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Jetset320
23rd Oct 2018, 10:03
The first item on the checklist is to press the Emer Elec Pwr Man On switch, while the second is to attain optimum relight speed. There is no mention of IGN ON until the page overleaf. Would a flamed out engine (fuel remaining) start just by windmilling, -does IGN come on automatically in such a circumstance (CFM)?

Goldenrivett
23rd Oct 2018, 11:08
does IGN come on automatically in such a circumstance (CFM)?

Yes.
See FCOM 70-80-30 ignition System, Continuous Ignition.
"AUTOMATIC SELECTION
The FADEC activates the automatic continuous ignition after the second attempt failed during the automatic sequence of the engine start, or, when an engine flameout condition is detected."

Jetset320
25th Oct 2018, 18:30
Thanks Goldenrivett. As one of the first things to do on a single engine failure is to put the ignition on, I would have imagined that it is just as important for a dual engine failure scenario.

Goldenrivett
25th Oct 2018, 20:00
I would have imagined that it is just as important for a dual engine failure scenario.
If both (all) engines have failed then there is probably a common reason - such as fuel starvation (e.g. no booster pumps?), volcanic ash? icing? etc. so until you are back in the relight envelope and away from the ash, ice etc. (or below the gravity fuel feed ceiling if no booster pumps) then relight attempts will be futile - so you may as well crack on with the more important stuff.

FlightDetent
25th Oct 2018, 20:34
The (one) Engine Fail ABN says: Selection of continuous ignition confirms the immediate relight attempt made by the FADEC.

It also says: IF NO ENG RELIGHT AFTER 30 S: (The 30 s countdown starts as soon as the ENG 1(2) FAIL alert is triggered) ENG MASTER (AFFECTED ENGINE)..................................................... ....................... OFF

The IGN then remains on for the remaining live engine.

Apparently, people who understand how the machine works inside, believe such confirmation within the first 30 seconds is not the critical item: establishing a source of electrical power is. Even as a confirmation of the automatic transfer.

Whoever feels lucky feel free to check if the IGN sw works in dual GEN FAIL situation at all...

vilas
25th Oct 2018, 21:19
Whoever feels lucky feel free to check if the IGN sw works in dual GEN FAIL situation at all... FADEC monitors N2 when a sub idle condition is detected for 30 seconds it attempts relight with both igniters and changing fuel flow. If it doesn't succeed then ignition is switched off. After that it will come on for the dead engine when engine master is put on again as in during relight. Same thing should happen in dual flame out case. Ignition is the fourth item in the check list. EMER GEN comes on automatically you just ensure if not then put manually on, thrust levere are brought to idle to prevent surges, FAC reset to get rudder trim and then engine mode selecor to ignition. If engine is not recovered by then, you will have to wait till the envelope to put masters off and on after 30 seconds ignition will come on.

Jetset320
29th Oct 2018, 11:19
If both (all) engines have failed then there is probably a common reason - such as fuel starvation (e.g. no booster pumps?), volcanic ash? icing? etc. so until you are back in the relight envelope and away from the ash, ice etc. (or below the gravity fuel feed ceiling if no booster pumps) then relight attempts will be futile - so you may as well crack on with the more important stuff.
If the inference is that it is vertually impossible to relight engines from a dual engine failure at altitude - say FL390, then why the rush (second line item) to attain optimum relight speed 300kts? Surely better managemnt would be to acheive the best drift down speed, gaining posibly precious miles, until approaching/below FL250 - as stated on Pg 2 of the checklist, when a windmilling relight would be possible - or aactually. keep the optimum drift down speed rather than 300kts between FL250 and FL200, and go for a starter assisted attempt at FL200.

vilas
29th Oct 2018, 12:33
say FL390, then why the rush (second line item) to attain optimum relight speed 300kts? because possibility of engine rotor seizure at low RPM due to low IAS. You should put the aircraft in shallow dive and pick up an airfield which is within the gliding distance from DATA-CLOSEST AIRPORT and head towards it, declare May day and then when within the envelope attempt relight.

Goldenrivett
29th Oct 2018, 15:00
why the rush (second line item) to attain optimum relight speed 300kts?

You may have "roll back" (very low RPM) and flying at the relight speed will help N2 to be at / above self sustaining RPM (provided combustion continues).
See Page 21 https://www.airbus.com/content/dam/corporate-topics/publications/safety-first/Airbus_Safety_first_magazine_07.pdf
"1) During the engine start sequence all fuel pumps were left in the OFF position, leading to the triggering of the following ECAM Cautions: FUEL L TK PUMP 1+2 LO PR FUEL R TK PUMP 1+2 LO PR The crew cleared both Cautions but left the fuel pumps in the OFF position. As a consequence, both engines were being gravity fed during the engine start, take-off and climb phases of the flight.

2) The behaviour of the engines was normal until the aircraft reached FL380, some 23 minutes after take-off. At that point, both engines rolled back, leading to: The Mach Number to decrease from M0.78 to M0.63 The disconnection of the Electrical Generators 1&2 (Engines 1&2 N2 being below 53%) The Ram Air Turbine deployment (Emergency Electrical Configuration).

3) The aircraft started to descend and the crew declared an Emergency. At FL 320, the engines were recovered leading to an automatic re-connection of both Electrical Generators. The crew then decided to turn back to the departure airport where an uneventful landing was performed."

WTF?