B787 FLT CONTROL MODE

[fast cruiser]

Hi Guys

Can anyone explain why when you have this failure you cannot use FLCH SPD with flaps not up and not allowed to follow flight director pitch guidance?

QRH notes indicates a service bulletin FCE CBP2 but i don't have this bulletin as it is engineers only by all accounts!

thoughts please?

[FCeng84]

This message is an indication that the 787 Primary Flight Control System has dropped to Secondary Mode. The Autopilot will no longer be available. I am not sure of the status of the Flight Director. One of the most likely reasons for losing Normal Mode and ending up in Secondary Mode is loss of valid air data which would make any Flight Director commands that rely on air data similarly suspect.

[Roj approved]

Hi Fast,

Do you have a reference for this? My company QRH doesn't mention it (although I do remember it from the type rating)

My take on it is the FLT DIR will indicate whatever the MCP/FMC is programmed, but the lack of Autopilot combined with what FCeng84 said, plus no autothrottle wake up in FLCH SPD will make this a perilous combination.