N1% for crossbleed
It must also be noted that at ground idle (N1 20%) the bleed air from an engine may be only approx 15 - 20psi. To obtain the required 30+ psi required to prevent a 'hung start' it is necessary to bring the N1% past approx 60% That can be very noisy and are avoided where possible. Usually, in our outfit, a cross bleed is only carried out iof the APU is inop...