FAA Aviation Mechanic Airframe (AMA)Airframe StructuresEasy
A technician is installing a removable inspection access panel that must be secured with machine screws from the exterior, while the fastener on the inside of the structure remains permanently attached to the skin so it cannot fall into the structure. Which fastener should be used?
- AA nutplate (anchor nut) riveted to the structure
- BA Hi-Lok collar and pin
- CA castellated nut with a cotter pin
- DA blind (pop) rivet
Show answer & explanationAnswer & explanation
Correct answer: A. A nutplate (anchor nut) riveted to the structure
A nutplate is riveted permanently to the airframe structure so that a screw can be installed and removed repeatedly from the outside without loose hardware falling inside. Castellated nuts, Hi-Loks, and blind rivets are not designed for repeated removal of access panels.
Why the other options are wrong
- B. Hi-Loks are permanent structural fasteners, not removable panel hardware.
- C. Castellated nuts require a bolt and cotter pin, not suited for removable panels.
- D. Blind rivets are permanent, not removable, fasteners.
Nutplate (Anchor Nut)
A fastener riveted permanently to structure that provides internal threads so a screw can be installed and removed from the outside.
- Commonly used on removable access panels and fairings
- Prevents loose nuts from falling inside the structure
- Comes in floating and fixed designs
Memory trick: Nutplate = the nut that never leaves home