November 20, 20187 yr Hi Folks, The Bleed Air system is a bit new to me - I don't think we had anything on the Lear like it... Do you leave the Bleed Air in "auto" at all times ? On some regionals I've messed with - I think it needed to be switched "OFF" for engine starts ? When would you use the APU Bleed Air switch ? I don't have the checklists available at the moment - maybe it's addressed there... Thanks... Regards, Scott
November 20, 20187 yr APU bleed air is used when you need air conditioning (or other pneumatic services) and the engines are not running (nor is an air conditioning cart available). I'm not au fait with the Falcon 50's engines, but most turbofans have pneumatic starters that require a high pressure bleed air source to spin them up (this could be APU bleed, another engine on crossbleed or an HP air-start cart). A minority of turbofans are on electric starters, and most turboprops are also electric start (generally this is done with APU or GPU, as it's hard on the batteries). EDIT: I believe the TFE731 engines use electric start (the generators double as starter motors) so you wouldn't need bleed air for starting. Edited November 20, 20187 yr by ckyliu ckyliu, proud supporter of ViaIntercity.com. i5 12400F, 32GB, RTX4070, more in "About me" on my profile.
November 20, 20187 yr The Falcon 50 uses electric starter/generators. The bleed air and pack switches are normally left in AUTO all the time. The bleed air valves on each engine won’t cycle open until the engine is stable at idle after start. It’s a very simple and trouble-free system. The only manual bleed air management required is to be sure to switch APU bleed air off (if used) before engine start, which is done on the APU control panel. Jim BarrettLicensed Airframe & Powerplant Mechanic, Avionics, Electrical & Air Data Systems Specialist. Qualified on: Falcon 900, CRJ-200, Dornier 328-100, Hawker 850XP and 1000, Lear 35, 45, 55 and 60, Gulfstream IV and 550, Embraer 135, Beech Premiere and 400A, MD-80.
November 20, 20187 yr Just looking thro the 'Before Engine Start t' check list for the Bleed AIr Panel … Cabin / Crew Auto, Bag on, Isolation Valve Horizontal (Tied ) HP1 HP2 HP3 PRV Auto. There is no mention of further action in other sections ( other than APU bleed air including shutting down), so as Jim noted they stay on and my thinking is that the check list item is to ensure they are still set. bob Edited November 20, 20187 yr by onebob
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