What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Easy Safety Check!

PerfTech

PerfTech

Well Known Member
.... I am posting this as it may help someone else from the same experience I had last weekend en-route to the Vans Homecoming. We traveled the last 200 miles or so VFR on top with no ground sightings or holes to be had. We were between layers and things were getting worse rapidly when all of a sudden my airplane began a turn to the left for no apparent reason. This is when I became aware that my auto pilot, True-Trac ADI Pilot II, was not functioning. This is where I really needed it and the first and only time it has failed to function perfectly in 600 hrs. The altitude hold was working, all indicator lights were on, but no roll servo action at all. After returning home I went to work locating the problem and found it had sheared off the shear pin in the servo arm. Not a difficult fix, but in retrospect I think I know what caused it to quit. I have on two occasions put considerable stress on the airplane, once in severe turbulence and one high G drop on landing. I am sure this is what stressed the pin and it finely just let go at a very inopportune time. The moral to this story is this, if you have been in extreme turbulence or a hard landing you may want to consider changing these pins. They are very inexpensive and easy to change. This ounce of prevention may save your axx one day. I definitely like a working auto pilot when in the clouds.:eek::eek: Thanks, Allan
 
We traveled the last 200 miles or so VFR on top with no ground sightings or holes to be had. We were between layers and things were getting worse rapidly

Isn't that IFR?
 
sirlegin said:
Isn't that IFR?
Click to expand...

"By the book" (FARs) it is VFR if you are 1000 feet above the layer below and 500 feet below the layer above and have 3 miles visibility. But let's get real. What does 500 feet below a layer look like? how do you know that there is 3 miles visibility with no reference. I don't have a problem with flying between layers, but only on an IFR flight plan in a properly equipped aircraft. Without complete understanding of the weather around you and a sure thing way out, it is a sucker move.

John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
 
PerfTech said:
found it had sheared off the shear pin in the servo arm. Not a difficult fix, but in retrospect I think I know what caused it to quit. I have on two occasions put considerable stress on the airplane, once in severe turbulence and one high G drop on landing.
Click to expand...

Thought that was the problem, glad you found it.
 
PerfTech said:
This is where I really needed it and the first and only time it has failed to function perfectly in 600 hrs.
Click to expand...

I've always thought of the autopilot as a luxury - not something I ever really *needed* in the true sense of the word. Do you have an instrument rating? I have found mine to be far more useful than an autopilot on numerous occasions.
 
It just so happens I read an article today in "Midwest Flyer" about how much today we rely on our autopilots and what would happen if it went poof at the absolute worst time. This article was from 2009 before the flight director and synthetic vision flooded the market but had many good points. Anything you can pass on to the lower time pilots (like me) that made it not such a big deal for the rest of the flight?
 
Last edited:
As a generalization; it is appears that many in the RV community DEPEND on the use the autopilot in lieu of skill/proficiency. It really should be a work load reduction tool & not a crutch.
 
Allen,
Thanks for sharing your story. I have the same servos in our plane. Did you have to get the new pins from Tru-Trak or did you find another source.

Don
 
thanks Allan for the heads up.
I have this autopilot as well and will replace these pins on my next condition inspection.


PerfTech said:
.... I am posting this as it may help someone else from the same experience I had last weekend en-route to the Vans Homecoming. We traveled the last 200 miles or so VFR on top with no ground sightings or holes to be had. We were between layers and things were getting worse rapidly when all of a sudden my airplane began a turn to the left for no apparent reason. This is when I became aware that my auto pilot, True-Trac ADI Pilot II, was not functioning. This is where I really needed it and the first and only time it has failed to function perfectly in 600 hrs. The altitude hold was working, all indicator lights were on, but no roll servo action at all. After returning home I went to work locating the problem and found it had sheared off the shear pin in the servo arm. Not a difficult fix, but in retrospect I think I know what caused it to quit. I have on two occasions put considerable stress on the airplane, once in severe turbulence and one high G drop on landing. I am sure this is what stressed the pin and it finely just let go at a very inopportune time. The moral to this story is this, if you have been in extreme turbulence or a hard landing you may want to consider changing these pins. They are very inexpensive and easy to change. This ounce of prevention may save your axx one day. I definitely like a working auto pilot when in the clouds.:eek::eek: Thanks, Allan
Click to expand...
 
Chris Thomas said:
As a generalization; it is appears that many in the RV community DEPEND on the use the autopilot in lieu of skill/proficiency. It really should be a work load reduction tool & not a crutch.
Click to expand...

Chris,

Where and how did you come to this generalized conclusion? I've been a part of the RV community for 15 years and have flown various autopilots in RVs for nearly all those years.....and know a host of RV pilots. I have not seen evidence to support your position. I am of the opinion that RV pilots as a general rule fly more than the "average" GA light plane pilot and demonstrate more proficiency. Change your statement from "many" to "few" and I would agree. But that would apply to GA pilots as a whole, not just RVers.

But...having said that, the FAA is really encouraging training in the use of autopilots in GA aircraft. Crutch or not, an autopilot is a huge aid when the workload gets heavy. But as an airline pilot you know that better than I.
 
Last edited:
Sam Buchanan said:
Chris,

Where and how did you come to this generalized conclusion? I've been a part of the RV community for 15 years and have flown various autopilots in RVs for nearly all those years.....and know a host of RV pilots. I have not seen evidence to support your position. I am of the opinion that RV pilots as a general rule fly more than the "average" GA light plane pilot and demonstrate more proficiency. Change your statement from "many" to "few" and I would agree. But that would apply to GA pilots as a whole, not just RVers.

But...having said that, the FAA is really encouraging training in the use of autopilots in GA aircraft. Crutch or not, an autopilot is a huge aid when the workload gets heavy. But as an airline pilot you know that better than I.
Click to expand...


To add to the thread creep I'd agree with Sam. I am a low time pilot, instrument rated. The only reason my RV-9A has an autopilot is because I can afford it and for resale. In fact I dread having to calibrate it in my phase 1. I will have it, I will use it, but it certainly won't be a crutch. I was taught better than that.
 
Wow! Thread Drift

....Looks like perhaps I should have left out the circumstances and just posted the autopilot check and repair. I guess the 10k or so hours I have survived flying were just a product of dumb luck. Couldn't be any skill or know how involved. :rolleyes:
....I made the shear pins or screws myself from 6-32 x 1/2" brass machine screws but they are available from Tru-Trac. I just didn't want to wait for them in the mail. I realize now that this issue was brewing for quite some time and was giving me some warning signs. My autopilot headings were wondering about 5 or 6 degrees and searching side to side. I just thought I needed to calibrate it and dial it in a little better. As it turns out, after replacing the pin all that went away and it now tracks perfectly with no other changes. I hope this will be helpful or save some time for some of you guys when diagnosing Auto-Pilot issues. Regards all, Allan....:D
 
Allan,

It was really great to meet you at Vans Homecoming and chat with you for a bit. I absolutely love my nosewheel mod that you guys did for the 7A that I'm building, and I look forward to incorporating many more of your fine products into my plane as I finish it up.

Thanks for posting this information. I'm installing a TruTrak A/P and this is good information to know. Much appreciated. :)
 
Thanks Alan!

Got my Tru Trak servos airborne first time this Friday past, I very much appreciate you telling us of your experiences!! Maybe saves me from having to wade the same creek....

Greg
 
PerfTech said:
....Looks like perhaps I should have left out the circumstances and just posted the autopilot check and repair. I guess the 10k or so hours I have survived flying were just a product of dumb luck. Couldn't be any skill or know how involved. :rolleyes:
....I made the shear pins or screws myself from 6-32 x 1/2" brass machine screws but they are available from Tru-Trac. I just didn't want to wait for them in the mail. I realize now that this issue was brewing for quite some time and was giving me some warning signs. My autopilot headings were wondering about 5 or 6 degrees and searching side to side. I just thought I needed to calibrate it and dial it in a little better. As it turns out, after replacing the pin all that went away and it now tracks perfectly with no other changes. I hope this will be helpful or save some time for some of you guys when diagnosing Auto-Pilot issues. Regards all, Allan....:D
Click to expand...



There are two types of pilots in the world. The first type are those that I tend to enjoy hanging out with, and the second are the other guys....who, as you have seen here, can not wait to say "let me tell you what is wrong with you". They will stroll up to the fuel pump or lunch stop to critique your landing or discuss how your pattern was too tight. I usually smile and ask if their advice is free or if there is a tip jar around somewhere. I get a lot of satisfaction out of their blank stare and silent retreat.

In any event, thanks for sharing the tip. No good deed goes unpunished though, eh? :)
 
PerfTech said:
I realize now that this issue was brewing for quite some time and was giving me some warning signs. My autopilot headings were wondering about 5 or 6 degrees and searching side to side.
Click to expand...

Errr, pins are either broken or not, I don't see how they'd cause something to get progressively worse....?

I don't think a broken pin was your only problem....
 
gtmule said:
Errr, pins are either broken or not, I don't see how they'd cause something to get progressively worse....?

I don't think a broken pin was your only problem....
Click to expand...

....When the pin (actually a screw) failed, it didn't break off clean. It left a large burr that was still trying to operate the arm, loosely and there or also two nylon screws that were helping the arm for a bit, until they failed as well. I could see on the rear side of the arm where they were working back and forth for some time before the burr wore down and stopped trying to operate the arm. Works great now! Just like when new. Thanks, Allan...:D
 
PerfTech said:
....When the pin (actually a screw) failed, it didn't break off clean. It left a large burr that was still trying to operate the arm, loosely and there or also two nylon screws that were helping the arm for a bit, until they failed as well. I could see on the rear side of the arm where they were working back and forth for some time before the burr wore down and stopped trying to operate the arm. Works great now! Just like when new. Thanks, Allan...:D
Click to expand...

Make sense. Threads in shear break, that's what they do. Doubt it was caused by your incidents.
 
Allan,
I had a very similar experience with the shear pin on the pitch servo. My altitude was drifting, slightly some days and worse on others. Looking back it was really dependent on the turbulence.

When I finally got tired of it drifting it was time to pull the rear baggage panel and see what was going on. As soon as I felt the servo arm it was easy to see what was wrong. Why didn't I think it was the shear pin? Because some days (in smooth air) it worked fine. The retaining screw was tight enough for it to work while not under load.

It would have been simple to engage the AP on the ground, set an altitude and actually hold the stick and see the servo arm was not fully engaged. That is how I check it now.


The plane has over 1000 hours now, the shear pin broke at around 800.

Thanks for the heads up.


Gary
 
Allan,
I am sorry you feel put-upon. But I cannot find fault with the posters. Read what you wrote: the autopilot failed "when I needed it most". Did you really need an autopilot, for day-vfr no less? I do not think that is what you meant. But it is what you wrote, and what people have focused in on. Similar comment applies to "the weather was closing in". All sorts of interpretations.
Moral: we all need editors.

I would think damage to the shear pin could only happen when the servo was engaged, ruling out a hard landing as a cause.
 
Please Allow Me To Continue The Thread Drift

This started with a question- "isn't that IFR?
I think John's response was spot on. He likely doesn't know if Alan's plane is equipped for instrument flight, or if Alan is instrument rated, or current, or had even needed or requested an instrument clearance. I didn't take his comments as a personal assault on Alan.
What he does know (better than many of his fellow pilots) is that continued VFR flight into instrument conditions is a BIG KILLER. He tried to point that out.
I find it amazing that a very high time pilot with credentials to match is put upon because he cares about aviation safety. I'm sure that John has seen more than his fair share of "stupid aviation tricks" over the years. I'm sure that more than once he's had someone tell him to mind his own business or some other cute response.
Look, he cares about aviation. He cares about our reputation with the public. He even cares that fellow pilots, no matter how independently minded, don't kill themselves or others.
LISTEN TO HIM. He knows of what he speaks. I'd hate to see him stop posting because of the way some folks want to respond to any advice.
Terry, CFI
RV9A N323TP
 
Sorry to add to the drift but ......

Allan -
It is a shame that your intention of trying to help fellow aviators with a possible auto pilot issue quickly degenerated into an assault on your flying abilities. Do not take it too personal, these are the same folks (one in particular) who told Randy Lervold he needed to take flying lessons when he asked a question about the Fiske Arrival into Oshkosh. Your in good company.
Doug and the group do a fantastic job keeping this website civil but you can not stop some personality traits from shining through.
 
Last edited:
I have no idea of Allan's abilities but reading his original post my initial thought was of the person who reportedly was flying to Oshkosh with others. They may have been between layers of clouds (I do not recall the exact details).

The end result is that something happened and an RV pilot died. This may be the event:

http://www.ntsb.gov/aviationquery/brief.aspx?ev_id=20130728X71223&key=1

http://www.vansairforce.com/community/showthread.php?t=102481&highlight=crash

" I spoke with other friends as to what happened and about all I can say on here is that a group was flying together out of Kansas enroute to OSH and got caught between cloud layers and lost site of him and the rest is history."

People make preventable mistakes. There is no reason why the RV community cannot become the safest within general aviation. But until the preventable problems are reduced, more people will needlessly die.

Having a working autopilot Minimum roll and ideally pitch as well) MIGHT save your hide if you screw up and need to get out of a bad situation. But you should know your options before it gets bad and far better to bail before it gets out of control. I have had to overnight and/or divert several times due to weather.
 
Last edited:
Don't wander

Seems like simple was overlooked. Reply to the topic. Simple.
Shear pin. Topic. Simple. Just check it. Over.
 
Easy Safety Check

Allen,
I'm flying PHL to Frankfort on Thursday. I'm gonna be one tired puppy when I get there 8 hours later without the autopilot, so I can prove I have the skills to hand fly all the way!!! Hope we don't have to hold!! :rolleyes:
Thanks for the post and helpful hints on building and flying RV's!!
 
Thanks Alan

Never thought of checking them. We will replace them at annual this year as the plane has over 900 hours now. Will probably just buy them from TT.

I am not going to get in the other discussion except to say that the TT is a great backup in case the EFIS system punts while IFR.

Thanks for posting!
 
You must log in or register to reply here.
Back
Top