Hinge Pins - Cessna and Piper

[robertb]

Hello everyone,
At the suggestion of my mechanic, I am looking to replace the aileron and elevator hinge pins on a Cessna 182P and 1976 Piper Archer. I have looked at the parts manuals and do not see the pins being available separately from the two hinge-halves. Aircraft Spruce has some pin material available (https://www.aircraftspruce.com/catalog/mepages/hingepin-ss.php?clickkey=7896) at 0.089" diameter. I'll need to remove one of my hinge pins (under A&P supervision, of course) and measure it. Anyone have experience of knowledge on replacement pin materials?

 

[NordicDave]

If the pins are worn, then very likely the hinge pivot sleeves are worn. What issue are you hoping to remedy, makes you suspicious of the pins as root problem?

 

[Magman]

Have you tried Macfarlane?

Replacing the Archer Tab Hinge pins is a much easier procedure than

replacing the entire assembly. Wear seems to start at the outboard hinges

and progress inward. A new pin will reduce the shaking and prolong the life

of the assemblies.

 

[robertb]

If the pins are worn, then very likely the hinge pivot sleeves are worn. What issue are you hoping to remedy, makes you suspicious of the pins as root problem?

There is a little slop in the hinges which, after 50 years and 4,000 hours, is not unexpected. If there are different metals involved, one may be wearing more than the other and the life can be extended. Hopefully, it is the pins and not the hinge as the pins appear far easier to replace.

 

[robertb]

Have you tried Macfarlane?

Replacing the Archer Tab Hinge pins is a much easier procedure than

replacing the entire assembly. Wear seems to start at the outboard hinges

and progress inward. A new pin will reduce the shaking and prolong the life

of the assemblies.

I reached out to McFarlane and they responded quickly. But, they do not offer any replacement hinge pins.

 

[Magman]

Generally I tell folks to get parts and then we install.

I should have the source today as we had just did this.

Better to do 100 hrs too early than wait and replace entire hinge.

 

[robertb]

Generally I tell folks to get parts and then we install.

I should have the source today as we had just did this.

Better to do 100 hrs too early than wait and replace entire hinge.

Thank you Magman! I look forward to the info.

 

[Magman]

Here it is!

btw I cut 1 end off with Dremel rather than straighten and damage hinge

when removing old.

 

[robertb]

Here it is!

btw I cut 1 end off with Dremel rather than straighten and damage hinge

when removing old.

Thank you sir!

 

[Dan Thomas]

Don't mess with replacing the pin. That pin is aluminum, inside an aluminum hinge, and both pieces gall and wear. You could replace the pin and still find the hinge sloppy.

The middle hinge wears in a fore-aft direction due to the push and pull of the pushrod. The outboard hinge wears vertically due to the weight of the mass balance at the outboard end. Push the outboard end up and down to see the hinge wear, and work the aileron up and down a little against the system friction to see the fore-aft slop in the middle hinge.

DON'T lubricate aileron hinges with oil. The service manual is clear on that. It attracts dust and grit that adds to the wear. The manual calls for dry graphite, but getting it in there is difficult, so I mixed the graphite with a bit of brake cleaner fluid in a cheap syringe and wicked that into the hinge. The fluid carries the graphite into the hinge and then dries, leaving no residue.

The elevator hinges don't have replaceable pins. They will likely have bolts passing though brackets on the elevator and through small ball-bearings in the stabilizer brackets. Mechanics are famous for leaving those bolts loose "so the elevator can pivot freely" and those thin elevator hinge brackets get wallowed out and ruined. That's expensive. Those bolts are supposed to be torqued up to clamp the brackets against the inner race of the small ball bearing. Some older airplanes might have bronze bushings with steel "spacers" that go through them, and the bolts are to clamp those spacers tight in the brackets. The spacers rotate in the bronze.

I have found those small ball bearings rusted up nearly solid.

 

[Magman]

Reference to Archer Trim Tab :

I believe the pins are brass.

A set of tab hinges is about 8 times the cost of the pin set.

There is a lot more labor involved with riveting new hinges in as well.

To me these pins are similar to Torque Link Bushings, Control Yoke

Universal Joints , Airbox Grommets , Seat Tracks, etc.

Normal Wear items that require replacement at times. I’ll bet the

folks with fleets can pretty much put a “time between changes” on

many of these.

 

[GeorgeC]

DON'T lubricate aileron hinges with oil. The service manual is clear on that. It attracts dust and grit that adds to the wear. The manual calls for dry graphite, but getting it in there is difficult, so I mixed the graphite with a bit of brake cleaner fluid in a cheap syringe and wicked that into the hinge. The fluid carries the graphite into the hinge and then dries, leaving no residue.

Do you need to clean out the hinge with solvent before lubricating it with graphite? The brake cleaner doesn't attack the paint?

 

[Dan Thomas]

Do you need to clean out the hinge with solvent before lubricating it with graphite? The brake cleaner doesn't attack the paint?

It would be good to get any oil and sludge out. I haven't seen the non-chlorinated brake cleaner harm paint, but you could use ordinary cleaning solvent (like Varsol) to clean them out. Wick it in, blow it out with compressed air. A couple of shots like that should do it. You'll have to wipe the wing and aileron clean of the gunk that comes out.

 

[Silvaire]

Just went through this with a PA-28. Tried just the pin first but no joy, made absolutely no improvement. Ended up replacing the whole assembly.

 

[Magman]

Replacing pins early may save replacing entire hinge.

While re-reading the entire thread you have to have to be careful to avoid mixing the different types

of “piano “ hinges.

Generally:

Cessna ailerons use a steel pin. Lube per manual.

Cherokee ailerons use a hinge with a Teflon (?) liner over the pin. Do not lube.

Cherokee trim tab hinges have brass pins. Lube per manual.

Hope that’s correct . I always have the owner do most servicing items.

Motivating as they pay for things that wear out!

 

[bnt83]

Judging by how many cessna 182/? LOSE COWL FLAPS because the piano hinge let go, just replace the whole assembly and get it over with.

 

[GeorgeC]

better-is-the-enemy-of-good dept.:

Better Lubricants than Graphite

www.graflex.org

 

[Magman]

Just what is the “ whole assembly” regarding 182 cowl flaps?

Hinge, cowl flap, or lower cowl?

Any one of these can cause the cowl flap to depart along with the control.

The hinge itself can ( and does) fail. But the hinge can also tear loose from either

the cowl flap or the lower cowl. This will oversize the rivet holes and render them unusable.

Drilling new holes may be necessary but more holes will weaken the structure.

Since these things are pricey it’s best to address worn pins/ hinges and loose rivets

before a “ departure”. Just like the rest of the aircraft.

 

[Jdm]

Some older airplanes might have bronze bushings with steel "spacers" that go through them, and the bolts are to clamp those spacers tight in the brackets. The spacers rotate in the bronze.

Yep, they should tighten down on the inner steel bearings so there’s no wear on the bracket. I just pressed in a new set of bushings and replaced the steel bearings.
What’s your preference for lubing them? Seems likely that nothing will properly penetrate between the bearing and bushing once it’s torqued against the brackets.

 

[Dan Thomas]

What’s your preference for lubing them? Seems likely that nothing will properly penetrate between the bearing and bushing once it’s torqued against the brackets.

From the Cessna 172 manuals:





That "general purpose oil" is the MIL-7870 (upgraded to something like MIL-PRF-7870 now). Royco 363 is a common brand of it. It will wick into those bearings; there's enough end play there. The 7870 is far superior to any LPS or CFC stuff commonly squirted everywhere by mechanics. Makes a mess, and turns to gum eventually.

I used cheap drugstore syringes, with one of those tiny tubes from an LPS or WD-40 can shoved into the end, to get one or two drops into the bearing. Any more than that is wasted and just drips out. The rubber seal in the syringe will eventually swell and stick, but they are cheap enough that you just grab another. You can even lube stuff that is overhead and up against something with this idea, stuff like control column rollers or U-joints or the sprocket bearings.

I have tried greasing the spacers before putting them into the bushing, but grease turns to sludge eventually as is mixes with dust and water, and then it's a bear to get out of there without taking the control surface off.

 

[Jdm]

Good stuff. Thanks for the lube info!
I put a thin layer of grease on the steel spacers before inserting them. Elevator isn’t attached yet though.

 

[GeorgeC]

I used cheap drugstore syringes, with one of those tiny tubes from an LPS or WD-40 can shoved into the end, to get one or two drops into the bearing. Any more than that is wasted and just drips out. The rubber seal in the syringe will eventually swell and stick, but they are cheap enough that you just grab another. You can even lube stuff that is overhead and up against something with this idea, stuff like control column rollers or U-joints or the sprocket bearings.

I ended up epoxying a wd40 tube into a kid medicine dropper, but that started to feel like work...

https://www.amazon.com/gp/product/B01NBSWJ5R/

 

[bluerooster]

Replacing pins early may save replacing entire hinge.



Cherokee trim tab hinges have brass pins. Lube per manual.

Mine had steel pins, so that's what I replaced them with. Also had to replace two of the hinges due to wear.

 

[GeorgeC]

I ended up epoxying a wd40 tube into a kid medicine dropper

Epoxy wasn't a good idea, because...

better-is-the-enemy-of-good dept.:

Using crc dry moly in the syringe also wasn't a good idea, because there's acetone in it.

It would be good to get any oil and sludge out. ... you could use ordinary cleaning solvent (like Varsol) to clean them out. Wick it in, blow it out with compressed air. A couple of shots like that should do it. You'll have to wipe the wing and aileron clean of the gunk that comes out.

I cleaned it with mineral spirits and blew it out with compressed air. I didn't see any gunk come out, but it must have done something, since my ailerons moved *much* more freely with fresh lubricant. Thanks!