C. A thrust lever actuated takeoff warning switch is installed on the engine No. 1 and 2 thrust lever switch mechanisms located in the ceiling of the electronic equipment compartment (Fig. 1). When either thrust lever is advanced to a takeoff power setting, a cam in a mechanism actuates the corresponding takeoff warning switch. The takeoff warning system is armed when either thrust lever is advanced to a position which actuates the corresponding takeoff warning switch and provides an EPR of 1.4 or greater. The EPR logic/sensing circuits are in the engine accessory unit.
D. Flap Takeoff Warning Switch - The flap takeoff warning switch is installed on the flap control valve follow-up mechanism (Fig. 1). It is actuated by a cam on the control valve follow-up drum shaft when the trailing edge flaps are outside the takeoff range. Contacts on the switch are also part of the landing gear warning system.
E. Stabilizer Takeoff Warning Switches - The two stabilizer takeoff warning switches are installed in the stabilizer actuator compartment and actuated by cams on the stabilizer center section leading edge structure (Fig. 1). The upper switch actuates when the stabilizer is outside the takeoff (green band) range in the leading edge up (APL NOSE DN) direction. The lower switch actuates when the stabilizer is outside the takeoff (green band) range in the leading edge down (APL NOSE UP) direction.
F. Speed Brake Takeoff Warning Switch - The speed brake takeoff warning switch is installed on the upper forward portion of the control stand. The switch is actuated when the speed brake control lever is lifted out of the down and locked detent.
5. Cabin Altitude Warning System
A. The cabin altitude warning system provides an audible signal when cabin pressure approaches an altitude detrimental to passenger comfort.
B. The cabin altitude warning system consists of a pressure switch, a cutout switch and a cutout relay. The system provides an intermittent sound signal when cabin altitude exceeds approximately 10,000 feet. The cutout switch and relay are installed in the cabin altimeter and rate of climb module on the P5 overhead panel.
C. The pressure switch is an aneroid type switch. When pressure sensed in the cabin port reaches approximately 10,000 feet, the difference in pressure inside and outside the bellows closes the switch contacts and provides a ground for the aural warning devices box. The switch is installed on the underside of the control cabin floor ahead of the control stand.
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