Aerospace applications: AS9100, traceability and special processes

What changes in an aerospace programme

An aerospace part is often not more difficult to make than an industrial part. It is more difficult to prove. The drawing carries the geometry, but the programme also carries a set of requirements about how the material was made, how the process was approved and how the part was inspected.

That shift changes the supplier conversation. A price is no longer the only output of an RFQ. The supplier has to show a quality system, a special process chain, a first article capability and a traceability system. A supplier that is strong on the machine but weak on the records will fail the audit before the first part is cut.

The buyer also carries more responsibility. Under the aerospace quality framework, the buyer flows requirements down to the supplier, and those requirements have to be specific. A purchase order that says make to drawing and comply with AS9100 is not a flow down. It leaves the supplier to guess which clauses apply.

AS9100 and the scope of the certificate

AS9100 is the quality management standard for aviation, space and defence organisations. It builds on ISO 9001 and adds requirements for risk, configuration management, product safety, counterfeit part avoidance and the control of external providers.

The certificate has a scope. It names the site, the product categories and sometimes the processes covered. A certificate for machining does not cover heat treatment, plating or welding, even if the same company performs them in another building. A buyer has to read the scope and match it to the work being placed.

Check the certificate's validity and the certification body. A certificate that has lapsed, or that was issued by a body without the relevant accreditation, is not evidence. Keep a copy with the expiry date and set a reminder before it runs out.

First article inspection under AS9102

AS9102 sets out the first article inspection process. The report has three forms. Form one identifies the part, the drawing revision, the material and the processes. Form two lists every characteristic with the drawing requirement, the measurement and the result. Form three records the material and process certifications.

The key word is every. A first article under AS9102 accounts for all drawing characteristics, not a sample. A dimension that is not measured needs a justification. A characteristic that is measured with a gauge needs the gauge identification. A process that is outsourced needs the certificate from the subcontractor.

A partial first article is a common finding in audits. The supplier measures the features that are easy on a CMM and omits the notes, the threads, the radii or the finish. The buyer should review form two against the drawing before approving, not after the parts arrive.

Special processes need their own approval

A special process is one where the result cannot be fully verified by inspecting the finished part. Heat treatment, plating, welding, brazing, bonding, shot peening and non destructive testing all fall into this group. The process has to be approved, and the approval is usually specific to the process, the specification and the site.

Nadcap is the common approval scheme for many of these processes in aerospace. A supplier may hold Nadcap approval for heat treatment of aluminium and not for titanium, or for one plating family and not another. The scope matters as much as the certificate.

If the supplier subcontracts a special process, the buyer needs to know who performs it and whether that site is approved. A chain of subcontractors is a chain of scopes. The purchase order should require written approval before any special process is moved to a new site.

Traceability from heat number to serial number

Aerospace traceability links the delivered part to the material and the processes that made it. The mill certificate names the heat number, the chemistry and the mechanical properties. The route card records the operations, the operators where required and the test results. The delivered part carries a serial or a batch identifier that points back to both.

The chain breaks in ordinary ways. Material is transferred to a different rack and the label is lost. A batch is split and only one part of it is recorded. A subcontractor returns parts without the original heat number. Each break is a finding, and each finding can ground a shipment.

• Mill certificate with heat number and chemistry
• Route card with every operation and sign off
• Special process certificates tied to the batch
• Inspection records with gauge identification
• Serial or batch number on the part and the pack
• Retention period agreed in the contract

Counterfeit parts and change control

Counterfeit electronic and mechanical parts are a recognised risk in aerospace supply chains. The controls include buying from approved sources, verifying incoming material, inspecting for signs of refurbishment and keeping records that show where each item came from.

The standards AS6174 and AS5553 address counterfeit electronic parts, and the principles apply more widely. A buyer should ask how the supplier approves a distributor, how it checks incoming material and what it does if a part is suspect.

Change control is the other half. A process change, a material substitution or a site move can invalidate a qualification. The supplier should notify the buyer before the change, not after. The contract should say what counts as a change and how long the approval takes.

Where India fits in the chain

India has an established aerospace manufacturing base with machining, forging, sheet metal, wire forming and assembly capability, supported by a growing special process supply chain. The cluster matters because the special processes and the testing houses tend to sit near the machining base, which shortens the route for a part that needs several operations.

The capability is not uniform. A supplier that machines a bracket may not have the approved heat treatment or the non destructive testing in house. The programme has to map the full chain, including the subcontractors, before the first order.

The commercial case is usually strongest for machined and formed parts with a stable design, where the labour content is meaningful and the documentation can be built into the process. It is weaker for a part that needs a specialised process with a single approved source.

What a buyer should verify before release

Verify the certificate and its scope, the special process approvals and the first article. Verify the traceability chain on a sample part and the calibration of the gauges used to inspect it. Verify that the drawing revision on the route card matches the revision on the purchase order.

Then verify the change process. Ask what happens when a drawing changes, who is notified and how the first article is updated. A supplier that treats a revision change as a small edit is a supplier that will ship a part to an old revision.