Uni-Systems Engineering refurbished two Boeing 777 landing gear elevator pits, which are used during attachment of the main landing gear (MLG) to the aircraft body. The elevator deck lowers the MLG into the pit area and a ‘claw’ reaches out and pulls the gear off the deck into the pit. The empty deck is then raised back up to factory floor level to provide a flush surface for workers and rolling equipment. Before the refurbishment, the deck was moved by four pneumatically powered jack screws, which produced hazardous noise levels and lacked position control required for a flush rolling surface. In addition, the control system was out of date and replacement parts were unavailable.

Uni-Systems Engineering replaced the jack screws’ pneumatic drives with servomotors that fully raise or lower the deck in 6.5 minutes while eliminating any hazardous noise. Each servomotor is equipped with an absolute encoder that provides continuous position data.  The positions reported by the encoders are continuously verified by four vertical laser sensors (one next to each servomotor). Four high-precision laser sensors located on the pit walls just below factory floor ensure the raised deck is positioned to provide a flush rolling surface.

Before the deck is lowered, removable guardrails are installed to protect the factory floor from fall hazards. RFID chips and sensors verify the required guardrails are in place for various equipment configurations before the elevator can be operated.

The new custom Allen Bradley operator interface is a human machine interface (HMI) pendant that can be plugged in for operation from inside the pit or from the factory floor.

Uni-Systems Engineering planned and staged all work to accommodate the active production line, and normal 777 aircraft assembly was unaffected by the refurbishment project.

General Information

Description: Landing gear elevators
Completed: 2019
Location: Everett, Washington
Scope of Work: Design, Supply, Installation