dr_anthony Posted July 3, 2016 Report Posted July 3, 2016 If battery drain in flight, or on ground it cause of lost ALL power from aircraft, even if it was powered by ENG generators, or APU. I mean, in this cause should be lost just only STBY power. Quote
dr_anthony Posted July 3, 2016 Author Report Posted July 3, 2016 (edited) FCOM 6.20.12. And 6.20.9: "The busses powered from the battery following a loss of both generators are: · Battery bus · DC standby bus · Hot battery bus · Switched hot battery bus · AC standby bus, from the battery bus, through an inverter." If i toggle battery OFF i lost all power from aircraft, it becomes CLD&DRK. Why? Lost of battery power cause impossibility of use STBY power in alternate ops, when STBY power not energizes from ENG gen or APU, and OFF bat switched bus. Maybe i mistakes? OFF the battery causes disconnect the transfer relay from busses? Thanks. Sorry for my english. )) Edited July 3, 2016 by dr_anthony 1 Quote
Litjan Posted July 4, 2016 Report Posted July 4, 2016 Hi, this is correct - the relais holding the connection to the generators are held close by battery bus current. Once the battery drains, you will loose all power to the aircraft. This will usually not happen, because the battery charger is powered through the ground service bus. If you turn off the battery switch, all buses will become unpowered, except for the hot battery bus. If you want to fly without AC generators you can - the battery will power all the buses you mentioned (but while on the ground, you need to move the standby pwer switch to "stby pwer", not to auto). But only if the battery switch is on. Once the battery is drained, you can not connect any power to the aircraft, anymore (not even GPU). Jan 1 Quote
dr_anthony Posted July 4, 2016 Author Report Posted July 4, 2016 Thanks for reply! I'm not an expert of 737CL, but it look very unsafe, if you lost ALL aircraft power in case of only bat drain or fault in connections, in FLIGHT. If "the relais holding the connection to the generators are held close by battery bus current", does not the battery bus powered by battery charger through the ground service bus or by TR 3? "Once the battery is drained, you can not connect any power to the aircraft, anymore (not even GPU)", except of use external dc receptacle )). FCOM: "In the event that the aircraft battery is depleted, the APU can be started using DC external power". Why to start apu without battery, if when you remove DC external power, all relais are disconnects? Sorry for my English. Thanks for reply anyway. Quote
slai Posted July 5, 2016 Report Posted July 5, 2016 Int 21 hours ago, dr_anthony said: I'm not an expert of 737CL, but it look very unsafe, if you lost ALL aircraft power in case of only bat drain or fault in connections, in FLIGHT. Interesting point so I looked it up. Plane flies perfectly well without electrical power due to battery loss as seen in below incident report. I wonder how many planes have similar electricals? I know the later NG has an independent AUX battery. https://www.fss.aero/accident-reports/look.php?report_key=1169 Quote
dr_anthony Posted July 5, 2016 Author Report Posted July 5, 2016 (edited) Hmm... In sim i was in FL360 near TS clouds, in night, and mountains below me, and at this moment ARCFT suddenly lost of all elec power. Approach to nearby field (120 nm) was very impressive for me )))))) Edited July 5, 2016 by dr_anthony Quote
Litjan Posted July 7, 2016 Report Posted July 7, 2016 (edited) Yeah, the plane will fly perfectly fine without any electrical power - as long as you are in VMC. So there is always that element of luck involved when these (rare) events take place. Jan Edited July 7, 2016 by Litjan Quote
dr_anthony Posted July 7, 2016 Author Report Posted July 7, 2016 Why QRH in this situation has no actions, like a "land in nearest suitable airport", not in 737CL, nor in 737NG with bat discharge light in it? For example in bat charge bus fail. After all only 30 min time left before aircraft lost all of it power? I'm not understanding this thing. It contrary to the all philosophy of aviation safety and double, or triple reserving of all systems. Quote
dr_anthony Posted July 8, 2016 Author Report Posted July 8, 2016 (edited) On 04.07.2016 at 11:38 PM, slai said: Int Interesting point so I looked it up. Plane flies perfectly well without electrical power due to battery loss as seen in below incident report. I wonder how many planes have similar electricals? I know the later NG has an independent AUX battery. https://www.fss.aero/accident-reports/look.php?report_key=1169 Its similiar to landing tu-154m in izma airport 07/09/2010. Plane has huge electrical failrues, loss all of elec power on 10600 meters, flown trough overcast clouds by stby pneu instr, has limited amount of fuel due to fuel pumps inoperative, and land with clean wings on deserted air strip in the forest, 1325 m length, without victims. This was avesome. http://www.pprune.org/rumours-news/426642-tu-154-emergency-landing-izhma-komi.html Edited July 8, 2016 by dr_anthony Quote
Litjan Posted July 8, 2016 Report Posted July 8, 2016 14 hours ago, dr_anthony said: Why QRH in this situation has no actions, like a "land in nearest suitable airport", not in 737CL, nor in 737NG with bat discharge light in it? For example in bat charge bus fail. After all only 30 min time left before aircraft lost all of it power? I'm not understanding this thing. It contrary to the all philosophy of aviation safety and double, or triple reserving of all systems. There is a non-normal checklist for this, it used to be called "loss of both engine driven generators" iirc. Jan Quote
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