Hi! Was flying trip a while ago that necessitated several legs to the journey and I noticed on one landing that it seemed like the pilot had the nose wheel fully braked before the nose wheel actually hit the ground and when the nose wheel did hit the ground it caused a huge jarring to the nose wheel assembly as if the nose wheel was fully locked when the nose wheel hit the ground.
So what happened in sequence seemed to be normal, ie, the rear wheels touched down and I can't remember for sure because there was nothing noteworthy at that time to pay much attention, but I don't remember feeling any braking action being applied to the rear wheels at that time, and I'm only guessing here, but wouldn't it be a little risky to apply braking to the rear wheels before the nose wheel is on the ground because wouldn't that slam the nose wheel into the ground at an unnecessary loading, and by the way, the nose wheel did not seem to be slammed into the ground by any braking action on the rear wheels and that's another part of my question.
But what happened next is the cause of my question.
When the nose wheel did hit the ground it felt exactly as if the front wheel brake was already fully applied, so it felt like the front wheel was not free to rotate when it hit the ground and that caused a massive jarring and shuddering at the front end and it felt like the pilot realized straight away what was wrong and released the front wheel brake so the wheel could then roll, and then when it was rolling, then it was fine to apply all the brakes in the normal way.
So it made me wonder, are passenger planes fitted with separate front and rear wheel braking abilities like on a motor cycle or do they have combined front and rear wheel braking like in a car?
I don't remember for sure but I think it was a 777 I was on at the time.
If the front and rear wheel brakes are indeed separate, as it appears they could be on the basis of what I perceived that day, then isn't there a way for the plane to override the pilot if he's applying the front wheel brake before the front wheel hits the ground on landings?
Or do they have that override system and it just failed that day?
Or, do they have a joined up brake system for the front and rear wheels and my perception that the rear wheels were not being braked before the front wheel hit the ground was wrong so then that too could account for the front wheel being locked when the front wheel hit the ground?
I would guess that rear wheel braking before the front hit the ground could be risky in case there was an imbalance between left and right braking that could cause some slewing to one side or the other and without the front on the ground at that time it would seem you have less control and less ability to correct by steering the front away from the side that the plane was veering towards.
I'm maybe guessing too much here, only being used to motorcycles and cars and having no experience at all in aircraft control but it did make me wonder what was going on that day.
I'm assuming the makers overbuild their structures to take into account some exuberant flying techniques but how many times can they handle that kind of abuse to the front wheel structure, not to mention the locked front wheel would be trying to tear the front wheel structure entirely off the chassis at those sort of speeds and with that sort of loading?
On another aircraft control matter, I've noticed that some passenger planes on braking when landing have a severe front end slew that causes the plane to veer from side to side at the front while under braking.
I guess that could be caused by the runway having grooves like you get on the highways from heavy traffic or it could be a design problem or a maintenance problem or maybe it's not even seen as a problem?