Page 185 - Demo

CHINA AIRLINES
AOM A330-300
OEB
NO ENGAGEMENT OF GUIDANCE MODE
2.50/3
REV 25
REASON FOR ISSUE :
The objective of this OEB is to highlight that in the event of an erroneous Radio Altimeter (RA) height indication, guidance modes may not engage as expected.
EXPLANATION :
If a RA transmits an erroneous height indication, this may have any of the following effects on the auto flight system depending on the flight phase. However, these effects may not necessarily occur in every case of an erroneous RA height indication.
Auto Flight System mode changes (indicated on FMA):
− NAVmodeengagementisnotpossibleaftertakeoff
− Incaseofgo-aroundandiftheRAisstillfrozenatavery
low height indication :
! SRSandGATRKmodesengage,
! NAV,HDGorTRKlateralmodescannotbeselected,
! LVRCLBwillnotbedisplayedontheFMAatTHRREDALT, ! ALT*andALTwillnotengageatFCUaltitude.
Disconnecting AP and resetting both FDs enable to recover basic mode (HDG and V/S).
PROCEDURE :
! During Go-Around
! If SRS and GA TRK modes remain engaged and other guidance modes cannot be selected or engaged as expected:
Note : At the thrust reduction altitude, LVR CLB
will not be displayed on the FMA,
ALT* and ALT will not engage at the FCU
altitude.
Disconnect APs.
Set both FDs to OFF then ON. FDs revert to basic modes (HDG - V/S).
Re-engage guidance modes as appropriate.
! For the approach that follows the go-around: Do not arm the G/S mode.
Flight crews must report, in the technical logbook, any of the above-listed consequences of erroneous RA height.