Piper Arrow trim gets stiff at 150 mph.

[RyanB]

I'm much more of an idiot than dealing with a jack screw. The tires also have visible wear. The spark plugs aren't new, either. The mags are fresh, but I coupled them with used spark plugs! I'm a COMPLETE MORON!

I’m with Glenn, as I originally asserted that the airplane needs to be grounded. If you’re not going to deal with maintaining the airplane, than who is? Are you just going let this go and not have it addressed? It needs to be corrected, end of story.

 

[paramax55]

There is a balance weight in the tail for the PA28s. In fact, there was an AD on them. If I remember correctly, it had to do with cracking of the tube if you didn't have the upgraded one. As far as paint goes, I have a strong suspicion that this airplane has its original paint. As far as balancing goes... I've heard both sides of the story. Yes, the absolute correct way is to remove the control surface and rebalance after painting - no question there. And it's easy to do. I've also heard that our airplanes fly so slow, that you'd never be able to create flutter from painting. One paint shop owner told me "You're taking paint off, and putting paint back on. It doesn't really change things." And they had 3 jets in the shop when I was there. But balancing IS the correct way.

I have thought about the cable being toward the end of its travel on the drum. That could be part of the problem, but it's not the whole problem. I haven't been able to recreate the issue on the ground, which means the load of flying is a contributing factor. I might be able to get someone to add resistance while I move the trim, but it's not scientific without a calibrated hand pushing on it. But it could be informative.

I'll get a new jack screw and drum and I'll go through the proper rigging procedure while I'm waiting on parts to come in. Someone who had done work on this airplane in the past was less than meticulous. It's possible that they had gotten to this trim cable and it's done incorrectly.

 

[paramax55]

I’m with Glenn, as I originally asserted that the airplane needs to be grounded. If you’re not going to deal with maintaining the airplane, than who is? Are you just going let this go and not have it addressed? It needs to be corrected, end of story.

Why do people assume I'm not going to fix the airplane? Just because I'm not going to ground it doesn't mean I'm not going to fix it. Why would I be looking for a part number to NOT fix the airplane?

 

[Fearless Tower]

Why do people assume I'm not going to fix the airplane? Just because I'm not going to ground it doesn't mean I'm not going to fix it. Why would I be looking for a part number to NOT fix the airplane?

You aren’t getting it.

It’s not that people think you aren’t going to fix it. It’s that YOU said it wasn’t a big safety thing and it was fine to keep flying it while you research parts.

 

[TommyG]

If it doesn’t feel right, don’t push it. If you’re not a mechanic. Have a mechanic look at it and determine the safety of the issue.

 

[paramax55]

You aren’t getting it.

It’s not that people think you aren’t going to fix it. It’s that YOU said it wasn’t a big safety thing and it was fine to keep flying it while you research parts.

You are right. I don't get it. It hasn't changed in over 200 hours. I'm not scared that I'm going to fall out of the sky in the next two weeks.

If it doesn’t feel right, don’t push it. If you’re not a mechanic. Have a mechanic look at it and determine the safety of the issue.

Read back on page 1. I did have a mechanic look at it.

 

[GlennAB1]

Alright, the aircraft has had a flight control discrepancy for over 200 hours, and you've deferred maintenance, in accordance with what?

 

[Dan Thomas]

You are right. I don't get it. It hasn't changed in over 200 hours. I'm not scared that I'm going to fall out of the sky in the next two weeks.

I've heard that before. "Been doing that for a long time. It ain't gonna quit." That's from non-mechanically-inclined folks who don't understand wear and tear and the symptoms of same. Sure, it will do that, but for how long? I've taken plenty of stuff apart that was acting up and found that it would have quit altogether within a very few more hours. And we sometimes hear of stuff that did finally fail after the pilot kept ignoring the issue.

Some mechanics will also ignore it. I often find that sort of mistake on airplanes I work on for the first time. Those guys leave themselves wide open to litigation when something finally injures or kills someone.

We will make a log entry when the owner doesn't want to have fixed some issue we consider an airworthiness item. We photocopy that and get his signature on the work sheets. He's on his on hook after that. Even then there are some defects I consider so serious that I will not sign out the airplane at all. Badly worn or damaged flight controls and cracked exhaust systems are two of them.

 

[James331]

You are right. I don't get it. It hasn't changed in over 200 hours. I'm not scared that I'm going to fall out of the sky in the next two weeks.

Have you had an engine failure or full on emergency yet?
Given enough hours flown you will, you like stacking the deck against yourself?

If I'm going to get myself best up, rather have it done by a hot blonde vs done by the instrument panel after my plane craps the bed because of me ignoring issues.

.. And they had 3 jets in the shop when I was there. ..

And that and 1 buck won't even get you on the bus.

Especially based on the other stuff that "shop" said.

 

[Bell206]

This airplane is both safe and legal.

This airplane is not getting grounded for this... [and] If the IA didn't think it was an issue while he was standing in front of the plane...

Paramax:
As I follow this thread, there’s one basic issue you seem to overlook. While in your opinion the aircraft is “safe” and “legal” which doesn’t require it to be grounded, your plane is in fact not airworthy. That is the critical term you should be concerned about.

Every time the aircraft flies it is in violation of the FARs. Not flying takes every Part 91 violation off the table. That would leave only your disassembly of the jackscrew as the issue. And that problem can be rectified with an entry signed by an A&P. I can 100% assure you disassembly of a flight control is not preventative maintenance.

And even though you had your mechanic look at it, that discussion is meaningless without a discrepancy write up by you and a corrective entry by him. It all falls on you as the owner.

So the next time you fly with your trim issue keep in mind you are neither “safe” nor “legal” from a regulatory perspective (i.e., airworthy) and the consequences of that could be endless.

 

[coloradobluesky]

Stiff is relative. I flew a Cessna 185 that had stiff elevator trim. But you could turn it the whole way. IMO it was still airworthy. I'd advise not buying parts until its taken apart. Lubing might fix it or it might be adjustable or maybe just one part, not the whole thing. I dunno. No way to tell until you examine it.

 

[James331]

Stiff is relative. I flew a Cessna 185 that had stiff elevator trim. But you could turn it the whole way. IMO it was still airworthy. I'd advise not buying parts until its taken apart. Lubing might fix it or it might be adjustable or maybe just one part, not the whole thing. I dunno. No way to tell until you examine it.

A 185 trim also will be harder than a 172 or 208B trim due to the design too.

I could legit almost spin the vans trim, never seen that on a wagon or even arrow

 

[Dan Thomas]

Stiff 185 trim is not a good sign. The jackscrews in those airplanes, unless the airplane has been modified as per the service kit, are inaccessible unless the whole tail is taken off the airplane. Fin, rudder, elevators, stab. All of it. The SK puts an access cover in the belly in the jackscrew bay. I have seen illegal access holes there, round holes like you see under the wings, but there's no reinforcing doubler to carry the stresses around the hole. Not safe at all. The stab/elevator loads as well as the tailwheel loads all pass through that skin.

Those jackscrews, being hard to get at, cost money to inspect and overhaul. Lots of money. So they don't get done. They get dried out, the dust boots debond and let in water and dirt, and corrosion sets in. A corroded jackscrew can break, and broken jackscrews can mean an uncontrollable airplane. The chain or cable can break and the jackscrews will then creep to full nose-up, sometimes quite rapidly. The oldest 180s didn't have the detented trim wheel and had plenty of problems with that. Cessna installed springs in the jackscrews, which didn't completely cure the problem.

 

[JAWS]

Stiff 185 trim is not a good sign. The jackscrews in those airplanes, unless the airplane has been modified as per the service kit, are inaccessible unless the whole tail is taken off the airplane. Fin, rudder, elevators, stab. All of it. The SK puts an access cover in the belly in the jackscrew bay. I have seen illegal access holes there, round holes like you see under the wings, but there's no reinforcing doubler to carry the stresses around the hole. Not safe at all. The stab/elevator loads as well as the tailwheel loads all pass through that skin.

Those jackscrews, being hard to get at, cost money to inspect and overhaul. Lots of money. So they don't get done. They get dried out, the dust boots debond and let in water and dirt, and corrosion sets in. A corroded jackscrew can break, and broken jackscrews can mean an uncontrollable airplane. The chain or cable can break and the jackscrews will then creep to full nose-up, sometimes quite rapidly. The oldest 180s didn't have the detented trim wheel and had plenty of problems with that. Cessna installed springs in the jackscrews, which didn't completely cure the problem.

This is a serious safety of flight issue and should garner more of a response from the owner other than ...

It hasn't changed in over 200 hours. I'm not scared that I'm going to fall out of the sky in the next two weeks.

I am sure Alaska Airlines felt the same way!

https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261

 

[ElPaso Pilot]

I don't get into this situation unless I have a situation in which I'm making a REALLY good ground speed - like a tailwind or cool, dry, dense air.

Not to pile on, but the trim system has no idea what the ground speed or tailwind is. These will have no effect on trim forces.

 

[James331]

Stiff 185 trim is not a good sign. The jackscrews in those airplanes, unless the airplane has been modified as per the service kit, are inaccessible unless the whole tail is taken off the airplane. Fin, rudder, elevators, stab. All of it. The SK puts an access cover in the belly in the jackscrew bay. I have seen illegal access holes there, round holes like you see under the wings, but there's no reinforcing doubler to carry the stresses around the hole. Not safe at all. The stab/elevator loads as well as the tailwheel loads all pass through that skin.

Those jackscrews, being hard to get at, cost money to inspect and overhaul. Lots of money. So they don't get done. They get dried out, the dust boots debond and let in water and dirt, and corrosion sets in. A corroded jackscrew can break, and broken jackscrews can mean an uncontrollable airplane. The chain or cable can break and the jackscrews will then creep to full nose-up, sometimes quite rapidly. The oldest 180s didn't have the detented trim wheel and had plenty of problems with that. Cessna installed springs in the jackscrews, which didn't completely cure the problem.

Gotta read what I wrote, said that jackscrew trim will always be a little "stiffer" than say 172 trim.

 

[DrT.AME]

I have a '72 Arrow II, 200 hp. When I bought the plane, the trim was SUPER stiff. Everyone who tried it complained about it. After a couple of months, I kicked myself because all it needed was a fresh lube. Well, here it is, a year amd a half later, and it started to get stiff while in the descent. I decided to fix it right, so I took the whole jack screw assembly apart. I cleaned everything down to metal and used fresh Luriplate Aero on it all before putting it back together (everything but the cable and outside of the drum).

Well, it works like a dream now - until you get up to about 150 mph. It stiffens up and the electric trim clutch just slips. Level off and slow down, and everything goes back to good. You can manhandle the yoke, take pressure off the trim tab, and it also works. I also noticed that the top part of the threads on the jack screw are worn. The bottom of the threads look normal - kind of how it would look if you used a bolt to "jack up" a heavy load and "stretched" the threads.

I'm thinking I'd like to try a new jack screw and see what happens, but I don't see a part number for it - only for the drum, washers, and cotter pins. I'm sure I could make another with the lathe and mill - maybe even using some all-thread (I doubt there's a ton of stress on it), but I'd prefer not to be a test pilot if a store-bought piece is available.

Anybody have any other ideas?

Did you ever find an answer to this? My Lance is doing the same thing.

 

[GeorgeC]

@Rgbeard @cowman @Jim K

 

[cowman]

I've never encountered such a thing but most of the mechanism for this is pretty simple and accessible. There's a cable that runs back from the trim wheel to a little drum on the jackscrew on the stabilator- you can see part of that if you lift the back of the stabilator and follow the little arm from the anti-servo tab through the slot on the tail faring. I would have an A&P look all of that over- it shouldn't be a terribly lengthy or invasive inspection. Take that rear faring off and open up the cover in the rear of the baggage compartment and you've got access to most of it.

I would have the A&P who looks at it also remove the bolts that attach the jackscrew assembly to the anti-servo tab. Although rare there have been cases of these bolts wearing internally where it's not visible and breaking during flight- that's a very bad and dangerous situation. The bushings on the jackscrew assembly have also been known to wear out, they're cheap and I had mine replaced when the assembly was apart just in case. I would also make sure your stabilator moves smoothly up and down and doesn't have any side to side or back and forth play as that's also a known issue.

 

[Jim K]

Can't say I've had that issue. My mechanic did replace the jack screw a couple years ago. He used a McFarlane part that was pretty reasonable iirc. He mentioned that it's a wear item that he likes to keep an eye on. I could see how slop in that screw might make it hard to turn under a heavier load.

@cowman had a broken cable a couple years ago, but i don't think he had any symptoms, just found it during inspection?

Welcome to poa, @DrT.AME

 

[DrT.AME]

I've never encountered such a thing but most of the mechanism for this is pretty simple and accessible. There's a cable that runs back from the trim wheel to a little drum on the jackscrew on the stabilator- you can see part of that if you lift the back of the stabilator and follow the little arm from the anti-servo tab through the slot on the tail faring. I would have an A&P look all of that over- it shouldn't be a terribly lengthy or invasive inspection. Take that rear faring off and open up the cover in the rear of the baggage compartment and you've got access to most of it.

I would have the A&P who looks at it also remove the bolts that attach the jackscrew assembly to the anti-servo tab. Although rare there have been cases of these bolts wearing internally where it's not visible and breaking during flight- that's a very bad and dangerous situation. The bushings on the jackscrew assembly have also been known to wear out, they're cheap and I had mine replaced when the assembly was apart just in case. I would also make sure your stabilator moves smoothly up and down and doesn't have any side to side or back and forth play as that's also a known issue.

Thank you for this. I plan to talk to my A&P. My plane is fresh out of annual and this was done during the inspection. It worked fine before they worked on it. Sigh. Do the worsening symptoms in high speed flight and lack of symptoms on the ground tell you anything about what could be the etiology?

 

[DrT.AME]

Can't say I've had that issue. My mechanic did replace the jack screw a couple years ago. He used a McFarlane part that was pretty reasonable iirc. He mentioned that it's a wear item that he likes to keep an eye on. I could see how slop in that screw might make it hard to turn under a heavier load.

@cowman had a broken cable a couple years ago, but i don't think he had any symptoms, just found it during inspection?

Welcome to poa, @DrT.AME

Thanks Jim! I've been a watcher for quite a while. Nice to start taking part.

 

[cowman]

@cowman had a broken cable a couple years ago, but i don't think he had any symptoms, just found it during inspection?

Basically yes, the cable broke and held together by safety wire- found when doing other work. It most likely broke right before landing because never noticed any in-flight issues.

Here’s a picture of the mechanism on my old plane which was an Archer but it’s pretty much identical on the Lance IIRC. Turning the trim wheel rotates that drum which moves the jackscrew which changes the length of that arm going to the anti-servo trim tab doohickey.

 

[cowman]

Thank you for this. I plan to talk to my A&P. My plane is fresh out of annual and this was done during the inspection. It worked fine before they worked on it. Sigh. Do the worsening symptoms in high speed flight and lack of symptoms on the ground tell you anything about what could be the etiology?

Pure speculation from a pilot who isn't a A&P but by guess would be something- maybe a pulley, maybe the jackscrew it's self is binding a little and when put under the extra loads experienced at cruise speed the binding gets worse. Given that they just worked on the cable I'd guess something either wasn't put together right or something about how they adjusted it caused an issue somewhere else in the cable system. Not sure, but like I said it's not that complicated or hard to get at so hopefully when they open it up it will be obvious.

 

[mandm]

Did you ever find an answer to this? My Lance is doing the same thing.

I think mine did that on my most recent flight, I’m going to go with it was too dang cold outside and that was what was causing it. But will keep an eye on it.

 

[DrT.AME]

I think mine did that on my most recent flight, I’m going to go with it was too dang cold outside and that was what was causing it. But will keep an eye on it.

Mine dramatically worsened as it's gotten colder here in NC, which never actually gets that cold, maybe 40 deg.

I'll be sure to update this thread as the solution comes, I know how frustrating it is when people post, get the problem fixed, but never update the thread on how.

 

[Rgbeard]

I appreciate being tagged in and always want to be helpful, but unfortunately, I’ve got no experience here because I’ve never had any problems in this part of the aircraft. Simply inspecting alongside my AP. (While on a ladder)

 

[DrT.AME]

I appreciate being tagged in and always want to be helpful, but unfortunately, I’ve got no experience here because I’ve never had any problems in this part of the aircraft. Simply inspecting alongside my AP. (While on a ladder)

Have an appointment with the A&P on the 28th. More updates after that.

 

[DrT.AME]

I was able to get in early, we have a diagnosis! The bottom bushing on the trim drum/jackscrew was worn. That made the entire drum a bit loose. Because of this, it was binding and didn't turn freely making the trim wheel forces excessive. Trim works so smoothly now and I can turn the wheel with my fingertips at cruise even above 150kias. Previously it was all but seized above 130kias.