Originally Posted by
john_tullamarine
Later there was a mod to permit retraction.
Closing the main gear door requires hydraulics. The Alt extension mechanically releases the main gear door and the gear which was supported by the door free falls and, hopefully, locks.
Why would alternate extension be used if there was hydraulic pressure available to close the door? A long time since I worked on MD-95 or MD-80 so may be forgetting some details.