A319 HYD Y OVHT

[Check Airman]

Hi,

I recently had a HYD Y RSVR OVHT ECAM pop up after landing. The EWD and SD gave the expected indications, but the Y pump and PTU buttons had no fault lights. We did a light test, and everything was normal. Any ideas why neither fault light illuminated?

[FlightDetent]

Did you have an overheat condition of the hydraulic system? I mean, as opposed to message about the said condition, i.e. false / spurious warning perhaps?

[Check Airman]

The message stayed on for maybe 5-10 minutes before disappearing. By that time we'd already performed the ECAM actions (shutting off the pumps).

[Uplinker]

Off the top of my head, because I haven't looked this up specifically, but I understand that some systems on the Airbus have several sensors for the same parameter; one for the ECAM, one for the instrumentation etc.

Sometimes you can get a spurious warning from one dodgy sensor, but the other sensor measuring the same parameter sees no fault, so you only get a partial fault indication.

That might be what happened here?

[FlightDetent]

I checked that already, expecting to see exactly as you say. But FCOM shows single source of information, a temperature sensor in the accumulator, feeding three indicating, otherwise independent, systems.

a) the individual OVBH PNL push-buttons
b) ECAM SD HYD pg
c) FWC

The period of steady indication by FWC is long. Was there OVHT indication on ECAM SD too? I feel this already is a trained MX territory, i.e. not mine. Through BITE they'd be able to recover more data on what has actually happened.

Well spotted CA!

[Check Airman]

Uplinker, I was thinking along your lines as well, but FlightDetent noted that there's a single sensor providing 3 outputs.

FD, the SD displayed the overheat as well.

[FlightDetent]

Many systems are far more elaborate than the schematics from FCOM suggest.

[bigbird]

I believe this phenomena was covered by an Airbus 'Flight Operations Transmission' dated 04 July 2013.
Airbus Ref: 999.0040/13
Subject:ATA 31/29 SPURIOUS Hyd B(G)(Y) RSVR OVHT ECAM ALERTS DUE TO SDAC MISBEHAVIOR.

Applicable to A318/A319/A320/A321

1.Background

Some operators of A320 family aircraft reported spurious triggering of several HYD B(G)(Y) RSVR OVHT ECAM alerts during cruise, on aircraft equipped with System Data Acquisition Concentrator (SDAC) H2 units identified wirh PN 350E550020x. These ECAM alerts affected one or several hydraulic circuits, and were not associated with the respective HYD ENG PUMP FAULT light indicators on the overhead panel'


2: Explanation

The SDAC receives several types of analogical signals, and converts them to ARINC information. These ARINC information are sent to several aircraft systems for the display of indications on ECAM system pages and for the triggering of aural alerts. These ARINC information are not used to ensure the lighting of local FAULT lights of the Engine Driven Pumps (EDP's), Electrical Pumps (EMPs), and Power Transfer Unit (PTU) pushbutton switches on the overhead panel.

Investigations confirm that the root cause of these spurious ECAM alerts is a faulty component in the SDAC H2 units identified with PN 350E550020x as per OIT REF 1.

The faulty component causes the SDAC to send erroneous ARINC information that may cause the ECAM to display erroneous information:
-One or several of the ECAM alerts HYD B(G)(Y) RSVR OVHT.
-Changes in parameters or erroneous indications on the ECAM system page 'HYD' (as described in OIT REF 1).

Investigations confirm that the ECAM alerts HYD B(G)(Y) combined with the 'OVHT' indication displayed on the HYD systems page, were not associated with the lighting of the respective FAULT lights of the EMP(s), and/or PTU pushbutton switches on the overhead panel.


3. Operational recommendations

If the HYDvB(G)(Y) RSVR OVHT ECAM alert(s) are triggered and combined with:
-An 'OVHT' indication displayed on the HYD system page
-The lighting of the respective FAULT lights of the EMP(s), and /or EDP(s), and/or PTU pushbutton switches, then

the flight crew must complete ECAM alert(s)

If one or several HYD B(G)(Y) RSVR OVHT ECAM alert(s) are triggered and combined with:
-An 'OVHT' indication displayed on the HYD systems page
-No associated lighting of the respective FAULT lights of the EMP(s), and/or EDP(s), and/or PTU pushbutton switches, then

The flight crew may suspect SDAC misbehavior (as described in this FOT and OIT REF 1) and can consider these alerts as spurious.

[Check Airman]

Many systems are far more elaborate than the schematics from FCOM suggest.

I don't doubt that, especially on the 320

[Check Airman]

Many thanks bigbird. This wealth of information is what makes this site great.

[Lantirn]

Very nice...

How one can have access to FOTs? I have seen some only via our technical pilot only.

Airbusworld or airbusupply maybe?

[bigbird]

Sorry, I don't know how we mere pilots have access to FOT's. The airline I fly just forward most stuff like this to the crews, to cover their ass i guess. I would suggest getting on to your fleet management, might be worth them sicking a notice out.
Good luck.

[Lantirn]

Its very interesting but you have to get filtered FOTs according to your fleet otherwise you would get a lot of unnecessary information. Maybe our fleet has been updated with newer installations so we get fewer such notifications.

Anyway it's good to know, you always learn something.