BOEING 737NG FORWARD OVERHEAD

Elements used on the overhead.

Element	Quantity	Note
Paint	-	RAL 7043 and RAL 7040
Keyswitch	7	panel mounting
Encoders	2	CTS-288
Rotary switches	9	12 positions, 1 circuit, break before make
Potentiometers	5
Guarded ON-OFF switches	7	installation diameter 12 mm.
Guarded ON-OFF-ON switches	4	installation diameter 12 mm.
ON-OFF switches	24	installation diameter 6,5 mm.
ON-OFF-ON switches	5	installation diameter 6,5 mm.
MON-OFF-MON switches	9	installation diameter 6,5 mm.
Locked ON-OFF switches	16	installation diameter 6,5 mm.
Locked ON-OFF-ON switches	7	installation diameter 6,5 mm.
MON-OFF-ON	1	installation diameter 6,5 mm.
Green leds	6	high efficiency
Amber leds	78	high efficiency
Blue leds	17	high efficiency
Resistors
Displays	10	Kingbright SC36-11YWA
USB Expansion card	1
Master cards	3
Displays card	1

 

Graphic design

Overhead panels consist in several pieces:

 

Methacrylate preparation.

We proceed like with the EFIS. In this case, the light grey color is RAL-7040.

 

Building the panels.

We proceed like with the EFIS. The finished pieces are shown in this picture:

 

Backlight.

In the case of overhead, I won't use leds, but fluorescent lamps. We will see later.

 

Components.

I won't use printed circuit boards to install the components neither. I'll install them directly on the different panels. These are the components needed:

 

Panels assembly.

First, I paint the border of every subpanel to avoid light escaping. Dark grey is RAL-7043 and light grey is RAL-7040.

Some of the panels consist in several pieces. Let's see how to assembly them.

Guarded switches. Pieces where the guarded switches are placed, are fitted to the panel with thermic glue. I install the switch first, then I open the guard and place it in its place.

  

I put glue in some points. While the glue is hot, I can correct the position.

When the glue is cold, I apply glue all around the piece.

  

Annunciators. annunciators are formed with two pieces: the annunciator and the back piecedores constan de dos piezas. Inside the back piece I will install one led with the correponding color. Back pieces have been made by Carlos López from some real parts. The process for doing that is explained here.

 

First we paint the annunciators edges with black paint. If we don't do this, when there are two annunciators near one from the other, the first one will light the second.

Then, we install the led inside the back piece, towards the back part, and fit it with termic glue. Write which colour the led is, and if needed, which pin is the cathode (the short one).

  

We fit the back piece to the annunciator with super-glue.

  

To finish, we fit the annunciator to the panel with termic glue, leveled in the back side of the panel. This way the annunciator will stand out 2 mm from the front panel. The space between annunciator and its hole is very narrow, so we must install the annunciator from the panel front side to the rear. This way, any scratch on the edges will be hiden. After that, we paint the back piece to avoid the backlighting on the annunciator.

  

Dual light intensity annunciators: there are some blue annunciators with three possible states: off, dim light and normal light. To simulate this behaviour we can use two Master card outputs and the following circuit:

Enabling output A, the annunciator light is dim; enabling both outputs, annunciator light is normal. The resistors values are: RA= *** ohms y RB= *** ohms.

Small switches: there are two ways of assembling these type of switches. Using nuts, or using glue.

1) These switches are delivered with a washer that avoid the switch turns.

We mark the position of the washer and make a little hole with the driller, but without trespassing the panel thickness.

   

Once the switch is fitted, it won't turn. Using this fitting, the nut is visible in the panel, not like in the real panel.

So I've chosen the second option.

2) Using thermic glue: We have to place the nut in the correct position, check that the switch works fine before using glue and apply the glue around the switch. We have to ensure the correct position before the glue is cold. If the switch goes out of work, it can be taken out easily by turning the whole switch.

   

 

Overhead structure.

I will install the overhead panels on a wood structure made with several pieces of wood. The following picture shows where each piece is placed (yellow areas) and the number we will use for referring:

The stiffness of the structure will be achieved using metal squares and the own panels when finally installed.

The pieces dimensions are as follows:

• 60x20x544 mm (4 pieces; numbers 5, 6, 7 and 8)
• 60x10x544 mm (2 pieces; numbers 2 and 4)
• 60x10x645 mm (2 pieces; numbers 1 and 3)
• 60x10x564 mm (1 piece; number 9)
• 60x10x334 mm (1 piece; number 10)

and the arrengement will be this one:

The pieces that will be on sight, must be prepared with several layers of wood sealer. Then sanding to obtain a smooth surface.

The holes for screws have been previously made with a diameter 1 mm. less than the screws, to avoid the wood breaks.

Space between pieces can be filled with a mixture of sawdust and wood glue.

I've started with the outer pieces (1, 2, 3 and 4) placing the squares in the corners to obtain a frame with external dimensions 645x564 mm. First I mark the squares position, then drill the holes and fit the squares.

Next step is fixing piece number 5 in its position. For that I use any subpanel on the left side. With a pen I mark where the holes must be done, I drill the holes and place the piece.

I repeat this process for pieces 6, 7 and 8.

Once finished the first part ot the structure, I put the subpanels on their positions, and mark the screws positions and the wood that interfere with some annunciators:

  

  

  

We take out some parts of the frame that don't let the panels fit properly:

  

The second part of the structure (wood pieces 9 to 12) is made using thermal glue. The pictures show the drills needed to fit this structure to the first one:

  

Now we fix both parts with screws:

  

Now we take out the exceeding glue with sand paper, and fill the wood imperfections with a mixture of sawdust and wood glue.

The last step is painting with RAL-7043 the part of the final structure that will be on sight, and the inner parts with white paint to reflect the backlight as much as possible.

 

Inputs identification.

Using "controlador.exe", we check the inputs correspondence for every panel. Inputs are ordered by subpanels, from left to right and from up to down:

Variable	Master1-J2 inputs		Variable	Master1-J2 inputs		Variable	Master1-J2 inputs
FLT CONTROL A (STBY, DN)	03, 07		SUPPLY (NORM)	72		VOICE RECORDER (ON)	95
FLT CONTROL B (STBY, DN)	04, 08		EXHAUST (NORM)	65		AIR TEMP (CONT CAB, FWD, AFT, FWD, AFT, R, L)	108, 109, 110, 112, 113, 116
ALTERNATE FLAPS (ARM)	06		EMER EXIT LIGHTS (OFF, ON)	136, 139		TRIM AIR	101
ALTERNATE FLAPS (UP)	00, 05		NO SMOKING (OFF, ON)	140, 141
SPOILER A	14		FASTEN BELTS (OFF, ON)	136, 139		L RECIRC FAN (AUTO)	104
SPOILER B	20		ATTEND	54		R RECIRC FAN (AUTO)	99
YAW DAMPER	21		GRD CALL	59		OVHT	102
			R WIPER (PARK, INT, LOW, HIGH)	120, 123, 124		L PACK (OFF, HIGH)	82, 85
VHF NAV (1, 2)	01, 02					ISOLATION VALVE (CLOSE, OPEN)	81, 89
ILS (L, R)	11, 12		WINDOW L SIDE	131		R PACK (OFF, HIGH)	105, 106
FMC (L, R)	15, 16		WINDOW L FWD	118		TRIP	86
SOURCE (1, 2)	10, 13		OVHT	75, 79		1	100
CONTROL PANEL (1, 2)	09, 17		WINDOW R FWD	121		APU BLEED	103
			WINDOW R SIDE	125		2	107
CROSS FEED	25		PROBE A	117		FLT ALT	83, 84
FUEL PUMP CTR L	24		PROBE B	122		VALVE	87, 88
FUEL PUMP CTR R	29					LAND ALT	155, 156
FUEL PUMP 1 AFT	30		WING ANTI-ICE	126		AUTO, ALTN, MAN	76, 80
FUEL PUMP 1 FWD	34		ENG ANTI-ICE 1	119
FUEL PUMP 2 FWD	33		ENG ANTI-ICE 2	78		RETRACTABLE L	56, 57
FUEL PUMP 2 AFT	19					RETRACTABLE R	60, 61
BATERIAS (TEST, STBY PWR, BAT BUS, BAT, AUX BAT, TR1, TR2, TR3)	36, 37, 38, 39, 40, 41, 44		ENG 1	92		FIXED L	18
GEN (STBY PWR, GRD PWR, GEN1, APU GEN, GEN2, INV, TEST)	45, 46, 47, 49, 50, 53		ELEC 2	93		FIXED R	22
BAT	55		ELEC 1	97		RUNWAY TURNOFF L	31
CAB/UTIL	58		ENG 2	96		RUNWAY TURNOFF R	32
PASS SEAT	62					TAXI	35
DRIVE 1	26		STATUS	91		APU (OFF, START)	132, 133
STANDBY POWER (BAT, AUTO)	42, 43		ERASE	94		1 (GRD, OFF, CONT, FLT)	48, 51, 52
DRIVE 2	27		TEST	98		ENGINE START (L, R)	138, 142
			ALT HORN	90		2 (GRD, OFF, CONT, FLT)	146, 147, 148
GRD PWR	128, 129					LOGO	137
BUS TRANS	28					POSITION (STROBE, STEADY)	73, 74
GEN 1	66, 70					ANTI COLLISION	127
APU GEN 1	68, 69					WING	130
APU GEN 2	63, 71					WHEEL WELL	134
GEN 2	64, 67
L WIPER (PARK, INT, LOW, HIGH)	111, 114, 115

For an easy connection to Master cards inputs, I've built some connection PCBs (tutorial here):

Outputs identification.

We do the same with outputs (annunciators). Annunciators are ordered by subpanels, from left to right and from up to down. Those marked with (*) have two possible light intensities, that's why two outputs are defined:

Variable	Master1-J2 outputs		Variable	Master1-J2 outputs		Variable	Master1-J2 outputs
LOW QUANTITY	12		GRD POWER AVAILABLE	41		COWL ANTI ICE	97
LOW PRESSURE	14		TRANSFER BUS OFF	43		COWL ANTI ICE	98
STDBY RUD ON	16		TRANSFER BUS OFF	45		L VALVE OPEN (*)	75, 77
LOW PRESSURE	18		SOURCE OFF	47		R VALVE OPEN (*)	79, 81
LOW PRESSURE	20		SOURCE OFF	49		COWL VALVE OPEN (*)	83, 85
FEEL DIFF PRESS	22		GEN OFF BUS	50		COWL VALVE OPEN (*)	87, 89
SPEED TRIM FAIL	24		APU GEN OFF BUS	51
MACH TRIM FAIL	26		GEN OFF BUS	52		OVERHEAT	107
AUTO SLAT FAIL	30		MAINT	53		OVERHEAT	108
YAW DAMPER	28		LOW OIL PRESSURE	54		LOW PRESSURE	109
			FAULT	55		LOW PRESSURE	110
ENG VALVE CLOSED (*)	11, 13		OVER SPEED	99		LOW PRESSURE	111
SPAR VALVE CLOSED (*)	15, 17					LOW PRESSURE	112
ENG VALVE CLOSED (*)	19, 21		SMOKE	76		FWD ENTRY	113
SPAR VALVE CLOSED (*)	23, 25		OFF	100		FWD SERVICE	114
FILTER BYPASS	32		OFF	78		LEFT FWD OVERWING	115
VALVE OPEN (*)	27, 29		NOT ARMED	101		RIGHT FWD OVERWING	116
FILTER BYPASS	34		CALL	80		FWD CARGO	117
LOW PRESSURE	36					EQUIP	118
LOW PRESSURE	38		OVERHEAT	102		LEFT AFT OVERWING	119
LOW PRESSURE	40		OVERHEAT	82		RIGHT AFT OVERWING	139
LOW PRESSURE	42		OVERHEAT	103		AFT CARGO	140
LOW PRESSURE	44		OVERHEAT	84		AFT ENTRY	141
LOW PRESSURE	46		ON	104		AFT SERVICE	142
			ON	86
BAT DISCHARGE	48		ON	105		ZONE TEMP	143
TR UNIT	31		ON	88		ZONE TEMP	144
ELEC	33		CAPT PITOT	106		ZONE TEMP	145
			F/O PITOT	93
DRIVE	35		L ELEV PITOT	90		DUAL BLEED	146
STDBY PWR OFF	37		R ELEV PITOT	94		RAM DOOR FULL OPEN	147
DRIVE	39		L ALPHA VANE	91		RAM DOOR FULL OPEN	148
			R ALPHA VANE	95		PACK	149
			TEMP PROBE	92		PACK	150
			AUX PITOT	96		WING BODY OVERHEAT	151
						WING BODY OVERHEAT	152
						BLEED TRIP OFF	153
						BLEED TRIP OFF	154
						AUTO FAIL	155
						OFF SCHED DESCEND	156
						ALTN	157
						MANUAL	158

For an easy connection to Master cards outputs, I've built some connection PCBs:

Displays identification.

Variable	Displays 1
FLT ALT
LANDING ALT

With these values we can start build the SIOC configuration for this panel. But we will see this at Software section.

 

 

Last edited: 02.05.2006