ANÁLISIS DE LA COMPETENCIA

PURPOSE

The special input check verifies the proper function of manual and automatic inputs. This check ensures all individually tested component circuits are operational prior to testing full solution data.

Note. Checks 4 and 5 do not test components of the fire control system; they test the ability of the CEU to compensate for the values received from these components and determine a ballistic solution for a given round.

CONDITIONS

1. The tank is on level ground with the solution board 100 meters (±3 meters) from the front edge of the tank.

2. Checks 1, 2, and 3 have been completed.

3. The horizontal reference line on the solution board is level with the gun trunnions. (Level criterion is achieved when the horizontal reference line on the solution board and the center horizontal reference line in the primary sight reticle is aligned with the gun at zero elevation. An easy way to check this is to move the MRS lever to IN and squeeze the palm switches on the power control handles [the main gun will move to zero elevation]. Move the MRS lever to OUT and align the reference line on the solution board with the center horizontal reference line in the primary sight reticle.) (Figure 3-1, Abrams Combined Solution Board, on page 3-8 is a scale drawing of the solution board to be used.)

4. An MBD is available.

5. The engine is off; the VEHICLE MASTER POWER, TURRET POWER, and AUX HYDR POWER are on; the CCP power is on; and the FIRE CONTROL MODE switch is in the NORMAL position.

Note. Checks 4 and 5 must be performed with the AUX HYDR POWER on. Performing checks 4 and 5 at zero pressure does not test the fire control system's ability to apply offsets to the gun.

PROCEDURE

WARNING

Range solutions must be entered manually with the CCP data key during checks 4 and 5.

Do not use the LRF; it may expose unprotected personnel to injury.

1. Record the GPS boresight, zero data (CCF), MRS update, and MRS boresight numbers from the CCP before conducting check 4.

2. Set zero data for all AMMO SUBDES, MRS update, and MRS boresight to 0 and 0 before conducting check 4. (Failure to do so may cause a failure of check 4.)

3. Grip one of the palm switches; then (with the palm switch pressed) press the RANGE push button, index 1,200 meters into the CCP, and press the ENTER push button. Hold the palm switch for five seconds, then release. (When conducting the special input check, the range values must be entered with the palm switch pressed. Failure to enter range with the palm switch pressed will result in a failure of check 4.)

4. Put the FCS in the BORESIGHT mode by pressing the BORESIGHT push button on the CCP.

Note. Do not rotate the MBD during checks 4 and 5.

5. Insert the MBD and direct the gunner to lay the main gun manually on the center of the target marked GUN on the solution board, with last movement up.

Note. When using the MBD at this distance, make sure the GPS browpad is adjusted to the gunner's face and the eyesight parallax shield (optic cover with hole) is used to reduce eyesight parallax.

6. When the main gun is properly laid for direction, the gunner toggles the GPS reticle to the center of the target marked GPS on the solution board.

7. Store the boresight data by pressing ENTER on the CCP.

Note. The gunner may refer the GAS boresight cross to the gun box as a reference for gun position, as well as the MBD.

8. Check the boresight solution.

a. Grip the palm switches for five seconds and release.

b. Press the BORESIGHT push button, and using a G pattern and manual controls, re-lay the sight on the GPS target, with last movement up. (The MBD aiming dot reticle should be pointing to the original aiming point of the GUN target on the solution board.)

c. Cancel the BORESIGHT mode by pressing the ENTER push button.

9. Enter the fire control inputs from Table 3-3.

a. Enter the basic solution.

Note. The basic solution has all manual and automatic inputs set at neutral values. Do not try the other solutions if the basic solution fails; notify organizational maintenance.

(1) Manually enter the data inputs (except for range) into the CCP.

(2) Index range, squeeze the GPCH, and press the ENTER push button. Hold the GPCH for five seconds.

(3) Using a G pattern and manual controls, lay the GPS aiming dot back on the aiming point, with last movement up.

(4) The crewman on the outside views through the MBD and confirms that the gun is on the correct block.

Notes. The crewman viewing through the MBD should make sure the aiming dot is on the appropriate block;

if it is not, he should note that the MBD was not on the appropriate block.

If the MBD is not on the appropriate block, possible problems are

• Incorrect boresight.

• Not taking the same sight picture with the MBD that was taken during boresighting.

• CCP not zeroed (for example, CCF).

• Incorrect entry of check data into the CCP.

• Problems with the FCS.

(5) Record the position of the MBD aiming point (in relation to the target block) on the Sample M1 AAC Data Sheet for Checks 4 and 5 on page 3-10.

Note. Repeat steps 9a(1) through (5) for each of the remaining solutions (cant, crosswind, and lead).

b. Enter the cant solution. (If it fails, the cant value is incorrectly set or the computer is not processing the cant function.)

c. Enter the crosswind solution. (If it fails, the crosswind value is incorrectly set or the computer is not processing the crosswind function.)

d. Enter the lead solution. (If it fails, the lead value is incorrectly set or the computer is not processing the lead function.)

10. After completing check 4 (all faults have been corrected), proceed to check 5.

Table 3-3. M1 Ballistic Computer Inputs for Check 4.

Ammo Indexed:

AMMO SUBDES:

HEAT 1 CCF

Elevation Deflection

(U) 0.6 (R) 0.0

Wind 0.0 0.0 45.0 0.0

Cant 0.0 10.0 0.0 0.0

Lead 0.0 0.0 0.0 5.0

Ammo Temp 69.8 69.8 69.8 69.8

Air Pressure 29.92 29.92 29.92 29.92

Air Temp 59 59 59 59

*Tube Wear 0 0 0 0

Range 1,200 2,000 2,000 2,000

Solution From

Board Basic Cant Crosswind Lead

*Record the original tube-wear value before changing it. The original value should be reentered in the computer after check 5 has been completed.

Figure 3-1. Abrams Combined Solution Board.

(continued on next page)

Figure 3-1. (continued from previous page.)