RAT Airbus
 

G'afternoon all: if I had an electrical failure, now in EEC, how long can I use the RAT? No limit?
TIA
DP

Choices?
 

Not sure what your question is. What choice do you have?

I want to know if there is a limitation in time for the RAT in the event of an electrical emergency config. Can I reach an airport at 45 minutes in Emergency Electrical Configuration?

The only RAT limitation is speed:

min 140 Kts
max 320 Kts (only for some serial numbers)

how much fuel do you have?

1% fuel penalty + 3-4% for EEC due Engine anti ice valves being opened.

Newer 320, min spd 125 kts, no max limitation for RAT however lack of high speed protection would be the limiting factor (still 320 kts).

No time limitation for RAT.

correct, newer types have 125 lts as min speed

There would be an implicit limitation on flying in the EEC with the RAT deployed IF the gear is down! Battery time.

Its a turbine
 

RAT is nothing but a windmilling turbine.As long as one can supply it with sufficient air it will run.once gear down the air flow is disturbed and hence stalls at140 (old RAT) 125 (newRAT).
So to answer your question it can run forever.
bear in mind you would run out of other things like battery, fuel etc..:hmm:

Knowing little about Airbus systems does their RAT only supply electrical power? When would it be deployed?

In the electrical scenario, the RAT extends automatically when :
1. Both, AC BUS 1 and AC BUS 2 are not powered, and
2. Aircraft speed above 100 knots.

The RAT can also be used to pressurize the BLUE HYDRAULIC system.

As far I Know, the RAT feed the battery, its that correct?

As far I Know, the RAT feeds the battery, its that correct?
Sorry, the RAT feeds the Hidraulic system, the hidtaulic system feeds the Emergency generator and the Emergency Generator feeds the Batterries

The RAT feeds the essential busses, AC ESS BUS and DC ESS BUS, though the ESS TR, not the batteries! Batteries are not charged by the emer gen, and they will drain whenever the emer gen is not on.

As DP said, the RAT feeds the Emer Gen, and this gen is no longer supplied when the gear is down. But if you go-around, rest is possible after the gear is up. Just reset the EMER GEN MANUAL ON switch

To clarify some of the above . The A320 Family comes with 2 standards of RAT and Emergency Electrical System .

For both standards , the RAT just pressurises Blue , which drives the EG which supplies AC ESS and DC ESS ( and AC ESS SHED and DC ESS SHED ) , It does not supply anything else , including the Batteries , and the only other Busbars available are the 2 Hot Bat Busses and the Static Inverter Bus. There is no published limit for Flight in this configuration , but ECAM will display LAND ASAP in Red . The aircraft is in Alternate law ; APs , FDs and A/THR are unavailable .

For the 'old' standard , a minimum airspeed of 140 kts is required for RAT operation ; but if the Nose Landing Gear is extended - at any speed - the EG is disconnected ; Batteries supply AC and DC Ess (and Static Inverter Bus) but both 'Shed' busses are lost ( leading to loss of FMGC1 , MCDU1 and ND1 , amongst other things ) . Battery Endurance is quoted as 22 mins , but may be extended to 'up to 30 mins' through application of the Paper 'Flight On Batteries Only' procedure , which involves de-powering ADR1 and the subsequent loss of PFD1 Air data ( use Standby Alt & ASI ) :eek:

After the GA , and following NLG Retraction , the EG can be recovered through the 'RAT and EG MAN ON' p/b ( min 140 kts) .

For the 'new' standard , RAT stall speed is 125 kts ; and there is no EG disconnect with NLG extension . The EG should remain supplying until touchdown and so the aircraft should never become 'Batteries Only' .

This explains the difference between the Procedures for the Old and New standards : in the former , there is a concern both with preserving Battery Power , and preparing for the consequences of loss of FMGC1 with Gear Extension ; for the New standard these are not considered important .

For instance , for the Old standard , the Procedure advises against attempting an APU start ( for 'simultaneous' loss of Gens/Busses 1 & 2 : even if the APU is started , the Electrical System Fault which has in all probability caused the original loss of both AC busses will also prevent APU use ; but the cost of the attempt is 3.5 mins worth of Battery ) .

For the New Standard , the advice is to try and start the APU . It might recover AC1 or AC2 ( or both) , but if it doesn't , any Battery power loss is not significant to the overall situation. :)

Ess Shed Bus
 

does anyone have idea how much time SHED BUS(es) power when emergency case? all the time right?
i ask this question 'cause I see in the test of AC Emergency, if test continues over 30 seconds, the legend FAULT of EXTRACT P/B SW comes on. However in this config. extract fan is fed from DC ESS SHED while DC ESS SHED is powered!!!
am waiting for ur ideas. thks all

No, 18HQ needs AC-power. He is powered by 2XP (AC BUS2). :ok:

If the RAT's deployed and you're in Emergency Electric configuration (ie. not a manual deployment for a blue hydraulic fault). Don't forget that LAND ASAP will appear on the E/WD. That's very significant. Maybe flying for 45 minutes wouldn't be so smart. Unless of course you're genuinely that far from the nearest suitable airport (eg. 40W!); in which case I apologise...

Cheers

Don't forget that A320 family aircraft can operate 180 minute ETOPS.

Why would there be a "minunum speed" for RAT deployment?

Isn't RAT deployment automatic?

Are you not allowed to have an emergency situaion where RAT deployment is required under 125/140 kts?