Rolls-Royce has completed flight testing for their Series 3.5 T56 engine modification program, a major step for the new engines the company believes could expand the life of the U.S. Air Force's C-130 fleet through 2040.
The results have been promising, the company said, with an almost 10 percent increase in fuel efficiency over the older Series 3 engines that power the Air Force’s C-130s.
Rather than developing a brand new engine, the Series 3.5 upgrades are “plug and play,” said Bob Settle, Rolls-Royce’s vice president for USAF programs, in a company statement. Parts from newer engines will be retrofitted into the Series 3 engine casing, replacing aging and inefficient components. These include compressor seals from Rolls’ Series 4 engine and uncooled turbine blades from the Rolls AE-1107C design.
Once the engineers have installed the new parts, pre-flight tests are run as normal and the engine is reinstalled. Because the upgrade occurs within the engine, there are no costly changes required to the C-130’s cockpit or airframe, providing a cheaper alternative to a full engine replacement. The upgrade also wipes out the labor cost of maintenance, such as cleaning and repairs, on the old Series 3 parts.
An Air Force business case analysis concluded that improving the T56 engines on the C-130 fleet could save $2 billion in fuel and upkeep costs over the lifetime of the engine. Those savings come in part from a 9.7 percent improvement on fuel consumption over the current engines, at a time when the Air Force has stressed being smart about the fuel supply. The 3.5 engines also run cooler, allowing more time on wing before needing costly maintenance.
Settle said the company is “working on” cost estimates for the engine upgrades, but he believes that savings from extended engine life will overtake the cost of each kit.
Aside from the C-130s, Rolls hopes to expand the Series 3.5 modifications to other planes, including the Navy's P-3.