section A-A, so that ballnut and snubber will not make contact. Position jackscrew ballnut electrically using control handle.

(c)  
Check the following using 28-volt dc test lights connected to terminals X1 of speedup relay and slow-down relay. 1) Check that from start of airstair extension until just before ladder unfolding, the

speedup relay test light is illuminated while the slow-down test light is
extinguished.
2)  Check that just prior to ladder unfolding the speedup test light extinguishes and the slow-down test light illuminates and remains so until ladder unfolding is complete.
3)  Check that the total airstair extension cycle time excluding door opening, is 25 +
2.0 seconds.
(2)  
Open forward entry door; extend and latch one handrail extension to support bracket in airplane.

(3)  
Using caution, verify that power has been interrupted to airstair control system by moving exterior control handle momentarily to NORMAL RETRACT position.

(a)  Check that carriage step is erected and against its stops.

(4)  
Stow handrail extension that was extended in step B. (2); extend and latch remaining handrail.

(5)  
Repeat step B.(3).

(6)  
Extend and latch both handrail extensions.

(a)  Check that handrail extensions are latched securely to support brackets.

(7)  
Check that all tread lights (22 places) on airstair are illuminated.

(8)  
Verify that STAIRS OPERATING warning light on interior control panel is not illuminated.

(a)  Use press-to-test light to check that power is available to warning light.

(9)  
Check that AIRSTAIR door warning light on control cabin forward overhead panel is illuminated.

(10)
Unlatch and stow both handrail extensions; check that handrails are secured in their stowed position.

(11)
Close and latch forward entry door.

(12)
Retract airstair and close airstair door by moving exterior control handle to NORMAL RETRACT position.

(a)  
Check that airstair and door operation is smooth and free of binding.

(b)  
Check that lower ladder uplock secures the lower ladder during retraction.

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Nov 01/73 52-61-0 Page 512A/512B BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

(c)  Check that springs in handrail extension support brackets stow and hold brackets in vertical position against airplane partitions.
(13)
Check that AIRSTAIR door warning light on control cabin forward overhead panel is not illuminated.

(14)
Extend airstair fully by moving exterior control handle to STANDBY EXTEND position.

(a)  Check that airstair and door operation is smooth and free of binding.

(15)
Check that all tread lights (22 places) on airstair are illuminated.

(16)
After the airstair is fully extended, verify that STAIRS OPERATING warning light on interior control panel is not illuminated.

(a)  Use press-to-test light to check that power is available to warning light.

(17)
Check that AIRSTAIR door warning light on control cabin forward overhead panel is illuminated.

CAUTION:  NO SAFETY SWITCH IS PROVIDED IN THE STANDBY SYSTEM. ENSURE THAT HANDRAIL EXTENSIONS ARE RETRACTED AND PROPERLY STOWED BEFORE ATTEMPTING RETRACTION.

(18)
Check that handrail extensions are retracted and properly stowed and forward entry door is closed and latched.

(19)
Retract airstair and close airstair door by moving exterior control handle to STANDBY RETRACT position.

(a)  Check that airstair and door operation is smooth and free of binding.

(20)
Check that AIRSTAIR door warning light on forward overhead panel is not illuminated.

(21)
Unlatch and open forward entry door.

(a) Check that AIRSTAIR door warning light on forward overhead panel is illuminated.
WARNING:  WHEN OPERATING AIRSTAIR FROM INTERIOR CONTROL PANEL, FORWARD ENTRY DOOR SHOULD BE OPENED FAR ENOUGH TO ALLOW OPERATOR CLEAR VISIBILITY OF AREA OUTSIDE AIRPLANE TO PREVENT INJURY TO PERSONNEL OR EQUIPMENT DAMAGE.
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(22)
Extend airstair fully by actuating NORMAL switch on interior panel to EXTEND position.

(a)  
Check that carriage and upper ladder extension speed is reduced approximately one-half just prior to rotation of upper ladder and remains reduced throughout ladder rotation.

(b)  
　
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