(3)  
The data keys (0 through 9) are used to enter numerical data into the CDU. The N2, 4W, 6E and 8S keys are used to initiate latitude and longitude data entries. The 7 and 9 keys double as minus (-) and plus (+) keys for temperature data entries. The data entered with the keys is sent to the computer unit. The computer unit formats this data to be shown in the display at a point determined by the line select switches. Displayed data can then be entered into the computer by depressing the INSERT key.

 (4)  
The MAN key, when pressed to produce a "MAN" message on the bottom line of the current mode page display, prevents automatic leg switching. In such cases, steering signals are provided to continue the present course until the MAN key is depressed again to extinguish the "MAN" message.

 (5)  
The CLEAR key is used to erase and cancel data entries. The entries can be cancelled before the INSERT key is depressed. Pressing the CLEAR key may also be used to reset line and display selections.

 (6)  
The INSERT key is used to command the computer to accept input data or mode commands. When a data entry is made or a mode selection is required, the INSERT key lights to show that it is armed. Pressing the key at this time tells the computer to accept the data or command. The computer then extinguishes the INSERT key.

 (7)  
The line select switches (1,2 and 3) are used to select a data entry point within a displayed page. If there is more than one data entry point on a display line, depressing the line select switch once selects the first (left) entry point for that line. Depressing the line select switch twice selects the second (right) data entry point for that line. A line select switch lights when depressed and it can also be lighted automatically by the computer unit as part of the mode commanding process. The line select switch light goes out when either the CLEAR keys or lighted INSERT key is depressed. Line select 1 switch is also used to stop present position and performance data displays from changing during flight.

 (8)  
The slew switch is used to page forward (FWD) or backward (BCK) in a multiple page display. Momentary activation of the switch steps the display a single page. Holding the switch in either position causes rapid, continuous paging until the switch is released.

 (9)  
The mode annunciators (CLB for climb, CRZ for cruise, and DES for descent) light to indicate the PMS mode of operation. These annunciators function only when the PMS is engaged.

 EFFECTIVITY

 AIRPLANES WITH PMS    02 Page 21  Aug 25/83

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 (10)
 The PMS annunciator lights steadily when a PMS malfunction error code is detected. The malfunction error code is detected by the software in the PMS computer unit.

 (11)
 The STS/TEST key when depressed causes the INSERT key and the line select switches to light or brighten. Also when the key is depressed the flight mode annunciators and the PMS annunciator light and uniform rectangles are produced on the CDU display. Depressing the STS/TEST key also initiates tests of the limit indicator display. If the STS/TEST key is held depressed during INS alignment an INS/HSI interface test is initiated. The DIM control, when rotated, adjusts the brightness of the CDU indicators and display. These indicators include the flight mode (CLB, CRZ and DES) annunciators, the line select (1, 2, 3) switches, the INSERT key, and the PMS annunciator.

 7.  Limit Select Panel (Fig. 7)
__________________
 A.  The limit select panel contains a power supply, logic circuits, controls, and indicators. The controls and indicators are used to insert limit mode and engine derating commands into the computer unit and to indicate that the commands have been accepted by the computer unit. The logic circuits transform inserted data into serial digital data and also convert serial digital data into illuminated indications.
 B.  The controls and indicators include means to select a limit mode. There is also a set of keys to permit selection of alternate engine ratings and another set of keys together with a display for selection of derating factors. Testing of the key and display functions is accomplished with the aid of logic circuits controlled by the TEST switch on the front panel of the unit.
 C.  Limit Select Panel Switch Controls and Display.
 (1)  
On IB Airplanes, the DERATE display and the up and down slew keys are used to command derate factors. Pressing the up key causes the displayed value to increase; pressing the down key decreases the displayed value. The value shown in the display is provided to the computer unit as the derate command. For EPR limits the display steps in .01 increments.

 (2)  
　
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