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L45-1001, ATA-31, Instrument Panels

Lear 45-1001 Build History

ATA-31, Indicating & Recording Systems, section -10

“Instrument and Control Panels”

Rev 5 Dec 2019

The L45-1001 introduction contains useful background information on this build. If somehow you have arrived at this place and have not read the L45-1001 introduction you will find it HERE:

This chapter covers fabrication of the main instrument panel (MIP), the lower switch panel (“knee panels”), and the glareshield panel.

Main Instrument Panel (MIP):

First, and very important, use the correct alloy of aircraft aluminum for the MIP, switch panel, and glareshield panel. For more tips on fabricating with aircraft aluminum refer to my post on “Aluminum Fabrication Tips” HERE. Those tips can save you time and aggravation.

The MIP is cut from a single piece of 2024T3-Alclad aluminum 0.090” thick. Before beginning the layout of the holes check the blank piece for scratches or other defects that cannot be sanded out. Your metal supplier should be able to provide you with clean and defect free material. If not, find another metal supplier. It’s difficult to sand scratches out of a finished panel.

I used Kraft paper for the layout. Tape the paper *tightly* to the MIP blank so that it will not move as you are cutting out holes. Make sure there are no wrinkles in the layout paper.

MIP1

MIP2

USE REAL PARTS to make the layout on the paper. Using the actual parts (vs. dimensions) allows you to check the alignment, clearances, and orientation before you start marking up the layout paper.

MIP3

Once the layout is completed – TAKE A BREAK – then come back and check it one more time before you start cutting holes. Avoid trouble. “Measure ten times, then cut once!”

MIP4

Cut out the smaller holes first, saving the large display unit (DU) holes for last. This preserves the strength of the blank panel across the middle during fabrication.

MIP5

MIP6

Once the MIP blank holes are cut, use the panel components to verify the dimensions of the holes. Dress the edges of the holes with a fine tooth file. Drill, countersink, and tap all screw holes as required.

MIP7

MIP8

Paint the MIP with aircraft zinc phosphate primer. Allow the primer to dry overnight before handling. Once dry, do an initial fit test of the MIP in your airframe.

MIP9

After passing the airframe fit test install the Dzus rails for the audio panels and apply a finish coat of gray paint to the MIP.

MIP10

Lower switch panel (knee panels):

In the real aircraft the lower switch panels consist of the left panel, center panel, and right panel. The “panels” in this area consist of the backer plates behind the light plates. There are only three backers - left, center, and right. The individual lightplates are separate, but the backers are combined into left, center, and right. The lower switch panel structure is made from right angle aluminum and is sized to accept the switch panels. The top of the lower switch panel structure attaches to the bottom edge of the MIP with three short hinge sections to form a shallow angle. The bottom of the lower switch panel structure rests on the top of the forward pedestal and is held by two screws. On L45-1001 the lower piece of angle aluminum extends out each side for attachment to the fuselage structure. This results in a sturdy and secure lower switch panel structure to which the backer/switch panels and lightplates are mounted.

LSP1

Drill and tap the necessary backer and lightplate mounting holes in the switch panel structure.

LSP2

Drill the attachment holes in the top of the forward pedestal. Notice that these screws are inserted from below and fasten to the lower switch panel structure. This arrangement permits access to the screws in the event you wish to remove the forward pedestal or the knee panel structure. (Removing the “Test” panel provides access the heads of these screws.)

LSP3

LSP4

Cut out the aluminum backers for the left, center, and right side switch panels. Install the backers and temporarily install the lightplates to verify that all parts fit properly.

LSP5

An assistant is helpful when checking the panel alignment on both sides.

Minion1

Glareshield structure and panel:

In the real aircraft the glareshield structure and panel are made from a single piece of metal. It is fabricated using large presses and bending brakes because it is a complex part with multiple angle bends. The photo below is a glareshield assembly from a real Learjet 45.

GS1

The bottom part of the glareshield structure has a double bend across the entire width. The panel area (where the display controllers and FGC are mounted) is formed with a radius bend on the lower edge. I don’t have the tooling needed to make a double bend or a radius bend in a single piece of metal of this width so the assembly in L45-1001 is made from three pieces. The three pieces are fastened together with splices and angle aluminum to form the glareshield assembly.

The lower part of the glareshield assembly has a double bend to accommodate the angle of the MIP flood light lamp shade that runs across it. The angle of the lamp shade must be perpendicular to the floor because the turn coordinators are mounted to the lamp shade. I made this double bend on the parts that make up the splice. The splice parts are within the capacity of an inexpensive bending brake and may be fabricated by an average builder. The distance and angle of each bend may be adjusted as needed to produce the desired angle for the glareshield and lamp shade.

Here is an edge view which illustrates how the splice and lamp shade parts fit together.  This is how my "spliced" version is made.  The real glareshield is made from a single piece of metal.

GS2

The glareshield lower part is made from two pieces of 0.090”, 2024T3-Alclad aluminum. The glareshield panel itself is made from a single piece of 0.063” 2024T3-Alclad aluminum. The splice parts are made from thinner material that is within the capacity of an inexpensive bending brake. The glareshield panel is attached to the lower part using cut down angle aluminum and flush head (countersink) screws. Remember to drill holes for mounting the MIP flood light, CVR microphone, electrical connectors, and FGC chassis.

Cut out the various glareshield parts and paint them with zinc phosphate primer.

GS3

If you have access to any avionics control unit that is the same size as the DC-550 display controller it can be used as an aid to locating the mounting holes for the Dzus rails. First, attach the Dzus rails to the control unit.

GS4

Carefully position the control unit and Dzus rails in the glareshield panel opening. Use a clamp to hold the Dzus rail in place. Then mark the exact location of the rivet holes using a pencil.

GS5

Center punch and drill the flush head threaded rivet holes per your pencil marks. These holes need to be drilled with precision because they are for flush head threaded rivets. The flush side of the rivets is the “finished” side and will be visible when the panel is completed. Many aviation fasteners require countersinking at a 100-degree angle. CHECK the rivets you intend to use and MATCH the countersink BIT to the rivet countersink angle. Failure to do this will cause the rivet to seat in an uneven manner and will adversely affect the appearance of the work.

GS6

Finish paint the glareshield assembly with gray paint. Allow the paint to dry overnight.

The glareshield assembly mounts to the top of the MIP with three hinge sections. The hinges allow the glareshield assembly to be lowered away from the glareshield cover for access to internal components and wiring. This is the method used in the real aircraft.

Assemble the glareshield components into a single assembly and mount it in the airframe for a fit test.

Notice the length of white rope holding the glareshield assembly in place. The glareshield assembly is normally supported by brackets on the glareshield COVER. Use a length of rope tied off to the cockpit ceiling structure as a temporary support for the glareshield assembly during fit testing.

GS7

As of this writing (December 2019) I don’t have a glareshield cover. I made a temporary bracket to support the glareshield assembly until I have a cover.

GS8

The FGC chassis box mounts on these two spacers. The spacers elevate the FGC chassis box so that the lower edge of the box clears the lip of the opening in the glareshield panel. The two short pieces of angle are used as stiffeners to add structural support to the glareshield bottom.

GS9

GS10

The FGC chassis box is fastened into the glareshield assembly with four screws that are inserted from below. These screws attach to nutserts in the bottom of the FGC chassis box. Also visible in this view are the flush head threaded rivets that fasten the Dzus rails to the glareshield panel.

GS11

BP12

 

HOME: This link goes to the L45-1001 build history introduction. Links to other L45-1001 posts are found at the END of the introduction.