I have a 56 182, so the horizontal stab trims like a 180, not like newer planes that have a trim tab.

The trim wheel operates smoothly in both directions direction, full travel. However, In the air, the faster I go, the more pressure it takes to trim nose down. I recall flying Cherokees with the same phenomenon just checking but not "trim tab" planes. Is this normal and/or what additional maintenance is needed here.


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No that's not normal. There is probably no grease left in the actuators/ Jack screws.
Mine was the same way. Worked ok on the ground but un useable at anything above about 80kts.
You have two options. Completely remove all the empennage, disassemble clean and re grease the actuators.
The other option is to move the boot and pump them full of new grease or stick a needle zerk fitting into the boot and pump a bunch of grease in with tail still installed.

I STRONGLY reccomend that you diassemble the tail and remove an inspect the jack screws. If it's been a long time since the tail has been off, there is a very good chance you will find other items that need attention. Cracked brackets etc are very common. Piece of mind when flying in turbulence that the tail is not going to fall off. Stiff trim system is not good !

Yes, it is a good idea to service the stabilizer trim jacks.
I believe it is a 500 hour repetitive inspection in the service manual on later aircraft with the same system. I will check my notes at the hangar which reference the correct grease MIL spec ...
Generally, the nose down movement of the stab trim wheel requires more force than nose up, especially if you have a big load in the back. My trim wheel forward technique includes some hands on forward pressure on the yoke.
Check the roll pin on the trim wheel sprocket shaft, making sure that connection is not sloppy. Continued excessive force applied to the trim wheel will make this a weak link in the system.

I had the same performance issues in the trim system of my Cessna 180. My mechanic and I removed the tail and disassembled the jack screw assemblies. The flange that contacts the bearing race on one of the screws had sheared and the whole system was binding. It had side-loaded and cracked the eccentric bushings. It was a real mess in there, so we rebuilt the system and now it operates very smoothly. As much as it wasn't what I wanted to be spending time and money on, it was a very good exercise to get in there and familiarize myself with the components and how it all works. Though it does not respond well to long periods of neglect, it is a great trim system.

Trimming my 180 nose down has always took a little more effort than nose up.
I had a few incidents of the trim slipping a while back, adding some nose up on its own.
I checked & found the cable were a bit loose and tightened them up, no more slippage.
Feels like it may have made the trim wheel slightly stiffer, maybe.
The previous owner & his IA went through the tail a year or two before I bought it in 2014.
They know their stuff so I'm pretty confident it's right.

There is not very good access back there but I removed what panels exist and took a look. On initial inspection nothing looks amiss. The interior looks immaculate and all the rigging is brand new and the . The boots around the jack screws are intact and the jack screws are lubricated. I lubed them up with A&P a bit and noticed a slight improvement.


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It is not as big a job as it seems to remove the empenage to get access to the trim jacks. I have done it twice (once for the SID inspections which are mandatory down here) . Lubricate the jack screws and replace the boots if they are damaged.

Hamish

ZK Kiwi wrote:It is not as big a job as it seems to remove the empenage to get access to the trim jacks. I have done it twice (once for the SID inspections which are mandatory down here) . Lubricate the jack screws and replace the boots if they are damaged.

Hamish

I agree. You get in there and then you have piece of mind that all is well, in addition to an understanding of the system's design details. The hardest part is getting the feckin elevator and rudder bolts back through the hinges and nuts on.

Lubricating parts that are possibly bent, broken, or worn out is potentially dangerous, because you could be masking a problem that needs to be looked at. It's not like the stabilizers are primary controls or flying surfaces or anything

Our 1956 airplanes are now 60 years old, and those tails may not EVER have been removed or repaired since it left Wichita.

There are far far far more experienced mechanics here than me, but I remember reading a story in one of the Cessna history books or websites about having the trim system "run away" on one of the Cessna 180 factory prototypes, scaring the crap out of the test pilots.

I'd be yanking it apart with your mechanic. I've seen quite a few of them bind up internally and some fail. Our old 180 used to be in the dust all the time and the tail was off at every annual....I know that doesn't sit too well with most owners, as they're looking for the $500 annual, but it's a price you pay to fly. Be safe and get it figured out.
John

Let me ask another question; are the trim wheels generally more friction to turn when flying than when on the ground?

On the ground, when I trim all the way back the wheel gets stiffer as it maxes out, as the springs on the jack screws become compressed.

In the air, The faster I go (more down pressure on HS) the harder it is to trim the stabilator up against the pressure.

Seems to operate smoothly, it's just the more pressure against the stabilator, the harder it is to trim. I don't recall this when trimming "trim tabs", but they are quite a bit smaller.


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I think it's been about 30 years or more since I last flew an early 182--I think it was a 57 or thereabouts, straight tail, narrow fuselage, tall gear, etc. Nice airplane. I don't recall anything different about the way its trim felt vs. newer models. If it were mine, knowing what a klutz I am as a mechanic, I'd be telling my IA about how it feels, solicit his advice, then have him do whatever he recommends. From what I do know about Cessna trim systems, I can imagine his advice ranging from simple lubing all the way up to replacing pieces and parts and cables and such, beginning at the trim wheel. You could have binding cables, binding cable guides, bad bearings, misrigging, and on and on.

One of the Skylanes my IA has had somewhat bitter experience with had a stiff control wheel in roll, i.e., the ailerons. Flyable, but unpleasant. An examination in the right wing showed that someone had misrouted the cable through the wrong hole in a rib, so that it was rubbing on the rib and had cut halfway through to the next hole.

Like EZ implied, it's not like the tail of your airplane is anything important!

Cary

Hi we have a 69 180 that is experiencing an almost impossible to move Trim wheel while it's loaded in flight.

The trim cycles and feels great on the ground.

New jackscrew brackets, McFarlane jackscrews, all other horizontal brackets inspected and replaced.

Is there a "gotcha" on the installation or some other issue we may be missing? That would cause the trimwheel to sieze under load?

Have tried various cg loads as well and no difference.

I’d worry about about a cable misrouting.

There can be a timing issue. If the jackscrews are not exactly at the same level when you assemble the stabilizer, they will tend to bind, especially in flight. So you may want to ensure they are not off in any way.

dogpilot wrote:There can be a timing issue. If the jackscrews are not exactly at the same level when you assemble the stabilizer, they will tend to bind, especially in flight. So you may want to ensure they are not off in any way.

This^^^

If you just had the jackscrew out they could be off a turn from each other. The eccentric bushings might make up the difference on the ground but then bind when they get an air load. Also need to check the cable tension.

Follow the AMM rigging instructions to the letter.

Thanks everyone - these suggestions were perfect and very helpful - it's all fixed up & back in the air!

So what was it?