are made up of the following components: canopy caution light on the cockpit left digital display indicator, master caution light on the left-hand advisory and threat warning indicator panel, and the maintenance code display on the nosewheel well digital display indicator. NORMAL OPERATION Learning Objective: Identify the canopy normal mode of operation to include the manual backup mode. The canopy is operated electrically by the external or internal canopy control switches in the normal control mode. The canopy can also be operated manually in the backup manual control mode if electrical power is not available. NORMAL CONTROL MODE The canopy may be operated with the external canopy control switch. To open the canopy, the switch is held in the OPEN position. The canopy stops automatically when the full open position is reached. To close the canopy, the switch is held in the CLOSE position until the canopy closes, moves full forward, and locks. The canopy stops automatically when the closed and locked position is reached. Motion may be stopped at any point during opening or closing by releasing the switch. The switch returns to the HOLD position when released. To open the canopy internally with weight on the wheels, the internal canopy control switch is set to OPEN and released. The switch is magnetically held in the OPEN position until the canopy raises to full open and stops. The switch then returns to HOLD. Canopy motion may be stopped at any point during canopy opening by manually setting the switch to the HOLD position, which overrides the magnetic holding coil. The internal canopy control switch opening circuit is equipped with a weight-off-wheels relay that de- energizes the magnetic holding coil when the aircraft is in a weight-off-wheels condition. With the holding coil de-energized, the switch must be manually held to the OPEN position when opening the canopy. When the canopy closes, moves full forward, and locks, the No. 4 right canopy latch depresses t h e  c a n o p y  p o s i t i on switch plunger. Simultaneously, the canopy actuator arm rotates overcenter and depresses the canopy locked switch plunger. Depressing both switch plungers causes the master caution light and the canopy display on the left digital display indicator to extinguish, indicating the canopy is fully closed and locked. If both switches are not fully depressed or a failure occurs in either switch, the master caution and canopy caution indicators will remain illuminated. If both switch plungers are not depressed within 15 seconds, the canopy switches disagree and the maintenance code (889) will be displayed on the nosewheel well digital display indicator. Electrical inputs supplied to the canopy actuator are transformed into mechanical motion used to raise and lower the canopy. The actuator is equipped with an up-travel-limit switch, which automatically interrupts power to the actuator when the full open position is reached. With no aircraft generator power or external power applied, a utility battery supplies power for at least five open and close cycles of the canopy. On some F/A-18 aircraft, a logic circuit in the battery and charger unit secures the canopy control power when the battery voltage drops below 19±1 volts. Due to decreased battery capacity at low temperatures, canopy operation using battery power is not recommended when ambient tem- perature is below 0°F. Under these conditions, external electrical power should be used. When external power is not available, the canopy can be operated using the backup manual control mode. To further understand how the opening and closing cycles function, refer to figure 2-9. BACKUP MANUAL CONTROL MODE The backup manual control mode is used to open and close the canopy when utility battery power is low, internal or external electrical power is not available, or a failure has occurred in the canopy actuation control system. The canopy actuator manual drive unit is operated from inside the cockpit by using the internal manual canopy opening handle. The handle is removed from its stowage receptacle and clip, and then it is inserted into the crank socket. The handle is turned 70±1 turns clockwise to close the canopy or counterclockwise to open the canopy. The internal manual canopy opening handle shaft assembly mechanically links the drive unit to the canopy actuator. By operating the drive unit internally or externally, mechanical motion is transferred through the shaft assembly to the canopy actuator. 2-7