The AH-64D Longbow Apache GPTT is one of the Apache training devices. The purpose of the GPTT is to develop the maintenance skills of Longbow Apache Maintainers. The primary training elements of the GPTT are the Hardware Training Device (HTD) and the Virtual Maintenance Trainer (VMT). The other elements of the GPTT are the seven safety fence sections, which restrict access to the Ammunition Handling System (AHS); and the Area Weapon System (AWS); the Hydraulic Power Unit (HPU), which supply the HTD with 3000 psi of hydraulics; and the Main Power Control, which supplies the GPTT with power from the facility. The HTD provides realistic training in ground maintenance operations and procedures.