Rolls-Royce has proven that an improved AE 1107C engine that powers all Bell Boeing V-22 tiltrotor aircraft is capable of performing to the “high and hot” envelope that the US military needs for missions in harsh terrain like the mountains of Afghanistan.

The enhanced capability is part of a series of upgrades that will boost engine power by at least 17%, improve time-on-wing, and reduce maintenance costs over the life of the aircraft, the company says. Flight tests have validated that a Block 3 turbine upgrade for the AE 1107C can propel an Osprey to 6,000ft at 35˚C (95˚F).

“It’s kind of a sweet spot that the [US] army in particular is focused on,” says Tom Hartmann, senior vice president for customer business at R-R. “This really came up from AFSOC [Air Force Special Operations Command] and SOCOM [US Special Operations Command] guys saying there are particular missions we’d like to do that if we could carry the full complement of equipment up to 6k/95, that would be swell.”

To achieve improved performance, R-R designed an upgrade to the turbine section of the AE 1107C by running the original turbine design through modern engineering tools. Engineers arrived at a more efficient set of components, including blades and other internal turbine parts, Hartmann says.

The new components are made from sturdier materials that are “more efficient at the extraction of power from the air stream” through the engine, he says. Development of the improved turbine took about seven months, and also tripled a V-22’s time on wing compared to 2007.

“The 1107 is a very specialised piece of equipment and we’ve been working with the customer for a long time to improve the capability,” says Paul Craig, president of defence services for R-R.

The manufacturer is making Block 3 engine retrofits during routine maintenance under a MissionCare contract with the US government. It has invested $90 million in AE 1107C improvements since 2009, which have reduced maintenance cost per flight hour by 34%.

The Block 3 turbine kit became standard on all V-22 engines in 2012. Recent testing at Kirtland AFB in New Mexico validated that the upgraded engine already could perform at altitudes of 6,000ft on a 35˚C day with minor tweaks to the fuel valve and software.

“We are overhauling engines on a daily basis and as the engines need those components, we replace them with the modern version,” Craig says.

The US military has put out a call for drop-in replacement engines to power all variants of the V-22. R-R did not anticipate the announcement, but it intends to respond with the improved AE 1107C.

The request for information calls for data on engines with a power rating of no less than 6,100shp (4,550kW) at 15,000rpm. It should operate at up to 25,000ft at up to 54˚C and fit into the aircraft’s existing nacelles.

In ground tests, the improved AE 1107C has produced more than 8,800shp.