Forward Airstair Drain Pan Access  500 
52-61-221Page 404   Figure 402 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Sep 20/81 

B.  Open airstair circuit breakers on panel P6. Disconnect airstair electrical connector (3) (Fig. 401).
C.  Disengage carriage drive pinions by moving carriage pinion disconnect lever (2) to unlocked position.
D.  Manually move carriage outboard to fully extended position and move carriage pinion disconnect lever to locked position.
E.  Engage carriage drive pinions by moving carriage pinion disconnect lever to locked position.
F.  Secure carriage to rail by inserting No. 2 rig pin through extend index hole (1) in aft rail end into index slot in aft beam of carriage.
G.  Secure ladders to carriage by inserting No. 1 rig pin through index hole (5) in ladder truck.
3.  Remove Forward Airstair Angle Gearbox
A.  Disconnect ball screw drive shaft and ball screw from angle gearbox by removing cotter pins and pins from splined couplings.
B.  Remove four bolts securing gearbox to carriage and remove gearbox.
4.  Install Forward Airstair Angle Gearbox
CAUTION:  ENSURE ANGLE GEARBOX IS CORRECT ONE FOR THE POSITION. A CLOCKWISE INPUT ROTATION INTO A FORWARD ANGLE GEARBOX GIVES A COUNTERCLOCKWISE OUTPUT, WHILE SUCH AN INPUT INTO AN AFT ONE RESULTS IN A CLOCKWISE OUTPUT.
A.  Place angle gearbox in position and install 4 bolts.
NOTE: Apply a film of grease to splines, bores, shanks and threads of parts before assy.
B.  Connect couplings and secure with pins and cotter pins.
5.  Restore Airplane to Normal
A.  Disengage carriage drive pinions by moving carriage pinion disconnect lever (2) to unlocked position.
B.  Manually move carriage inboard to fully retracted position and insert No. 2 rig pin through retract index slot (4) and into retract index hole in aft carriage beam.
C.  Using No. 1 rig pin check that it can be inserted through upper ladder index slot (5). Remove No. 1 rig pin.
D.  Engage carriage drive pinions by moving carriage pinion disconnect lever to locked position and install safety wire on lever.
E.  Remove No. 2 rig pin and connect electrical connector (3) to receptacle.
F.  If required, install drain pan through airstair door opening inside of fuselage (Fig. 402).
G.  Close forward airstair system circuit breakers on circuit breaker panel P6.
H.  Extend airstair and install drain pan attachment fasteners if removed. Install drain pan access hatch and connect drain hose.
500 
Feb 20/92  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  52-61-221 Page 405 

FORWARD AIRSTAIR DOOR - DESCRIPTION AND OPERATION
EFFECTIVITY
Standard Passenger Airplanes
1.  General
A.  The forward airstair door is a plug type door, which closes the cutout in the lower fuselage directly below the forward entry door. The door opens inward by moving inboard and down along door tracks to a position below the airstair. The door is opened by a jackscrew driven by an electrically operated actuator. The door installation consists of a door, door tracks, a carriage, carriage tracks, an actuator, door lock mechanism, and an electrical system (Fig. 1)
 .
2.  Airstair Door Assembly
A.  The door is an aluminum structure with an inner and outer skin and internal webs and stiffeners. A continuous seal around the periphery of the door provides a pressure seal to prevent loss of cabin pressure during flight. The door is equipped with adjustable stops that transmit pressure loads to the fuselage structure and allow adjustment of the door for proper fit. The door is also equipped with guide pins and rollers to provide for alignment of the door with the door cutout as the door closes.
3.  Door Tracks
A.  Door tracks provide a guide for the rollers on the door guide fittings during opening and closing operations and support the upper part of the door.
4.  Carriage
A.  The carriage is connected to the lower part of the door and to the actuator jackscrew. It is equipped with rollers that travel in the carriage tracks to guide the carriage during opening and closing operations.
5.  Carriage Tracks
A.  The carriage tracks provide a guide for the rollers on the carriage as the carriage is driven by the actuator jackscrew during opening and closing operations. The tracks also support the carriage and door when in the open position.
5C8
Feb 20/84 52-61-500 Page 1
BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.

Forward Airstair Door  525 
52-61-500 Page 2  Figure 1 (Sheet 1) BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  Aug 15/72 
　
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