Key takeaways
- A revision is a change to the process, not only to the PDF.
- Screen every revision against four things: the tool, the gauge, the test and the stock.
- Compare the new revision with the one the last article was approved against, not with the model.
- A revision that changes nothing measurable still needs a record, a date and a supplier acknowledgement.
Why a revision is a process change
A drawing revision looks like a document event. A note moves from the title block into the general notes, a tolerance tightens by a tenth, a finish callout changes from zinc to nickel. The PDF is reissued, the revision letter goes from B to C and the file is uploaded. None of that touches a machine, which is why the change is often released without a process decision.
The process does not read the revision letter. It reads the drawing. A tighter tolerance can need a new gauge. A changed note can add a test that nobody has quoted. A moved hole can need a tool insert. A finish change can add a process step and a certificate. If the release is treated as a filing task, the first evidence of the change is often a failed first article, or worse, parts that fit but do not meet the standard behind the drawing.
A revision review is a short, formal gate between the drawing being issued and the next production order being placed. It asks what changed, what the change touches, and what evidence has to be renewed before the parts are made.
Start from the approved baseline
The comparison is not between revision B and revision C in a document system. It is between revision C and the revision that the last first article or production part approval was signed against. Those are not always the same document, because a concession, a deviation or an accepted note may sit alongside the drawing.
Collect the drawing revision on the approved FAI report, the control plan, the inspection standard, the tool drawing and the material specification. If they disagree, that mismatch is the first finding of the review. A supplier who is running to revision C while the control plan still describes revision B has an uncontrolled process, even if the parts happen to be good.
The CAD model is a useful check but a poor baseline. A model does not carry the notes, the general tolerance, the finish callouts or the accepted concession. Compare drawings with drawings, and use the model only to understand a geometry change.
Screen the change by type
Most revisions fall into a small number of classes, and each class has a different release question. Sorting the change before discussing cost keeps the review short and stops a geometry change being treated like a spelling correction.
A nominal dimension change asks whether the tool can hold the new position. A tolerance only change asks whether the gauge can resolve it and the process can meet it. A datum or geometric control change asks whether the fixture and the inspection programme still apply. A material or finish change asks for a new process route and new certificates. A note or standard callout asks whether the test method, the sample size and the laboratory are defined.
The class does not decide the outcome by itself. A one-word note can require a new test, and a small dimension change can be inside the existing tool capability. The class tells you where to look.
| Change on the drawing | What it can affect | Release question |
|---|---|---|
| Nominal dimension | Tool position, insert or fixture | Can the current tool hold the new position without correction? |
| Tolerance only | Gauge, fixture and process capability | Can the gauge resolve it and the process meet it? |
| Datum or geometric control | Fixture, CMM programme and FAI basis | Are the old results still comparable? |
| Material grade | Process route, certificates and performance | Is the new grade approved and tested? |
| Finish or plating | Process step, thickness, embrittlement controls | Is there a new specification and a test? |
| Note or standard callout | Test method, sample size and records | Which standard revision, which laboratory? |
| Marking or packaging | Label, traceability and handling | Does the customer or the route require a change? |
The table is a prompt, not a decision rule. A note can be more demanding than a dimension change, and a dimension change can be inside the existing capability.
Check the tool before the tolerance
A geometry change is a tool question first. Ask whether the current tool, insert or program can produce the new feature, and whether the change lands on a wear surface, a gate, an ejector or a slide. A hole that moves by a millimetre may need a new insert; a hole that moves by a tenth may be a wire cut on the existing insert.
The tool drawing and the last correction record are the evidence. A tool that was already at the edge of its adjustment has less room than a new tool, and a repaired cavity may behave differently from the rest. If the change needs a correction, the review should record who pays, when the tool is available and whether production continues on the old revision in the meantime.
For a moulded part, add the flow and cooling view. A wall or rib change can move a weld line, change the shrink and create a sink on a visible face. A dimensional change that looks simple on the drawing can need a flow review before the tool is cut.
Check the gauge and the inspection plan
A new tolerance is a measurement decision. A gauge that was adequate for plus or minus 0.20 mm is not automatically adequate for plus or minus 0.05 mm. The rule of thumb is that the gauge should resolve a small fraction of the tolerance, and the measurement system study should show it. If the gauge cannot see the change, the inspection cannot prove it.
A datum change is more disruptive than a tolerance change. It can invalidate the fixture, the CMM programme and the first article results, because the part is now located differently. The old report is not comparable even if the numbers look similar.
Update the control plan at the same time as the drawing. A new critical characteristic that is not in the control plan will not be monitored, and a characteristic that has been removed should not stay in the plan as a cost with no purpose. The inspection standard, the ballooned drawing and the recording sheet all follow the revision.
Check the test and the standard revision
Notes carry more risk than dimensions because they are easy to read past. A callout for passivation, a hi-pot test, a glow wire rating, a salt spray duration or a material declaration changes the evidence that ships with the part, not the geometry. The review should name the test, the standard revision, the laboratory and the record.
A standard callout without a revision is a moving target. The test method can change between editions, and a supplier may hold an older certificate. State the edition, or state that the current edition applies at the date of the order, and record which one was used.
If the test is new to the part, agree the sample size and the acceptance criterion before the run. A test added after the parts are made is a dispute waiting to happen, because the first result is often the first time either side has discussed what a pass looks like.
Decide what happens to parts in flight
A revision does not stop the parts already made. There may be finished stock, parts in transit, work in progress at the supplier, raw material cut for the old revision and purchased components that only fit the old design. The release gate should decide the disposition of each, not leave it to the next delivery.
The options are to use up, rework, scrap or ship under a written concession. Each has a cost and a record. Using up old parts is often the cheapest route, but it needs a quantity, a cut-off date and a check that the old parts still assemble with the new ones. A mixed build where old and new parts meet in the same unit is the case that needs the most care.
Tell the supplier in writing and get an acknowledgement with the date. A revision that the supplier has not confirmed is not in production, however clearly it sits on the customer portal.
Record the decision and the re-approval
The output of the review is one page, not a meeting. It states the old revision, the new revision, the change list, the effect on the tool, the gauge, the test and the stock, the action, the owner, the date and the re-approval required. The re-approval can be a full first article, a partial first article on the affected characteristics, or none, with the reason recorded.
A change that requires no re-approval still needs the page. The record is what protects the decision later, when someone asks why the revision was released without a new sample. A short note with a date and a name is enough, provided it says what was checked.
Keep the superseded drawing marked as superseded and keep the approved revision with the FAI and the control plan. A drawing that is current in the system but not on the shop floor is the same failure as a revision that was never reviewed.
Frequently asked questions
Does every drawing revision need a new FAI?
No. It depends on what changed. A note, a marking change or a packaging change may need only a record and a supplier acknowledgement, while a datum, material, finish or geometry change usually needs a full or partial first article. Decide at the review and record the reason for the decision.
What should the new revision be compared against?
The revision that the last first article or production part approval was signed against, together with the control plan, inspection standard and tool drawing. Comparing only with the CAD model misses notes, general tolerances, finish callouts and accepted concessions.
What if the supplier has already made parts to the old revision?
Decide the disposition before the new revision is released: use up, rework, scrap or ship under a written concession. Record the quantity, the cut-off date and the owner, and check that old and new parts still assemble where a build may mix them.
Can a revision be released without telling the supplier?
It can be uploaded, but it is not in production until the supplier has acknowledged it. Send the revision in writing, ask for confirmation of the effective date and keep the acknowledgement with the release record.
Sources and further reading
- ISO 9001:2015, clause 8.5.6, Control of changes
- ISO 10007:2017, Quality management, guidelines for configuration management
- AS9102, Aerospace first article inspection requirement
Qumek Quality Desk
Quality team
The quality team responsible for first article inspection, PPAP packs, supplier audits and the records shipped with production parts.
Send a revision for a release review
Send the old and new drawing, the tool drawing and the current control plan. The quality desk will set out what the change touches and what evidence to renew.
Send a drawing