Can you use commercial metals for aerospace applications? It’s one of the most common questions we hear at Flight Metals, particularly from machine shops and fabricators who are new to aerospace work. The short answer: sometimes — but only when the engineering documentation explicitly allows it, and never as an undisclosed substitution.
Here’s how to think through material grade requirements for aerospace applications.
## Start with the Drawing
The engineering drawing is the authoritative source for material requirements. It will specify, at minimum:
– The alloy (e.g., “Titanium Ti-6Al-4V”)
– The material specification (e.g., “per AMS 4928”)
– The product form and condition (e.g., “bar, annealed”)
If the drawing calls out AMS 4928, you need AMS 4928-certified material. Period. Commercial titanium bar — even if nominally Ti-6Al-4V — does not meet AMS 4928 unless it has been produced, tested, and certified to that specification. Flight Metals stocks Ti-6Al-4V bar to [AMS 6931 (annealed)](https://www.flightmetals.com/products/titanium/ams-6931-titanium-6al-4v-annealed-bar/), [AMS 4965 (STA)](https://www.flightmetals.com/products/titanium/titanium-sta-round-rectangle-bar-ams-4965/), and [AMS 6930 (STA)](https://www.flightmetals.com/products/titanium/titanium-6al-4v-bar-per-ams-6930-flight-metals/) — with full mill-traceable CMTRs.
Substituting a commercial-grade material for an AMS-specified material without a documented engineering deviation is a nonconformance. On certified aerospace hardware, this isn’t a gray area.
## When Might Commercial Material Be Acceptable?
There are legitimate cases where commercial-grade material may be used in aerospace-related work:
### Non-Flight-Critical Tooling and Fixturing
Ground support equipment, manufacturing fixtures, inspection tools, and assembly jigs are typically not part of the type-certificated aircraft. The material requirements for these items are set by the manufacturer’s internal engineering standards, which may or may not require AMS certification.
### Prototype and Development Hardware
Early-phase development parts — especially in R&D programs — may use commercial materials when the goal is form and fit verification rather than airworthiness. These parts should be clearly marked as non-flight hardware.
### Interior and Non-Structural Components
Some interior components (brackets, standoffs, non-structural panels) may be specified to ASTM standards rather than AMS, particularly in older designs or general aviation. Always check the drawing. Our [aluminum](https://www.flightmetals.com/products/aluminum/) and [stainless steel](https://www.flightmetals.com/products/stainless-steel/) inventories include both AMS and ASTM-certified product.
### Experimental Aircraft (EAB)
FAA Experimental-Airworthy homebuilts are not type-certificated aircraft. Builders have more latitude in material selection, though best practices still favor traceable, certified material for primary structure.
## The Approved Supplier Requirement
Even if your material meets the specification on paper, many aerospace programs require that it be sourced from an approved supplier. Prime contractors and Tier 1s maintain approved supplier lists (ASLs) or qualified manufacturer lists (QMLs). If Flight Metals isn’t on your customer’s ASL, there’s typically a qualification process we can support.
Flight Metals is AS9100-certified and actively works with customers to complete supplier surveys, provide documentation packages, and support qualification requirements. Our certifications and quality system documentation are available on request. [Learn more about Flight Metals](https://www.flightmetals.com/about-new/).
## What About “Equivalent” Specifications?
Sometimes a drawing references a specification that’s been cancelled or superseded, or a customer asks whether a different spec can substitute. Common examples:
– MIL-T-9046 (titanium) was superseded by AMS 4928 — often interchangeable with documented approval
– ASTM B265 (titanium sheet) vs. AMS 4911 — not automatically interchangeable; requires engineering review
– QQ-A-250 (aluminum) was cancelled; AMS equivalents exist but require drawing revision or deviation
These substitutions require an engineering disposition or deviation from the responsible design authority. Your quality engineer or DER should be involved in any spec substitution decision.
> When in doubt, get it in writing. An approved deviation or engineering order documenting the substitution protects you, your customer, and the end user.
## The Risk of Undisclosed Substitution
Using a non-conforming material without disclosure is not a cost-saving shortcut in aerospace — it’s a quality escape that can trigger a SCAR (supplier corrective action request), removal from the ASL, liability exposure, and in the worst case, contribute to a safety incident.
The aerospace supply chain is built on trust and traceability. Every shortcut erodes both. For a deeper look at what traceability actually requires, read: [How Do I Know If a Metal Is Aerospace Grade?](https://www.flightmetals.com/aerospace-grade-metal/)
## Flight Metals Can Help You Get It Right
If you’re trying to determine whether a specific material meets your drawing requirements, our team can help you evaluate the specification, review CMTR documentation, and confirm compliance before you cut metal. We stock aerospace-certified [titanium](https://www.flightmetals.com/products/titanium/), [nickel alloys](https://www.flightmetals.com/products/nickel/), [stainless steel](https://www.flightmetals.com/products/stainless-steel/), and [aluminum](https://www.flightmetals.com/products/aluminum/) — all with full AMS certification and mill-traceable CMTRs.
Don’t guess on material compliance. [Contact Flight Metals](https://www.flightmetals.com/contact-us/) or [request a quote](https://www.flightmetals.com/quote/) and let’s get it right the first time.
Related reading: [What’s the Difference Between Aerospace and Regular Metal?](https://www.flightmetals.com/difference-between-aerospace-and-regular-metal/) | [What Metals Do Aerospace Companies Actually Use?](https://www.flightmetals.com/what-metals-do-aerospace-companies-use/)
