Triple 7's and Main Wheel Alignment
 

Was watching the news the other day with the B52's touching down in England in crosswind.

Typically the point came up about the main gear on these aircraft being able to align with the runway, when a friend mentioned that this can also be done on the 777, by dialling the QDM into the FMS..........any truth to the rumour?

Main gear steering is commanded locked when takeoff power is set. It's not armed anyway until >13 deg of nose gear steering is selected and it is only the rear two wheels of the truck that are steerable (upto 8 degrees!) Designed just to reduce tyre scrub.
I can't remember when it becomes active on the rollout though!

The main gear steering is only a function of steering tiller position.

When either tiller is turned more than 13 degrees a signal is sent to unlock the main gear steering actuator. The aft axle is then steered proportional to NLG steering position.

When tiller angle is less than 9 degrees the steering actuator is signaled to lock in the centered position.

Hope this clears things up.

Certainly does...sounded a bit of an 'old wives tale'!

Thank you chaps

Older models (1960?) of the Cessna 180 had a X-wind function on the mains allowing to land with drift, some fun observed on taxi at times.
Better boffins than me can add I am sure.