A330 Emergency electric configuration

[BITE System]

Was looking at the emergency electric configuration and it seems that if you are down to the emergency generator, powered by the RAT, for navigation you have RMP1 which will give you access to the ILS and VOR 1 or ADF 1 depending on which one has been selected on the DDRMI but ……..on many of the new A330s you do not have the DDRMI (nice familiar instrument) and your ND is not working (emer gen powered by RAT). So when you are in this situation you are only able to fly to an airport with an ILS? Am I missing something? I realise that the probability of this happening is very low. My question …..How has airbus been able to get certification for aircraft without this stby instrument? It seems that many national authorities have gone along with airbus and certified this?

[Henry VIII]

As far as I know DDRMI is an optional.
No idea about certification procedure.

[Capt Turbo]

BITE
The RAT will deploy if you have an "emergency in an emergency", namely to cover the extreme situation, where - on takeoff - you have an engine explosion that results in dual hyd line damages and subsequent leaking of Green + Yellow or Blue hyd fluid. The green HYD shutoff valve will close and the RAT automatically deploy to pressurize the remaining green fluid to ensure some flight control efficiency.
If - at the same time - you are in EM ELEC COND and your speed is below 260 KIAS the RAT efficiency is insufficient to both supply flight controls and EM GEN fully, and some elec bus shedding occurs. I believe this is the situation that you refer to, but this situation will probably not occur outside the terminal area.

In other words, the situation where you will have three generator failures + an engine explosion with separation and dual HYD loss in the middle of nowhere and be forced to slow down to low speed thereby loosing part of the NAV is highly unlikely. However, your concerns are shared by many pilots as the FCOM and the type conversion program does not emphasize the remoteness of this situation to occur.

As this explanation is purely from memory, do correct me if there are more likely scenarios where you end up on "RAT only" outside radar coverage. We all know that "S**t happens" and unexpected system interface ruins the day!

Out of curiousity, which airlines do not have the DDRMI installed? It is not described as "optional equipment" by AI.

Capt T.

[BITE System]

Capt T

We have quite a few A330s and a few new shiny ones. The new kit do not have the DDRMI, hence my question.

[A330AV8R]

BITE ,

The newer A330's are the one's ( at least all of our 13 fleet ) do not have the DDRMI's installed , that is simply because now on the newer mod's (company optional) mind you when you are in EMER ELEC CONFIG the Capt's PFD1 AND ND1 are still fully functional (EDP power source only) when your on the RAT PFD 1 only avail cutting a long story short !

If you want detail let me know .

:ok:

[BITE System]

Airfranz

Exactly my point, in that configuration ….. RAT powering the Emergency generator; you have lost the ND1 and if you do not have the DDRMI (on these new aircraft) you only have the STBY magnetic compass to navigate with………

[A330AV8R]

BITE

I apologise , I misunderstood your query . . . . in Emer Elec Config WITH RAT as the only power source , you STILL do have RMP 1 and VOR 1 to navigate , when LAND RECOVERY is pressed you then recover ILS 1 .

In some of the later mods ( in this case ) even the ND 1 is still available with the RAT as the power source( which I have seen in the SIM ONLY ) that would depend on individual aircraft mod , hope this answers your question , you might have to check with the ramp rats for your aircraft specific .

:}

[BITE System]

I was recently quizzing a long time airbus colleague and he said that in this situation (RAT powering the Emergency generator) you could push the PFD/ND push button to change over from the PFD to the ND in order to have a VOR display indication and use the STBY horizon for attitude information. Not sure if this would work?