Aviation and Aerobatics: Tech Tips: Pitts Parts and Hardware

Part NumberDescriptionNotes
AN526C-832R6SS #8 Machine Screw 3/8" length

These are the R6 length stainless steel machine screws used to fasten the majority of the sheet metal panels to the fuselage. The nylon washers protect the paint from wearing away underneath the truss head of the screw.

The longer R8 screw works in places where several pieces come together or where the shorter screw won't reach.

Aircraft Spruce catalog page

AN526C-832R8SS #8 Machine Screw 1/2" length
04-00217#8 Nylon washer
AN526C-1032R8SS #10 Machine Screw 1/2" length You'll find these larger radius #10 machine screws holding the sheet metal of the cowling around the engine, firewall and forward.
04-00218#10 Nylon washer
4x1/4-A-TR-PH-SS#4 Sheet Metal 1/4" length

Sheet metal screws

Most of the trim pieces attach with sheet metal screws. The rear part of the metal fuselage, where the covering transitions into fabric, is attached with #4 sheet metal screws, not machine screws.

I use the smallest screw that will tighten, then go to a longer screw up to 3/8", then go to a larger screw. These screws tend to loosen up and fall out with repeated removal and installation. I also use Permatex thread locker blue for screws that won't stay in, before making a step up in size.

Sheet metal screws have points. Aircraft Spruce calls these "Type A." Do not confuse them with tinnerman screws, that have square ends.

Aircraft Spruce catalog page

4x3/8-A-TR-PH-SS#4 Sheet Metal 3/8" length
6x3/8-A-TR-PH-SS#6 Sheet Metal 3/8" length
6x1/2-A-TR-PH-SS#6 Sheet Metal 1/2" length
8x3/8-A-TR-PH-SS#8 Sheet Metal 3/8" length
8x1/2-A-TR-PH-SS#8 Sheet Metal 1/2" length
10x3/8-A-TR-PH-SS#10 Sheet Metal 3/8" length
4x3/8-B-TR-PH-SS#4 Truss head Type B Machine Screw 3/8" length

The screws holding the banana together were originally machine screws threaded through the fiberglass. These were forever falling out.

My solution was to attach some Tinnerman nuts on the back-sides using black Permatex Gasket sealant. The 3/8" Tinnerman screw worked best for me here.

Aircraft Spruce catalog pages: "Type B" machine screws and Tinnerman hardware

A1776-4Z-1#4 Tinnerman nut
06-035004" diameter tail wheel with 5/8" axel on ball-bearings My particular tail wheel Aircraft Spruce catalog page
05-18400Pressure fuel cap, 2" diameter The fuel cap that fits my tanks. Aircraft Spruce catalog page
AN970-4Flat Washer These are the screw and washer that attach the wheel faring to the wheel hub. I was losing these in the early days. With the right screw well tightened that problem has gone away. I still check these during preflight and occasionally find a need to tighten them up.
AN526-C-428R12SS Truss Screw
Type II BungeeThe Bungee MIL C-5651D date coding is as follows: Paired stripe indicates year in five year cycle beginning 2006 green, red, blue, yellow, black. Solo stripe indicates quarter being red, blue, green, yellow in that order.