In one of the ships, at 2 hrs notice the M/E stopped and tried out ahead and astern direction, as per the regular routine. Found Main Engine did not turn. At the same time noticed ME control air pressure dropped. Control air pressure switch in Pneumatic logic box checked and cleaned off moisture and dirt. Then noticed control air pressure passes from turning gear interlock to activate to main VV.

Turning gear engaged, opened indicator valves and turned the engine. The maneuvering changed over to manual mode and vessel berthed.

Checked all starting air v/vs operation & all units’ start air distributor v/vs overhauled. M/E auto starting air drain v/v overhauled. Control air pressure reducing station air filters cleaned. Engine tried out satisfactory.

After that again on one of the voyages in early 2006, observed ME RPM reducing drastically to 30 rpm on its own. At first raised the fuel lever to increase but later found speed setting air pressure not correct. Fuel pressure & Lub oil pressure, fluctuating when speed was raised and remains steady when speed drops.

Control air line from governor to logic box passage checked with compressor air.

Control air line from scan air manifold to pressure gauge to logic box passage checked.

There problem were happened due to control air drier not working, and no spares on board. Manual draining found to be insufficient.