Video #2 (start question)
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Absolutely loving the videos - just watched #2 and have a question:
After engine start we switched on alternators 1-4 but later isolated 1,3, & 4 leaving 2 connected but at the hold point AEO check it seems all the alternators were isolated as the indicators were across including #2?
What is the correct end state prior to departure?
Thanks!
Sorry - supplemental but related after reading the auto AEO article
in the flow below - we see #3 connected in climb@ 5,000
then #4 connected @ 20,000
so I assume at 20k we have both 3 & 4 on busOn descent below 20,000 we again connect #3 then isolate #4 - unsure how #3 was disconnected or does it relate to never exceeding 20,000 in cruise?
Sorry - always questions....
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ClimbClimbing through 5,000ft with the undercarriage up and the RPM governor set to CRUISE:
Connect the No 3 alternator to the sync busbar
Confirm all four alternators, both 28v TRUs and 115v transformers are ON
Trip the extra supplies from the sync busbarClimbing through 20,000ft with the undercarriage up, the RPM governor set to CRUISE and the No 3 alternator connected to the sync busbar:
Connect the No 4 alternator to the sync busbar
Shut down the AAPP (master switch to OFF)
Confirm all four alternators, both 28v TRUs and 115v transformers are ON
Trip the extra supplies from the sync busbarDescent
Descending through 20,000ft with the undercarriage up and the No 4 alternator connected to the sync busbar:
Connect the No 3 alternator to the sync busbar
Isolate the No 4 alternator from the sync busbar===================
ok - I should have watched ALL the videos first and I now think I understand...- below 20k have #3 connected
- above 20k have #4 connected
to connect AAPP to bus for t/o and landing - first connect #2 then AAPP on which disconnects #2 again
so - either the AAPP is powering the a/c OR #3 / #4 depending on altitude
Phew. Now a nap :-)
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I think you got there in the end! The electrical system in the Vulcan is like nothing I've experienced in any other aircraft, and I still learn new things about it daily, so it does take some getting used to!
The general rule of thumb is you only need one alternator connected to the Synchronising Busbar at any one time, and that one alternator is enough to supply electrical power to the aircraft.
During the pre-flight checks, you check that each of the alternators connects to the Synchoriusing Busbar, and then isolate them.
For Take-off and landing the AAPP alternator should be the only alternator connected to the synchronising busbar.
For flights below 20,000ft, alternator 3 should be connected to the Synchronising Busbar. To do this after take-off, the AAPP should first be disconnected (by pressing the EXTRA SUPPLIES TRIP pushbutton) and then shutdown, before then connecting alternator 3.
For flights above 20,000ft, alternator 4 should be connected to the Synchronising Busbar. To do this during the climb, connect alternator 4 and then isolate alternator 3. If you isolated alternator 3 before connecting alternator 4, then alternator 2 should be connected automatically as a fail-safe.
During the descent, it's the same procedure just in reverse.
The AUTO AAPP option can also be a useful tool to visually see the process working in the simulator. With AUTO AAPP enabled, if you switch to the AEO position prior to takeoff you should see the panel set up correctly. Then if you switch to the AEO panel when passing 5,000ft and 20,000ft you should see the switches move as the AEO manages the alternators.
Hope that helps!
Mark - Just Flight
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Yes it does - last question (Columbo mode engaged) :
"For flights below 20,000ft, alternator 3 should be connected to the Synchronising Busbar. To do this after take-off, the AAPP should first be disconnected (by pressing the EXTRA SUPPLIES TRIP pushbutton) and then shutdown, before then connecting alternator 3."Does this sequence not mean that for a moment there is no alternator on the bus between AAPP coming off and 3 being connected?
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In that situation (in the climb at 5,000 ft after takeoff), pressing the EXTRA SUPPLIES TRIP would disconnect the AAPP alternator from the Synchronising Busbar, leaving no alternator connected. So as a fail-safe, the No2 alternator would be automatically connected so that electrical power is not interrupted. You would then connect the No3 alternator, and disconnect No2.
For reference, I'll copy the actual procedure from the After Take-Off/Overshoot Checks in the real manual below:
Electrics . . . . No 3 or 4 alternator on synch busbar, AAPP OFF
a. Press EXTRA SUPPLIES TRIP
b. Check No2 on synch busbar
c. Synch No4 (High Level) or No3 (Low Level) with No2, isolate No2
d. AAPP master switch OFF
e. Check scoop closed, 30 to 50 voltsMark - Just Flight
