Details
This 22ND8-02 - Nut - Spline is in NS condition and has a nylon insert. AirCorps has and can provide manufacture certs if requested.
Spline nut part numbers can be a challenge to understand, here is a breakdown and some beneficial technical resources AirCorps can provide.
The actual thread for the 22ND8-02 spline nut is 10-32 or .1900-32UNJF-3B by current ESNA production & engineering specifications. In reference to 22ND8-02, the "8" is often mistaken for an 8-32 thread pitch, instead the shank length of the spline nut is what the "8" in the part number represents. We have provided a link below to the spline nut section of the ESNA catalog detailing the dimensions of the component. Fiber vs Nylon is a common question when procuring locking insert nutplates, nuts and spline nuts. While many original WWII era drawings call out 22D8-02 for example that early spline nut was produced with a fiber insert that has shown a propensity to crack due to age, ESNA added the "N" to the 22ND8-02 part number when the nut has a nylon insert. We recommend using nylon insert fasteners wherever possible.
22ND8-02 ON THE P-51 MUSTANG
There are 17 occurrences of this spline nut on the P-51D, and a total of 25 units per P-51D. Principally this product is most commonly known as the spline nut installed as a part of 73-22007 - FITTING ASSEM. - TRIM TAB HINGE. This assembly and the spline nut is the basis for the Mandatory Service Bulletin detailed below. There are a total of (15) 73-22007 trim tab hinges per P-51 with three units installed on each of the rudder, (2) aileron assemblies, and (2) elevator assemblies respectively.
Mandatory Service Bulletin P51-001 and Supplement 1 dated May 1, 2013 is issued by Cal Pacific Airmotive Inc. in cooperation with the National Transportation Safety Board (NTSB) as holder of Limited Type Certificate LTC-11-5 for the P-51B,C,D,K, F-51D and F-51K model aircraft. It is recommended that all P-51 & TF-51 model aircraft comply with this Service Bulletin, Including those with an experimental airworthiness certificate.
As referenced in the Cal-Pacific Supplement 1 (Page 9) there are some P-51 Maintenance manuals, and parts catalogs that incorrectly identify a screw with a #8-32 thread to be used with this spline nut. It is critical to use the correct NAS221 series 10-32 brazier head screws.
From P51-001 -Supplement 1.
- Refer to Parts Catalog AN 01-60JE-4 USAF Series F-51D, TF-51D and F-51K Aircraft dated March 10, 1945, revised May 15, 1953, page 20D figure 4B “Aileron Assembly” index no. 33 to install the correct part number structural screw NAS221 series (10-32 thread). This parts catalog is also reference for the P-51D thru P-51K aircraft. Length of screw may vary from those published in the North American Aviation & USAF maintenance and parts manuals if trim tab is original, rebuilt, phenolic or metal covered.
- When installing structural screws to secure the trim tab to the hinge fitting P/N 73-22007, make sure the screw shank does not bottom in the threads of the spline nut and at least one full thread extends through the locking nut insert.
Warranty Information
All NS parts are sold "as-is". Airworthiness to be determined by an appropriately rated certificate holder. No warranty is implied. AirCorps Depot reserves the right to charge a restocking fee when deemed appropriate.
