MAN Dual-Fuel L35/44DF Four-Stroke Engine Closer to Market Entry

| Germany, Augsburg
MAN Dual-Fuel L35-44DF Four-Stroke Engine May2015

MAN Dual-Fuel L35-44DF Four-Stroke Engine

Representatives from all major classification societies have awarded type approval to MAN Diesel & Turbo’s L35/44DF engine. The engine is now certified for GenSet and Controllable Pitch Propeller (CPP) operation all over the world. Lasting from March 30 to April 2, in Augsburg, this has been the longest type approval test (TAT) MAN has run so far. Within the shipping industry, all new engines require type approval before installation on board a ship. Class certificates are valid for 5-7 years.

The first L35/44DF’s FAT (Factory Acceptance Test) will take place at MAN Diesel & Turbo’s Frederikshavn, Denmark facility in May, for which the Type Approval Test in Augsburg is a prerequisite.

MAN Dual-Fuel L35-44DF Four-Stroke Engine May2015.bmp“The 35/44DF showed a spotless overall performance without any unplanned quick changes over from Gas to Diesel during operation or any of the type approval tests”, sums up Dr. Günter Heider, Senior Manager at MAN Diesel & Turbo and Head of Test & Validation Four-Stroke Diesel & Gas Engines. “Among the features that were specifically appreciated and praised by the association members were the quick changes over from gas to diesel mode at 100% load, the restriction-free gas load performance at an overload of 110% and the engine’s logic and clear modular design.”


  • Fulfills IMO Tier III NOx, and Sox requirements in gas mode
  • Reduces CO2 emissions by up to 20 % when using gas
  • Runs on HFO, MDO, MGO and LNG
  • Takes advantage of the increasing price gap between fuel oils and gas

Type approval tests
The entire TAT process involves a series of thorough running tests along with the detailed study of all documentation, sketches and calculations relevant to proceedings.
There are three main test blocks:

  1. Extreme Conditions Test – this tests the engine with minimal oil pressure and max temperature at 110% performance, a cyclic loading operation over the course of 40 hours and 1- hour full-torque test at 87% of the nominal speed with a shutdown by engine overspeed, all to stress the engine and its components as much as possible. The engine is opened up afterwards and its parts checked by the classification societies.
  2. Emergency Operation – here, the engine needs to perform in non-supercharged conditions (suction engine). This test block usually takes 1-2 days with just one or two classification societies present as observers.
  3. Type Approval Test – this demonstrates an engine’s ability to perform under different, defined engine loads and covers the engine’s ability to switch smoothly from diesel to gas operation and back. The engine´s Alarm & Safety System is also tested to proof compliance with MAN’s Safety Concept for Marine DF Engines. In addition an Integration Test has to be performed to show the engine’s reliability in the event of the control system partly or completely failing.

(Source: MAN Diesel & Turbo)

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