N. Install access door and seal.
O. Provide system A hydraulic power (Ref 27-81-0).
O1. Retract leading edge flaps and slats by placing flap lever in FLAP UP detent.
P. Place flap control lever in 1-unit detent. Check that amber TRANSIT lights on leading edge annunciator panel on the aft overhead panel come on as slats extend and go off when extended. Check that green EXT lights come on when slats are extended.
Q. Place flap control lever in FLAP UP detent. Check that TRANSIT annunciator lights come on as slats retract. Check that all lights on annunciator panel go off when slats are fully retracted.
R. Remove system A hydraulic power (Ref 27-81-0).
27-81-111 Oct 20/87 Page 408
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
LEADING EDGE FLAP AND SLAT POSITION INDICATING SYSTEM -DESCRIPTION AND OPERATION
1. General
A. A position indicating system provides visible indication of the position of the leading edge flaps and slats. (See figure 1.) The system includes system indicator lights on the center instrument panel and individual flap and slat indicator lights on an annunciator panel in the aft overhead panel. This provides indication of normal operation on the center panel and enables the pilots to easily determine which flap or slat is not in the proper position when normal indications do not appear. The indicating system consists of reed switches in the slat actuator, proximity sensors, a leading edge flap and slat position indication module, the pilots' indicator light panel, and the annunciator panel.
2. Proximity Sensors
A. Proximity sensors indicate the position of each leading edge flap and slat. (See figure 1.) Each proximity sensor consists of an induction coil and an actuating bar. Each sensor coil is connected electrically to a transistorized switch card (switch) in the leading edge flap and slat position indication module (module). Each sensor coil is mounted on fixed leading edge structure and each actuating bar moves with a flap or slat. When the system is on, a constant current flow exists through each coil to ground. When an actuating bar is brought into position adjacent to the coil, the current flow is increased and a switch in the module is triggered. Two sensor coils are mounted adjacent to the inboard hinges of the leading edge flaps. The actuation bars are mounted on the inboard hinges. One sensor coil is installed adjacent to each leading edge slat inboard auxiliary track and an actuation bar is mounted on each inboard auxiliary track arm. At slats 1 through 6, a sensor coil and actuation bar is mounted at the middle auxiliary track.
3. Leading Edge Flap and Slat Position Indication Module
A. A leading edge flap and slat position indication module controls the operation of the position indicating system. (See figure 2.) The module consists primarily of plug-in switch and logic cards in the LE DEVICES annunciator panel light circuits, additional transistor circuits that work with the plug-in cards to control the pilots' indicating lights, and interconnecting circuitry. The module receives 28-volt ac power from the 28-volt ac transfer bus and 28-volt dc power from the No. 1 dc bus; it provides a reduced dc voltage to the proximity sensor coils. The module is located on equipment rack shelf E3-2.
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Leading Edge Flap and Slat Position Indicating System Component Location 500
27-88-0 Figure 1 (Sheet 1) Feb 15/68
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
531 Leading Edge Flap and Slat Position Indicating System Component Location
May 15/71 Figure 1 (Sheet 2) 27-88-0
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
Leading Edge Flap and Slat Position Indicating System Component Location 500
27-88-0 Figure 1 (Sheet 3) Nov 15/67
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BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.
B. AIRPLANES WITH POSITION INDICATION MODULE THAT HAS THE BUILT-IN-TEST EQUIPMENT (BITE); The BITE is provided to aid in fault isolation, to test the proximity sensors, and to test the system configuration (Fig. 3).
4 Leading Edge Flap and Slat Position Indicator
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