, including feature control frames.
- Notes and general requirements that impose a verifiable condition.
- Surface finish and coating callouts.
- Material requirements stated on the drawing.
- Reference dimensions, where they are carried onto the form.
This is where ballooning most often goes wrong. It is easy to number every dimension and skip the notes — which are requirements too, and which Form 3 is supposed to account for.
Why the numbering has to come first
Form 3 rows are keyed to balloon numbers, so the sequence of work is fixed:
- Balloon the drawing and settle the numbering.
- Build Form 3 rows in that numbering order.
- Attach measured results to those rows.
If ballooning and form filling happen separately — different people, different times, without a frozen numbering scheme — the numbers drift apart. Form 3 then references characteristics that do not exist on the drawing, which is a reconciliation job nobody wants.
Numbering schemes
AS9102 does not prescribe a particular numbering convention beyond requiring that characteristics be identifiable and traceable. In practice you will see:
| Scheme | How it works |
|---|---|
| Sequential across the drawing | 1, 2, 3 and so on in reading order. Simple, but inserting a missed requirement later disturbs the sequence. |
| Sequential with gaps | 10, 20, 30 and so on, leaving room to insert without renumbering. |
| Sheet or zone prefixed | Numbers tied to where the feature is, which helps on multi-sheet drawings. |
Whatever you choose, the constraint is the same: it has to be stable once work has started, and reproducible by someone reading the drawing cold.
Ballooning and the toolchain
Ballooning is the step most often sold as software, because doing it by hand on a dense drawing is slow and easy to get wrong. Dedicated ballooning tools exist that place callouts semi-automatically and produce the numbered drawing.
What those tools generally do not do is the downstream work: getting the resulting row data into a structured table for Form 3, or moving an existing Form 3 into a spreadsheet. That is a separate step, and it is where hand transcription usually creeps in. Where this converter sits.
A note on revisions
When a drawing is revised, the ballooning has to be re-examined. New callouts need numbers, removed ones leave gaps, and changed ones may or may not keep their original number. Whether that results in a full or partial FAI is a separate question — see when a FAI is required — but the numbering has to be correct before any form is rebuilt.
Frequently asked questions
What is ballooning a drawing?
Assigning a sequential number and callout marker to every requirement on a controlled drawing or model, so each one can be referenced individually, typically by the rows of AS9102 Form 3.
Do notes and surface finishes get balloon numbers?
They are requirements, so they are ballooned along with dimensions and geometric tolerances. Skipping notes and finishes is one of the most common ballooning gaps.
Does AS9102 specify a balloon numbering scheme?
It requires that characteristics be identifiable and traceable rather than prescribing a specific convention. Common practice is sequential numbering, often with gaps or sheet prefixes so items can be inserted later.
Why do balloon numbers and Form 3 rows get out of sync?
Usually because ballooning and form filling were done separately without a frozen numbering scheme. Form 3 rows are keyed to balloon numbers, so the numbering has to be settled first.
Sources
- IAQG — AS9102 forms and supporting form instructions
- Connect981 — When first article inspection is required
- Net-Inspect — Form 3 Excel template guidelines
Standards are revised. Always work from the current published edition of AS9102 from SAE International. This page is orientation only and is not a substitute for the standard.