Airbus Boeing Objective Differences Compilations (Not a discussion)
The older Boeings maintain a full manual reversion in the event of hydraulic failure.
Starting with the 747, you've pretty much needed hydraulics to have a happy outcome.
Really? I thought all the models pre-737 had manual reversion as well. It's a luxury I'm loth to give up, having only been rated on aircraft that have cables as the ultimate backup.
That's what he said actually.
B707 was always in 'manual reversion' as it used control tabs for most control surfaces except rudder.
B727 controls were fully powered but had complete manual reversion available and rudder control through a standby system.
B707 was always in 'manual reversion' as it used control tabs for most control surfaces except rudder.
B727 controls were fully powered but had complete manual reversion available and rudder control through a standby system.
Last edited by stilton; 5th Dec 2014 at 08:20.
Join Date: Nov 2003
Location: Amsterdam
Age: 70
Posts: 159
Likes: 0
Received 0 Likes
on
0 Posts
I thought all the models pre-737 had manual reversion as well
short flights long nights
I may do it, without noticing that I am doing it, but I find compared to the 737, I hardly trim the 777 at all.
Join Date: Jun 2012
Location: -
Posts: 1,175
Likes: 0
Received 0 Likes
on
0 Posts
Once again, not rated, but is my understanding that the 777 trims on her own, you just select the trim reference speed and then based on your attitude and thrust she trims to chase that trimmed speed. She also trims on her own with configuration changes (gear down, flaps). Is that correct?
Join Date: Jan 2006
Location: US
Posts: 2,205
Likes: 0
Received 0 Likes
on
0 Posts
It's been a couple years since I've been in the books but here goes - moving the trim switch basically takes a snapshot of the current speed. I think the actual limit it will adjust is 10 kts per click. So if you're 20 kts off of trimmed speed - click, click, and you're in trim. Because of that you trim a lot less.
And it auto trims for configuration changes. Very user friendly.
And it auto trims for configuration changes. Very user friendly.
Last edited by misd-agin; 7th Dec 2014 at 15:31. Reason: Added last two sentences.
Join Date: Feb 2009
Location: Seattle
Posts: 379
Likes: 0
Received 0 Likes
on
0 Posts
777 Speed Trim
The 777 system requires pitch trim input to adjust the control system's target speed during manual (i.e., autopilot disengaged) flight when changing speed. With the pitch trim input activated (wheel mounted thumb switch or aislestand alternate pitch trim levers) the target speed is ramped up or down at a rate of 10 knots per second.
The 777 system automatically adjusts the elevator and stabilizer to balance pitch trim disturbances associated with configuration changes such as flaps, speedbrakes, or gear extension/retraction and changes in thrust. There is no need for the pilot to make trim inputs unless changing the desired steady operating speed. As a result, the pitch trim workload on the 777 is much less than on an unaugmented airplane.
Note that with automatic balancing of thrust pitching moments, it is common to fly the 777 with manual path control while the autothrottle is engaged. That combination is not recommended on most unaugmented airplanes as the pilot would find it necessary to adjust pitch trim every time that the autothrottle changed the thrust level.
The 777 system automatically adjusts the elevator and stabilizer to balance pitch trim disturbances associated with configuration changes such as flaps, speedbrakes, or gear extension/retraction and changes in thrust. There is no need for the pilot to make trim inputs unless changing the desired steady operating speed. As a result, the pitch trim workload on the 777 is much less than on an unaugmented airplane.
Note that with automatic balancing of thrust pitching moments, it is common to fly the 777 with manual path control while the autothrottle is engaged. That combination is not recommended on most unaugmented airplanes as the pilot would find it necessary to adjust pitch trim every time that the autothrottle changed the thrust level.
