FMC FAIL

P6-1D Transfer Bus 1 Sect 1-115v ac
P18-2A Stanby Bus Sect 1-115 ac (as wired)
Transfer Bus 2 Sect 2-115v ac (optional FMC 2)

Condition : “FMC” message or MENU page on both (M) CDU
Other indications are LDG ALT message displayed on the altimeter(because the landing field elevation is missing) and A/T LIM on the TMAP

(As installed) The MCDU remains available for ACMS - ACARS functions.

On GND - Refer to MEL 34-xx[(Flight Management Computer System (FMCS)]
File new flight plan without RNAV capability.
- Enter the aircraft parking position through ISDU on aft OVHD panel
- Obtain takeoff thrust setting in FPPM or PI [General - Takeoff %N1]
Verify if your SOP allow redueced thrust with (both) FMC inoperative.
Calculate also climb %N1 for thrust reduction after takeoff and the maximum continuous %N1 for an engine failure on takeoff. For the latter, use table PI [Engine Inoperative - Max Continuous %N1 - 10000 FT to 1000 FT].
Insert N1 via the N1 Set knob as follows :
SP 7.x [Setting N1 Bugs with an Inoperative FMC]
- Select BOTH and insert N1
- leave the knob in BOTH, do not return to AUTO
Insert V1and VR via the SPD REF selector as follows :
SP 10.x [Setting Airspeed Bugs with an Inoperative FMC]
- select and insert V1 (to display V1 on speed tape)
- select and insert VR (to display R on speed tape)
- select and insert WT (for flaps smaneuvering speeds)
- select SET
- The A/T is not available for takeoff, however, the A/T can be used in flight.
Nevertheless, press TO/GA on takeoff to engage the F/D.

In FLT
- LNAV and VNAV are no longer available. Advise ATC “UNABLE RNAV”.
Use conventional navigation with VOR mode. MAP mode can still be used for navigation to intersections (select STA and WPT). The FMC is not required for CAT II/III approach and not for RVSM.
- Obtain final approach speed from PI [General - VREF].
Insert VREF and landing weight via the SPD REF selector as follows :
SP 10.x [Setting Airspeed Bugs with an Inoperative FMC]
- select and insert VREF (to display REF on speed tape)
- select and insert WT (to display all flaps maneuvering speeds)
- select SET
- Obtain the G/A thrust setting from PI[General - Go-Around %N1].
Insert the N1 setting via the N1 SET knob as follows :
SP 7.x [Setting N1 Bugs with an Inoperative FMC]
- select BOTH and insert N1
- leave the knob in BOTH, do not return to AUTO

RIGHT FMC FAIL (DUAL FMC - As installed)
SOP - B-RNAV requires only one FMC. Both FMC must be available for P-RNAV.
The message “SINGLE FMC OPERATION” appears on the CDU screen. LNAV and VNAV are not available on Autopilot B.
VTK amber annunciation appears on the right ND. If the VTK amber annunciation does not appear, the right FMC did not fail, but both FMC data disagree. Position the FMC Source Select Switch to BOTH on FMC L to resynchronize the right FMC. The message DUAL FMC OP RESTORED apears when resynchronization is completed.

LEFT FMC FAIL (DUALFMC - As installed)
SOP - B-RNAV requireds only one FMC. Both FMC must be available for P-RNAV.
The following illustration shows dual FMC normal operation and FMC-L failure.

FMC FAIL

Condition : Display of VTK followed by MAP failure flags on one or both navigation displays.
Objective : To restore dual FMC operation, configure for single FMC operation or resume conventional navigation.

Note: LNAV/VNAV may disengage.
Note: The FMC FAIL checklist is written solely for an inflight failure of the FMC. Before takeoff, refer to the MEL.

1. Check both navigation display MAP modes and FMC CDUs.

2. Choose one:
   No FMC data on the captain’s and first officer’s navigation display MAP modes and no FMC data on both CDUs:
   Both FMCs are failed.
   Go to step 7
   No FMC data on the captain’s navigation display MAP mode and no FMC data on both CDUs:
   Left FMC is failed.
   Go to step 3
   No FMC data on the first officer’s navigation display MAP mode, MSG light is illuminated and SINGLE FMC OPERATION scratchpad message is shown:
   Right FMC is failed.
   Go to step 3

3. FMC source
   Select switch BOTH ON L or BOTH ON R
   Select the operating FMC.

4. Wait 1 minute.

5. Check for FMC-L and FMC-R bearing/distance information on POS SHIFT page 3/3.

6. Choose one:
   Bearing/distance information for both FMCs are displayed:
   FMC source select switch NORMA:
   COMPLETE
   Bearing/distance information for only a single FMC is displayed:
   Continue with single FMC operation.
   COMPLETE

7. Resume conventional navigation. Without and operating FMC, LNAV and VNAV are not available.

8. Verify position relative to terrain using convertional navigation.
   Note: EGPWS may use unaccurate GPS position data or an inappropriate value of RNP. This could result in a VSD terrain display that is incoorectly positioned relative to the airplane track.

9. When preparing for the approach:
   Use the SPD REF selector to set the current gross weight.
   Use the SPD REF selector to set the reference airspeed bugs.
   Use the N1 SET selector to set N1 bugs.
   COMPLETE