Built by United Technology’s Sikorsky Aircraft, the UH-60A Black Hawk helicopter first entered into service with the U.S. Army in 1979. Power for the four-blade main and tail rotors is provided by two GE T700 turboshaft engines. Approximately 3,000 are in use around the world; primarily for military tactical support, troop transport, electronic warfare, combat support, and aeromedical evacuation. AMT spent time with the soldier technicians of the Army Aviation Support Facility (AASF) located at Downtown St. Paul Airport in Minnesota.
Keith Shelstad, maintenance test pilot (MTP) for the St. Paul AASF, explains, “This AASF is responsible for the maintenance on 10 Black Hawks operated by the Minnesota Army National Guard Aviation’s 34th Combat Aviation Brigade (CAB). The maintenance organization consists of approximately 40 people.”
Shelstad went on to explain most are technicians assigned to flight line or phase maintenance, and a variety of support shop functions such as sheetmetal repair, engine repair, and nondestructive inspection tasks. There are four technical inspectors (TIs), one production controller, and one person assigned to manage the Unit Level Logistics System Aviation (ULLSA) which is the computer system that houses the technical data including the helicopter logbooks.
The group has three maintenance and one inspection supervisors, and two MTPs responsible for maintenance-related helicopter run-ups and the after maintenance test flights. Maintenance management is the responsibility of the maintenance officer, whose role can be compared to a civilian director of maintenance having responsibility for the maintenance, budget, staff, and 10 aircraft.
The Army’s maintenance program
Shelstad explains, “The Army program consists of three maintenance levels: Unit level, intermediate level, and depot level maintenance. Unit and Intermediate Level is what we are authorized to accomplish at the AASF.” The preventative maintenance daily (PMD) checks take place daily when the helicopter flies or every seven days if the helicopter is not flying.
The preventative maintenance services (PMS) checks are required every 40 flight hours; they take 15 to 20 man-hours and can generally be accomplished in one day with two technicians. There’s a host of other hourly and calendar driven service and inspections tasks, such as gearbox oil samples, battery checks, 30-day engine wash programs, 90-day corrosions checks, and the 120-hour inspection which takes two to three days and includes critical vibration checks of the engine high-speed shafts, tail rotor, and oil cooler fan.
Unit level also includes the phase maintenance inspection (PMI) which is a large check accomplished every 360 flight hours. Alternating between PMI 1 and PMI 2 with some common tasks, the PMI 1 is primarily focused on the cabin and tail section, while PMI 2 has a focus on the systems and components which are primarily located above the cabin, the main rotor, and tailboom.
Limited depot level maintenance is accomplished by Aviation Classification Repair Depot (AVCRAD). For the Minnesota AASF, Springfield, MO, is the AVCRAD location and covers a 14-state area. When the AASF requires a higher-level of maintenance than it is authorized for, either the helicopter is taken to AVCRAD or a team is sent to accomplish or assist. Sikorsky and GE technical representatives are located at the AVCRAD.
Depot level maintenance is the extensive maintenance or modifications. As an example, several of the Black Hawks maintained by the St. Paul AASF are UH-60 L models, which are upgrades from A models. These upgrades were done at the depot located at Corpus Christi, TX.
Black Hawk maintenance at the AASF
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