Boeing BMS vs BAC Specifications Guide
Boeing BMS vs BAC Specifications — Material Spec or Process Spec?
What a BMS callout means, what a BAC callout means, why the same tape can appear under both, and how to order the right tape from either one.
Boeing drawings, work orders and RFQs call out tape in two different ways. A BMS (Boeing Material Specification) callout tells you what the tape is: its construction, properties and the products qualified to it. A BAC callout is a Boeing process specification. It tells you how a job is done — protecting a surface, laying up a composite part, installing carpet — and names the tapes and materials approved for that job. Both are proprietary Boeing documents, both are legitimate reasons to buy a specific tape, and they are not interchangeable. This guide explains the difference and maps each callout to the tape that meets it.
Looking for a specific callout? Every Boeing BMS, BAC and BSS spec we stock is listed with its matching products on our specifications page.
View Boeing Specs → Technical Data Sheets →The three Boeing spec families you will see on a tape callout
Boeing uses several document families. For tape, three come up most often:
Boeing Material Specification. Defines a material: construction, physical properties, flammability and test requirements, usually broken into Type, Class and Grade. Products are qualified to it, and only qualified products can be sold as meeting it. Example: BMS 5-146 cargo compartment tape.
Boeing process specification. Defines how work is performed — surface protection, sealing, composite fabrication, carpet installation — and lists which materials are approved for each step. A tape is "approved for use" under it rather than "qualified to" it. Example: BAC 5034 temporary surface protection.
Boeing Specification Support Standard. Defines a test, not a product. A BMS spec often requires a material to pass a BSS test. Example: BSS 7230 flammability, the vertical burn test our insulation splicing tapes pass.
In short: BMS = what the tape is. BAC = what the tape is used for, and how. BSS = how the tape is tested.
BMS vs BAC side by side
| BMS (Material Specification) | BAC (Process Specification) | |
|---|---|---|
| Controls | The material itself: carrier, adhesive, thickness, strength, flammability | A manufacturing or maintenance process and the materials allowed in it |
| Typical callout | BMS 5-146 Type I, Class 1, Grade A | BAC 5034 Type IV, Class 1, Grade A BAC5034-4 Sec. 5.1.a(1)(b) |
| How a tape gets there | The manufacturer qualifies the product by testing to the spec; Boeing lists it as a qualified product | Boeing lists the product as an approved material for a specific section, table or step of the process |
| What the code tells you | Type / Class / Grade describe the tape's construction and performance tier | Type / Class / Grade, or a section or table number, point to the step and material choice in the process |
| Who uses it | Purchasing and engineering buying a material to a drawing callout | Shops performing the process: MRO, paint, composites, interiors, machining |
| Can you substitute? | Only with another product qualified to the same BMS Type / Class / Grade | Only with another material the BAC lists for that same step |
| What to ask for | Certificate of Conformance stating the BMS spec, revision, Type, Class and Grade | Certificate of Conformance stating the BAC spec and the section or table that lists the product |
Decode your drawing or RFQ callout
These are the Boeing callouts we stock against. Find the callout on your drawing, work order or RFQ and match it to the product.
| If the callout says… | Spec family and what it means | You need |
|---|---|---|
| BMS 5-133 Type II, Class 1 or 2 | Material spec — flame-retardant double-coated aircraft carpet tape (guide) | Polyken 108FR |
| BMS 5-146 Type I, Class 1, Grade A | Material spec — flame-retardant cargo compartment tape (guide) | Polyken 296FR |
| BMS 5-157 Type I, Class 1–3, Grade A / C / E | Material spec — insulation blanket cover splicing tape (guide) | E&H 743-MT, 743-T, 753-MP, 753-MPE |
| BMS 8-346 | Material spec — aircraft waterseal / moisture barrier tape (guide) | Patco D9100, Patco 9425FR |
| BAC 5034 Type IV, Class 1, Grade A | Process spec — temporary protection of parts and assemblies with pressure-sensitive tape (guide) | Protex 5, 10V, 20V, 8216-2L |
| BAC5034-4 Sec. 5.1.a(1)(a) | Process spec — temporary, non-flame-retardant carpet tape | Polyken 105C |
| BAC5034-4 Sec. 5.1.a(1)(b) | Process spec — flame-retardant carpet tape | Polyken 108FR |
| BAC 5317 | Process spec — fabrication of fiber-reinforced composite laminate and sandwich parts; lists its own approved process materials | Not stocked — send us the callout |
| BSS 7230 | Test method — flammability (vertical burn). Not a product spec on its own | Required by the spec on your drawing; our E&H insulation tapes pass it |
Why one tape can meet a BMS and a BAC at the same time
Because the two families answer different questions, a single product can carry both. Polyken 108FR is qualified to BMS 5-133 Type II, Class 1 and 2 — the material spec for flame-retardant carpet tape — and it is also the tape listed in BAC5034-4 Sec. 5.1.a(1)(b), the process step where a flame-retardant carpet tape is required. One document says what the tape must be; the other says where it is used.
The reverse is also true: the BAC can list a material that is not qualified to any BMS. Polyken 105C is listed in BAC5034-4 Sec. 5.1.a(1)(a) for temporary, non-flame-retardant use. It is the right tape for that process step, and the wrong tape for any callout that requires flame retardance.
How to order from a Boeing callout
- Copy the full callout, not just the number. "BMS 5-146" alone is not enough; "BMS 5-146 Type I, Class 1, Grade A" is. For a BAC, include the Type / Class / Grade or the section and table number.
- Note the revision if the drawing gives one. Specs are revised over time, and a qualification can be tied to a revision.
- Do not substitute across families. A tape approved under a BAC process step is not automatically qualified to a BMS, and a BMS-qualified tape is not automatically listed in every BAC.
- Do not substitute a "similar" tape. A tape with similar construction or data-sheet values is not compliant unless it is qualified to the BMS or listed in the BAC. A cross-reference is not a substitution approval.
- Ask for the Certificate of Conformance. The C of C should name the spec and the Type / Class / Grade or section that applies. We include one with every order where the manufacturer provides it.
Frequently asked questions
What is the difference between a BMS and a BAC specification?
A BMS (Boeing Material Specification) defines a material — what the tape is made of and how it must perform — and products are qualified to it. A BAC is a Boeing process specification that defines how a job is done and lists the materials approved for each step. BMS tells you what the tape is; BAC tells you where and how it is used.
What does BMS stand for?
BMS stands for Boeing Material Specification. BMS documents are proprietary Boeing standards for materials such as tapes, sealants, adhesives and composites. A tape callout like BMS 5-146 Type I, Class 1, Grade A identifies the material and its performance tier.
Is a BAC specification a tape specification?
No. A BAC is a process specification. It can name approved tapes — for example, BAC 5034 lists surface protection tapes and BAC 5317 lists process materials for composite fabrication — but the tape is approved for use in that process, not qualified to a tape material spec.
Can one tape meet both a BMS and a BAC?
Yes. Polyken 108FR is qualified to BMS 5-133 Type II, Class 1 and 2, and it is the flame-retardant carpet tape listed in BAC5034-4 Sec. 5.1.a(1)(b). The material spec and the process spec describe the same tape from two angles.
What is the difference between BAC 5034 and BAC5034-4?
They are different documents. BAC 5034 covers temporary protection with pressure-sensitive tape and uses Type / Class / Grade codes, such as Type IV, Class 1, Grade A for the Protex papers and films. BAC5034-4 uses section and table numbers, such as Sec. 5.1.a(1)(b) for flame-retardant carpet tape. See our BAC 5034 guide for the full breakdown.
What is a BSS specification?
BSS stands for Boeing Specification Support Standard. A BSS defines a test method rather than a product. For example, BSS 7230 is a flammability test that many BMS tape specs require a material to pass.
Are BACB and BACN numbers specifications?
No. Numbers such as BACB30 or BACN10 are Boeing standard part numbers for hardware like bolts and nuts. They share the BAC prefix but are part standards, not process specifications.
Can I substitute a similar tape for a BMS or BAC callout?
Not without approval. For a BMS callout, the replacement must be qualified to the same Type, Class and Grade. For a BAC callout, it must be listed in the same section or table of the process spec. Similar construction or data-sheet values do not make a tape compliant.
Have a BMS or BAC callout you need to fill?
Send us the full callout from your drawing, work order or RFQ — spec, revision, Type / Class / Grade or section — and we'll confirm the qualified product, lead time and pricing. Certificate of Conformance included with every order where available.
Ask Our Team →This guide is a general explanation of how Boeing specification families are used on tape callouts. BMS, BAC and BSS documents are proprietary to The Boeing Company and are the controlling source; product qualifications and approvals are taken from current manufacturer data sheets and certifications. Boeing, BMS, BAC and BSS are trademarks of The Boeing Company. Polyken, Patco, E&H, Mask-Off and Protex are trademarks of their respective owners. A cross-reference is not a substitution approval. Always verify requirements against the controlling drawing, the current specification revision and the manufacturer's data sheet before purchase.