The invention relates to a method for preparing butadiene-based aqueous dispersions in the presence of at least one azocarboxylic acid ester. The engine ignition control apparatus includes a stroke determination unit for determining a stroke based on crank pulses and on an output signal of an intake pressure sensor. The system includes an aircraft electrical servicing adapter that facilitates the safe supply of power to a 270 VDC aircraft via the 115V400 Hz AC cablehead.