USAF unit restores test stand for F-22 and B-2 accessory drives

A squadron at Hill Air Force Base in Utah has put the only test stand for Aircraft Mounted Accessory Drives back into service. The equipment is used to check and repair the drives, which the U.S. Air Force depends on to keep its F-22 Raptor and B-2 Spirit fleets flying.

According to a 75th Air Base Wing release dated Sept. 18, the 530th Commodities Maintenance Squadron, the service's depot-level repair organisation for aircraft secondary power systems, did the work in-house after the stand failed.

The job was not straightforward. The team worked around constrained supply chains, verified a replacement motor fitted to the stand, found further faults and brought the technical documentation up to date. Over a year, the unit logged 563 hours of overtime, the release said. That work returned several aircraft to mission-capable status and averted what the release described as a potential sustainment gap for two frontline stealth types.

The squadron also repaired and rebuilt another critical piece of equipment, the release stated.

An accessory drive is a gearbox bolted to the outside of a gas turbine engine, usually on the upper or lower casing. It powers a range of engine and aircraft systems, including starters, hydraulic pumps, fuel and oil pumps, generators and compressors. Test stands are support equipment rather than aircraft systems, but without them the components they are built to validate cannot be checked or repaired.