IRS Fault 737NG
Thread Starter
Joined: Nov 2008
Posts: 31
Likes: 0
From: east boston..
IRS Fault 737NG
Hi guys just a quick question
Regarding an IRS Fault on a 737NG and can i still use the F/D, according to the QRH checklist im no longer able to use the autopilot.
But im wondering can i still use the F/D if i switch the IRS mode selector on failed side to ATT and let it re-level after 30secs etc etc ??
I know autopilot uses pitch data from on-side IRU and roll data from the other IRU so this would tell me that if i reset the IRS using the ATT selection and the outcome is successful i can use the F/D ??
The other option in the QRH is to switch the failed side onto the functioning IRS using the IRS switch L or R, so im thinking if this option is used the F/D can no longer be used as i then just have one source of data.
Just want to clear this up and thanks for any replies.
Regarding an IRS Fault on a 737NG and can i still use the F/D, according to the QRH checklist im no longer able to use the autopilot.
But im wondering can i still use the F/D if i switch the IRS mode selector on failed side to ATT and let it re-level after 30secs etc etc ??
I know autopilot uses pitch data from on-side IRU and roll data from the other IRU so this would tell me that if i reset the IRS using the ATT selection and the outcome is successful i can use the F/D ??
The other option in the QRH is to switch the failed side onto the functioning IRS using the IRS switch L or R, so im thinking if this option is used the F/D can no longer be used as i then just have one source of data.
Just want to clear this up and thanks for any replies.
Joined: Apr 2010
Posts: 1,320
Likes: 102
From: IRS NAV ONLY
If you put IRS transfer switch to the operating side, you will have both F/D and A/P.
The reason why QRH (and the MMEL) say A/P should not be used is because you are left with only one source of data and no way of knowing whether the supplieed data is faulty or not.
The reason why QRH (and the MMEL) say A/P should not be used is because you are left with only one source of data and no way of knowing whether the supplieed data is faulty or not.
Joined: Jan 2002
Posts: 114
Likes: 0
From: germany
Nope, AP will not necessarily work. Depends on the config, eg with the analog SBY ATT indicator it won't work. With the ISFD usually the AP will work with one ADIRU failed.
Had one fail on me and had to handfly quite some time..
Had one fail on me and had to handfly quite some time..
