ExpressJet Improves Maintenance Facility Efficiency with Vertical Lift Modules

VLMs help reduce floor space required for parts storage and improve part retrieval efficiency

VLMs replace bays of shelving
VLMs replace bays of shelving

Hatfield, Pa.—Feb. 28, 2012—At the ExpressJet Airlines Inc. maintenance facility in Newark Liberty International Airport, a new approach to storing service parts has reduced the amount of space required by traditional shelving, and has helped that operation more efficiently handle slow and medium-moving inventory items.

The facility stores a wide range of parts for aircraft service and maintenance-from small fasteners to large air valves. In order to reduce the amount of floor space required for parts storage and to improve part retrieval efficiency, ExpressJet installed two Vertical Lift Modules (VLMs) to replace bays of shelving.

The VLMs, which are now being sold and serviced as the Viper VLM by Sapient Automation, a provider of automated storage and retrieval systems, were originally purchased and serviced by another organization (under the Power Column II brand). Sapient Automation now has the exclusive rights to sell and provide factory replacement parts and service to this VLM in North America.

The Viper VLM is an enclosed high-density storage and retrieval system that consists of two columns of trays in the front and in the back with a robotic extractor that delivers trays to an ergonomically positioned work counter. Vertical lift modules take advantage of unused overhead space to reduce the amount of floor space required by traditional shelving by up to 85 percent.

Efficient inventory management

In addition to the space-savings benefit, the installation of the VLMs gave management the flexibility to retrieve parts inventory in a more efficient manner.

"We placed our slow-to-medium movers—those parts that we don't retrieve on a regular basis for service and maintenance jobs—in the VLMs and kept our fast-moving items, along with just a few bulk items, on the remaining shelving," said Gloria Hume, Materials Services Supervisor.

With slow and medium movers, retrieval velocity is low but the number of stock keeping units (SKUs) is large. This strategy helps dramatically reduce floor space by maximizing otherwise wasted vertical height and helps eliminate the walking and searching otherwise required when using shelving.

By analyzing Express Jet's inventory by size, velocity and value it is easy to create classes of items and determine the proper slow-to-medium moving items to store in the VLM. It is easy to then configure the VLM's trays and storage strategy to accommodate every inventory class.

“There are approximately 3,000 SKUs in the two VLMs—2,000 parts in one and 1,000 in the other,” said Hume. “They are divided that way so that the larger, heavier parts are located in one unit and the smaller parts in the other to optimize the storage efficiency of the units.”

A Viper VLM comes with the ability to designate specific storage locations or to use the unit's optimization program. To optimize the storage cube of the VLMs, a dynamic tray height sensor automatically scans and optimizes storage density every time a tray is stored in the unit. The VLM's control automatically directs every tray to the least amount of vertical space possible necessary for storage.

“The enclosed design of the VLMs also helps maintain the cleanliness of the parts more effectively than using the shelving, since these parts are slow to medium movers and stayed on the shelves longer than faster moving parts,” Hume added. “Next to space savings, cleanliness has been the biggest benefit of the system for us.”

The modular design of the VLM also proved beneficial to the organization when it moved its operations, including all of its inventory and the VLMs, from one storage facility to another between 2004 and 2005. The VLM can be disassembled and reassembled and made shorter or taller. This makes moves such as this less costly and more efficient. Likewise, the VLMs can change to reflect an organization's current business requirements.

Parts retrieval

At the ExpressJet maintenance facility, all parts stored in the VLMs are labeled with a location number. To retrieve parts, operators key in the location number using the touch screen controls on each unit. The VLM automatically delivers the tray containing the part to the work counter.

“Inventory levels are monitored by the software program,” said Hume. “We have established minimum and maximum levels and we keep track of the levels through management reports.”

Vertical Lift Modules have helped ExpressJet reduce the amount of space required for storing a wide range of maintenance parts with a varied range of sizes, weights and shapes while providing a more efficient way to handle slow and medium moving parts retrieval.