INTERNATIONAL AEROENGINES RUN UP PROCEDURE

OPERATION OF V2500 ENGINE INSTALLED ON A320 AIRBUS AIRCRAFT In the cockpit, the engine mode selector switch is selected to ignition/start. The engine page on the lower ecam comes in view. The engine start valve opens and the pneumatic air from auxiliary power unit at the tail section of the airplane through the pneumatic duct reached the start valve. The engine electronic control regulates the opening and closing of the start valve. The pneumatic starter gives torque to the n2 drive shaft. The oil pressure starts rising. Through aerodynamic coupling n1 shaft also start rotating and as such l.p. compressor fan rotates. At about 23 to 24% n2 rpm ignition takes place through eec and at the same time fuel is also injected by the fuel pump through fuel metering unit, which is also controlled by e.e.c. now all the gas path parameters – n1, n2 and egt rise along with engine pressure ratio. Epr is the index of thrust being produced by the engine. At the same time engine shaft parameters – oil pressure, oil temperature,n1 and n2 shaft vibration levels are also registered. At about 43% n2 the start valve closes and the pneumatic start disengages. Now the engine has reached the selfsustaining r.p.m at about 45% -47% n2 the engine generater comes online for delievering the electrical power. Finally the stabilized idle engine r.p.m is reached at about 59-60% n2 r.p.m. engine is run at the idle engine power for about 5 minutes for thermally stabilizing the engine hot section. Also all type of leak check – engine fuel leak, oil leak, hydraulic fluid leak checks are also done at the idle engine power. After satisfactorily idle run for 5 minutes, the engine is accelerated to higher power by moving the engine throttle lever from idle gate to climb gate. At idle power, the engine develops the epr of about 1.05 approx. the engine is accelerated to 1.2 e.p.r –power assurance e.p.r and at this power engine gas path parameters are critically examined, mainly e.g.t and n1 and n2 shaft vibrations are monitored very carefully to ensure that they do not reach their critical values. The engine e.g.t is the health of hot section of the engine h.p.t 1st and 2nd stage n.g.v and rotor blades similarly n1 and n2 shaft vibrations levels determine the health of various engine bearings. There are four handling bleed valves, 3 at the compressor 7th stage and 4th at the 10th stage along with variable stator vane actuator which synchronizes smooth airflow through compressor section during engine start and acceleration mode thereby preventing engine stalling or surging during these phases. After ensuring all parameters are ok at the engine power assurance check, the engine is further accelerated to takeoff power at about 80-85% n1 the engine n1 and n1 vibration levels re recorded to assess the engine fan trim balance status. If the n1/n2 vibration level reaches more than 5 units, the engine power is reduced to idle power and finally engine is shutdown to carry out engine fan trim balance by analyzing the engine fan trim balance data – n1 , n2 vibrations their phase angles and n1 rpm.after satisfactory high power run up at the takeoff power the throttle lever is brought back idle power and engine is run at the idle power for about 5 minutes for thermally stabilizing the engine before shutdown. After engine shutdown all the engine reports – engine idle run, engine takeoff report, fan trim balance report are carefully studied and necessary corrective actions are taken to ensure good health of the engine.after shutdown, the engine is once again checked for any fuel, oil, hydraulic or pneumatic leaks and necessary corrective action taken. Finally engine cowls, thrust reverser cowl latches are checked to ensure that they are all properly closed.