After the ignition switch is turned ON, my Captain always increases the RPM (throttle) very slowly. I don't know why, because our helicopter has an ECU. One day, my Captain asked me "Do you know why we increase RPM slowly?" so I answered "umm, to prevent a hot start?" Then my captain said "Nope. It is related to ENG OIL PRESSURE."
Is there any other reason about this slow operation (related to ENG oil pressure)?
Maybe compressor stall or surge?