Pneumatic air supply
The pneumatic system distributes compressed air for aircraft functions. The ECS page turns an abstract collection of switches into something you can trace.
Find the source
Identify the source that should be available for the current phase, such as the running APU or an engine.
Bleed selections
Inspect the corresponding APU BLEED, engine BLEED and XBLEED controls. FSS describes pushed-in controls as allowing automatic system operation.
Open ECS
Check source, valve, pressure and flow indications. A control selected for automatic operation is not a promise that the valve is open at every moment.
Check the packs
FSS describes a pushed-in PACK control as allowing automatic pack operation; pushed out commands the associated valve closed.
Observe the start
Watch the pack and bleed indications during engine start. The pneumatic page describes an emergency ram-air-valve test that holds PACK 1 off. Compare the timing and CAS message with the installed build before treating a brief PACK 1 change as a fault.
Pack status after start
Once the engines are stable, check source and pack indications again. Follow the aircraft-specific normal flow for any subsequent APU shutdown. [101]
On the overhead, pushing a BLEED, XBLEED or APU BLEED button out commands the associated valve closed. A pushed-in button allows automatic operation; check the ECS indications to see what the system is actually doing.
If ENG REF ECS DISAG appears, compare REF ECS on the takeoff dataset with the actual bleed and pack configuration. The CAS page describes an emergency ram-air-valve test that holds PACK 1 off for about 90 seconds at the first engine start of the UTC flight day, except when spawning in turnaround mode. With REF ECS ON and both engines running, the caution can appear until the test ends. Compare the timing and CAS with your installed build. An open APU bleed with both engines running can also make REF ECS ON disagree. FSS describes the caution as active below 1,700 ft radio altitude, outside landing mode, with both engines running; it clears when the mismatch ends or 120 seconds after takeoff. For this comparison, FSS treats ECS as ON only when both packs are on, both engine bleeds are open, APU bleed is not supplying the manifold and the ram-air-valve test is not holding PACK 1 off. REF ECS is a thrust-calculation assumption; it does not operate the packs. FSS CAS [102].