Legend with auto pilot

[Richgj3]

Anybody ever fly one with the auto pilot? I think they used tru trak

 

[CubCruiser]

The Legend’s I’ve flown that have come out of the factory in the last several years have Garmin autopilots.

 

[Richgj3]

Reason I ask is a friend just bought a 2008 AL3. Looks like it was a factory demo. It has every option including the auto pilot. He’s on his way home and says the ailerons “feel stiff”. He has not messed with the auto pilot and we are wondering if maybe he is fighting a servo or it just feels that way. The airplane is very low time and has been sitting for several years. I had my Legend for over 700 hrs and never thought the ailerons felt stiff. I never flew one with the auto pilot option. We intend to go over it in detail when it gets here tomorrow.

Thanks

 

[JWE]

If there is any question about the autopilot the first thing I would do is pull the autopilot CB until on the ground and then have it checked out.

 

[Steve Pierce]

Check the connections at the rear stick and the pulleys. I have had several Carbon Cub with those connections tight (don't swivel) and the pulleys where the cables exit the top of the wings were tight and did not rotate. Several factory birds and more recently a kit EX Carbon Cub. Also had a EX2 that someone had zip tied the wiring harness to the torque tube.

 

[Richgj3]

The Legend is home. Mechanically disconnected the auto pilot from the aileron controls. It connects to the torque tub under the front seat. This caused no noticeable change. All pulleys lubed and turning. Not much change. Torque tube lubed and worked caused the most improvement. I’m leaning toward Steve P. theory. But we ran out of time today. We will loosen the clamps and see what happens. I have heard some needed spacers/washers there.

 

[Steve Pierce]

Also check aileron cable tension. People think 30 lbs is good but makes the ailerons stiff, I like them looser.

 

[skywagon8a]

Also check aileron cable tension. People think 30 lbs is good but makes the ailerons stiff, I like them looser.

Ball bearings or bushings in the pulleys make a big difference.

 

[Richgj3]

True, but there’s something wrong here. I flew my Legend for 700 plus hrs since new. Never felt anything as tight as this. And the pulleys/ control system in mine is the same as this one. Except that mine being the first one used the Piper control stick/torque tube set up. By the time this one was built Legend had designed a lighter version which they made themselves. That’s why I’m leaning toward Steve’s suggestion of the mounting clamps being overly tight/needing spacers. This was brought up in an old tread I missed at first.

The previous owner said “it’s been like that since I’ve owned it.” It has not flown very much in the last several years if at all. I suspect the condition inspections during those years didn’t include a lot of lubrication or perhaps anything else. But that will get cured now. It has around 250 hrs total time and most of that was in its infancy in 2008-9.

I’ll report what we find…..when we find it

Cable tensions “feel” ok but have not been measured yet.

 

[skywagon8a]

Rich, Piper calls out the 41371 spacers to limit overnighting the torque tube. https://www.supercubproject.com/drawings/pdfs/A3290351.pdf Try just loosening the bolts first.

 

[Richgj3]

Pete

Got a closer look today. The Legend control stick torque tube clamp is not a clam shell type (in two halves). It is an casting (aluminum?) with a hole through which the torque tube goes and ears to bolt it in place. The torque tube is meant to rotate in this fixture which holds it to the airframe on both ends. Removing the bolts holding the front results in showing the fit of the torque tube is very tight. So tight it’s very difficult to move the fixture on the tube. After much grunting, we slid the front support back far enough to clean and luricate the tube. I fear this won’t be enough and we may have disassemble the whole thing to get the brackets completely off the tube in order to clean both the tube and inside the bracket.

The good news is this 2008 airplane looks brand new. The bad news is it looks like nothing has been lubricated since it left the factory. So, the mystery appears to be solved. It’s clear all the resistance is coming from the torque tube assembly. I can’t believe it was “always like this”. The airplane has less than 250 hours on it and most of that was put on by the factory as this was a demonstration aircraft. It’s loaded with a lot of options and was displayed at OSH and SNF. I’ve been involved because of my experience with Legends. The new owner has an IA and another A&P doing a complete inspection per the Legend check list. I’m there to interpret .

Another update tomorrow.

 

[BC12D-4-85]

Remove tube (heat castings with hot air; wrap tube with ice pack), use fine abrasive flapper wheel inside casting until looser, reassemble?

Gary

 

[Richgj3]

Pretty much what I was thinking. I don’t think or hope at least, we will have go the thermal route. Definitely have get a look into the bore of the casting. I’m sure it’s just fouled with crud.

Rich.

 

[BC12D-4-85]

Maybe some galling or transfer. Polish surfaces and use an anti-seize lube? If it's tight now I wonder what real cold would do to the friction?

Gary

 

[BC12D-4-85]

If crud is found or potentially common, consider rolling a couple of O-rings over the tube up against each casting interface as seals.

Gary

 

[JohnnyR]

Our 2023 Legend AL18 MOAC build is much stiffer on the controls than the PA18’s I’ve flown. Darin Hart (Legend company owner) said it’s due to being a faster, burlier bird with more control forces at work. It does become easier to stick around when slowed up.

The Legend is home. Mechanically disconnected the auto pilot from the aileron controls. It connects to the torque tub under the front seat. This caused no noticeable change. All pulleys lubed and turning. Not much change. Torque tube lubed and worked caused the most improvement. I’m leaning toward Steve P. theory. But we ran out of time today. We will loosen the clamps and see what happens. I have heard some needed spacers/washers there.

 

[skywagon8a]

Our 2023... said it’s due to being a faster, burlier bird with more control forces at work. It does become easier to stick around when slowed up.

What is meant by "faster"? My TCOW -18 normal cruise is 108 and is light and easy on the controls.

 

[JohnnyR]

Dunno - that’s just what I was told by a guy who knows ‘em better than I do. I’ll have a good Cub mech here in AK take a look during upcoming annual for any issues.

 

[Richgj3]

Soooo, there is a bushing in the casting. Don’t know what it’s made of. The Legend Brake reservoir is under the front seat. Right over the torque tube. It appears sometime in the dim past (not flown for several years, previous owner says “it’s always been that way”) somebody spilled 5606 which ran down the tube. The whole bottom of the tube is sticky.

I don’t think 5606 is bad for nylon but it has to be something that swelled the bushing. I can’t imagine Legend letting something this tight go.

Or, perhaps the bushing is made of something that doesn’t like 5606. Or it’s simply an accumulation of residue in side the bushing.

The whole thing has to come out so the castings front and back can be removed from the torque tube so the bushings can be cleaned or replaced. The owner needs to contact Legend and ask what those bushings are made of and get some new ones just in case.

Stay tuned.

Rich

 

[BC12D-4-85]

5606 has turned to gum for me when exposed to air. I used it as a lube for locks and railroad jack pins. All I had at the time at the plane.

Gary

 

[skywagon8a]

Yup, It does get sticky when exposed to air. Hopefully a good cleaning and some light oil or grease (lubriplate) will do the trick.

 

[BC12D-4-85]

I doubt it's possible, but maybe they formulated 5606 to not wet and flow forever in air like ATF for transmissions does. Hard to believe a petroleum product could form gum without some help. Normally when the volatiles disperse it just turns to thicker oil, like WD-40 or Kroil can.

Gary

 

[Richgj3]

Combination of brake cleaner to clean off the residue, allowed us to slide the brackets (front and rear) away from their correct position then polishing the torque tube with 400 grit while lubricating. After a lot of polishing the result feels normal, same in roll as pitch.

We think it will get better with continued use and lubrication but it’s acceptable now. Very much better than before. Nobody really wanted to remove the whole assembly.

Thanks for all the advice. We accomplished a complete Condition Inspection per the Legend checklist and everything is lubed including the pulleys and controls.

Rich.