boeing 777 ADIRU

[allflight57]

How come in the 777 you usually see the ADI on the PFD is up while parked at the gate even though the ADIRU is off b/c theres no hdg info on the nav display? is the ADI fed information from a different source than the navigation info? basically im comparing the 777 to the rest of th boeings how the IRS i nthe others is off the ADI goes out too except of course in ATT mode. why is the ADi up on the 777 even tho the ADIRU is off? thank you for replies
http://www.airliners.net/open.file/1196630/L/

http://www.airliners.net/open.file/1059910/L/

Tyler

[cirrus01]

SAARU is your answer......will give ATT info. When you electrically power up a dead 777 this is what you get. The aircraft goes thru a series of power up checks which take about 6 minutes and has noticeable cockpit effects, then is fully powered ( like in the supplied picture -link )
Switching on the ADIRU and inputting a valid Lat / Long position will then give you the rest ATT/ Hdg /Pos . ( after a further 11 minutes )

[allflight57]

o ok thanks for the info, do you know of any websites besides smartcockpit.com that go into good detail about the 777 systems? thanks

Tyler

[MrBernoulli]

I've looked for a long time now - not much out there!

[stevehudd]

Ive flown 35 hours in a PA28 and forgot what an ADI is :ugh: and ive searched google. Is it attitude direction indicator or am i suffering aero toxins?

[stevehudd]

OK Ive found a link telling me what ADI means, thanks for getting back to me :rolleyes:

http://www.aircav.com/cobra/cockpit/pilot/adi.html

[SuperRanger]

hi allflight57,
the reason there is no 'HDG' info is because the ND is selected to MAP which will give TRK info and as it was probably the end of the flight, thus no route info in the FMC i.e. no TRK info on ND. this is the normal confiq when the acft comes to the parking gate. if you switch to VOR iso MAP, then you WILL see the HDG info.
the b777 PFD works the same with other boeings. the photo you posted, the ADIRU was aligned!
hope this helps...
SR
ps: perhaps i will take a photo of the flight instruments WITH the ADIRU OFF on my next flight and post it here.

[pinkhyppo]

You will see that HDG in amber is displayed at the bottom of the AH.
What it means is that the AIDRU is aligned but awaiting LAT/LONG input.

In another words, it is waiting to be initialised.

If it is not aligned, there will be yellow flags all over the place just like any other Boeing.

Hope it helps.

Cheers!

[Swedish Steve]

The B777 is not like any other Boeing because of the SAARU. When you turn off the IRU (There is only one, but it has lots of gyros in it) the SAARU, or standby IRU, keeps running, powering the Standby Horizon, like on any other aircraft, but on the B777 its output is also fed to the main AHs. To get all yellow flags on them you must switch off the SAARU as well, which can only be done by tripping the CB.