How do you test a Piper Autopilot...

Jay Honeck

Jay Honeck

Touchdown! Greaser!
Joined
Jun 6, 2008
Messages
11,571
Location
Ingleside, TX
Display Name
Display name:
Jay Honeck
...on the ground?

Our wing leveler in our '74 Pathfinder went Tango Uniform a few weeks ago. Usually reaching behind the panel and giving the power plug a good wiggle gets the thing back on-line, but not this time.

So, today we took the power connector off the back of the unit, sprayed the contacts with Corrosion X, and put everything back together. In a perfect world, what I described would have been a 10 minute job, but, of course, in the world of 35 year old airplanes, this is far from the case. It ended up taking nearly two hours, with lots of sweat and cursing -- but we got 'er done.

But then how to test it? The wind was gusting to 45 today, so a test flight was not in the cards. Is there a way to ground test an autopilot? Simply turning the unit on and turning the attitude knob did nothing -- but I'm fairly certain it never DOES do anything on the ground. Right?

Thanks!
 
Most of the autopilots with a knob to command a turn should indeed move the yoke when the autopilot is engaged on the ground, or if nothing else "freeze" the roll axis when the autopilot servomotor engages. But your particular airplane and autopilot may not - it's possible (I don't know your model of autopilot) that there may be an input to the system that says there's weight on the wheels and that would force a disconnect.

If there's a flight manual supplement for the autopilot, it should tell you how to preflight it on the ground.

As an example, the STec 40 test process was to engage the autopilot on the ground, and turn the roll knob left and right, with the yoke following. Then you'd engage the altitude hold and put pressure on the yoke and validate that the appropriate trim light came on.
 
Last edited:
I think I have the same wing-leveler in the Cherokee. Since it's not connected to any instrument and only "holds" the yoke in place, I don't think there's any way to test it.

Hm...since it's electric, try turning on the battery, then the wing leveler switch and see if there's resistance to turning the yoke. If there is, the WL is probably working as well as can be.
 
Jay,

The Piper autopilot tests I'm familiar with are the ones for something more than a wing leveler (Autocontrol IIB?) where you put it in HDG mode and turn the bug to the left and right and make sure the yoke follows; then put it in Nav mode and twist the OBS so the needle is left and then right and make sure the yoke follows that too. Not sure how you'd test a wing leveler, but the back part of your POH should have an autopilot supplement with the procedure.
 
flyingcheesehead said:
Jay,

The Piper autopilot tests I'm familiar with are the ones for something more than a wing leveler (Autocontrol IIB?) where you put it in HDG mode and turn the bug to the left and right and make sure the yoke follows; then put it in Nav mode and twist the OBS so the needle is left and then right and make sure the yoke follows that too. Not sure how you'd test a wing leveler, but the back part of your POH should have an autopilot supplement with the procedure.
Click to expand...

Unfortunately, as old as some of these Pipers are, the autopilot/wingleveler info is usually missing. I've got the AutoFlite wing leveler in the Cherokee - this was the factory-installed gadget - and after 8 years of ownership, found the little tag stuck behind the battery. With that I could track down the very limited user manual. Officially, it's the "Piper Pitch Trim System Maintenance Manual", $25 from Essco.

No, I didn't buy it.
 
Jay Honeck said:
But then how to test it? The wind was gusting to 45 today, so a test flight was not in the cards. Is there a way to ground test an autopilot? Simply turning the unit on and turning the attitude knob did nothing -- but I'm fairly certain it never DOES do anything on the ground. Right?

Thanks!
Click to expand...

ok, dumb question: your POH (or equivalent) doesn't have any preflight actions for the autopilot?
 
Autopilots typically get their reference information from one or more gyros. In the simple wing levelers it's from the T&B or TC.

Power up the airplane, allow the gyros to spool up then use the turn knob to check right and left turn, the yoke should follow.
 
Jay Honeck said:
...on the ground?

Our wing leveler in our '74 Pathfinder went Tango Uniform a few weeks ago. Usually reaching behind the panel and giving the power plug a good wiggle gets the thing back on-line, but not this time.
Click to expand...

The flight school I learned at had an archer with one of those. The instructors called it the autopilot of death. If you engaged it, the plane would slowly start a left turn and then keep on going, even if you wanted it to turn right. Sort of had a one track mind. It wanted to be the autopilot of unusual attitudes.

My Archer has a KAP140. I try not to engage it on the ground since it will try to turn to the DG heading and getting no response that its actually turning will basically bury the yoke in the direction of turn.... hard.... seems like its bad for the servos.

The KAP140 has a TEST button however, and that's a preflight item before takeoff (before it can be engaged actually).

Brian
 
bdlarkin said:
The flight school I learned at had an archer with one of those. The instructors called it the autopilot of death. If you engaged it, the plane would slowly start a left turn and then keep on going, even if you wanted it to turn right. Sort of had a one track mind. It wanted to be the autopilot of unusual attitudes.

My Archer has a KAP140. I try not to engage it on the ground since it will try to turn to the DG heading and getting no response that its actually turning will basically bury the yoke in the direction of turn.... hard.... seems like its bad for the servos.

The KAP140 has a TEST button however, and that's a preflight item before takeoff (before it can be engaged actually).

Brian
Click to expand...

KAP140 should NOT follow the heading bug when you turn the autopilot on unless you put it in heading mode. The default roll mode is wings level (stop turns) based on the turn coordinator. So if your T/C is showing a turn the autopilot should be "fighting" it with an opposite roll.

Either you're gyro's not right, you put it in heading mode, or there's something wrong.

Way too many people fly around with autopilots with way too little knowledge of how they work and what the various modes actually do (said the CFI who has automation as a specialty :D ).
 
flyingcheesehead said:
Jay,

The Piper autopilot tests I'm familiar with are the ones for something more than a wing leveler (Autocontrol IIB?) where you put it in HDG mode and turn the bug to the left and right and make sure the yoke follows; then put it in Nav mode and twist the OBS so the needle is left and then right and make sure the yoke follows that too. Not sure how you'd test a wing leveler, but the back part of your POH should have an autopilot supplement with the procedure.
Click to expand...

Sorry, I misspoke. This is the unit I have, with the heading bug. It will track a heading, normally, so long as you reset your DG regularly.

I'm hoping to test-fly it in a day or two, to see if our contact cleaning exercise had any effect. I tried powering it up on the ground, and the yoke didn't twitch, so I doubt it's gonna work -- but I must confess that I have never, in 9 years of owning Atlas, turned on the autopilot while on the ground. For all I know, there's some sort of squat switch preventing it from working.

If it's still dead, anyone got any other ideas? I've checked the circuit breaker, obviously, and it's fine.
 
Jay Honeck said:
Sorry, I misspoke. This is the unit I have, with the heading bug. It will track a heading, normally, so long as you reset your DG regularly.

I'm hoping to test-fly it in a day or two, to see if our contact cleaning exercise had any effect. I tried powering it up on the ground, and the yoke didn't twitch, so I doubt it's gonna work -- but I must confess that I have never, in 9 years of owning Atlas, turned on the autopilot while on the ground. For all I know, there's some sort of squat switch preventing it from working.

If it's still dead, anyone got any other ideas? I've checked the circuit breaker, obviously, and it's fine.
Click to expand...

There is no squat switch on these. If it doesn't test on ground it won't work in flight.

Suggest you find an avionics shop and have it repaired properly.
 
Jay Honeck said:
Sorry, I misspoke. This is the unit I have, with the heading bug. It will track a heading, normally, so long as you reset your DG regularly.

I'm hoping to test-fly it in a day or two, to see if our contact cleaning exercise had any effect. I tried powering it up on the ground, and the yoke didn't twitch, so I doubt it's gonna work -- but I must confess that I have never, in 9 years of owning Atlas, turned on the autopilot while on the ground. For all I know, there's some sort of squat switch preventing it from working.

If it's still dead, anyone got any other ideas? I've checked the circuit breaker, obviously, and it's fine.
Click to expand...

Go to Century's website and download the manual & diagrams. Read manual. After doing that call Autopilot Central in Tulsa and talk it over with those folks. Make appointment and fly up there to get it fixed right with a meaningful guarantee.
 
The old STEC 55X preflight test was involved. It runs roughly:
1. HDG and VS
2. move the bug watch the controls
3. Move the VS watch the controls
4. Test CWS
5. Test Disconnect
6. REV+ALT
7. Move the course pointer observe controls (reversed)
8. Push /pull on the yoke, watch the trim.
9. Hit the panel switch.
10. Reengage the panel switch, NAV+ALT
11. Work the electric trim to see if it disconnects

The newer procedure is even more involved.
 
Clark1961 said:
Go to Century's website and download the manual & diagrams. Read manual. After doing that call Autopilot Central in Tulsa and talk it over with those folks. Make appointment and fly up there to get it fixed right with a meaningful guarantee.
Click to expand...

Although I've heard good things about them, Tulsa is a bit of a stretch.

Can anyone recommend a good avionics shop in South Texas?
 
Jay Honeck said:
Although I've heard good things about them, Tulsa is a bit of a stretch.

Can anyone recommend a good avionics shop in South Texas?
Click to expand...

Jay:

Pippen-York at Fredericksburg is legendary for quality and value; Dr. Bruce was going to fly down from Illinois to have them install a new autopilot in his plane, until he found out that his Seneca is very limited in which autopilots are STC'd for it.
 
SCCutler said:
Jay:

Pippen-York at Fredericksburg is legendary for quality and value; Dr. Bruce was going to fly down from Illinois to have them install a new autopilot in his plane, until he found out that his Seneca is very limited in which autopilots are STC'd for it.
Click to expand...

Thanks!
 
SCCutler said:
Jay:

Pippen-York at Fredericksburg is legendary for quality and value; Dr. Bruce was going to fly down from Illinois to have them install a new autopilot in his plane, until he found out that his Seneca is very limited in which autopilots are STC'd for it.
Click to expand...

Just FYI -- I sent Mr. York (one of the two owners) an email over the weekend, which is my usual approach to all things for my aircraft. If a company responds quickly to an email inquiry, they are worthy of my business. It's a pretty low bar to clear, and it quickly separates the chaff from the wheat.

No response = fail.

Any other suggestions or an avionics shop in Texas? I'd like to get this thing looked at before OSH.
 
Jay Honeck said:
Just FYI -- I sent Mr. York (one of the two owners) an email over the weekend, which is my usual approach to all things for my aircraft. If a company responds quickly to an email inquiry, they are worthy of my business. It's a pretty low bar to clear, and it quickly separates the chaff from the wheat.

No response = fail.
Click to expand...

May I suggest that email-savvy isn't what I look for in an Avionics company. I want a company that will fix it right the first time for a fair price. Email-savvy isn't part of that equation.
 
Bob Noel said:
May I suggest that email-savvy isn't what I look for in an Avionics company. I want a company that will fix it right the first time for a fair price. Email-savvy isn't part of that equation.
Click to expand...
+1
Many aviation shops aren't exactly internet-savvy, and there are plenty of mechanics and avionics specialists who'd rather be elbows-deep in the plane than elbows on the desk typing on the keyboard. I hardly think that's a bad thing.

I'd trust recommendations from folks who have experience with their work and customer service, rather than the results of an arbitrary email "test".
 
Bob Noel said:
May I suggest that email-savvy isn't what I look for in an Avionics company. I want a company that will fix it right the first time for a fair price. Email-savvy isn't part of that equation.
Click to expand...

To be email-savvy nowadays means you have the intellectual capacity of a 6-year-old. We're not talking rocket science -- we're talking about the company's electronic front door.

Any business that doesn't answer email sent to the address that is published on their webpage within three days isn't going to get my money -- whether it's a motel, a coffee supplier, or an avionics shop. My experience has shown that when I break this simple rule, I end up disappointed.

Basically it comes down to this: Business folks who take care of the little stuff can usually be trusted to handle the big stuff. Not always, but most of the time.

Same goes with returning phone calls, or any of the other basic tenets of business. Those who perform, win. Those who don't, lose.
 
Jim_R said:
+1
Many aviation shops aren't exactly internet-savvy, and there are plenty of mechanics and avionics specialists who'd rather be elbows-deep in the plane than elbows on the desk typing on the keyboard. I hardly think that's a bad thing.
Click to expand...

I would submit that this is no longer true, even in the calcified world of aviation. Even my crusty old 64-year old friend and A&P mechanic now checks email several times a day at his shop, simply because that's a big source of his business nowadays.

And it's to his advantage to do so. Everything is in writing, and there's no "He said-she said" when it comes down to what was agreed upon. This has saved his bacon on more than one occasion.

Email has become an essential part of the business world. Those who ignore it show either arrogance or ignorance -- neither of which I want from an avionics shop.
 
FYI: Mr. York has responded. His shop has no capability to repair a Piper autopilot, and is scheduled 3 weeks out. For $80/hour he has offered to check the wiring, but states that he could not fix anything beyond a broken wire, if found.

Back to Square One. Any suggestions?
 
Jay Honeck said:
Those who perform, win. Those who don't, lose.
Click to expand...
Guess it all depends on your definition of "perform". For you, the absolute most important thing an avionics shop can do is return an email promptly. Without that, you won't even consider them. That's your prerogative.

For me, it's more important that the shop does quality work at reasonable prices. I don't mind if I have to communicate with them via telephone.

Diff'rent strokes for diff'rent folks.

The shop I use in the Houston area that has a very strong positive reputation doesn't do email very well, so I won't bother to tell you who they are. That's fine by me--you'll be one less person I have to compete with to get on to their busy schedule.
 
Come on up to MWL, visit the Century guys. Or Oklahoma, and Autopilots Central.
 
Jay Honeck said:
Back to Square One. Any suggestions?
Click to expand...

Tulsa. There's a reason I use them even though it's a state away.

Of course there's always the factory in Mineral Wells. Can't hurt to give'em a call.
 
Jay Honeck said:
To be email-savvy nowadays means you have the intellectual capacity of a 6-year-old. We're not talking rocket science -- we're talking about the company's electronic front door.

Any business that doesn't answer email sent to the address that is published on their webpage within three days isn't going to get my money -- whether it's a motel, a coffee supplier, or an avionics shop. My experience has shown that when I break this simple rule, I end up disappointed.

Basically it comes down to this: Business folks who take care of the little stuff can usually be trusted to handle the big stuff. Not always, but most of the time.

Same goes with returning phone calls, or any of the other basic tenets of business. Those who perform, win. Those who don't, lose.
Click to expand...

Your measure of using email response timeliness only measures their business process. It won't tell you if they are good or bad at the core of their business, in this case whether or not they are good at fixing avionics.

The contractor that put an addition on my house isn't good at returning emails. He does one job at a time, finishes it, and then moves onto the next job. He broke ground on the addition at the end of October, it was completed at the end of January (3 months) for a 1200 sq foot finished addition (plus full unfinished basement). Good luck finding a contractor that would be more reliable.
 
Jay Honeck said:
FYI: Mr. York has responded. His shop has no capability to repair a Piper autopilot, and is scheduled 3 weeks out. For $80/hour he has offered to check the wiring, but states that he could not fix anything beyond a broken wire, if found.

Back to Square One. Any suggestions?
Click to expand...

Disable it, and plan on replacing it with a model STCed for your airplane. Depending on what you want, I'd recommend an STec/Cobham Series 30 with altitude hold and GPSS for lateral navigation and altitude hold, up to a Series 50 or 60 for a true two-axis system.

I like the KAP140 but I'm not sure what it's STC'ed for. I wouldn't buy any mechanical system with a flight director - in my experience the AI/Flight director unit costs more than an Aspen PFD1000.

Just all depends on what capabilities you want in an autopilot.
 
I asked Mr. York who he would recommend. Now that we've got a dialogue going, his email responses have been prompt!

He recommends these folks in San Antonio:

Lone Star Aero
477 Sandau, Hangar F
San Antonio, TX 78216
210-979-6313

Anyone ever use them before?
 
Bob Noel said:
Your measure of using email response timeliness only measures their business process. It won't tell you if they are good or bad at the core of their business, in this case whether or not they are good at fixing avionics.

The contractor that put an addition on my house isn't good at returning emails. He does one job at a time, finishes it, and then moves onto the next job. He broke ground on the addition at the end of October, it was completed at the end of January (3 months) for a 1200 sq foot finished addition (plus full unfinished basement). Good luck finding a contractor that would be more reliable.
Click to expand...

I've worked 18 hour days for 14 months. I don't have time to eff-around with contractors, so I use short-cuts like the "does he return email" test to eliminate people I don't want to work with. It saves me time, and usually gives me a pretty good read on how a company will be to deal with.

As with all things, there are exceptions.
 
Jay Honeck said:
I asked Mr. York who he would recommend. Now that we've got a dialogue going, his email responses have been prompt!

He recommends these folks in San Antonio:

Lone Star Aero
477 Sandau, Hangar F
San Antonio, TX 78216
210-979-6313

Anyone ever use them before?
Click to expand...

e-mail them!! :D




Sorry, couldn't resist.
 
Telephone for time-sensitive stuff. Usually calling a small shop will get voice mail. Expect a return call that day, even if it's later on.

E-Mail isnt intended for instant communication for anyone other than me the IT-weenie carrying around four mobile devices that all ding when the damn things come in. Real people in craft shops sit down to e-mail a couple times a day, tops.

The guy who put in my house windows, no e-mail. The lawn guy when I need something bigger than I feel like tackling done, no e-mail. The roofers, no e-mail.

An expectation of fast e-mail is an extension of mobile devices and office workers. An airplane hangar isn't an office.

In fact, getting a fast reply in e-mail from most mechanic shops probably means you're paying for the overhead of a receptionist. If the shop is huge and has four or five mechanics, maybe they need one. But small shops? Nah.

Many of them only have an e-mail address because the "web developer" said they did. Pick up the phone. Expect paying customers to come before you, and wait a day or so. Ain't no big deal.
 
denverpilot said:
Telephone for time-sensitive stuff. Usually calling a small shop will get voice mail. Expect a return call that day, even if it's later on.

E-Mail isnt intended for instant communication for anyone other than me the IT-weenie carrying around four mobile devices that all ding when the damn things come in. Real people in craft shops sit down to e-mail a couple times a day, tops.

The guy who put in my house windows, no e-mail. The lawn guy when I need something bigger than I feel like tackling done, no e-mail. The roofers, no e-mail.

An expectation of fast e-mail is an extension of mobile devices and office workers. An airplane hangar isn't an office.

In fact, getting a fast reply in e-mail from most mechanic shops probably means you're paying for the overhead of a receptionist. If the shop is huge and has four or five mechanics, maybe they need one. But small shops? Nah.

Many of them only have an e-mail address because the "web developer" said they did. Pick up the phone. Expect paying customers to come before you, and wait a day or so. Ain't no big deal.
Click to expand...

Right you are. Just called the San Antonio shop. Voicemail. :(

Oh, well. When you're dealing with antique avionics, in a dying hobby, beggars can't be choosers. Quite frankly, I'm just glad here are still people out there to work on these things.

And I really don't NEED an autopilot...
 
You might also get a bit of sticker shock if/when you find a repair place. :(

We fixed our Cessna 300 "Wing Rocker" autopilot this winter and while the fix was simpler than expected (replace the turn-coordinator that was sending bad signals to the AP), the overall avionics bill was... Well... An avionics bill. The work was done well, was only about a week and a half longer than expected (we didn't know what to expect) and the airplane got to sit in their heated hangar during the coldest week of the year instead of our unheated one.

Worked out okay, really...but wasn't the cheapest two and a half weeks in our maintenance journey. ;)

Not sure the AP was worth it, but we all dislike broken stuff on our bird. It'd keep you right-side up and somewhere approximating ten degrees of your intended course-line while you dig for something in the back, after it settles down a bit.

We'll see how it does on the XC to OSH. With two pilots on board, there's no need, but I'd like to see it in action a bit more to determine if it's more likely to be helpful single-pilot IMC or just going to be a distraction that'll kill me. ;)

The 182 is such a pickup truck that it doesn't wander around a whole lot anyway hands-off. I just want to see it properly track a VOR for a leg. LOL.
 
Just an update: Lone Star Aero never returned my call.

Upon being informed of this, Mr. York responded that they MAY be out of business.

Guess so...

The good news? The wing leveler portion of the AP came back to life. It won't track the heading bug, but at least we'll have something for the flight to OSH. Meanwhile, my search for a legitimate shop continues.
 
You must log in or register to reply here.
Back
Top