CFS Locking & Anti-Vibration Fasteners Flashcards
6 cards from real CFS practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CFS Locking & Anti-Vibration Fasteners flashcards as text
A castle nut (castellated nut) with a cotter pin provides locking by:
Answer: Positive mechanical restraint — the cotter pin through the bolt hole prevents nut rotation regardless of clamp load
The cotter pin passes through slots in the castle nut and a cross-drilled hole in the bolt, creating a positive mechanical lock that prevents rotation even under complete loss of preload.
Thread-locking adhesives (e.g., anaerobic adhesives like Loctite) cure in the absence of air and presence of metal ions. What property distinguishes a 'medium strength' grade from a 'high strength' grade?
Answer: Medium strength allows disassembly with standard hand tools; high strength typically requires heat or special tools for removal
Medium-strength (typically blue) anaerobic adhesives are designed to be disassembled with standard tools, while high-strength (typically red) grades require heat application or significant force to break the bond.
Which type of serrated flange fastener provides locking action by biting into the mating surface upon tightening?
Answer: Serrated (tooth) flange nut
Serrated flange nuts have radial teeth on the flange bearing surface that bite into the mating material when torqued, creating mechanical locking resistance against vibration-induced loosening.
A jam nut (thin nut) used as a locking method works by:
Answer: Compressing the bolt threads between the two nuts, creating a locked friction grip
When a jam nut is tightened against a primary nut, the bolt is placed in tension between them and the threads are loaded in opposite directions, creating high friction that resists self-loosening.
Wiring (safety wiring) of fasteners is a positive locking method most commonly required in which industry?
Answer: Aerospace and military aviation
Safety wiring is mandated in aerospace and military aviation (per MIL-DTL-83519 and AC 43.13) to provide positive locking for critical fasteners that cannot be allowed to loosen in flight.
What is the correct direction to route safety wire between two fasteners to ensure the wire tensions both fasteners in the tightening direction?
Answer: Wire is routed so that any loosening tendency in either fastener pulls the wire taut and tensions the adjacent fastener toward tightening
Safety wire must be routed so that the pull on the wire — if either fastener begins to loosen — applies a tightening torque to that fastener, providing active locking restraint.