WASHINGTON — The Rolls-Royce Series 3.5 engine upgrade completed its first successful live flight aboard a US government aircraft, a milestone the company hopes will convince customers to jump onboard the upgrade program.

The engine upgrade is targeting the world-wide fleet of C-130H and P-3 models, which use the T56 engine developed by Rolls.

The flight occurred June 3 aboard a National Oceanic and Atmospheric Administration (NOAA) P-3 "Hurricane Hunter" surveillance aircraft. NOAA signed on as the first customer for the program in November 2013.

The flight, out of MacDill Air Force Base in Tampa, went exceptionally well, according to Tom Hartmann, Rolls' senior vice president for customer business.

As part of the test, the P-3 was able to reach 30,000 feet and cruise at 200 knots on a 90 degree day, while showing a 12 percent fuel savings over the pre-modified engines.

That's larger than the 7.9 percent fuel savings Rolls has been guaranteeing as part of the 3.5 upgrade package, Hartmann noted.

In the Series 3.5 engine enhancement, Rolls retrofits parts from newer engines into the Series 3 T56 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.

The retrofit can occur during regular maintenance of the older engines, which takes in the range of 30-45 days.

Hartmann said the company has had "a bunch of nibbles" from customers, but aside from NOAA has not locked anyone down. The hope, he said, is that "real data" will convince customers to jump onboard.

"This is the kind of performance and data we needed to go out and sell this worldwide, and it's going to help us turn interest into sales, which is what we were hoping for," he said.

The addressable market Rolls is looking at is 400-500 aircraft worldwide, the largest chunk — roughly 200 — of which is the C-130H fleet used by the US Air Force.

Twitter: @AaronMehta