Electric Trim Question

H

Holding Short

Well-Known Member
Does anyone know why the electric trim switch on the yokes are split in two ? Either side of the switches will make the trim wheel move. :confused:

Did I miss something in training ? I don't wanna die !!! :eek:

HS
 
Speaking generally, there are two trim switches because one switch activates the motor and the other engages the clutch on the motor, at least on seminoles and barons.

On the DC8 one switch runs the hydraulic pump and the other opens the appropriate port for the direction you want the trim to go.
 
So you don't accidentally bump the trim switch with your thumb. This way it has to be more deliberate.
 
averyrm said:
So you don't accidentally bump the trim switch with your thumb. This way it has to be more deliberate.
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Hey guys, thanks for responding.

I could've sworn that I was able to move the trim wheel with either switch, independently.

HS
 
In all the planes I've flown with split switches, it shouldn't be able to move via just one switch.

However, if you move the switches in opposite directions the trim will move on some. (Night freight sometimes leads to ... experimentation)
 
Dude, I never tried that...tried a lot of other experiments, but not that one...thanks. Gives me something new to try in various a/c.
 
Trim switch are split for safety. It takes two switches to move the trim. This prevents 1 switch from getting stuck and creating a trim runaway. Also the captains switch should override the first officers.

Speaking of night freight. If you move 1/2 of the switch on one yolk and 1/2 on the other yolk the trim will move. Found that on a preflight check many years ago.
 
YGBSM

Timbuff10 said:
Ahhhh, that explains the higher requirements and incident rates when compared to 121 stuff.
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Oh please. Here we go again. Another know-nothing wanna be regional pilot talking crap about something they know nothing about. Shut your trap, or come up with some proof that you're not talking out of your ass. This is getting old. Go back to the right seat of your 172 and STFU. :argue:

The requirements are higher, because someone with 500 hours, with little night/IFR experience would probably kill themselves flying freight. They can go to a 121 regional and be babysat by a captain flying a jet that all but flies itself with the latest and greatest in avionics. Pity the captain.

IF incident rates are higher, it's because we often fly OLD equipment, A LOT, in all kinds of weather*, with a limited or no autopilot, and limited avionics compared to what the regionals get. Not to mention the single-pilot factor, and the fatigue issue with certain schedules.

*And before you or some other knob starts more verbal diharrea about this- not out of wrecklessness, but simply because a lot of us can't climb above it due to short legs, mountainous terrain, limited aircraft capability, etc.
 
That's just quality right there. He'll have fun in the RJ's. His Captain, on the other hand, will actually have to earn his keep.

It really is a shame that because we learn about our airplanes, we are considered reckless, because we learn about icing, we are yahoos, because we fly when the schedule shows us flying, we are "one of them cowboys".

Tim, did you know about the trim switches and how they could be used? Did you know all the functions on each type of GPS our company owns...how about the LORAN we have? We also have RNAV equipped airplanes. Some have none of the above. How do you figure we can get by with all this different equipment without "playing" with it to figure out how to get my GPS linked to my HSI to show me the heading of the runway, so I don't overshoot on the Visual or worse, the contact approach. I know how to in 3 different GPS systems...how about you?

How about the different RADAR systems we have. Have you ever had any experience with radar? I didn't, at least not with civilian airborne weather radar...now I feel very comfortable with it.

We are not talking about doing barrel rolls while flying, although I have heard of some people doing it, which would be stupid of people. We are talking about knowing your equipment. How well do you know your trusty 172? Well, I know all 3 of my airplanes very well.

For those who haven't done it and have no idea what it's all about, get off your high horses and maybe you'll learn something. Otherwise, as said above, go to your RJ and shut it. Maybe your captain will have some freight time and actually know what he/she's doing, or at least experienced some of the things we do on a nightly basis. Because right now, the few of you trying to beat the war drum are making a$$es of yourselves.
 
averyrm said:
In all the planes I've flown with split switches, it shouldn't be able to move via just one switch.

However, if you move the switches in opposite directions the trim will move on some. (Night freight sometimes leads to ... experimentation)
Click to expand...
And in some it locks the trim out completly because it thinks its a fault.
 
Wow, you freight dawgs sure are sensitive. Is there really a need to immediatly turn to RJ-pilot bashing? I don't think Tim meant anything by it, just an observation.

Back to the original question, it's done that way to help prevent inadvertant trim actuation. If it's working properly, moving just one side of the switch shouldn't actuate the trim. In the aircraft I fly, if you hold one side of the split switch down for more than 7 seconds, the trim switch will automatically become disabled.
 
Alchemy said:
Wow, you freight dawgs sure are sensitive. Is there really a need to immediatly turn to RJ-pilot bashing? I don't think Tim meant anything by it, just an observation.
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His comment was pretty inappropriate . . .
 
averym said:
(Night freight sometimes leads to ... experimentation)
Click to expand...
txpilot said:
Dude, I never tried that...tried a lot of other experiments, but not that one...thanks. Gives me something new to try in various a/c.
Click to expand...
txpilot said:
How do you figure we can get by with all this different equipment without "playing" with it
Click to expand...

As a former freight dog, I hate to say this but when you guys post this type of stuff it makes you sound unprofessional. I can sorta understand Timbuff’s response, as most people don't associate professional piloting with “playing,” experimenting or fiddling around with important systems. Not trying to bust your guys' balls, it's just the impression you gave off. It also doesn't help that you guys got super angry and defensive, either! :)

I can think of one flight in the recent past where some "dudes" decided to "experiment" with their plane without passengers onboard. We all know the outcome of Flagship 3701.

Maybe just something to be aware of...
 
Alchemy said:
Wow, you freight dawgs sure are sensitive. Is there really a need to immediatly turn to RJ-pilot bashing? I don't think Tim meant anything by it, just an observation.
Click to expand...

I'm not sensitive, in fact, normally I could care less what other people think. I'm just getting a little sick of comments like TimBuff's. Where did he come up with that gem? I'll tell you where. Straight out of his arse.

Misinformation (aka downright BS), is more harmful and useless than no information at all. In other words, if you don't know what you're talking about, sit on your hands instead of typing out some BS, stereotypical nonsense about a section of the industry you have no experience with. Please and thank you.
 
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