Bleed air PSI required for start?

• A. 45 ± 3 psi
• B. 50 ± 5 psi
• C. 40 ± 2 psi
• D. 60 ± 4 psi

Answer: (A)

The engine start relies on a specific bleed air supply to power the pneumatic starter. That starter must receive a precise pressure to spin the engine up to the speed needed for reliable ignition, and for the CRJ-550 the required bleed air pressure is 45 psi with a tolerance of ±3 psi. Keeping the pressure in roughly 42–48 psi ensures the starter reaches the right rpm across different temperatures and altitudes; if it’s too low, ignition may not occur, and if it’s too high, the system can limit or stress components. The other options lie outside this recommended band, which is why they aren’t used.