Nas0331 Pdf Jun 2026

The "NAS" designation indicates that this part meets the rigorous quality and dimensional standards required for flight-critical aerospace applications.

A significant portion of the NAS0331 PDF is dedicated to dimensional data. The document defines the exact geometry of the housing chamfers, undercuts, and the receiving pockets necessary for proper installation. This is not a guideline but a specific engineering standard. If the housing does not fit the specifications laid out in the PDF, the retention will not meet certification requirements. The usage criteria also help design engineers determine which method (100, 200, or 300) is appropriate based on material properties, load requirements, and operational environment.

Involves deforming the ductile housing material onto the bearing using a non-spinning tool. Technical Specifications nas0331 pdf

: Uses a hydraulic or pneumatic press to apply high axial pressure to a bearing’s "V-groove," forcing the metal into the housing. It is prized for being fast and cost-effective. Swaging (Method 200)

The key principles of NAS0331 are:

The primary purpose of NAS0331 is to standardize how grooved outer-race bearings are mechanically retained inside a structural housing. In aerospace design, bearings cannot simply be press-fit; flight control surfaces, landing gear, and engine linkages experience severe vibrational and multi-axial forces that could cause un-retained bearings to back out or displace.

The specification, formally titled "SCREW, MACHINE - PAN HEAD, CROSS RECESS, FILLISTER HEAD, DRILLED, 100 DEGREE COUNTERSUNK HEAD, CORROSION AND HEAT RESISTANT STEEL, UNJF THREAD" (note: always verify the exact title with the latest AIA/NAS release), defines a specific family of precision fasteners used in extreme environments. The "NAS" designation indicates that this part meets

Specific guidelines for using swaging tools to permanently fix bearings in place.

: Recommended dimensions for the housings where bearings will be installed. This is not a guideline but a specific engineering standard