The LM2500 gas turbine has been used in Italian Navy (ITN) ships for more than twenty years, as the first engines were installed on board the “Lupo” class Frigates during the second half of the 1970s.
The LM2500 during its service has proven to be reliable in both the “Combined Diesel or Gas” (CODOG) and the “Combined Gas and Gas” (COGAG) propulsion plant, with Controllable Pitch Propeller (CPP) and Fixed Pitch Propeller (FPP) as the ITN marine operational experience demonstrates. The last application was in the DURAND DE LA PENNE Class DDG with a CODOG arrangement and two shaft lines with Feathered Controllable Pitch Propellers (FCPP), produced by FINCANTIERI shipyard, which may range from a forward to an astern direction till the blades reach a flag position. This type of propeller allows a considerable drop in the absorbed power and therefore in fuel consumption and noise when using a single shaft.
Based on the ITN experience with the DDG class, the use of FCPP achieves remarkable fuel savings with the gas turbine since, due to the high specific consumption of the engine at low speeds, it is cheaper to have a single shaft running.
The maintenance approach to the engines installed on board ITN ships, based on the “on condition” concept, has been developed by the ITN and Fiat Avio to maximise the availability of the vessels. This covers both on-board corrective maintenance (inspection, special maintenance and / or introduction of improvements) and the substitution maintenance, with successive overhaul and application of decided updating of gas generators and power turbines.