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FIX: loss of avionics, engines crossfeed (Read 1826 times)
windplayer
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FIX: loss of avionics, engines crossfeed
Aug 05th, 2011, 8:06pm
 
If you lose avionics after some time, - you shut down APU incorectly. im not shure if this is bug or what, but deffinitely problem with manual Smiley manuals for 707 much more detailed.

Proper way to break generators in:

before APU start check GENERATORS BREAKER, TIE, FIELD switches in NEUTRAL position. They have 3 positions: open, neutral, close.
Same for APU BREAKER, FIELD switches

Start Battery, check battery ammeter shows negative so battery discharges.
Start APU as told in manual part III
APU BREAKER LAMP should light up.
switch APU BREAKER to CLOSED and back to neutral. BREAKER lamp should dim.
switch Essential power to APU, check battery ammeter show possitive current, so battery charges.
start engines.
GENERATORS TIE LAMP should light.
switch GEN TIE to CLOSED and Back to neutral.
GEN TIE LAMP should dim, and APU BREAKER LAMP should light.
set essential power to Generators.
shutdown APU.
check battery ammeter shows possitive current, so it charges from GEN.
check DC AC on all buses.
avionics should work on GEN power, not on battery.

this should be in manual, and it is there, but not so detailed Smiley

http://www.youtube.com/watch?v=528XovrLqFs - this video shows it. it's not mine and i got it from there.

there is another way to "fix" it.
go to SETTINGS\CONTROLS\KEYBOARD\ and map a key to GENERATORS\ALTERNATORS switch. no key mapped to this function by default. so after APU shutdown just click that key and all should work.

no *.CFG modification needed.

Also not covered by manual and not all may be aware of it.

****corrected THANKS TO member LOU****
how to feed engines 1,3 from central tank.
you should do all as in manual, so eng 1,3 crossfeeds closed, eng2 crossfeed open, all boost pumps on.
to feed engine 1 from central tank, just open eng 1 crossfeed valve,  and _TURN OFF_ boost pumps on Eng1.
Check that fuel quantity in ENG1 tank not decreasing. Eng 1 will use fuel from central tank.
If you leave boost pumps running on end1, it will eat its own fuel, and shut-down then the tank will empty regardless on crossfeed valve possition.

P.S. i got basic pack with 727-100 only. v 2.4. no problems with engine power, or whatever. I fixed sound problem as writen on this forum. im loading flight 2 times, and all works.
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LOU
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Re: FIX: loss of avionics, engines crossfeed
Reply #1 - Aug 5th, 2011, 9:23pm
 
I'm not sure I know where I should start.... Shocked

I don't know where you got your information.



From the CS 727 manual...

COCKPIT APU START PROCEDURE
(1) BATTERY SWITCH. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ON (VOLTAGE 23.5 MIN)
(2) APU FIRE WARNING (IF FIRST FLIGHT OF DAY) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .TEST
- TEST PROCEDURE -
APU FIRE WARNING TEST (PRIOR TO APU START):
(a) APU AUTOMATIC SHUTDOWN SWITCH . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . .ARMED
(b) APU FIRE WARNING TEST-RESET SWITCH. . . . . . . . . . . . . . . . . . . . . . . . . . . .. . .”FIRE TEST” AND HOLD ONLY UNTIL THE FIRE WARNING LTS. ILLUMINATE (MAX 60 SEC.)
(c) APU FIRE WARNING TEST-RESET SWITCH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .RESET
(d) APU FIRE WARNING TEST-RESET SWITCH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .RESET
- END OF TEST PROCEDURE -
(3) AC METERS SELECTIONS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .APU
(4) AIR CONDITIONING PACK SWITCHES
(IF NO ELECTRICAL POWER ON A/C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .OFF
The PACK switches are checked OFF to prevent high initial electrical loads from the pack cooling fans when APU of external power is connected.
(5) APU CONTROL PANEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CHECKED
(a) APU FIRE HANDLE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .CHECK IN
(b) APU AUTOMATIC FIRE SHUTDOWN SWITCH. . . . . . . . . . . . . . . . . . . . . . . . . . . CHECK ARMED
(c) GENERATOR FIELD BREAKER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .CLOSED
(6) APU MASTER SWITCH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ON
Check that APU light (S/O lower panel) illuminates. This light illuminates only if the #1 DC bus is energized, and therefore will not illuminate when the APU is being started from the battery alone.
(7) APU MASTER SWITCH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .START
(8) APU CRANK LIGHT . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . ILLUMINATES
(9) MASTER SWITCH. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .RELEASE TO “ON”, UPON OBSERVING CRANK LIGHT
(a) APU CRANK LIGHT. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .EXTINGUISHES
This indicates that the starter motor is de-energized. Light should extinguish in approx. 10 seconds. If APU crank light does not extinguish within 30 seconds after APU start initiation, terminate APU start by pulling APU FIRE switch.
(10) APU EXHAUST GAS TEMPERATURE INDICATOR. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .MONITOR
(11) Check for stabilized speed by observing APU generator frequency (approximately 400 CPS)
(12) ALL BUS TIE BREAKERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CLOSED
(13) VOLTAGE, FREQUENCY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . CHECK WITHIN LIMITS
(14) APU GENERATOR BREAKER SWITCH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .CLOSE
Closing the APU GENERATOR BREAKER switch will trip the EXTERNAL POWER switch or the
engine-driven generator’s GEN BREAKERS, if either were supplying the bus.
(15) ESSENTIAL POWER SELECTOR. . . . . . . . . . . . . . . . . . . . .APU; CHECK ESSENTIAL POWER LIGHT OUT
The # 3 BUS TIE BREAKER must be CLOSED.
(16) VOLTAGE, FREQUENCY, AND AMPS. . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . CHECK UNDER LOAD
Electrical power during pre-flight throughout engine start is normally furnished by the APU. External power may be connected through the external power receptacle as an alternate source of electrical power.
Normal ground or flight operation is with the busses in parallel (BUS TIA BREAKERS CLOSED, lights out) and operating as a synchronous bus.




727 fuel panel:



PLEASE re-read the manuals.

You are mixing the fuel system with hydraulic pumps in system A & B????  Huh

Lou


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windplayer
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Re: FIX: loss of avionics, engines crossfeed
Reply #2 - Aug 5th, 2011, 10:59pm
 
i named FWD and AFT boost pumps wrong. my mistake, sorry corrected it Smiley

Manuals and checklists correct of course but some points should be detailed more for ordinary folks like me Smiley

like all tie, breaker, field switches wich have 3 positions, and should be in middle. manuals said they should be just closed. if you'll leave APU breaker closed, not return it to neutral before closing GEN TIE and APU shutdown, - then avionics die Smiley Cant say for real craft, - you're the boss for sure;) but sim have this tiny detail in programming, so dudes going to edit cfg etc. so it's not a sim craft bug, just misunderstanding of 2 pos switch(Close/Trip), or 3 pos switch(CLOSE/Neutral/Trip). it's unclear from manual.

Same for fuel operation. unclear from manual that you should turn off boost pumps on recieving engine. Simple to you, not so clear for ordinary users Wink

Thanks for reaction Smiley
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Re: FIX: loss of avionics, engines crossfeed
Reply #3 - Aug 6th, 2011, 3:43am
 
First I'll talk about the fuel system in the 727...

When the 3 tanks are equal, you burn the fuel - TANK to ENGINE



In the above picture, the three tanks are about equal. The number 2 cross feed is open to maintain fuel pressure in the cross feed manifold. Tanks 1 & 3 cross feeds are closed to prevent any movement of fuel. ALL fuel boost pumps are ON.

When there is more fuel in tank 2 than in tanks 1 & 3 you cross feed the fuel as follows....



You are burning the fuel from the center tank through the cross feed manifold by opening ALL cross feeds, and turning off the boost pumps in tank 1 & 3. The panel is pretty simple, just look at the white lines and follow the flow.

I go over the electric system later. This is a more complex system and needs some hand holding.
I'll explain the names of the various breakers and switches and how they work.

Lou

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Re: FIX: loss of avionics, engines crossfeed
Reply #4 - Aug 6th, 2011, 10:57am
 
Thanks! That would be really helpful!
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Re: FIX: loss of avionics, engines crossfeed
Reply #5 - Aug 6th, 2011, 5:34pm
 
One thing that bothers me is the fact that there are no master radio switches on the 727 overhead panel. You need to have these switches so you can really turn off the captain's radios in the event of an electrical fire. If the avionics switches are left on the battery will transfer power to the captain's radio bus. The battery system in the 727 has the battery bus, the battery transfer bus and the hot battery bus. The hot battery bus is powered whenever the battery is installed in the plane. It powers stuff like the PA and the fire bottle buttons. When external power is connected the battery charger is powered and charges the battery. Normal A.C. power powers the battery as well through the T.R.'s (transformer rectifiers) that make 28 volt D.C. and thus keep the battery charged. If you were to kill all power to the 727 and left the essential radio bus turned on the battery would die. So to truly be cold and dark you need to be able to turn off the essential radio master switch as well.

Each engine driven generator is able to produce 54 KW for 10 mins and 36 KW continuous. The APU generator is the same as the engine driven generators, except it is rated at 54 KW continuous because it is better cooled. DON'T turn the frequency knobs to max - keep them around the middle. The AC system needs 400 cycle power +/- a few cycles. Here is how the generators are handled during engine start...
All fields and Bus Ties are closed.
1. - APU is supplying electrical power to the aircraft.
2. - Turn off packs to reduce electrical load (pack fans) and air load to start engines. Duct pressure should read around 40 PSI.
3. - Start engine one. As engine comes up to idle check AC meters to engine one and look for 115 volts and 400 cycles. Adjust CSD to obtain 400 cycles.
4. - Move the Essential power switch to the number one engine generator.
5. - Close Main Generator Relay (middle switch). This action will trip the APU generator off and connect the engine one generator to power the plane. The same would happen if you were using ground power. Closing the MGR on generator will trip other power sources.
6. - Start next engine. Move meter selector to that engine and observe volts and freqs.

Here is where it gets complicated. Until now only one power source was connected to the aircraft. The bus ties were used to connect the load buss in series. Just like a power strip with several outlets and items plugged in to them - it is still one power source providing all the power. When you start the second engine generator and connect it to the aircraft you are using more than one power source and something special happens. The bus ties now become part of the Sync-Bus and a whole different system of control comes into play.

With just one power source generator protection consisted of overload protection and high or low voltage protection with wide latitude in the limits. Look at the meters gauge for voltage and frequency. The limits are the full scale of either gauge. This all changes when you connect the second generator. Now the bus ties change protection and become a Sync-Bus. A very complicated electrical system comes into action and load sharing of the generators starts. Now the two generators work together and attempt to equalize their loads. The limits on voltage and frequency variation are lessened because of this paralleling of generators. Overload protection changes and other faults related to the sync-bus come into the system.

In normal operation all the bus ties should be closed (lights out). This will allow ground power or APU power to flow through the bus ties to their load buss.

Had enough? It is a somewhat complicated system and you would need to study the system for some time to be able to understand what is happening to all the electrons.

OK, now you asked for it! Here is a look at the 727 electrical system. Give it a good read and then if you have any questions, ask away.

http://www.smartcockpit.com/data/pdfs/plane/boeing/b727/systems/B727-Electrical....


Lou
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windplayer
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Re: FIX: loss of avionics, engines crossfeed
Reply #6 - Aug 7th, 2011, 10:57pm
 
O_O Thanks Smiley That'll keep me busy for some time Smiley
..gone to do homework
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Re: FIX: loss of avionics, engines crossfeed
Reply #7 - Aug 8th, 2011, 9:00am
 
windplayer wrote on Aug 7th, 2011, 10:57pm:
O_O Thanks Smiley That'll keep me busy for some time Smiley
..gone to do homework

Lou is good for giving us some fantastic information. I have trouble keeping up with it all. Huh

Mark
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Mark Fletcher


CS L-1011 - RPLL-RJTT - 4.2 hours

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Re: FIX: loss of avionics, engines crossfeed
Reply #8 - Aug 9th, 2011, 10:31pm
 
Smiley  i dig CS727, i dig that Lou said, i dig manuals (especially when autopilot drives Wink)
its a lot of dig Smiley))  lot of dig = lot of fun in this case Smiley

little offtopic: Are you still using EZDok? i want to buy it, but some folks says it dont recodnizes CS727 camera posittions, so it needs to be tunned manualy. same for effects. is it? have you had any problems with tunnig EZDok on CS727?

P.S. Im just out of Australia Smiley landed yesterday in Port Morseby, Papua New Guinea.
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Re: FIX: loss of avionics, engines crossfeed
Reply #9 - Aug 10th, 2011, 6:00am
 
Are you still using EZDok?
No. Not any more. I gave up on it because I just could not get it working quite the way I wanted it too.

I still think it's a great program, but I don't think it is suitable for me. I used it for about 4 or 5 months, so I gave it a helluva (good) workout. In the end I uninstalled it. I doubt I will install it again.

P.S. Im just out of Australia Smiley landed yesterday in Port Morseby, Papua New Guinea.
You are a neighbor then! Wink

Mark
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Mark Fletcher


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Re: FIX: loss of avionics, engines crossfeed
Reply #10 - Aug 15th, 2011, 5:17am
 
Lou,
Thanks for the 727 electrical information. I think I see the big picture of running generators in parallel to share the  loads but I'm still unclear on the function of the field breaker, bus tie breaker and generator breakers.
Accord to what I read, the generator breaker in the closed position provides power from the generator to its bus, and the bus tie provides power from the bus to the sync bus, which enables parallel operation of more than one generator.  And the filed generator energizes each generator when closed.
With that said,  if you want power the aircraft with just one generator ( I don't know if you'd ever want to do this)  would you have just that particular field and generator breaker closed and all other field and generators breakers tripped?
In another scenario, if you wanted parallel #1 and #2 you would close their field, bus tie, and generator switches and trip # 3 bus tie?
Also, it seems in normal operation all bus ties, field and generator switches are closed. Does that mean that all three generators are operating in parallel?
I hope I'm some what on track here. This electrical configuration seems hard to grasp. Thanks for providing this information.
Regards,
Brian
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