SMC-S-011 Fastener Requirements for Aerospace & Space Applications
Based on SMC-S-011 (Rev E, 31 July 2015) — Parts, Materials, and Processes Control Program for Expendable Launch Vehicles
1. Overview
SMC-S-011 defines the Parts, Materials, and Processes (PMP) Control Program for expendable launch vehicles (ELVs). For mechanical fasteners, the standard specifies approved part numbers, allowable materials, surface finish requirements, installation procedures, and a list of prohibited or reliability-suspect items. Compliance is mandatory for all fasteners used in flight-critical and mission-essential assemblies.
2. Approved Fastener Part Numbers (Appendix A, Section 6.1)
The tables below list fastener categories approved under SMC-S-011. All limitations noted in the original standard apply and must be verified against the current revision before procurement.
Screws
| Specification | Part Number | Description | Limitations |
|---|---|---|---|
| NASM565 | AN565*C* | Set screw, hexagon and fluted socket, headless | CRES only; passivated |
| NASM16995 | MS16995-* | Screw, cap, socket head-hexagon, CRES, UNC-3A | Passivation only |
| NASM16996 | MS16996-* | Screw, cap, socket head-hexagon, CRES, UNF-3A | Passivation only |
| NASM24693 | MS24693-C* | Machine screw, flat countersunk 100°, cross recessed | CRES only; passivated |
| NASM51021 | MS51021-* | Setscrew, hexagon socket, cup point, CRES, passivated | UNC-3A; plain & self-locking |
| NASM51957 | MS51957-* | Machine screw, pan head, cross-recessed, CRES | CRES only; passivated |
| NASM51958 | MS51958-* | Machine screw, pan head, cross-recessed, CRES, UNF-2A | CRES only; passivated |
| NAS662 | NAS662C* | Machine screw, flathead 100°, plain & self-locking | CRES only; passivated |
| NAS673–NAS678 | NAS673V** – NAS678V** | Bolt, close tolerance, hexagon head, titanium | Uncoated or dry film lubricated only |
| NAS1081 | NAS1081C* | Setscrew, self-locking | CRES only; passivated |
| NAS1101 | NAS1101E*, NAS1101V* | Machine screw, flat fillister head, full thread | E = CRES passivated; V = Ti uncoated |
| NAS1102 | NAS1102E*, NAS1102V* | Machine screw, flat 100° head, full thread, Torq-Set® | E = CRES passivated; V = Ti uncoated |
| NAS1131–NAS1138 | NAS1131E* – NAS1138E* | Machine screw, pan head, close tolerance, short thread | CRES only; passivated |
| NAS1191 | NAS1191E** | Screw, self-locking, flat fillister head | CRES only; passivated |
| NAS1218 | NAS1218-04E*, -06E*, -08E* | Bolt, pan head, self-locking optional | CRES only; passivated |
| NAS1351 | NAS1351C*, NAS1351N* | Screw, cap, socket head, undrilled & drilled, plain & self-locking | CRES or heat-resistant steel; passivated |
| NAS1352 | NAS1352C*, NAS1352N* | Screw, cap, socket head, UNRC-3A & UNRC-2A | CRES or heat-resistant steel; passivated |
| NAS1578 | NAS1578C* | Bolt, flat pan head | CRES only; passivated |
| NAS1635 | NAS1635-*-* | Machine screw, pan head, cross-recessed, full thread | — |
| NAS1802 | NAS1802* | Hex head screw, cruciform recess, full thread, A286 CRES, 160 ksi | CRES only; passivated |
| NAS6303–NAS6320 | NAS6303*U* – NAS6320*U* | Bolt, tension, hex head, close tolerance, A286 CRES, 160 ksi FTU | Passivated only |
| NAS6403–NAS6420 | NAS6403*U* – NAS6420*U* | Bolt, tension, hex head, close tolerance, 6Al-4V Ti | Unplated only |
| NAS6703–NAS6720 | NAS6703*U* – NAS6720*U* | Bolt, hex head, close tolerance, A286 CRES, long threads | Passivation per QQ-P-35 only |
| NAS6803–NAS6820 | NAS6803*U* – NAS6820*U* | Bolt, hex head, close tolerance, 6Al-4V Ti, long threads | Unplated only |
| NAS8100–NAS8106 | NAS8100*U* – NAS8106*U* | Screw, pan head, cruciform recess, A-286 CRES, full thread | Passivation only |
Nuts
| Specification | Part Number | Description | Limitations |
|---|---|---|---|
| AS9361 | MS9361-** | Nut, plain, hexagon, check, UNS S66286, 130 ksi min | — |
| SAE-AS9362 | MS9362-** | Nut, plain, hexagon, check, A-286, silver-plated | MIL-S-8879 |
| NASM21043 | MS21043-* | Nut, self-locking, 800°F, reduced hexagon, reduced height, ring base, CRES | — |
| NASM21045 | MS21045C* | Nut, self-locking, hexagon, regular height, 450°F, 125 ksi FTU | CRES only |
| NASM21060 | MS21060* | Nut, self-locking, plate, two lug, floating, low height, CRES, 125 ksi FTU, 450°F & 800°F | — |
| NASM21070 | MS21070* | Nut, self-locking, plate, two lug, reduced rivet spacing, low height, CRES | — |
| NASM21076 | MS21076* | Nut, self-locking, plate, two lug, floating, reduced rivet spacing, low height, CRES | — |
| MS27130 | MS27130-CR* | Nut, plain, blind rivet, flat & countersunk head, open end | CRES only; passivated |
| MS25082 | MS25082-C* | Nut, plain, hexagon, electrical, thin | CRES only; passivated |
| MS35649 | MS35649-204, -224, etc. | Nut, plain, hexagon, machine screw, UNC-2B | CRES only; passivated |
| MS35650 | MS35650-314, -324, etc. | Nut, plain, hexagon, machine screw, UNF-2B | CRES only; passivated |
| NAS671 | NAS671C* | Nut, plain, hexagon, small pattern, nonstructural | CRES only; passivated |
| NASM45938/1 | MS45938/1-*C | Nut, plain, clinch (self-clinching, round) | CRES; passivated |
| NAS1068 | NAS1068C* & RC* | Nut, self-locking plate, two lug, low height, C-bored, floating | A286 CRES only |
| NAS1291 | NAS1291C*, NAS1291C*M | Nut, self-locking, hexagon, low height, lightweight | CRES only; silver-plated or dry film lube; silver-plated shall not contact titanium |
| NAS1329 | NAS1329N* | Nut, blind rivet, flat head, internal thread, nonlocking & self-locking | CRES 316 only; passivated |
| NAS1330 | NAS1330N** | Nut, blind rivet, countersunk head, internal thread | CRES only; passivated |
Washers
| Specification | Part Number | Description | Limitations |
|---|---|---|---|
| AN960 | AN960C* | Washer, flat | CRES only; passivated |
| MIL-W-12133/4 | M12133/4-*** | Washer, spring tension, wave, CRES 302 | Passivated only |
| MS9768 | MS9768-** | Washer, flat, CRES AMS5525 or AMS5737, countersunk | — |
| NASM15795 | MS15795-8* | Washer, flat metal, round, general purpose | Passivation only |
| MS51848 | MS51848-49 | Washer, lock, helical spring, hi-collar | 300 series CRES only; passivated |
| NASM35338 | MS35338-134 through -152 | Washer, lock, spring, helical, regular series | Stainless steel only; passivated |
| NAS549 | NAS549G* | Washer, nonmetallic, electrical insulating | Epoxy glass (MIL-I-24768/3) only |
| NAS620 | NAS620C* | Washer, flat, reduced outside diameter | CRES only; passivated |
| NAS1149 | NAS1149C*R, NAS1149E*R, NAS1149V*H, NAS1149T*H | Washer, flat | C/E = CRES passivated; V = Ti 6Al-4V unfinished; T = passivated CRES |
| NAS1587 | NAS1587-* | Washer, plain and CSK, 1200°F | — |
| MS51496 | MS51496P61 through P87 | Washer, flat, narrow series | CRES only; passivated |
Pins
| Specification | Part Number | Description | Limitations |
|---|---|---|---|
| MIL-P-21143/2 | M21143/2-* | Pin, straight, headless (dowel), 0.0002 under size, CRES 303 | — |
| NASM16555 | MS16555-6** | Pin, straight, headless (dowel), 0.0002 over nominal | Stainless steel only; passivated |
| NASM51987 | MS51987-369 through -455 | Pin, spring-tubular, coiled, light duty | CRES only; passivated |
| NASM16556 | MS16556-6** through -7** | Pin, straight, headless (dowel), 0.001 over nominal | Stainless steel only; passivated |
| NASM16562 | MS16562-189 through -282 | Pin, spring, tubular, slotted | CRES only |
| NASM24665 | MS24665-300, -302, -372, -376, -437 | Pin, cotter (split) | CRES; passivated |
Threaded Inserts
| Specification | Part Number | Description | Limitations |
|---|---|---|---|
| MS51830 | MS51830CA*, MS51830CA*L | Insert, screw-thread, locked in, key-locked, miniature & lightweight | A286 CRES only |
| NASM122076–NASM122115 | MS122076 – MS122115 | Insert, CRES, helical coil, coarse thread, 1× dia. nominal length | — |
| NASM122116–NASM122155 | MS122116 – MS122155 | Insert, CRES, helical coil, coarse thread, 1.5× dia. nominal length | — |
| NASM122156–NASM122195 | MS122156 – MS122195 | Insert, CRES, helical coil, coarse thread, 2× dia. nominal length | — |
| NASM124691–NASM124730 | MS124691 – MS124730 | Insert, CRES, helical coil, fine thread, 1.5× dia. nominal length | Uncoated or dry film lubricated only |
| NASM124731–NASM124770 | MS124731 – MS124770 | Insert, CRES, helical coil, fine thread, 2× dia. nominal length | Uncoated or dry film lubricated only |
| NASM21209 | MS21209* | Insert, screw thread, coarse & fine, screw locking, helical coil, CRES | — |
| NAS1130 | NAS1130-*-* | Insert, helical coil, free running & self-locking, tangless | — |
| NAS1395 | NAS1395C* & NAS1395CA* | Insert, threaded metal, heavy-duty, self-locking & non-self-locking | CRES or heat-resistant steel; passivated |
Rivets
| Specification | Part Number | Description | Limitations |
|---|---|---|---|
| NASM20426 | MS20426AD-*, MS20426E-*, MS20426T-* | Rivet, solid, countersunk 100°, precision head, Al & Ti-Columbium alloy | 2117-T4 "AD", 7050-T73 "E", Ti-Cb "T"; MIL-C-5541 Class 1A or MIL-A-8625 Type II Class 1 |
| NASM20470 | MS20470-AD-*, MS20470-E-* | Rivet, solid, universal head, aluminum alloy & Ti-Columbium alloy | 2117-T4 "AD" or 7050-T73 "E"; MIL-C-5541 Class 1A or MIL-A-8625 Type I Class 1 |
| NAS1919 | NAS1919B**-**FC | Rivet, blind, general purpose, bulbed, protruding head, mechanically locked spindle | MIL-C-5541 Class 1 conversion coated only |
| NAS1921 | NAS1921B**-**FC | Rivet, blind, general purpose, bulbed, 100° flush head, mechanically locked spindle | MIL-C-5541 Class 1 conversion coated only |
3. Approved Metallic Materials for Fasteners (Section 6.2.1.3)
| Alloy Designation | Condition | Specification | Limitations |
|---|---|---|---|
| 15-5 PH | H1000 and above | AMS5659 | — |
| 17-7 PH | C, CH900 | AMS5529, ASTM A313, ASTM A693 | Procured in condition C per AMS5529 shall be aged to CH900 |
| PH15-7Mo | CH900 | ASTM A693 | — |
| Custom 450, 455 | H1000 and above | AMS5936, ASTM A693, AMS5617, AMS5860, AMS5578, AMS5672 | — |
| 301 | All | AMS5517, AMS5518, AMS5519, AMS5901, ASTM A666 | Non-welding applications only |
| 303 | Solution heat treated (annealed) | AMS5640 Type 1 | — |
| 304 / 304L | Solution heat treated (annealed) | AMS5569, AMS5647, ASTM A240, ASTM A666, AMS5513 | 304 approved for non-welding applications only |
| 316 / 316L | Solution heat treated (annealed) | AMS5653, ASTM A240, ASTM A666 | 316 approved for non-welding applications only |
| 321 | Solution heat treated (annealed) | AMS5570, AMS5645, ASTM A240, ASTM A666 | — |
| 347 | Solution heat treated (annealed) | AMS5646, ASTM A240, ASTM A666 | — |
| 440C | All | AMS-QQ-S-763, AMS5618 | Approved for bearing balls only |
| A286 | All | AMS5525, AMS5731, AMS5732, AMS5734, AMS5737 | — |
| 302 | Solution heat treated (annealed) | AMS5516 | Non-welding applications only |
| 316 (¼ Hard) | ¼ Hard | AMS5907, AMS5910 | Non-welding applications only |
| 304 (Full Hard) | Solution heat treated & cold rolled, full hard | AMS5913 | Non-welding applications only |
4. Fastener Installation Requirements (Section 5.5)
| Requirement | Specification / Rule |
|---|---|
| General installation standard | NASA-STD-6012 or MIL-STD-403(C) |
| Liquid locking compounds — Category I | Prohibited as secondary locking features |
| Liquid locking compounds — Category II | Permitted only with PMPCA approval and validated processes |
| Self-locking fastener reuse | Not permitted under any circumstances |
| Wet installation | Required when exposed to aqueous corrosive environments or condensation; apply corrosion-resistant sealant while still wet |
| Titanium fasteners | Must comply with NASA-STD-6012 requirements |
5. Prohibited and Reliability-Suspect Items (Sections 2.1.6 & Appendix F)
| Item | Status | Reason / Restriction |
|---|---|---|
| Lock washers (split or star type) | Prohibited | Damage mating surfaces, generate debris, unreliable locking effectiveness |
| Liquid locking compounds — Category I | Prohibited | Unreliable in flight-critical applications |
| Zinc plating or coatings | Prohibited | Whisker growth risk; vacuum contamination |
| Cadmium plating or coatings | Prohibited | Toxic; vacuum contamination; prohibited on all space hardware |
| Pure tin (Sn) or tin alloys with <3% Pb | Reliability suspect | Tin whisker growth risk; requires PMPCA-approved mitigation |
| Lubricants on fasteners (critical cleanliness zones) | Reliability suspect | Must be precleaned prior to use |
| Cold-flow-susceptible materials (e.g., PTFE terminals) | Reliability suspect | Cold flow potential must be evaluated before use |
| Solder-coated or solder-plated washers | Controlled | Ensure solder does not creep under torque or generate whiskers |
6. Key Compliance Checklist for Fastener Procurement
| Priority | Action Item |
|---|---|
| 1 — Material | Use only approved CRES grades (303, 304, 316, 321, 347, A286) with passivation as the primary surface finish |
| 2 — Coating | Silver plating is permitted only for specific nuts (e.g., NAS1291); silver-plated fasteners must not contact titanium |
| 3 — Self-locking | Deformed-thread prevailing torque design required; no reuse of self-locking fasteners permitted |
| 4 — Traceability | Full documentation required: lot date code, manufacturer name, CAGE code for all flight-critical fasteners |
| 5 — Testing | 100% screening for Category I items; verify mechanical properties, chemical composition, dimensions, and surface finish |
| 6 — Outgassing | Nonmetallic materials on fasteners must meet ≤1% TML and ≤0.1% CVCM per ASTM E595 |
| 7 — Prohibited finishes | No zinc, cadmium, or pure tin coatings without explicit PMPCA approval |
7. Reference Documents
- SMC-S-011 — Parts, Materials, and Processes Control Program for Expendable Launch Vehicles (Rev E, 31 July 2015)
- NASA-STD-6012 — Corrosion Protection for Space Flight Hardware
- MIL-STD-403 — Preparation for and Installation of Rivets and Screws
- MIL-STD-889 — Dissimilar Metals
- ASTM E595 — Total Mass Loss and Collected Volatile Condensable Materials from Outgassing in a Vacuum Environment
This article is provided for reference and informational purposes only. Always verify requirements against the current revision of SMC-S-011 and applicable program documentation before procurement or installation.