Specification guide
AMS7276 O-Rings
AMS7276 fluorocarbon O-rings for aircraft fuel and engine oil systems, called out by AS3209, AS3208 and AS83248/1: the document, the part numbers, the material and the RFQ.
AMS7276 is the SAE Aerospace Material Specification for fluorocarbon (FKM) rubber seals in aircraft fuel systems and specific engine oil systems: high-temperature fluid resistant, very low compression set, 70 to 80 Type A hardness. It is the live document behind a common aerospace Viton® callout, the successor to the cancelled MIL-R-83248 Class 1 material, and the specification that the SAE O-ring part standards AS3209, AS3208 and AS83248/1 invoke. The dash numbers on those part standards follow the AS568 size system. This guide covers what the document is, the part numbers that carry it, the material behind it, and what an RFQ needs to state.
What the document is
| Item | Value | Source |
|---|---|---|
| Full title (SAE) | Rings, sealing, fluorocarbon rubber, high-temperature-fluid-resistant, very-low-compression-set, 70 to 80 | SAE Mobilus standard page for AMS7276J |
| Title (DLA ASSIST) | Rubber: fluorocarbon (FKM) high temperature-fluid resistant low compression set, 70 to 80 Type A hardness, for seals in fuel systems and specific engine oil systems | ASSIST document record 105727 |
| Status | Active; current SAE revision AMS7276J (18 May 2020); ASSIST record dated January 2023 | SAE and DLA ASSIST records, read September 2026 |
| Material | Fluorocarbon (FKM) | Document title |
| Hardness | 70 to 80 Type A (75 A nominal) | Document title |
| Qualified products list | Non-government QPL held by SAE, not the DLA database | ASSIST prints "Non-government QPL" for this document |
| Part standards that invoke it | AS3209 (AS568 dash sizes), AS3208 (boss sizes), AS83248/1 (successor to M83248/1) | SAE part standard records; Conquest's legacy cross-reference chart |
| Supersedes, in practice | MIL-R-83248 Class 1 (cancelled 2001) | The cancellation title names AMS7276 first |
Two authorities print two titles for this one document, which is why the source is named beside each. Neither title carries a temperature.
Part numbers that carry AMS7276 material
| Part number form | Part standard | Sizes | Note |
|---|---|---|---|
| AS3209-XXX | SAE AS3209, "Packing, preformed, AMS 7276 O-ring"; reaffirmed AS3209C (2021) | AS568 three-digit dash sizes | The AS number carries the sizes, the AMS number the compound |
| AS3208-YY | SAE AS3208 | Two-digit boss-seal sizes on Conquest's legacy chart | Straight-thread fitting seals in AMS7276 material |
| AS83248/1-XXX | SAE AS83248/1, "O-ring molded from AMS7276 material" | AS568 dash sizes | The live replacement for the cancelled MIL-R-83248/1 sheet |
| M83248/1-XXX | MIL-R-83248/1 (cancelled 2008) | AS568 dash sizes | Legacy part number still ordered; supplied to AMS7276; see the M83248 guide |
| MS9387-YY, MS9388 | AMS7278 | Boss sizes | Listed with AMS7276 on Conquest's legacy cross-reference chart as one compound family |
| AS3084-YY, AS3085-XXX | AMS7280 | Boss and dash sizes | The older fluorocarbon O-ring standard; see the AMS7280 guide |
| AS3581-XXX | AMS7259 | AS568 dash sizes | The 85 to 95 A companion specification (successor to M83248/2) |
What material is it, and what can it take?
Fluorocarbon (FKM) rubber, the family covered in the Viton guide. The Parker O-Ring Handbook (ORD 5700) rates standard FKM compounds for continuous service from -26 C (-15 F) to 204 C (400 F), with low-temperature grades to -46 C (-51 F) and short excursions to 232 C. The document title names the service (aircraft fuels and specific engine oils, high temperature, very low compression set), and a specification is not a temperature: the handbook's caution is that spec limits do not necessarily represent operating limits, and the qualified compound's sheet governs. Compression set is the property the title leads with: AMS7276 compounds are formulated to keep their sealing force through long hot service, which is why the same document is invoked for engine oil seals as well as fuel.
How does AMS7276 differ from AMS7280 and AMS7259?
| Specification | Hardness | Part standards | Status | When you see it |
|---|---|---|---|---|
| AMS7276 | 70 to 80 A | AS3209, AS3208, AS83248/1 | Active, revision J (2020); SAE-held QPL | The current default aerospace fluorocarbon O-ring callout |
| AMS7280 | 70 to 80 A (FPM type) | AS3084, AS3085 | Revision F (1992) | Older drawings; Conquest's legacy compound chart lists one compound against both 7276 and 7280 |
| AMS7259 | 85 to 95 A | AS3581 | Active (2017); SAE-held QPL | High-pressure and extrusion-resistant seals; successor to M83248/2 |
| AMS7278 | 75 A | MS9387, MS9388 | Legacy chart entry | Boss seals |
| AMS7379 | 75 A | per print | Current; low-temperature FKM (a -40 F glass transition in the title) | Cold-soak fuel systems |
| AMS-R-83248 | Class 1 75 A, Class 2 90 A | M83248/1, /2 | SAE re-issue (2005) of the cancelled MIL spec | Prints that still name the MIL number |
Reading the revision letter and the qualification
A trailing letter on the document is a revision: AMS7276J is the 2020 revision of AMS7276, and a print that says AMS7276 with no letter accepts the current one unless the program freezes a revision. A trailing letter inside a part number is not a revision; on many suppliers' part numbers a trailing letter identifies a compound. Qualification is separate from both: a manufacturer whose compound has passed the document's tests is listed on the qualified products list that SAE holds for AMS7276, and the certificate of conformance that ships with the part names that manufacturer and the document. A commercial FKM O-ring of the same size is the same polymer family but is not a qualified part, and the difference is exactly what an aerospace receiving inspector checks.
What should the RFQ state?
The part standard and dash number (AS3209-214, for example), or the AMS7276 material callout with the AS568 size, the quantity, the revision if the drawing names one, and the documentation required (certificate of conformance to AMS7276; the manufacturer's test report if the program requires it; lot traceability). If the drawing names M83248/1 instead, say whether the AS83248/1 or AS3209 equivalent is acceptable; the material is the same document.
How Conquest Seal supplies it
Parts to these documents are made by manufacturers on the relevant qualified products list, where the document has one; Conquest supplies them as a distributor and provides the certification paperwork (certificate of conformance naming the specification and, where the manufacturer issues one, the test report). Conquest's quality management system handles the order and the paperwork; it is not a product qualification and is unrelated to any QPL. See aerospace and defense sealing.
Viton is a trademark of The Chemours Company. No affiliation or endorsement is implied.
Sources
- Parker O-Ring Handbook ORD 5700, section 2.2, read 2026-09-14
- AMS 7276
- AMS-R-83248
- AMS7259
- AMS7278
- AMS7280
- AMS7379
- AS3084
- AS3085
- AS3208
- AS3209
- AS3581
- AS568
- AS83248
- DLA ASSIST
- MIL-R-83248
- SAE Mobilus
- SAE and DLA ASSIST document records for the specifications named, read September 2026
Reviewed by Grant Midstokke, Conquest Seal Corporation. Last updated September 2026. Spec values in this guide are drawn from the sources named in the sentence where each appears; the compound datasheet and your application conditions govern the final choice.
Frequently asked questions
Is AMS7276 the same as Viton?
AMS7276 is a material specification; Viton is one polymer maker's trademark for FKM. An AMS7276 O-ring is fluorocarbon rubber that a listed manufacturer has qualified to the document's tests, whichever polymer source it uses.
Who holds the qualified products list?
SAE. DLA ASSIST records the document with a non-government QPL, so the listing is not in the DLA database.
What is the difference between AS3209 and AMS7276?
AS3209 is the dimensional part standard (the O-ring sizes); AMS7276 is the material it is molded from. The AS number carries the sizes, the AMS number the compound.
Does AMS7276 replace M83248/1?
Yes, in material: the cancellation of MIL-R-83248 names AMS7276 as a successor, and the live O-ring sheet AS83248/1 is titled as molded from AMS7276 material.
What temperature is an AMS7276 O-ring good for?
The document is a materials and test specification, not an operating limit. For the FKM family the Parker handbook range is -26 C to 204 C continuous; the qualified compound's sheet and the application govern.
Which part standards invoke AMS7276?
AS3209 (revision C, 2021), AS3208 (revision A, 2020) and AS83248/1 (revision A, 2021), which is the live replacement for the cancelled MIL-R-83248/1 slash sheet. All three carry AS568 dash numbers, so an AS3209-214 has the same 0.984 in inside diameter and 0.139 in section as any -214.
How does AMS7276 differ from AMS7259?
Hardness. AMS7276 covers 70 to 80 Shore A fluorocarbon and is the Class 1 successor for M83248/1; AMS7259 covers 85 to 95 Shore A and stands behind AS3581 and the old M83248/2 Class 2 parts. Both are active SAE documents with a non-government qualified products list.
What about the low-temperature fluorocarbon documents?
AMS7287 (revision A, 2022) and AMS7379 (revision A, 2020) are 70 to 80 Shore A fluorocarbon specifications whose titles state a glass transition of -30 C and -40 C respectively, for cold-start service that standard AMS7276 material does not cover; the cancelled MIL-R-83485 low-temperature family lives on as AMS-R-83485. The Parker handbook puts low-temperature FKM grades to -46 C.
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