The U.S. Air Force is updating plans for its combat search and rescue (CSAR) needs that will determine whether current fleet-sizing assumptions for the Sikorsky HH-60G Pave Hawk and eventual replacement Combat Rescue Helicopter (CRH) still reflect operational requirements.

The baseline demand for the service has been for 148 rotorcraft, although available funding only allows for 112. An update of the combat rescue helicopter plan, due for completion in the fall, could alter that figure as the service assesses strategic assumptions, says Col. Bernie Willi, personnel recovery lead for Air Combat Command at Langley AFB, Va. The forthcoming plan will take into account a shift in military strategy to focus less on operations in Europe and more on the vast Pacific region.

Even as the USAF looks to select a new helicopter through the CRH program, with a planned initial operational capability in 2018, officials and industry have been in dialogue over the draft request for proposal (RFP) for CRH, issued in March, with the service recently announcing the final RFP will not be out until late June. The Air Force has been moving to assure the solicitation does not narrow the field to just another version of the Sikorsky UH-60M, but will allow room for competition as requested by Congress.

This replacement effort has been one of the victims of the Air Force's procurement missteps, with a previous effort to buy Boeing CH-47s for the combat search and rescue role canceled in 2009, and numerous false starts since then.

But the service can ill afford additional delays to the modernization program. Three HH-60Gs have reached more than 10,000 flight hours, with eight more having around 9,000. Those are mainly used in the U.S. to preserve less-used airframes for overseas use. One challenge is that the Air Force lacks a service-life estimate for the aircraft, adding to uncertainty about the fleet's future, Willi says.

Structural and avionics maintenance problems are also on the rise. Since 2008, the maintenance-man-hour-per-flight-hour demand on the Pave Hawk fleet has increased 30%, says Willi, in part reflecting the high operational pace. Although the drawdown of military activity in Iraq and Afghanistan has slightly moderated the pace of operations, it has not dropped as fast as some believe, Willi notes.

Structural fatigue is believed to have caused the retractable refueling probe on one HH-60G to fall off in flight about a year ago, another alarming issue for the fleet. The root cause analysis for that mishap is still ongoing.

USAF's problems are compounded by the fact that the UH-60L, on which the Pave Hawk is based, is being upgraded by the U.S. Army, so the Air Force is struggling to figure out how to preserve its access to spare parts.

The Air Force currently has a fleet of 98 HH-60Gs based on the L-model Black Hawk. The Pentagon also has provided funding for five UH-60Ms to be converted into CSAR helicopters to fill the gap—three have already been delivered by Sikorsky. A total of 25 of these “operational loss replacement” aircraft are planned. But the Air Force is considering trading those with the Army for L-models, because the M-model and L-model are very different and there is currently no design process to turn a UH-60M into an HH-60G. Details of that transaction are still being worked out. Meanwhile, the delivered aircraft remain unused.

Even with the CRH program on the horizon, the HH-60G is still seeing incremental upgrades. For instance, the U.S. Navy has loaned 10 missile warning systems with hostile fire indicator capability to the Air Force for use on the HH-60Gs. Those are now operational in Afghanistan.