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APQP

PPAP explained: 18 elements, 5 levels, one checklist

July 2026 · 7 min read

PPAP - the Production Part Approval Process - answers one question for your customer: can this supplier make this part, to this drawing, at production rate, repeatably? Not "can they make a good one" - anyone can make a good one with a fitter and an afternoon. PPAP is evidence that the production process itself, with production tooling, production operators and production cycle times, produces conforming parts.

It comes from the AIAG manual and the automotive world, but customers in appliances, electronics, medical and general manufacturing borrow it constantly, sometimes under other names. If you supply a drawing-controlled component to a serious customer, sooner or later someone will say "we need PPAP level 3 before first shipment" - and the difference between a smooth approval and a two-month email chain is knowing exactly what that sentence means.

The 18 elements, in plain English

The AIAG list is eighteen items of evidence. They cluster naturally:

• The definition of the part - design records (the drawing, at the right revision), any engineering change documents, and customer engineering approval where the customer requires it.
• How you will make it and what could go wrong - the process flow diagram, the Process FMEA and the control plan. These three must tell one coherent story: every step in the flow appears in the PFMEA, every significant risk in the PFMEA lands a control in the control plan. Reviewers check the joins first, because that is where copy-paste jobs fall apart.
• Proof your measurement can be trusted - measurement system analysis (Gauge R&R on the gauges that matter) and, where required, a DFMEA from whoever owns the design.
• Proof the parts conform - dimensional results on actual production parts (this is where a first article inspection earns its keep), material and performance test results, and an initial process study showing capability on the special characteristics.
• The supporting cast - qualified laboratory documentation, an appearance approval report if the part is cosmetic, sample production parts, a master sample, checking aids, records of compliance with any customer-specific requirements, and the Part Submission Warrant.

The Part Submission Warrant (PSW) is element eighteen and the one that makes it official: a single signed page declaring that everything above is true. When people say "the PPAP was approved" they mean the customer signed the PSW.

The five levels - and the matrix everyone forgets

Here is the part that generates the most confusion and the most rework. PPAP has five submission levels, and the level does not change what you must do - it changes what you must send:

• Level 1 - send the warrant only (plus appearance report if applicable). Everything else you keep on file.
• Level 2 - warrant, samples and limited supporting data.
• Level 3 - warrant, samples and complete supporting data. The default for new parts and new suppliers.
• Level 4 - whatever the customer specifically defines.
• Level 5 - everything available for review at your site: a witness audit rather than a parcel.

Against those levels, the AIAG manual publishes a matrix: for each of the eighteen elements, S means submit, R means retain at your site, and * means retain and submit on request. The trap is the word retain. A level 1 PPAP still requires the PFMEA, the capability study and the dimensional results to exist - the customer has simply chosen not to read them yet. "We are only level 1 for this customer" is never a reason to skip the work; it is a reason the missing work will not be discovered until the first quality problem, which is the worst possible moment.

The level decides what travels. The eighteen elements decide what exists. Confusing those two is the single most expensive PPAP mistake.

When PPAP is required (it is more often than you think)

A new part is obvious. But the manual also expects a new or updated submission for engineering changes, a new or transferred tool, a new process or site, a supplier change on a critical input, production restarting after more than twelve months idle - and, the one that catches everyone, any change the customer would consider significant. When in doubt, ask before shipping; customers forgive questions and do not forgive surprises.

What gets submissions rejected

Reviewers see the same failures on repeat: dimensional results from hand-finished sample parts rather than the production process; a PFMEA that does not match the process flow because one was updated and the other was not; capability studies on the easy characteristic instead of the special one; gauge studies missing for the gauge that measures the critical feature; and a PSW signed before half the file existed. Every one of these is a bookkeeping failure, not an engineering one - which is why the fix is a checklist that tracks all eighteen elements, knows your submission level, and computes an honest readiness figure that excludes the elements that genuinely do not apply.