In this part we show you some details on piano hinges and floating anchor nuts, also known as nut plates. These items are used with trim tabs and removable panels as oil and other inspection doors or baggage hatches.
By using hinges and nut plates, life will be easier to do the preflight and aircraft maintenance as you will find them near aircraft parts or structure where regular (daily) inspection is necessary by the pilot during preflight.
These inspection areas must be closed during flight so small doors are created and they use hinges and nut plates enabling the doors to be opened and closed easily.
As said previously, this continuous hinge is used in lightly loaded applications such as hinges for control surface tabs and small doors. It is available in either aluminum alloy or corrosion resistant steel material. Corrosion resistant steel is indicated by the letter "C" following the part number. The part is available either as a complete hinge as shown or as a half hinge without the pin. The letter "H" following the part number indicates a requirement for a half hinge. The first dash number indicates the available widths as shown in the table. Length is indicated by the 2nd dash number in inches and hundredths.
Nut Plates are used in areas where you need to frequently remove a plate or part for inspection purposes. Installing Nut Plates: To install use the appropriate size bolt to hold the nut in place. If a hole is not already in place, locate the area where you wish the nut, layout and drill a larger hole to accommodate the bolt. With the nut held in place drill #40 holes through the flanges on the nut. Remove the nut and drill the two flange holes out to #30. On your work area drill the two #40 holes out to #30 and countersink (or dimple) to accept a RV-4412 CSK rivet. Deburr all parts. Cleco the nut plate on the back side of the work and rivet.
Below an image of different nutplates:
These are primarily used to attach access plates, doors, inspection covers and any part that must be fastened securely, yet be easily opened. These create vibration proof attachments. Usually 3/32" diameter rivets are used for attachment. Shown is a NAS444.
These anchor nuts can be bought in three sizes: for screw sizes #6, #8 and #10. Install them with AN426AD-3 rivets. Remember that speed nuts for aircraft are designed to fit standard AN530-AN531 type B sheet metal screws only. Do not use pointed type A sheet metal screws with aircraft speed nuts. There is a difference in root diameter and thread pitch.
Screw lengths: B type sheet metal screws have a blunt taper at the end. To be certain the fastener prongs grip on the full root diameter, the screw should protrude two to three threads beyond the prongs.