nr1chris
6th Sep 2023, 11:10
Having smoke in the A330 cockpit with intentional ELEC EMER CONGIG set I push all GEN ON before landing.
Question 1:
Does the ECAM show a ELEC EMER CONFIG status (GEN 1 and/or GEN 2 RECOVERED) asking me for RAT MAN ON (before LAND RECOVERY ON) and L/G GRVTY EXTN?
Question 2:
Why do I extend the RAT and the L/G by gravity when I have a normal hydraulic and a normal electrical configuration?
SECsmachine
10th Sep 2023, 07:16
Not speaking from experience (I’ll try and have a look what the sim does when I'm in next time), but things to consider:
You’re not really in a normal electrical or hydraulic configuration, even after restoring the GENs, since the AC and DC ESS BUSs remain connected to the EMER GEN (along with their respective SHED buses). The G HYD is also still supplying the EMER GEN which is not a normal situation.
According to the diagram in FCOM DSC 24-10-10, and FCTM PR-AEP-ELEC, LAND REC busses remain disconnected from the DC and AC busses until the LAND REC pb is pushed, so pressing it prior to approach is still a requirement,
Dropping the landing gear by gravity avoids transient fluctuations in G HYD pressure which might affect the EMER GEN.
Not 100% sure on the role of the RAT in this scenario, since the HYD EMER GEN is running, but dropping it does ensure some G HYD fluid becomes isolated in the RAT system, so is protected from leaks/problems with the rest of the HYD circuit and would offer some redundancy at low altitude in the event of G HYD pressure issues (maybe a higher risk on gear extension?). Looking for a definitive answer in that one though.