Panel-fastening systems rely on a combination of oversized structural holes and nut-element float to accommodate panel removal and installation. Improvements in positional tolerances of tooling used to produce interchangeable panels, makes a new Panel Aligning Fastener System (PAFS) feasible.
PAFS differs from common panel fastening systems in that the access panel and its mating structure are treated as a stiff-spring system in which each fastener loads/unloads the spring system a small amount. With PAFS "pinning'' panels in place, it should be possible to design and manufacture improved, lighter weight, more efficient structure using fewer fasteners. Other advantages:
All male fasteners for a given panel can be identical, regardless of substructure thickness
The fastening system eliminates bending moment failures in the threads
Receptacle has no moving parts for high reliability
Improved fastener flushness
Improved fuel sealing (gasket chafing eliminated)
Inherent low cost
|Panel hole misaligned with structure hole||With > 3 threads engaged, fastener becomes a jackscrew||Fastener chamfer engages receptacle barrel||Major diameter of bolt moves into the shear plane|
Jim Landgrebe, Lockheed Martin Tactical Aircraft Systems, MZ 4266, Box 748, Fort Worth, TX 76101; (817) 763-2113.