Fastener Locking Features
Self-Locking Nuts, Wire, and Thread-Locking Systems
Fastener locking features—including prevailing-torque nuts, safety wire, and deformed-thread all-metal locknuts—prevent joint loosening caused by operational vibration and thermal cycling. Chemical thread adhesives are unsuitable because they outgas in the lunar vacuum and fail under thermal cycling, necessitating purely mechanical retention methods. Friction-based MS21044 nylon-insert locknuts are limited to operating temperatures below 120 °C, requiring NAS 1291 all-metal deformed-thread locknuts in higher-temperature applications. For critical assemblies, 0.032-inch MS20995 stainless steel safety wire provides positive mechanical anti-rotation, though the labor-intensive nature of manual safety wiring requires the development of robotic installation capabilities for lunar surface operations.
Locking features preventing fastener loosening from vibration and thermal cycling
Purpose
Locking features preventing fastener loosening from vibration and thermal cycling
Context
Child of L2-STR-FAST
Principles
- ▸Self-locking nuts (MS21044 Nylok) provide friction-based prevailing torque locknut
- ▸Safety wire (MS20995) provides positive mechanical anti-rotation for critical fasteners
- ▸Deformed thread locknuts provide all-metal locking for high-temperature applications
- ▸Loctite thread adhesives not suitable for vacuum/thermal cycling applications
Typical implementations
- ▸MS21044 self-locking nut (Nylok insert)
- ▸MS20995 safety wire standard
- ▸NAS 1291 all-metal self-locking nut for high temperature
Lunar considerations
- ▸Nylon insert locknuts limited to <120C - all-metal required for high-temp zones
- ▸Safety wiring is manual-intensive - robotic safety wiring capability needed
- ▸Chemical thread lockers outgas in vacuum - mechanical locking preferred
Specifications
Functional
| primary function | Locking features preventing fastener loosening from vibration and thermal cycling |
Physical
| materials | MS21044 self-locking nuts, 0.032" stainless safety wire, NAS 1291 all-metal locknuts |
Interfaces
Provides
- Anti-loosening features for all structural fasteners
Requires
- Robotic safety wire installation capability
Cite this entry
Lunar Ark Codex. "Fastener Locking Features" (L3-STR-FAST-LOCK). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-STR-FAST-LOCK
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.