(c)
Leave handrail extensions in stowed position.
(23)
Move FORWARD AIRSTAIR TREAD LIGHTS switch on attendant's forward auxiliary panel to OFF position.
(a)
Check that all tread lights (22 places) are extinguished.
(b)
Return FORWARD AIRSTAIR TREAD LIGHTS switch to AUTO position and observe that all tread lights are illuminated.
(24)
Retract airstair fully by actuating NORMAL switch on interior control panel to RETRACT position.
(a) Check that STAIRS OPERATING light on interior control panel is illuminated during airstair and door retraction cycle and is extinguished when airstair door is fully closed.
(25)
With forward entry door open, extend airstair fully by actuating STANDBY switch on interior control panel to EXTEND position.
(a)
Check that STAIRS OPERATING light on interior control panel is illuminated during door and airstair extension cycle and is extinguished when airstair is fully extended.
(b)
Leave handrail extensions in stowed position.
(26)
Retract airstair fully by actuating STANDBY switch on interior control panel to RETRACT position.
(a) Check that STAIRS OPERATING light on interior control panel is illuminated during airstair and door retraction cycle and is extinguished when airstair door is fully closed.
(27)
With forward entry door open, actuate NORMAL switch on interior control panel to EXTEND position.
(a)
While airstair is operating and, just prior to full extension, move NORMAL switch to center position.
(b)
Check that airstair will stop and remain in a cantilevered position.
(28)
Move FORWARD AIRSTAIR TREAD LIGHTS switch on attendant's forward auxiliary panel to ON position.
(a) Check that all tread lights (22 places) on airstair are illuminated.
(29)
Return FORWARD AIRSTAIR TREAD LIGHTS switch to AUTO position and observe that all tread lights are now extinguished.
(30)
Retract airstair by actuating NORMAL switch to RETRACT position.
(31)
With forward entry door open, actuate STANDBY switch on interior control panel to EXTEND position.
(a)
While airstair is operating and, just prior to full extension, move STANDBY switch to center position.
(b)
Check that airstair will stop and remain in a cantilevered position.
(32)
Retract airstair and close airstair door fully by actuating STANDBY switch to RETRACT position and close forward entry door.
(33)
With forward entry door closed, actuate NORMAL switch at interior control panel to EXTEND position for approximately five seconds.
(a) During this period, the airstair door motor should not operate.
(34)
Repeat step (33) using STANDBY switch on interior control panel.
(35)
Remove electrical power from airplane.
(36)
Fully extend airstair by moving exterior control handle to STANDBY EXTEND position.
NOTE: Tread lights will not illuminate.
(37)
Fully retract airstair and close airstair door by moving exterior control handle to STANDBY RETRACT position.
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FORWARD AIRSTAIR - DESCRIPTION AND OPERATION
EFFECTIVITY
Standard Passenger Airplanes
1. General
A. The forward airstair installation consists of forward and aft rail assemblies, carriage, stair, handrails, handrail extensions, actuation system, and electrical system (Fig. 1).
2. Rail Assemblies
A. The forward and aft rail assemblies are attached to the airplane structure to provide a set of rigid parallel rails on which the airstair carriage travels during the extension and retraction cycles.
3. Carriage
A. The carriage is mounted on the rail assemblies and supports the stair. It also contains the stair drive mechanism for extending and retracting the stair. The carriage consists of side beams connected by a torque box, shear panels, cross braces, and the carriage step (Fig. 1).
B. The carriage is supported by rollers that are mounted on the outside surface of each side beam at the upper right end of the beam (two rollers on each beam). The pinions that drive the carriage along the rail assemblies protrude beyond the outside surface of the beams and are located adjacent to the rollers.
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