PA-28-140 Rudder Trim

[alistomalibu]

Hi

I was looking for some information about the rudder trim in the Piper PA-28-140 aircraft.
The rudder (with the pedals) can be moved 27 degrees to the right and 27 degrees to the left.
Do you know how many degrees can you move the rudder to the left and to the right using the rudder trim.
I think the PA-28-140 doesn´t have a rudder trim tab. With the rudder trim, you move all the rudder.
I didn´t find this information in my manual.

Thanks!

[BackPacker]

FWIW, all my instructors on the -161 have told me to leave it alone. It's useless and ineffective. After some (stubborn) experimentation I found they were right.

[FlyingKiwi_73]

Its difficult to use and in a pig of a place to get too. I think its actually uses bungies to fiddle with the rudder peddles rather than using a tab (there is s a ixed one on the tail, fiddle with this at your peril).

Its only useful for log straight legs with a crosswind, other wise don't bother.

[alistomalibu]

Yes, I thought the same.
I think it´s not very effective. During cruise I moved the rudder trim control wheel to the right and I didn´t notice any change.
But, during the flare at a speed near the stall, I noticed a nose tendency to the right. The wind was blowing from the left. So, I think that maybe it could be effective at slow speeds...? It doesn´t make sense aerodynamically...

Thanks

[mad_jock]

Its only there to trim out the rudder for various cruise power settings in theory but in practise its useless.

[bingofuel]

Its only useful for log straight legs with a crosswind, other wise don't bother.

Why does a crosswind make a difference to a long straight leg? Allow for drift. yes, but you still want to fly in balance, which is the same with any wind.or no wind.

[FlyingKiwi_73]

Ok maybe i should have explained, the PA28 i rent normally is a bit bent and requires a certain amount of input to fly level in the cruise, a port or wind exacerbates the problem espcially when its close to 90 deg

If you trim the nose and let go of the controls it will slowly turn right.

[smarthawke]

The PA28 is actually a spring whose effective force is controlled by a knob turning a screw thread, allowing the spring to expand or causing it to compress. One end is attached to the aircraft structure, the other end is attached to the right rudder torque tube.

There is no fixed tab on the PA28 rudder.

[FlyingKiwi_73]

I heard it was bungies' but the same principle.

I think its actually uses bungies to fiddle with the rudder peddles rather than using a tab (there is s a ixed one on the tail, fiddle with this at your peril).


Why atached only to the right rudder torque tube, can you explain.

[Morrisman1]

The rudder trim must work, because everyone in my flight school seems to trim for the climb and then must fly out of balance for the remainder of the flight!! I always seem to need to fix this.

It isn't overly effective but i think its just to allow enough to keep in balance during cruise. Not like it has to be capable of trimming for asymmetric flight!

[smarthawke]

As the trimmer effectively pulls and pushes, it only needs to act on one torque tube.

[Them thar hills]

"Its only useful for log straight legs with a crosswind, other wise don't bother"

Since when ??!! :)

[stevef]

FlyingKiwi - if the ailerons are rigged right and the aircraft tends to turn to one side, the recommended solution (by Piper) is to have the flap lowered slightly (by operating rod adjustment) to bring the wing back up. Might be worth chatting to the AMO the next time the aircraft's in on check.
Sorry about the slight drift. :)
The rudder trim really is a poor design on the PA28; the rigging also affects nosewheel steering if my memory serves right.

[FlyingKiwi_73]

SteveF, its been mentioned several times. Although i will suggest the flap extension, seems a good idea ... of course as long as that is a legal mod.

[englishal]

It is not a "mod". Sometimes if one flap is slightly out of adjustment then you will get a rolling tendancy one way or the other...Our plane is currently like that so we asked our maintenance outfit to check and they found one flap slightly lower than the other when flaps are up. This is being adjusted at the annual in March.

[Genghis the Engineer]

I've not flown the -140, but in the -161 I used to go touring in, it was a spring device, and in long legs, yes it worked fine. The indicator however is fairly useless, so I'd work the rule of whoever last flew it, must have had it roughly in balance, then trim it by feel and the slip ball once established in the cruise.

G

[tmmorris]

Agree it doesn't do much, but if you wind on a decent amount it's useful. Like someone else above I tend to find ours has been left too far to the right after someone doing circuits.

I do trim it as part of my general cleaning up/sorting routine on long cruise legs, along with trying to lean a bit more scientifically, to get best performance. (And also on long climbs, if I'm heading for what we here call the stratosphere, i.e. anything above FL40!)

Tim