The forward airstair of an airplane can be operated from two locations: the inside control panel located at the forward attendant station and the outside controls located on the plane’s fuselage behind the airstair door.
Both control sets allow for operation in either the NORMAL or STANDBY mode.
The Key Features include:
Automatic Sequencing: All powered operations of the airstair are automatically sequenced by its control circuitry.
Manual Extensions: Handrail extensions for the airstair are operated manually. After extending the airstair, the handrails must be extended and secured manually and should be stowed back before retracting the airstair.
Interior Control Panel: When the airplane is on the ground, this panel becomes active.
There are two main push-button switches’:
RETRACT: Retracts the airstair and closes its door.
EXTEND: Opens the door and extends the airstair.
You need to keep holding the respective button for the operation.
A light will illuminate while the system operates and goes off when the operation completes.
Exterior Controls: A control handle sits flush with the airplane’s fuselage. By using a marked release trigger, you can access the handle. You rotate this handle clockwise to extend and counterclockwise to retract the airstair. Behind this handle, a toggle switch lets you choose between NORMAL and STANDBY operating modes.
Safety Considerations are important for the air stairs including the following:
Ensure the handrails are securely stowed before retracting to avoid damage and the airstair should not operate unless both sides of its ladder firmly touch the ground.
It’s essential not to operate the airstair under specific conditions such as high winds (above 40 knots), when the area near the forward entry door isn’t clear, or after 3 full cycles within 20 minutes.
Maintenance persons have a maintenance switch under the airstair ladder for maintenance purposes, allowing one retraction cycle by bypassing the airstair’s protection circuitry.
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