GAMEOVER
8th Aug 2013, 16:44
Hi all กก
Having read POWER PLANT PW 127 (FCOM ATR 72) is impossible to understand the sequence and how work each and every one of the main components during an engine start.
I think that there should be an explanation about it, but not.
Could anyone describe briefly what is happening inside the engine from the time I announce "Starter ON" to finish the procedure? There are 8 or 10 main components involved during the whole sequence.
I fly atr42z, I may not be able to give a complete picture but would give a basic idea of pw127e. There are two independent ignition systems per each engine (1- ignition excitor - that produces high voltage electrical current, 2- spark ignitor - to produce spark with high voltage current) so, When you select the start rotary selector to any of the setting, the relevant system is ready to spark - except if u start in air, both A and B would be energized irrespective of selection, now as soon as u select the starter Pb "on" the starter/generator rotates the high pressure spool with either battery only, extrnal power or if other engine is running then from 10% to 45% (45 is self sustaining rpm) the live engines electrical power supports the revving up along with the battery. We input fuel via CL between 10-20% nh depending on ITT n as soon as fuel is purged in ( 14 fuel nozzles of which 4 are connected to secondary fuel supply only) the spark ignitors start their action to light up the engine ( in case we don't input fuel or delay, the Max Nh values by starter only would be about 30% approximately). At 45% the starter generator stops Assisting the Nh, which comes back online as a DC generator at 61.5% Nh. Until the CL is not in AUTO the PL will directly govern fuel and hence the Nh.
Capt. On Heat
9th Aug 2013, 10:50
It is not "impossible" if you read ALL the information.
Do you have notes from the ACOS? And try the FCTM and 'Procedures and Techniques' in FCOM 2 to fill in some holes- better yet, ask your training Capt or Sim instructor........