sjb5001 Posted May 15, 2013 Posted May 15, 2013 On shutting down the aircraft, if I switch off the MAIN and WING fuel pumps while the engines are running, why don't the engines shut off? Are these dummy switches or is there a real-world mechanism I'm not understanding? Thanks! Intel i5-4690K 3.5GHz 8GB Kingston HyperX DDR3, 1600MHz NVidia GeForce GTX 760 Windows 8 Pro Operating System - 64-Bit Saitek X52 Pro Joystick and Throttle
Shepski Posted May 15, 2013 Posted May 15, 2013 Most likely there is suction feed in the event pumps fail.
Yskonyn Posted May 15, 2013 Posted May 15, 2013 Indeed, suction feed. [sIGPIC][/sIGPIC] Asus Z390-E, 32GB Crucial Ballistix 2400Mhz, Intel i7 9700K 5.0Ghz, Asus GTX1080 8GB, SoundBlaster AE-5, G15, Streamdeck, DSD Flight, TM Warthog, VirPil BRD, MFG Crosswind CAM5, TrackIR 5, KW-908 Jetseat, Win 10 64-bit ”Pilots do not get paid for what they do daily, but they get paid for what they are capable of doing. However, if pilots would need to do daily what they are capable of doing, nobody would dare to fly anymore.”
IonicRipper Posted May 15, 2013 Posted May 15, 2013 ^ x3 i5 4590 @ 3.77GHz | GTX 1060 6GB | 16GB 1600MHz DDR3 | 1TB HDD+500GB HDD | Win10 Home X64 [sIGPIC][/sIGPIC]
Luzifer Posted May 15, 2013 Posted May 15, 2013 As the manual says, gravity/suction feed is enough to keep the engines running (off the internal tanks at least, don't know about external) below 10000 ft.
Robert1983NL Posted May 15, 2013 Posted May 15, 2013 I don't understand why you need to turn on the main fuel pumps for the startup of engine 2 in the A10... Can someone explain that to me?
NoCarrier Posted May 15, 2013 Posted May 15, 2013 I don't understand why you need to turn on the main fuel pumps for the startup of engine 2 in the A10... Can someone explain that to me? From the A-10A dash one: Boost pressure is provided by boost pumps located in each main and wing tank. A DC boost pump, located in the left main tank is used during engine and APU starts if the left main boost pump is inoperative.
Robert1983NL Posted May 15, 2013 Posted May 15, 2013 What's a dash-one? So... You NEED a boost pump for startup regardless of the suction feed? I always thought you could startup without boost pumps on.
Dejjvid Posted May 15, 2013 Posted May 15, 2013 When you start the engine, suction is not enough, you need the boost pumps to get the flow started. Once the engine is running the suction is sufficient at low altitudes. You use the throttle to shutdown the engines. i7 8700K | GTX 1080 Ti | 32GB RAM | 500GB M.2 SSD | TIR5 w/ Trackclip Pro | TM Hotas Warthog | Saitek Pro Flight Rudder [sigpic]http://www.132virtualwing.org[/sigpic]
sobek Posted May 15, 2013 Posted May 15, 2013 What's a dash-one? It's a type of manual for US military aircraft. So... You NEED a boost pump for startup regardless of the suction feed? Yes. Also you can't even attempt to (in case of the left engine) start it without boost because the auxiliary boost pump is driven by the DC essential bus. The right engine simply won't start. Good, fast, cheap. Choose any two. Come let's eat grandpa! Use punctuation, save lives!
NoCarrier Posted May 15, 2013 Posted May 15, 2013 (edited) So... You NEED a boost pump for startup regardless of the suction feed? I always thought you could startup without boost pumps on. No running engine, no suction. As I stated earlier, the left engine (not to mention the APU) will start because of the DC boost pump, wich is powered by the DC essential bus (i.e., DC battery). The right-hand side boost pumps (right AC bus) are needed to start the right engine. No way around that. EDIT: Just realized that you can hit the Crossfeed switch and feed your right engine that way. Just tried it and it works just fine. So the last sentence above is not true. EDIT AGAIN: The above would also explain why the emergency checklist wants you to hit the Crossfeed switch during a windmill restart of the engines. It's so that the DC boost pump can feed both engines instead of the left one only. I've always wondered. At least now that I know the purpose behind it, I'm less likely to forget. Edited May 15, 2013 by NoCarrier
Robert1983NL Posted May 15, 2013 Posted May 15, 2013 It's a type of manual for US military aircraft. Yes. Also you can't even attempt to (in case of the left engine) start it without boost because the auxiliary boost pump is driven by the DC essential bus. The right engine simply won't start. What type of manual? I'm only familiar with the dash ten.
NoCarrier Posted May 15, 2013 Posted May 15, 2013 (edited) What type of manual? I'm only familiar with the dash ten. The A-10A Flight Manual—TO 1A-10A-1. Both links in the A-10C manuals and documents collection thread seem to be dead, but I can send you a copy if you want. Edited May 15, 2013 by NoCarrier
Robert1983NL Posted May 15, 2013 Posted May 15, 2013 Nah that's ok. I learned something today. I thought that only -10's were flight manuals. Maybe -1's are just old fashioned or something.
311Gryphon Posted May 15, 2013 Posted May 15, 2013 No running engine, no suction. As I stated earlier, the left engine (not to mention the APU) will start because of the DC boost pump, wich is powered by the DC essential bus (i.e., DC battery). The right-hand side boost pumps (right AC bus) are needed to start the right engine. No way around that. EDIT: Just realized that you can hit the Crossfeed switch and feed your right engine that way. Just tried it and it works just fine. So the last sentence above is not true. EDIT AGAIN: The above would also explain why the emergency checklist wants you to hit the Crossfeed switch during a windmill restart of the engines. It's so that the DC boost pump can feed both engines instead of the left one only. I've always wondered. At least now that I know the purpose behind it, I'm less likely to forget. It's nice to know the hows and whys! Thank you! I have to say that doing a mid-air windmill restart has been one of the highlights of my short flying career in DCS! http://www.youtube.com/user/311Gryphon i7-8700, 32 GB DDR4 3000, GTX 1080 TI 11GB, 240 GB SSD, 2TB HDD, Dual (sometimes Triple) monitor, TM Warthog HOTAS, Saitek Pro Combat Pedals, TrackIR [sIGPIC][/sIGPIC]
AlphaOneSix Posted May 15, 2013 Posted May 15, 2013 Nah that's ok. I learned something today. I thought that only -10's were flight manuals. Maybe -1's are just old fashioned or something. Nah just a USAF thing, they call it a -1, U.S. Army calls the same thing a -10.
Donglr Posted May 16, 2013 Posted May 16, 2013 It's nice to know the hows and whys! Thank you! I have to say that doing a mid-air windmill restart has been one of the highlights of my short flying career in DCS! I always wonder in what situations pilots do that. I never had my engines shut down by themselves, only when I got shot at and the engines were hit. So when my engine shuts down because it was damaged by the enemy something obviously is broken, meaning I cannot use that engine anymore anyway. So why try to restart, it's full of bullet holes? Is there really a chance that I can just restart a damaged engine? What are the situations where I might be able to restart an engine mid-air? First of all the engine must still be functional, so direct damage to the engine is a show stopper. Random failure - unlikely. The only probable situation I can think of is when my fuel system is partially damaged and one of the pumps is not working. But then again as long as the engine is running suction should be enough to feed it. If one of the tanks got nailed and one engine runs out of fuel and I do not realize that in time to enable cross feed before the engine shuts off, that could be a situation. Any others?
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