Features orwaud rst FORWARD AIRSTAIR ” ‘An optional forward airstar provides terminal self-sufficiency without sacrificing passenger space. Miscellaneous 214Forward Airstair Doo"Opened Forward Airstair A self-contained forward airstair is. available as a standard option on the 737 airplane. Itis installed behind an inward-opening plug door located below the main entry door. The airstair can be electromechanically extended or retracted by either the normal ac 21-2 land de motor system or by the standby de system from either inside or outside the airplane. When operating the normal extend system, the standby de stair motor ‘operates in conjunction with the ac motor during a portion of extension to provide faster operation. The airstair assembly is an easily removable package installed through the airstair door opening, Forward Airstair Extending and Unfolding The carrlage contains the actuation mechanism and electrical sequence switches. The stair consists of two sections, as well as folding handrails and illuminated treads, When extended, the stair unit rests firmly on the ground and self-adjusts to changes in height from the ground to the aircraft door opening. After the stair is extended, telescoping handrail sections are extended manually into the entry doorway for passenger safety. For normal operation, electrical switches prevent retraction until these handrails are disconnected and stowed.Operation of the stair from inside the airplane is accomplished, in either the normal or backup. standby mode, using switches located on the control panel near the upper forward corner of the forward entry door. The main entry door must be open before electrical power is available to operate the airstair from inside the airplane, With the switch in the "EXTEND” Position, the airstair door is first opened, followed by extension of the stairs. When the stairs reach {ull extension, the electrical power is automatically shut off to the motors and the tread lights are turned on. Operation from outside the airplane is accomplished using the control lever located near the lower aft corner of the airstair door. The forward entry door may be either open or closed when extending the stairs from outside the airplane. Forward Airstair Fully Extended ‘As a backup to the “NORMAL” mode of operation, airstair extension and retraction are accomplished using the “STANDBY” mode. In the “STANDBY” mode, independent dc electrical motors operate the airstair door and the airstair. If 115V ‘ac power is available, the source of dc power is from the transformer! rectifier unit. If 115V ac power is not available, 28V de power is obtained from the aircratt battery. Miscellaneous During ground servicing or maintenance, the main entry door can be closed with the airstair extended, provided the telescoping handrail extensions are stowed. The forward entry door may also be used with passenger jelways or Portable stairs without extending the airstair. 21-3FWD AIRSTAIR eats Airstair read _ Nights switeh ji “© (ore) OPERATING AuTo ane Norma! mode AIRSTAIR extendlretract RETRACT RETRACT ‘switch ‘The following controls are on the forward airstair interior contro! panel located above the forward entry door, AIRSTAIR TREAD LIGHTS ‘SWITCH IN"—turns on the forward airstair tread lights. + “OFF"—Tumns off the forward airstair tread lights. + “AUTO"—The airstair tread lights are automatically turned ‘on when the forward airstairs are fully extended, and turned off when retracted, STAIR OPERATING LIGHT Illuminated amber when airstair door is open and while stairs are extending or retracting, or when’ airstairs are retracted and airstair door is open. 21-4 Stair operating light (amber) aren exTEND NORMAL STANDBY Forward Airstair—Interior Contro! Panel NORMAL MODE EXTEND/RETRACT SWITCH Momentary switch (must be held until stairs are fully extended or retracted). ‘+ "EXTEND"—The normal and standby de stair door motors ‘operate to open the stair door The normal ac and the standby de motors extend the stairs. The switch is deactivated if the forward entry door is closed + RETRACT" —The normal ac motor operates to retract the stairs. The normal de stair door motor operates to close the stair door. The switch is deactivated if the handrails are not stowed. Standby mode ‘oxtondretract ‘switch STANDBY MODE EXTEND/RETRACT SWITCH Momentary switch (must be held until stairs are fully extended or retracted), + “EXTEND"—The standby de stair door motor opens the stair door and the standby de stair motor extends the stairs. The switch is energized by opening the forward entry door. + "RETRACT"—The standby de stair motor retracts the stairs and the standby de stair door motor closes the door. Caution must be exercised as the retract switch can be activated in the standby mode with the handrails extended.The following forward airstair controls are located on the exterior of the airplane below and aft of the forward entry door. HANDLE RELEASE BUTTON "PUSH"—Releases control handle from flush position, CONTROL HANDLE Control handle spring loaded to center "OFF" position, + "EXTEND" (Mode select switch in "NORMAL")—The normal and standby de stair door ‘motors open the stair door. The normal ac and the standby do stair motors extend the stairs (forward entry door may be either open or closed), butlon Forward Airstair— Exterior Controls ‘* "RETRACT" (Mode select switch in "NORMAL")—The normal ac stair motor operates to retract the stairs. The normal de stair door motor closes the stair door, NORMAL/STANDBY MODE SELECT SWITCH Momentary position in "STANDBY." * "NORMAL" (Switch spring loaded to "NORMAL" position)—When control handle Is rotated to "EXTEND" or “RETRACT,” stairs operate from normal system. Normalistandoy mode select ‘switch Control handle ia released position Handle release STANDBY" (Switch held in position) —When control handle is rotated to "EXTEND” or "RETRACT," stairs operate from de standby system. It the airstair handrails are extended the airstair retract switch is deactivated in the "NORMAL” mode, but can be activated in the standby mode. 21-5Att galley service oor ‘Aft cargo Emergency exit sore hatch (ght side) Fwd galley service d00r Emergency exit hatch Fwd entry door (Additional Fwd cargo wd airstair door emergency exit ‘compartment fontonad hatch, each side sone ‘on 737-400) Fwd Electronic ‘equipment ‘access door Exterior Door Locations Exterior Doors Plug-type exterior entry and access doors include the forward and aft entry doors (left side), forward and aft galley service doors (ight side), forward and att lower cargo ‘compartment doors (ight side), the forward airstair door (i installed), the lower nose compartment and the electronic equipment access door aft of the nose landing gear. ‘These doors operate manually except for the forward airstair door. ‘Amber lights on the overhead panel in the flight deck for each of these doors advise the crew when any one is open or not completely latched. A passenger cabin emergency exit haich is provided over Both the left and right wings (wo over each wing on the 737-400.)Miscellaneous Airstair door (installed) Forward entry \\ Forward cargo door compartment door Forward galley service doot \ \ [Att ontry door Att galley Lower nose. ‘At cargo. ‘compartment and ‘compartment electronic door equipment access doors Advisory Lights on the Overhead Panel Entry Door Mechanism