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Boeing Trim:Wheels Vs Lever  
User currently offlineChamonix From France, joined Mar 2011, 429 posts, RR: 2
Posted (3 years 3 weeks 3 days 11 hours ago) and read 9027 times:
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Why does the B739 still have trim wheels whilst the other Boeings have a lever?
Are there no picth trim switches on B739 yokes?
What are those odd looking 3 "toothpicks/fork-teeth" selectors on the B739 yokes.
Any reason why B787 has 1 lever for instead of 2 on the other Boeings?
Many thanks!

32 replies: All unread, showing first 25:
 
User currently offlineyeelep From United States of America, joined Apr 2011, 671 posts, RR: 0
Reply 1, posted (3 years 3 weeks 3 days 7 hours ago) and read 8991 times:

Quoting Chamonix (Thread starter):
Why does the B739 still have trim wheels whilst the other Boeings have a lever?
Are there no picth trim switches on B739 yokes?

All 737's have a direct mechanical link from the trim wheels to the stabilizer jackscrew. The wheels are there to provide the means to physically move the stab. The 737 also has a electrically driven trim actuator controlled by trim switches on the outboard side of each control wheel. I assume the later model Boeing aircraft have multiple electrically driven systems for redundancy instead.

Quoting Chamonix (Thread starter):
What are those odd looking 3 "toothpicks/fork-teeth" selectors on the B739 yokes.

Its a customer option, the altitude clearance reminder. Think of a combination lock that doesn't do anything.


Quoting Chamonix (Thread starter):
Any reason why B787 has 1 lever for instead of 2 on the other Boeings?

From a quick look at some flight deck pictures, it looks like you may be mistaking the parking brake lever for the horizontal trim switches which appear to be the two black switches just inboard of that lever. Keep in mind that I have no knowledge of 787 systems, so I may be wrong.


User currently offlineDavid L From United Kingdom, joined May 1999, 9545 posts, RR: 42
Reply 2, posted (3 years 3 weeks 3 days 6 hours ago) and read 8985 times:

I hope these will help...

739 (left) and 738 (right):


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Photo © Andre Klass
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Photo © Alexander Tarasenkov - St.Petersburg Spotters




788:


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Photo © Sam Chui



User currently offlineDavid L From United Kingdom, joined May 1999, 9545 posts, RR: 42
Reply 3, posted (3 years 3 weeks 3 days 6 hours ago) and read 8970 times:

Quoting yeelep (Reply 1):
I assume the later model Boeing aircraft have multiple electrically driven systems for redundancy instead.

I included the 738 to show that the trim wheels are not unique to the 739 but I came to the same conclusion that clean-sheet designs that came after the 737 didn't have the trim wheels. Unable to say why, I left it alone.  


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 4, posted (3 years 3 weeks 3 days 6 hours ago) and read 8950 times:

Quoting Chamonix (Thread starter):
Why does the B739 still have trim wheels whilst the other Boeings have a lever?

Commonality to other 737's.

Quoting Chamonix (Thread starter):
Are there no picth trim switches on B739 yokes?

They're still there.

Quoting Chamonix (Thread starter):
Any reason why B787 has 1 lever for instead of 2 on the other Boeings?

It's what yeelep said:

Quoting yeelep (Reply 1):
From a quick look at some flight deck pictures, it looks like you may be mistaking the parking brake lever for the horizontal trim switches which appear to be the two black switches just inboard of that lever. Keep in mind that I have no knowledge of 787 systems, so I may be wrong.

Just aft of the captain's touchpad is a silver lever and a wide black switch. The lever is the parking brake, the wide black switch is really two switches side by side to control trim. The two red guarded switches just inboard of that are the stab trim cutouts.

Quoting yeelep (Reply 1):
I assume the later model Boeing aircraft have multiple electrically driven systems for redundancy instead.

Yes. It's not always electric by there's always some kind of dual path control and actuation for redundancy.

Tom.


User currently offlineBarney Captain From United States of America, joined Nov 2001, 999 posts, RR: 12
Reply 5, posted (3 years 3 weeks 23 hours ago) and read 8600 times:

Quoting David L (Reply 2):
Its a customer option, the altitude clearance reminder.

Fairly certain their intended purpose is for the current flight number - not altitude clearance.



...from the Banana Republic....
User currently offlineDavid L From United Kingdom, joined May 1999, 9545 posts, RR: 42
Reply 6, posted (3 years 3 weeks 23 hours ago) and read 8591 times:

Quoting Barney Captain (Reply 5):

You might be right but, on the other hand and taking a variety of factors into consideration... it wasn't actually me who said it.

  


User currently offlineoldtimer From United Kingdom, joined Aug 2006, 191 posts, RR: 1
Reply 7, posted (3 years 3 weeks 22 hours ago) and read 8578 times:

Quoting Barney Captain (Reply 5):
Fairly certain their intended purpose is for the current flight number - not altitude clearance.

Was always the altitude reminder on my 707, 727 and 737 courses.

oldtimer



Oldtimer, I should have known better!
User currently offlineBarney Captain From United States of America, joined Nov 2001, 999 posts, RR: 12
Reply 8, posted (3 years 3 weeks 11 hours ago) and read 8445 times:

Quoting David L (Reply 6):
You might be right but, on the other hand and taking a variety of factors into consideration... it wasn't actually me who said it.

Sorry about that....not sure what happened.

Quoting oldtimer (Reply 7):
Was always the altitude reminder on my 707, 727 and 737 courses.

Over 20 years flying Boeing's and I can honestly say, that's the first I've ever heard of this. Isn't that what the altitude window in MCP is for (or ALT Alerter going back to the classics)?

We are talking about the same thing right? The 3 digit numeric thumb wheels on the yoke?



...from the Banana Republic....
User currently offlineoldtimer From United Kingdom, joined Aug 2006, 191 posts, RR: 1
Reply 9, posted (3 years 3 weeks 9 hours ago) and read 8422 times:

Quoting Barney Captain (Reply 8):
We are talking about the same thing right? The 3 digit numeric thumb wheels on the yoke?

Yes, the same thing was fitted to BAC1-11 and again was used as altitude reminder. You have to remember this goes back to pre INS and GPS days, these early a/c had only an altitude hold, you climbed on a/p and trimmed out at requested level and selected Alt. hold. You are only a sprog young man, pilots had to really work for a living in those days  



Oldtimer, I should have known better!
User currently offlineBarney Captain From United States of America, joined Nov 2001, 999 posts, RR: 12
Reply 10, posted (3 years 3 weeks ago) and read 8311 times:

Quoting oldtimer (Reply 9):
these early a/c had only an altitude hold, you climbed on a/p and trimmed out at requested level and selected Alt. hold.

True - just like we always did in the -200's. But we still had an Altitude Alerter for that purpose.

Quoting oldtimer (Reply 9):
You are only a sprog young man, pilots had to really work for a living in those days

Awe shucks, and here I thought those 14 hour/12 leg days hand flying a Metroliner were all for fun  



...from the Banana Republic....
User currently offlinemandala499 From Indonesia, joined Aug 2001, 6968 posts, RR: 76
Reply 11, posted (3 years 2 weeks 6 days 15 hours ago) and read 8208 times:

And the wideblack trim switches on the pedestal is also not unique to the 787s...

Here's one from the 767-400:

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Photo © Daniel Piotrowski



So, new cockpit designs after 777 don't have the Trim Tabs?

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineChamonix From France, joined Mar 2011, 429 posts, RR: 2
Reply 12, posted (3 years 2 weeks 6 days 7 hours ago) and read 8146 times:
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Amazing as ever,mandala499!
Never ever seen a Boeing w/o a ALT Pitch lever!
That is really weird!
So 767 does not have it,777 does,787 does not!
I can not figure out what that that tiny lever is behind the touchpad on the 787 next to Trim Tabs?
http://cdn-www.airliners.net/aviation-photos/photos/3/5/1/1942153.jpg
Maybe someone has a better pic?


User currently offlineDavid L From United Kingdom, joined May 1999, 9545 posts, RR: 42
Reply 13, posted (3 years 2 weeks 6 days 6 hours ago) and read 8138 times:

Quoting Chamonix (Reply 12):
I can not figure out what that that tiny lever is behind the touchpad on the 787 next to Trim Tabs?

Do you mean this one...

Quoting tdscanuck (Reply 4):
Just aft of the captain's touchpad is a silver lever and a wide black switch. The lever is the parking brake,


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 14, posted (3 years 2 weeks 6 days 5 hours ago) and read 8128 times:

Quoting Chamonix (Reply 12):
Never ever seen a Boeing w/o a ALT Pitch lever!
That is really weird!
So 767 does not have it,777 does,787 does not!

It's basically chronologic. The original 767's have pitch trim levers:

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Photo © Richard Barsby - Aviation Photographer
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Photo © Jorge Meneses



Then they developed the 777 and the levers are still there:

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Photo © Ken Iwelumo - Global Aviation Images
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Photo © Hannes Schauer



Then they did the 767-400ER and the levers disappeared from all versions of the 767 (not sure if by SB for the older models) and became the wide switches:

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Photo © Ryan Gaddis - Spot This!
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Photo © Charlie W Carter (EGTESkyGod)



The 787 kept going and stuck with the wide switches.

Tom.


User currently offlineChamonix From France, joined Mar 2011, 429 posts, RR: 2
Reply 15, posted (3 years 2 weeks 6 days 5 hours ago) and read 8123 times:
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http://www.airliners.net/photo/Delta...Lines/Boeing-767-432-ER/0784430/L/

CWS/CMD have been blanked-out.


User currently offlineChamonix From France, joined Mar 2011, 429 posts, RR: 2
Reply 16, posted (3 years 2 weeks 6 days 5 hours ago) and read 8120 times:
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Digressing onto the MD-11:Does it have 2 Flap selectors next to F/O?
http://flyawaysimulation.com/media/i...images/pmdg-md11-fsx-review-35.jpg (click to expand)
A380:Can anyone pinpoint where exactly are the new electronic tabs that have replaced the wheels on the Flightdeck?


User currently offlinemandala499 From Indonesia, joined Aug 2001, 6968 posts, RR: 76
Reply 17, posted (3 years 2 weeks 6 days 3 hours ago) and read 8096 times:

Good catch by Tom...
It seems that all BA/exBA 763s originally came with the twin trim switches at the pedestal in place of the trim tabs...

Here is one from over 10 yrs ago!

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Photo © Matthew R N Clarkson


Interesting that they had the paddle CMD switches a la 747!

I guess they retrofitted the paddle switches to the button switches for the exBA 767-336s that went to Qantas... and also the PFD/EADI received the new format... whilst the BA one, stayed as it is!

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Photo © Wingnut



What is interesting is that BA 757s have both the trim tab version, and the wide trim switches version!


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Photo © Emil Almestad
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Photo © Mike Moores

Quoting Chamonix (Reply 15):
CWS/CMD have been blanked-out.

CWS mode was always an option, therefore, some/most, prefer to blank it out.

Quoting Chamonix (Reply 16):
Digressing onto the MD-11:Does it have 2 Flap selectors next to F/O?

It is remnant of the old days when slats and flaps were two separate levers... one of the reason is that, that was the norm in those days, and also for the crew to not make a mistake whether they're on a Slats equipped jet or not (DC-8s didn't have them, and some of the DC-9s didn't have them)... Here's a no-slat DC-9...

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Photo © Julian Whitelaw



And in the end, both the slats and flap lever were fused as one, but with two selectors... and you get:

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Photo © Roberto Leiro - SVZM Spotters



So, when they went to the DC-10... they went with a mechanical link like the DC-9...

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Photo © Europix - AirTeamImages



And some had it detached (or can have it attached or detached by choice?... need some DC-10 drivers to give better info...)

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Photo © David Watkins 82



So when they went to make the MD-11, they still kept that slot, and it's used for "Dial-a-Flap"... well, Wilco737... are you reading this???

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlineChamonix From France, joined Mar 2011, 429 posts, RR: 2
Reply 18, posted (3 years 2 weeks 6 days 1 hour ago) and read 8059 times:
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Spanair crash entirely forgot to engage Flaps/Slats for T/O.
Taken off with flaps at 0°.
==================
Which is better and easier to use:Levers or Wide Tabs?


User currently offlinetdscanuck From Canada, joined Jan 2006, 12709 posts, RR: 80
Reply 19, posted (3 years 2 weeks 5 days 22 hours ago) and read 8024 times:

Quoting Chamonix (Reply 18):
Spanair crash entirely forgot to engage Flaps/Slats for T/O.
Taken off with flaps at 0°.
==================
Which is better and easier to use:Levers or Wide Tabs?

I'm not really following you here...the lever/switch/wheel discussion (so far) has been all about stabilizer trim. That had nothing to do with the Spanair crash. I'm not aware of any large jet that doesn't use some kind of lever for flaps.

Tom.


User currently offlinePGNCS From United States of America, joined Apr 2007, 2858 posts, RR: 48
Reply 20, posted (3 years 2 weeks 2 days 19 hours ago) and read 7778 times:

Quoting oldtimer (Reply 7):
Quoting Barney Captain (Reply 5):
Fairly certain their intended purpose is for the current flight number - not altitude clearance.

Was always the altitude reminder on my 707, 727 and 737 courses.

Oh yes, the REALLY old days before altitude alerters were required. (Don't feel bad, I remember them too!)

Quoting Barney Captain (Reply 8):
Quoting oldtimer (Reply 7):
Was always the altitude reminder on my 707, 727 and 737 courses.

Over 20 years flying Boeing's and I can honestly say, that's the first I've ever heard of this. Isn't that what the altitude window in MCP is for (or ALT Alerter going back to the classics)?

We are talking about the same thing right? The 3 digit numeric thumb wheels on the yoke?

Ah, but not all B-727 and DC-9's (and I believe B-737's as well, but I don't recall flying one without it installed) originally came with altitude alerters, and many even came with the dreaded three-pointer altimeter! (And yes, you are talking about the same thing.)  
Quoting Barney Captain (Reply 10):
Quoting oldtimer (Reply 9):
these early a/c had only an altitude hold, you climbed on a/p and trimmed out at requested level and selected Alt. hold.

True - just like we always did in the -200's. But we still had an Altitude Alerter for that purpose.

Oh I hated that autopilot (SP-77, I believe) and remember it well.

Quoting mandala499 (Reply 17):
Quoting Chamonix (Reply 15):
CWS/CMD have been blanked-out.

CWS mode was always an option, therefore, some/most, prefer to blank it out.

Yes, and even when installed few people bother with it as the Boeings in CWS are a pretty unharmonious and unpleasant experience.

Quoting Chamonix (Reply 18):
Which is better and easier to use:Levers or Wide Tabs?

They aren't ever used in normal operation, and I don't think in my simulator experiences there is a particular advantage to either.

Quoting Chamonix (Reply 18):

Spanair crash entirely forgot to engage Flaps/Slats for T/O.
Taken off with flaps at 0°.
==================
Which is better and easier to use:Levers or Wide Tabs?

I'm confused. What does the Spanair accident have to do with stab trim switches?


User currently offlinemandala499 From Indonesia, joined Aug 2001, 6968 posts, RR: 76
Reply 21, posted (3 years 2 weeks 2 days 14 hours ago) and read 7730 times:

Quoting PGNCS (Reply 20):
Oh I hated that autopilot (SP-77, I believe) and remember it well.

SP-77 Mode 1... Lovely piece of engineering !    We call it, the "kitchen stove".
It really is a "point and hold" kind of automation... not the "press and forget" types...
But then... it hand flies beautifully, who needs CWS? (Well, CWS for the roll, hand flying for pitch"    )

*OK, I'm asking for you and Pihero to throw a rotted-away 732 AFM at me!*

Mandala499



When losing situational awareness, pray Cumulus Granitus isn't nearby !
User currently offlinePGNCS From United States of America, joined Apr 2007, 2858 posts, RR: 48
Reply 22, posted (3 years 2 weeks 1 day 18 hours ago) and read 7635 times:

Quoting mandala499 (Reply 21):
SP-77 Mode 1... Lovely piece of engineering ! We call it, the "kitchen stove".

I laughed so hard I came out of Normal law!  
Quoting mandala499 (Reply 21):
It really is a "point and hold" kind of automation.

Wait! It's automation? Seriously?

Quoting mandala499 (Reply 21):
But then... it hand flies beautifully, who needs CWS? (Well, CWS for the roll, hand flying for pitch" )

I will say that the 732 is nicer to hand fly than some other Boeings, still not nearly as nice as the 757 though. It's sure easy to land, too. It's kind of like flying a big Cessna only not nearly as comfortable, ergonomic, or automated!


User currently offlineChamonix From France, joined Mar 2011, 429 posts, RR: 2
Reply 23, posted (3 years 2 weeks 1 day 11 hours ago) and read 7588 times:
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Quoting PGNCS (Reply 22):
I will say that the 732 is nicer to hand fly than some other Boeings

My Father-In-Law says his favourite of all times in terms of handling is the B727-200 ADV.


User currently offlinemandala499 From Indonesia, joined Aug 2001, 6968 posts, RR: 76
Reply 24, posted (3 years 2 weeks 1 day 1 hour ago) and read 7531 times:

Quoting PGNCS (Reply 22):
I laughed so hard I came out of Normal law!

It's no joke that they use that term for the SP-77 here!   

Quoting PGNCS (Reply 22):
Wait! It's automation? Seriously?

Sorry, it's "non critical phase workload reducing apparatus"... Since it can be quite useless on critical phases!



When losing situational awareness, pray Cumulus Granitus isn't nearby !
25 Post contains images PGNCS : OK, that's much better! I will certainly believe it's a NCPWRA (or a Kitchen Stove!) before I'll believe it's an autopilot!
26 francoflier : I still don't like Boeing dropping the trim wheel. There's nothing like the precision of a trim wheel when hand flying. Of course, we're not really su
27 Post contains images PGNCS : There's also nothing like it for finger and knee injuries.
28 Post contains links and images Pihero : especially when one had forgotten to retract the handle ! doesn't hold a candle to the best ever solution : The Tristar electric trim thumb wheel, se
29 tb727 : Remember, it will whack you in the knee 3 times before you can say ouch!
30 Pihero : Must have been drinking more than usual, that dear man: The 727 has never been an easy airplane and in terms of control balance.... it wasn't there w
31 Post contains images PGNCS : YOW! I just got knee pain thinking about it. What an awful artifact of aircraft design from the 1950s! Absolutely correct Pihero! Easily the best way
32 tdscanuck : The wheel hasn't been directly connected to the stab, at least on a Boeing, since at least the 757 (maybe the 747). On the 777 and 787 it isn't even
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