LGCIU A320

[Royale]

I am relatively new to the A320, and I am trying to better understand the Landing Gear indication and the LGCIU's.

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/1191x754/landing_gear_indicator_panel_6a60fe333a55f921d9c0f4a02562376 d3de2efd6.jpg

With reference to the above text, the highlighted text in particular, is would seem the the Landing Gear Indicator Panel, works as long as LGCIU1 is electrically supplied, and even if you have a L/G LGCIU 1 FAULT.

Is that correctly understood?
How does this actually work technically speaking, I have read on the internet that its "Hardwired" through LGCIU1, if so is there any official documentation supporting this?



https://cimg6.ibsrv.net/gimg/pprune.org-vbulletin/810x737/landing_gear_selector_lever_fd8c6ca07f3c52bef28776e6105e558a 35d75c9a.jpg

On the Landing Gear Selector Lever there is a Red Arrow (2), which will come on when the Landing Gear is not down under certain conditions.

Where does this arrow get its information from, is that also LGCIU1 - the FCOM does not state this as far as I can see?
A colleague told me that the Red Arrow operates independently to the LGCIU's, and would work correctly even if both LGCIU's were lost, and even if LGCIU1 was unpowered, so that in the case of no Landing Gear Position indication after emergency extending the landing Gear, if the Red Arrow did NOT come on during approach the Landing Gear is down and locked. I cannot find any thing to prove or disprove this in the FCOM. Is his statement correct on not?



Can anyone with access to more detailed information than the FCOM for example Maintenance Manuals enlighten me on this subject, it would be highly appreciated.

I am only looking for documented information, all the "rumors" I can find for myself using google.

Stay safe and healthy.

[vilas]

Royale
Landing gear control panel shows indications only from LGCIU1 when it’s supplied electrically. Obviously when LGCIU1 is faulty the indication will be unlocked. It has nothing to do with LGCIU2.
Landing gear lever red arrow comes into play below 750ft if flaps are in landing configuration and lever is up. It is either connected directly or indirectly to both LGCIUs or ECAM warning.
Below 750ft if gear lever is down and one of the LGCIU1 sensor spuriously detects not down locked it will trigger unlock light on the panel as well as on SD wheel page unlock indication on LGCIU1. But no red light on landing gear lever.
If one of the struts is genuinely detected by both LGCIUs as unlocked it will trigger
“L/G NOT DOWN LOCKED” ECAM WARNING
Continuous repetitive chime with Master warning
Unlock red warning on landing gear control panel
On the ECAM SD page both red lights on affected gear strut.
Red arrow on landing gear lever control panel.
ECAM MEMO will remain blue.
You may refer to Airbus Safety first issue #10

[Royale]

Hi Vilas thank you for replying.


Obviously when LGCIU1 is faulty the indication will be unlocked.


That is actually the crux of my question, and maybe not so obvious to me, there is a big difference between being electrically supplied, and being faulty. As I see/read it is is a possibility that you have an L/G LGCIU 1 FAULT, and at the same time LGCIU1 is still electrically supplied, the fault could be caused by a multitude of other reasons. Taking the FCOM verbatim in that context, the Landing Gear Indicator Panel should still work.

[vilas]

Hi Vilas thank you for replying.



That is actually the crux of my question, and maybe not so obvious to me, there is a big difference between being electrically supplied, and being faulty. As I see/read it is is a possibility that you have an L/G LGCIU 1 FAULT, and at the same time LGCIU1 is still electrically supplied, the fault could be caused by a multitude of other reasons. Taking the FCOM verbatim in that context, the Landing Gear Indicator Panel should still work.
The indicator panel works with bulbs which are connected to LGCIU1 sensors. It has two indications green traingle or red UNLK. If one of the sensors senses a strut is unlocked that particular gear unlock light will be on, that's all. It doesn't show anything else. But to indicate that status it needs electric supply. If not supplied it will remain blank. The landing gear lever down red indication is most probably linked to gear not locked ECAM warning which comes when both LGCIUs confirm that. Other than that it remains off.

[vilas]

What is important to know is there are two ECAM warnings Landing gear not down and Landing gear not down locked. They are different. Not down locked warning will come with advice to recycle and if not successful gravity extension.
With gear not down message you need to check on wheel pagea least one green on all three and Landing Memo landing gear DN in green ensures gear is down and locked.
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