why do Ryanair 737s only turn on the apu before engine start because what your supposed to do is turn on the battery, test the apu and engine fire alarm system and then turn the apu on before you do the rest of the checks and before people board
+Norwegian Boeing 737-800 APU is a jet turbine which produces electric power and air pressure for air conditioning and engine start. You need the APU turned on to provide air pressure to spin the turbines in order to start the engines. Hope this helps if not ask further :)
pirek97 I meant because when you turn on a cold and dark airplane normally you would normally turn on the battery do apu fire test and start the apu and then do the rest
+Norwegian Boeing 737-800 oh i see what u mean u meant that apu should be turned on way before ryanair does it? Well i guess it depends on the airline i noticed too that the apu is turned on late just before pushback. If ground power is available then there is no need for apu which wastes a lot of fuel hehe ;) then apu would be turned on when its really needed.
![Ryanair FR754 London Stansted (STN) - Frankfurt Hahn (HHN) 737-800 (EI-EBF) *FULL FLIGHT* [1080p HD]](/img/logo.svg){kind=logo}
