Efis one flying update.

To those who have hashed it out with me, in this forum during our EXTREMELY difficult RV10 E-1 installation, and others concerning throwing thousands of dollars at BMA, please note the following:
This unit is installed in RV 10 number 15 to fly. I did 95% of the install for my friend, and the archives will show all our tribulations from no jumpers, to inop boards, to horribly misleading and incorrect and information missing manual, to accusations from BMA. Here are my notes after 13 hrs of flight testing:

**** The previously forum discussed "jittering" is worse inflight. The numbers in the heading compass jump around continuosly, and heading "jitters" +/- 1 deg while holding constant heading.
****The Tach is unusable below 1200 RPM. Calibrations can not fix, even though we calibrated with handheld down to 500 RPM.
**** When HSI, attitude display (without 3D terrain enabled I might add) and terrain is displayed, the heading updates about 4 times per second as well as the terrain display. This equates to a VERY "steppy" heading, attitude and map display. Also on the map page, the terrain displays, ie. airport names and towers for example, jump around continuously. Some have defended BMA saying that this is a high demand display setting, but is this not what everybody would like to see in a $19,000 set up while flying?
****Still unable to get any axis of the autopilot to engage. We got the typical BMA response so far to change the gain and check the wires. Wireing today checked good and gain change offers no help so far. BMA has promised, as they always do actually, to "get us up and running".
****Ammeter is unreliable and gives constant alarms with the great variation in readings.
**** CHT only reads above 230 deg.
**** Oil pressure will occasionally jump around during radio transmit.
****BMA has suggested that we sheild affected wires, even though the harnesses supplied by them (very expensive) were not delivered shielded.

Now PLEASE, those who I have now just enraged who think I am trying to hammer BMA, please note that overall I am very impressed with this unit. I am horribly disillusioned though, with the manual, INITIAL factory support, and their misinformation giving order dept. Those who own BMA or read this forum know her name.
I am merely giving my observations and perceptions of a VERY expensive, high tech, and actually very impressive unit. I am trying to, in my own way to inform those considering buying this unit, on the less than flattering aspects of BMA and specifically the E-1. BMA supporters and the company itself would never bring the above into a public forum. I have, and sincerely hope that each and every one of the above items can be corrected in this and every future BMA unit.
BMA recommends the extremely knowledgable "Bob" to install their untis for $1500 plus airfare. Listen folks, unless you do this stuff every day, this is worth every penny. I am not a novice around avionics, and had a horrific time. I can now probably do another in half the time, due to my experience, even with the horrible, manuals.
As a final note, the owner of this plane is extremely impressed with the way his panel looks and the displays, and overall with the E-1. He says I am being too "anal". He is in 100% agreement with me though, of how horrible the installation went. (As a reminder, I received a refund for my lite after waiting 3 months after the promised delivery date, while others received theirs while ordering theirs well after me, ...another story) My friend says I am being too "anal", perhaps, but for anybody considereing buying this unit, I will be more than happy to speak with them or even send them video of some of the above inflight.
I am also extremely open to objective comments and sincerely hope this forum is helpfull to every one of us.
Glen
561-670-6095

inspection plate cometh

I am trying to figure out how to install an inspection plate. I absolutely didn't want my top deck with camlocs or a plate but you know how tough it is to make mods to the CPU....

On my first engine start two known "in ops". No tach, still needs calibrating; erratic amp readings. Amp gauge rewired so that power doesn't go thru the BMA. If I had the top deck in place; big repair. and haven't had a second engine run to verify problem is fixed.

I wanted an emer. hatch with studs sticking down that I access from under the panel ( so no access from outside plane) but I can't think of a way yet. Didn't want a piano hinge.

thanks for the input.

(thanks gil in AZ)

Ammeter & tach

mark manda said:

I am trying to figure out how to install an inspection plate. I absolutely didn't want my top deck with camlocs or a plate but you know how tough it is to make mods to the CPU....

On my first engine start two known "in ops". No tach, still needs calibrating; erratic amp readings. Amp gauge rewired so that power doesn't go thru the BMA. If I had the top deck in place; big repair. and haven't had a second engine run to verify problem is fixed.


I wanted an emer. hatch with studs sticking down that I access from under the panel ( so no access from outside plane) but I can't think of a way yet. Didn't want a piano hinge.

thanks for the input.

(thanks gil in AZ)

Click to expand...

Hey Mark. Been there done that on the rewire on the ammeter guage, not gonna fix it. Good luck on low RPM readings. If you figure out the secret, let us know!
Glen

I played around with the AD settings and got the rpms to register -8 and the amp setting is at -3 now. So, I'll fire it up tomorrow hopefully. and then decide what to do about an inspection cover. water cut, laser cut?

RPM and Ammeter.

Hi Mark, listen,... the AD settings can be played with and you can get the display to read anything that you wish, on any display. The problems come up with, I believe (and the knowledgable "Bob"), induced currents and low, low, low voltage signal inputs that cause readings to be totally useless with the engine running, or inflight. ie, RPM at low RPM's and ammeter all the time when engine is running.
I am somewhat dissapointed that neither BMA nor readers of this forum that are BMA gurus, have not, offered anything to fix some of these anoying problems.
I have heard rumor that BMA now has a software update that will address the display jumping around issues IAW headings and map displays. Brent is checking on this, as he is our software guru, and right now has tons more patience with BMA than myself.
Glen

BMA just lost another customer!

darn, i was hoping for some advice on cutting an inspection plate NOT causing the company lost business.

I hate to send my large top deck out. got to be a place within 400 miles of me. or I cut it out and maybe even do a fiberglass lid. I"m worried about it changing shape, like everything else...

Mark,
you are not causing BMA lost business. They are doing it to themselves. After all the bad publicity they get ,one couldnt expect people to buy their product.Building a plane is hard enough work without having to deal with supplier issues. Grand Rapids and Dynon seem to get favourable reports .
The BMA units seem like a great concept on paper. Maybe one day their product and service will catch up, but for now..........

More Efis 1 flying info...

We are having some really good dialogue right now directly with Greg at BMA reference some of my previous complaints, and problems with RV 10 335JH. It seems to me that with the newest 2.5 software (yet to be installed), and the in testing phase software we are hearing about, and maybe the new gyro hardware options, it seems that BMA is getting their act together and it appears they have listened to every one commenting good and bad. Greg has apologized to me personally concerning my delivery nightmare earlier this year, and assures myself and all others that all future deliveries will not be promised until units are on the shelves. Apparently the "Glen" nightmare will be a thing of the past.
Oh, and I would like to personally thank all those who cut and pasted to Greg, several of my past comments, which most, were completely out of context or without my balancing comments. I thought that was quite a professional touch. Thanks soooooo much.

My complaints with the ammeter and tach will hopefully be solved in the following manner IAW Greg's suggestions and assurances:

***Greg says that new and coming software will address the tach not reading below 1000 RPM. I have played extensively with damping and calibrations, and we now have a rock solid RPM reading (above 1200 RPM).
***Ammeter, still wilder than I would like, but I will try Greg's suggestion to add more damping to lower false alarms, and I think a new deadline will probably get us to an acceptable ammeter reading situation.
***The autopilot continues to stump everybody. We have replaced everything ( control unit, both servos and wires) except the CPU (All shipped quickly and free of charge from BMA). We are waiting for the knowledgable "Bob" to come down (paid for by BMA) possibly with a CPU and find our final gremlin. The autopilot continues to function in ground test mode, and lock up the controls very solidly while "flying" on the ground. It fails though, to lock up the controls/servo and fly the plane inflight. Greg promises we will get it fixed, and references the hundreds of units flying perfectly in the field.
***Flew the first VOR courses and an ILS today. Vor and ILS needles are rock steady, and appear to be perfectly accurate. The VOR's checked within 1 degree on the VOR check. They do not follow their jittery cousin, Mr Map. The digital interface between the E 1 and the SL30 is an awsome touch. Navigating though without reading the manual or a thorough checkout, will stump the most confident IFR pilots to get the displays and course desired. Watch all that heads down flying guys! Once set up, it is a great HSI display to follow. Took a little X-country today to the edges of our box, and I am really impressed with the virtual 3D on the ADI. This alone makes the price of admission worth while IMHO.
Glen

thanks for the positive news glen.

I sent my CPU off on friday for the gyro upgrade. It will probably keep me from flying this year though. It only took 4 hrs. to drop the cpu out the bottom and the screws, and the ribbon cord was the worst part so i'll plug it in prior to reinstalling. ( i should be faster the next time.)

I'm going to forego an inspection plate on the top deck since it came out the bottom okay. keep the info coming.

All BMA autopilot owners CAUTION!

A VERY scary thing happened yesterday when I went out to fly 331JH. It was a beautiful morning and Jim is geting REALLY excited since there are less than 10 hours left in testing for him to take his first ride in his new 10!
I sat down and turned on the master and immediatly there was a loud squeal from the left wing tip(servo installed there) and the aft fuselage. At the same time the stick abruptly jammed to the left and aft. (Efis 1 powered by standby battery and autopilot controller powered by the main bus through a button CB) I immediatly turned off the master and found the elevator free but the ailerons jammed almost full travel to the left!
What happened was, the servos went nuts for whatever reason ( Brent spoke to larry and he cannot see how this happened, Bob and possibly Greg are coming here next week to cure our gremlins hopefully) and went full travel left and up. Now, here is where EVERYBODY should take note. Yes.... the directions and common sence says to ABSOLUTELY make sure the servos CANOT go over center, and we thought we prevented that with the aileron stops, But.........We had the servo set up with the arm pointing down. Apperently, when the servo went nuts, it pushed so hard on the pushrod going to the bellcrank, (3.5 feet or so long), it bent the pushrod sufficiently for the servo arm to travel over center and the arm to then jam itself against the upper wing skin!. Ok, so I disconnected the controller power plug and went to fly. For grins, I tried to fly with the ailerons deflected the same amount to the left as they were when the controls jammed. Nuh uhhh, I could not maintain level flight with even HALF the aileron travel as when they were jammed and full rudder.
Goes without saying what would have happened if this occured inflight.
I recommend that unless your servos can travel 360 degrees without jamming your controls or you have hard stops on your servos, that you consider pulling the breaker until further inspection.
Questions or comments, please call or write....With BMA coming next week we will keep everybody posted so we can all learn and be safe from this.
Glen 561 - 670 - 6095

what was your pushrod made of?

Sounds to me like you need to reconsider what you are using for that 3.5' long pushrod. I hope you'll use something thicker for the replacement.

Yep, will put in stops.

Jim decided to go with an internally threaded rod that bends easier than say, hollow tubes like the aileron push tubes. I think even say, a 3/4' tube would have had the same effect and over center problem.... I am actually very happy with Jims install, and it made for a very easy install. We never expected this kind of failure though of the autopilot. I just spoke to Jim and we both agree we that with that length of push/pull tube, (servo is located inside of outer wing rib) that an over center condition is only to be prevented in the future by installing stops on the servo body itself, stopping the arm from not much more than the recommended 30 deg travel, and NOT rely on the aileron stops!!!!
As a side note, when I "pulled" the servo arm back over center to the 6 o'clock position yesterday, it took a hell of a lot of force, much more force than we ever thought the servo could produce!!! If you manually push and pull on the arm, the aileron stops seemed to provide more than ample stopping force...Obviously this is not the case.
But any way, thanks for the input, and PLEASE everybody check your installs!
PS, Jim's elevator push rod is only 6" long, so the elev. stops there, are WAY sufficient.
Glen

My 2 cents EFIS One in flight

Well, our RV-10 N331JH has now completed Phase I and my Dad and I took our first ride in this incredible flying machine that Vans has created. Dad decided to go with the Blue Mountain EFIS One, and other than a few things that are still buggy, this is an incredible piece of electronics.

We took off from Wellington (FD38) around 4pm and headed North and then East to the coast, flying the EFIS One using several different Terrain settings on the EADI. One thing we noticed is after changing to different EADI Terrain settings, there was several minutes of lag before the actual Terrain would come up in the EADI. It seemed to stay in the traditional Blue over Brown for quite awhile before finally displaying actual terrain.

I have been studying the Pilot's Manual for several months now and I know my way around this EFIS and feel very comfortable finding all the various information available. Our Pilot for this ride is a 767 Pilot for AA and is having a ball with the EFIS. He was trying to recall a Com Freq for one of the local airports nearby to check traffic, and it was really handy to pop up the FLT screen and look up the CTAF in an instant. We also used the Flt Screen to setup a Direct To for the nearest airport....really great for an emergency if you need it.

After our flight along the coast...right up the beach at 500 feet and over the Jupiter Inlet and Lighthouse, we headed West towards Lake Okeechobee and setup for ILS approach into North County (FD 42). We tuned our SL30 for the Localizer Freq and the HSI comes alive with CDI needle showing we were way left of the runway and below the glideslope. Turning south flying at 2,000 the CDI needle started lining up and as we turned East lining up we flew into the glide slope and setup for long 5 mile approach at 90 IAS, adjusting for a slight cross wind that is displayed in the upper left of HSI. We followed localizer and glide slope, making only minor adustments to the airplane bringing us perfectly onto the end of runway 8 Right. ILS approaches in actual IFR with this instrument seems very straight forward.

After a full stop, we immediately taxied back to 8 Right and took off and departed to the South, contacting Palm Beach Approach to enter KPBI airspace. We used the FLT Screen again for the appropriate frequencies and was given instructions for overflying PBI at 2,000 over the West end of the active runway. This is where it would of been nice to have a higher resolution zoom on the moving map to see what we flew over.

All the time during this flight, we continued to use the FLT screen to input a nearby airport as a destination and we made another landing at KLNA Lantana, then set our Direct To for Wellington Aero Club (FD38) back home, and I flew the plane out of PBI controlled airspace, out and around a few communication antennas that were shown on the moving map, and as the sun was setting and getting dark, I matched the GPS ground track with the Course To WP that brought us right back home and we landed at dusk.

One thing that happened during final approach on the EFIS moving map...the ground started showing up in red, but very streaky and jumpy and didn't turn completely red until we slowed to taxi speed. Seems that our EFIS has a little lag in the EADI and Moving Map.

The other thing that is nice with this instrument is the Engine Monitor screen...you can leave it off and if there is any instrument that goes out of range, it automatically pops up showing the out-of-range sensor flashing red. We are leaving Engine Monitor OFF during takeoffs and you'll be alerted immediately if it pops up instead of leaving it on during takeoff. You might not see a flashing sensor as quickly if the whole screen was displayed.

The only thing we haven't been able to test so far is the Auto Pilot. It still won't engage and BMA is aware of our issues and will be making a special trip to our site to troubleshoot and debug these problems. We're anxiously awaiting their arrival the week after Thanksgiving and finalizing our installation. After many discissions on the phone and thru email, they have promised a full solution and will get us up and flying with all features and the latest and greatest software. I have all confidence in BMA's promises that we will have one of the most state of the art systems in an incredible flying machine....the new RV-10, by Vans Aircraft. Everyone here at the Aero Club who sees this plane fly, and who sits in the cockpit and the back seats, is overwhelmingly impressed with our very own 200mph - 4 place - glass cockpit airplane that we built in less than 2 years.

Happy Flying,
Brent

I find BMA amazing..........amazing that they have to come to your airplane to get their unit to work! How many times have I read this from a customer? We have one on our field and I know from the owner that Greg or his engineers have been to Indianapolis at least twice, and possible three times to work on his unit. I love the way it looks and I think it is a super sharp unit, but I'm amazed they are still in business. I hope he gets things straightened out because I really like the unit and we (sport aviation) could use the product.



I went with dual screen GRT EFIS 1 units. I plugged it in and it's been nearly flawless from day one. The only problem I've had is that I moved the airplane during startup once and when I took off, the AHRS got lost. I did a quick re-boot in the air and all was fine. GRT is supposed to offer terrain later this year or early next and that should help to bring the moving map up to a par with some other displays, although it still won't be quite as functional as the BMA unit.

I feel for you guys. I hope it works out for you and for BMA.

Yikes!!!

glenmthompson said:

Apperently, when the servo went nuts, it pushed so hard on the pushrod going to the bellcrank, (3.5 feet or so long), it bent the pushrod sufficiently for the servo arm to travel over center and the arm to then jam itself against the upper wing skin!.

Click to expand...

Holy Macaroni!!!! Thank God it happened on the ramp!! This is beyond "scary"... does anyone recall the rudder servo problem on B737's that caused a crash? sounds mighty similar.

I had to read your story several time to make sure I was reading it correctly because several SERIOUS items jump out at me:

1) they're products are sexy, but the history of BMA issues is frightening

2)"threaded tube" in place of Van's aileron tubes ??? This should be removed IMMEDIATELY. Threaded rod/tube is like spaghetti. Large-diameter thin-wall tubes are MUCH stiffer than rod. This is also a recipe for FLUTTER given the tendency of thin rod to bend. Simple test: suspend Van's original aileron tube and your threaded tube at the ends on a bench. Hang 5 lbs from center of each. Measure deflection. If your rod bends AT ALL, you are playing with fire. The forces on ailerons at 200 mph are much higher than you'd think....the rod can act like a guitar string with aileron vibes....your flutter speed might be WELL below Van's published Vne.

2a) if the rod bends as described, a full control input at high maneuvering speeds could result in bent rod on the "push" side. Needless to say, the aileron control would be compromised.

3) force...a/p servos should n-e-v-e-r generate any max force that could not be overriden by manual control input. based on your description of your event, this would've been a 100% fatal in flight.

4) elevator rod length only 6" means nothing if the breakout force is more than can be overcome by manual control input. base on your description, the servo forces are extreme. If possible, repeat the situation and see if you can move the elevator manually via stick WITHOUT bending anything.

5) power surge event: the reaction of these servos to a surge event is now suspect. Since aircraft electrical power is notoriously "dirty" the mere fact that it happened AT ALL would break my trust in the system if it were in my plane.

ship said:

2)"threaded tube" in place of Van's aileron tubes ???

Click to expand...

This would not be a case of replacing the original aileron tube. This is a seperate linkage from the auto-pilot servo located in the wing tip, back to the bellcrank.

Would not have to be as strong as the aileron tube, but I prefer an aluminum tube myself, for flexing issues, as I also have a servo in my RV6A's wingtip.

L.Adamson

L.Adamson said:

This would not be a case of replacing the original aileron tube. This is a seperate linkage from the auto-pilot servo located in the wing tip, back to the bellcrank.

Would not have to be as strong as the aileron tube, but I prefer an aluminum tube myself, for flexing issues, as I also have a servo in my RV6A's wingtip.

L.Adamson

Click to expand...

oh...maybe I read it wrong...this would be "better"....but the 3.5' length he mentioned is what really got my attention....that's a long stretch for a threaded tube even if it's 4130 (which would be getting quite heavy too)

ship said:

oh...maybe I read it wrong...this would be "better"....but the 3.5' length he mentioned is what really got my attention....that's a long stretch for a threaded tube even if it's 4130 (which would be getting quite heavy too)

Click to expand...

Hello Ship,

Threaded tube isn't exactly what we used for the 3.5' linkage, it is solid hex alum bar stock. We are certainly concerned about the flex in this linkage, but to eliminate the "over center", we are adding stops on either side of the servo control arm to make things safe. We're interested in what BMA can add to this when they look at our installation, too.

For now the linkage and servos are not connected and we intend to add a dedicated toggle switch as another safety precaution to the separate breaker already dedicated to the autopilot controller. This will allow us to power up the Master Switch and avoid sending any surges or low voltage spikes to the controller after the main buss is powered up.

I checked my elevator throw and i'm at 53 deg and 55 deg. Can't check ailerons yet. thanks for update.

holy macaronic-- thanks for verbalizing what i didn't want to think about-- but can't stop talking about over breakfast.





big control pushrod tube-- Dad tossed the original smaller pushrod a 1.5 yrs ago after relocating the servo from the mid way inspection rib to the outer wingtip.

Mark, check your linkage...

Nice pic ,Mark, ..... I seem to remember greg mentioning needing 30 deg. or so for throw, IMHO, 55 deg. is quite bit and if there is ANY play/slop/hysterisis in your rod ends, and you have the same failure I saw , well, ....I hope you have your parachute on that flight. If you look at your push rod, it seems to only take 1/2 an inch or so of for/aft movement at 55 deg. to make that servo arm go over center and point/jam below the 9/3 o'clock position, causing a fatal malfunction. Pushing the rod will have a greater chance of a malfunction, than pulling...Imagine if you will, that servo arm moving/jamming in the fwd and down position. The arm will jam against the bellcrank bracket/floor in an almost full down elevator position.... or, if you will, the mounting bracket for the servo could bend/torque a little, and you will have the same result.
Jim says he wants stops at the servo arms, say at the 60 deg travel limit or so. I whole heartedly agree!!!!!! This could have been a once/100 year event I witnessed, by like yuz guz said, there are 2 each 737's that had their 100 year event happen some what recently.

PS, I am extremely honored to have been the first one to give Jim the first ride in his pride and joy, modern, awsome, light, eye catching, best value for the dollar airplane!!!!!! Pretty much makes up for not having a life since last february while I helped him finish the 10. Keep it up boys and girls, this is the 6'th plane I have built/helped finish, and it ALWAYS seems like there is no light at the end of the tunnel BUT, remember all tunnels have an end and these planes, despite an occasional glitch, are always well worth it. Keep going and join the "I built an airplane club". You will NOT regret it. Right Brent and Jim?

Glen

glenmthompson said:

PS, I am extremely honored to have been the first one to give Jim the first ride in his pride and joy, modern, awsome, light, eye catching, best value for the dollar airplane!!!!!! Pretty much makes up for not having a life since last february while I helped him finish the 10. Keep it up boys and girls, this is the 6'th plane I have built/helped finish, and it ALWAYS seems like there is no light at the end of the tunnel BUT, remember all tunnels have an end and these planes, despite an occasional glitch, are always well worth it. Keep going and join the "I built an airplane club". You will NOT regret it. Right Brent and Jim?
Glen

Click to expand...

Really enjoyed the flight Glen....this was the pay-off for all the hard work we put into this project. Dad was either overwhelmed sitting in the back seet with the excitement, or he couldn't get a word in edgewise with Glen and I jabbering back and forth about EFIS stuff and piloting the plane we helped make fly. As my 3 year old grandson keeps saying " Good Job Paw Paw....awepane fwey in da sky"

Has Blue Mountain shown up yet?

If so what did they have to say?

Milt

N395V said:

Has Blue Mountain shown up yet?

If so what did they have to say?

Milt

Click to expand...

They will be here this Wed, Nov 30th

brenthg said:

Hello Ship,

Threaded tube isn't exactly what we used for the 3.5' linkage, it is solid hex alum bar stock. We are certainly concerned about the flex in this linkage, but to eliminate the "over center", we are adding stops on either side of the servo control arm to make things safe. We're interested in what BMA can add to this when they look at our installation, too.

Click to expand...

just curious why you chose a solid rod vs. a larger diameter thin-wall tube since rod is far more flexible under compression than tube at this length.

brenthg said:

For now the linkage and servos are not connected and we intend to add a dedicated toggle switch as another safety precaution to the separate breaker already dedicated to the autopilot controller. This will allow us to power up the Master Switch and avoid sending any surges or low voltage spikes to the controller after the main buss is powered up.

Click to expand...

The additional lockout is worthwhile precaution, but just another element to add to checklists, etc. Hope it all works out for you.

brenthg said:

They will be here this Wed, Nov 30th

Click to expand...

This event STILL gives me the creeps.

I would be very interested in the following:

1) seeing if they can repeat the conditions/event
2) somehow measuring/calculating the force generated by the servos during this "surge" event.

Based on Glen's description, the servos acted more like solenoids than servos (as happened in 737 crashes) .....very dangerous.

+90% of flight hours are in cruise or pattern.

if this event happens on departure/approach/pattern, the RV10 is probably unrecoverable beyond 90* bank angle, i.e. less than a few seconds. TOAST

if this event happens at cruise speed (above Vma) we're talking possible bent/broken spar with consequent results. TOAST

glenthompson said:

What happened was, the servos went nuts for whatever reason ( Brent spoke to larry and he cannot see how this happened, Bob and possibly Greg are coming here next week to cure our gremlins hopefully

Click to expand...

"he cannot see how this happened" This is a frightening statement by the mere fact that it DID happen. Voltage spikes are a fact of life in small airplanes. As painful as it might be, if BMA cannot repeat the event, you may need to consider an alternative system or fly with the a/p disconnected. Hopefully they'll find a fix for you.

Did the autopilot come with servo mounting brackets and hardware or were they built by the end user? I've heard they don't come with brackets. Just curious.

Jim Wright RV-9A 90919 wings Arkansas

rv9aviator said:

Did the autopilot come with servo mounting brackets and hardware or were they built by the end user? I've heard they don't come with brackets. Just curious.

Jim Wright RV-9A 90919 wings Arkansas

Click to expand...

Servo mounting is left up to the builder. We are going to add stops in both directions to eliminate this ever happening again.

How about a nylon shear bolt and then have straps or tube where the rod won't hinder movement?

I think having the servo brackets furnished and engineered is a big plus when buying an autopilot. Also, I believe some sort of shear pin should be mandatory. There are two many ways a novice builder could build in a design flaw that might proove fatal, but that's just me ranting. Good friends especially RV friends are hard to come by.

Jim Wright RV-9A wings 90919

As much of a Blue Mountain fan as I am I must say the one thing I do not like is the autopilot going full throw when the servos powers up. I have always had mine on a separate switch and power up of the servo's is part of my pre take off checklist. It was rather exciting the first time I ever powered up in flight and I no longer do that under any circumstances.

I have the servos coupled with very short tubes and only have about 30 deg of swing. To go to or over center my tubes would have to buckle or break.

I am anxious to see what BM has to say about this.

Milt

Mine have never done that. at least in the shop it's never done that. I've pitch on several times. I'll have to watch that.

Mine have never done that either... What version software are you running?

concerned about this picture...

mark manda said:

I checked my elevator throw and i'm at 53 deg and 55 deg. Can't check ailerons yet. thanks for update.

holy macaronic-- thanks for verbalizing what i didn't want to think about-- but can't stop talking about over breakfast.

Click to expand...

This picture worries me...
Connecting the AP pushrod to the bellcrank at the position you show will cause too much travel of the AP servo arm. I'd drill a hole lower on the bellcrank and connect it there. (let me know if you need a picture)

ClayR_9A said:

Mine have never done that either... What version software are you running?

Click to expand...

The Version before 2.51. My last update was in July of this year.

Now with 2 "mine has never done that" comments I am wondering if Ihave connected something improperly. Sounds like I need to talk to Greg also.

Milt

Clay-- just so we're looking at the same thing-- my pict shows full down position.

Concern

Hi Mark,

I think the instructions show the AP attachment below the elev pushrod location on the bellcrank. I also wouldn't have it on this same bolt.

This would be a 10 minute change.

Darwin N. Barrie
Chandler AZ

I'm thinking.... you got me thinking...

Spent a half hour on the phone with Bob Northrup yesterday and then took my panels down to see how much throw I had during power up. What I percieved as full throw was slightly over 5 deg on the acuator. I apparently have a first generation AP into which they built in a stick bump to assure the pilot the servos were alive. I powered up a second time holding the stick firm without difficulty and only felt a slight bump aft and left. Most people had this feature removed and subsequent APs were manufactured without this feature. I must have been sleeping through that discussion.

In any event Bob and Greg will be in Florida today looking at the problem and hopefully we will all have some answers to our concerns shortly thereafter.

Limit switches?

Has anyone considered installing limit switches as well as hard stops on the servo? Seems to me if you have a runaway servo, that constitutes a fault condition worthy of immediately deactivating the AP. This could be accomplished with microswitches on the stops.

I know this is a BMA autopilot question, but the TruTrak servos have a hard stop bracket screwed to the face of the servo to prevent the servo arms from going over center. I would view these as absolutely necessary. You might need to fabricate some of these for your BMA servos.

randy-- appreciate the picts. I was actually looking at the BMA hsg. and thinking of a similar stop. but with the force that Glen mentioned-- I figured it's not going to stop, just tear stuff up. I'm still thinking; thanks for picts.

man, i sure love that short throw. all those brackets look nice.

Again on the TruTrak units, the arm has a shear pin. If the unit were to force itself against the stop, the pin would shear and the controls would be freed. You can also shear the pin by agressively moving the controls against the force of the AP while engaged. I would think the BMA units would do the same.

BMA AP servos use a magnet to engage

The BMA AP servos "engage" with the use of an electromagnetic plate that links the arm to the motor. When the unit is off, the arm swings completely freely, unlike the trutrak where the arm is permanently moving the stepper motor, even with the AP turned off.

I've always been able to overpower the motor on my BMA servos when engaged, but I would assume that at some point, that magnetic plate has got to start slipping too... (maybe I'm underestimating the power of the magnet, I don't know)

In any event, the autopilot controller should always be wired with a separate switch so that it can be turned on only when needed, and turned off when you want it to disengage no matter what. Turning off the switch is going to release the electromagnet and decouple the arm from the motor if anything bad is happening.

Now, if the arm has gone over center, that's a different problem, and should be avoided by making sure there are aileron/elevator stops in place and that the pushrod is not going to bend if those stops are hit. Care should also be taken to keep the throw of the AP arm to a reasonable minimum.

BM Autopilot Installation Manual

The following are excerpts from the installation manual that I relearned by re reading it after the experience above.

Electrical Connections
Power
Aircraft power from 10-32V is supplied to the Autopilot controller which, in turn, supplies power to
each of the servos through the BMA supplied interconnect cables. A 10 Ampere circuit breakershould be used in conjunction with a Master Autopilot switch to supply power to the controller. (This suggests an appropriate wire size.
The black or green wire is ground. Removing power from the controller via AP Master Switch also
removes power from the servos and their associate magnetic clutches. Without power, there is
no physical link between the servo motor and the controls of your aircraft. Note, there is also an
Autopilot disengage option but the disengage option does not remove power from the servos and
may not disengage the Autopilot if there has been a malfunction of the EFIS/One system.EFIS/One Processor to Autopilot Interconnect

Important Safety Information
Please read this document thoroughly before installing your Autopilot system. If you have any
doubt or questions, do not hesitate to get help, either by calling Blue Mountain Avionics or by
obtaining the help of a qualified A&P mechanic or avionics technician. Incorrect installation could
lead to unpredictable results and possible loss of aircraft control.? Under no circumstance should the operation of the aircraft?s control system be limited or
restricted by the attachment of the Autopilot motors to the control system.
? Under no circumstance should the Autopilot?s servo arm move more than 60 degrees in
either direction from a central or neutral position. Move the aircraft?s control system to
maximum deflection in either direction to ensure that the servo arm does not move more
than 120 degrees from full deflection in one direction to full deflection in the other.
? Under no circumstance should the Autopilot?s servo arm be able to go ?over center?.
Your aircraft?s control limitation should also limit the maximum travel possible on the
servo arm which must not get close to going over center.

? When the aircraft?s controls are in the neutral position, the servo arms must also be in
their neutral position, perpendicular to the connecting push rods and at the center of
travel for the servo arm.

? Under no circumstance operate the Autopilot without a Master Autopilot power switch.
Turning off the power is different from the ?disengage? signal which is a software
disconnect. If your EFIS/One has failed or stopped processing the disengage signal will
not work. Turning off the Master Autopilot power switch removes power from the servo
clutches, controller and motors, thereby preventing it from controlling the aircraft.

TruTrack stops must be new

Hi Randy,

I had a pict of your Trutrack servo sitting on my workbench and a guy with a RV-8a walked in and said, "mine doesn't have that."

so those stops must be on newer units. (?)

mark

The stops are part of the servo kit and you need to install them yourself. I bought my servos in 2002. Call TruTrak or the place you bought you servos and ask them to send them along. You should have them.

Great info here...

f1rocket said:

The stops are part of the servo kit and you need to install them yourself. I bought my servos in 2002. Call TruTrak or the place you bought you servos and ask them to send them along. You should have them.

Click to expand...

Listen all, this makes me feel relieved that maybe our less than optimum installation/one in a million malfunction, just might save some lives one day. I have the following to add at this time:

Now....Put aside any and all accusations and thoughts of less than perfect installs....ok? Now, imagine that perfect install with your BMA, true Trak, whatever, servo in the wingtip. Now, imagine if you will, the servo getting a little older with associated slop in the arm, bearings and rod end. Remember that heavy servo that the DAR liked how you installed in the wingtip? Imagine with age the end rib now beginning to oil can, or God forbid loose nutplate rivits or fastening screw, whatever.


You are now flying IFR, autopilot on, distracted, busy and the alternator quits, and you only have a voltage meter, so you do not pick up the failure until voltage drops and the radios give up transmitting...Oh MAN! In the soup, losing electrics, ...Oh, damn, the alternator field breaker tripped, well, just push the breaker in, right? Of course! BUT.... the autopilot controller, now very confused with the lower, now higher voltage, decides to roll the aircraft to the left with full servo deflection.. Yea, not a big deal, right? Just do that pilot stuff and grab the stick to stop the roll. NOW, unknown to you, the previously mentioned, perfectly installed, +/- 45 deg. throw servo arm, decides to take full advantage of the ageing hardware, and provide you with 3/4 of full throw aileron roll to the left. Jammed there, and King Kong cannot budge the stick. Think you can stop the roll at ANY speed with rudder? Think again.

This is one very plausable nightmare scenario that could happen to any plane/install/autopilot. If I have not finally convinced EVERYBODY to install stops on their servo arms, well, then I have tried my best.


Now Jim in currently CNC manufacturing a prototype for BMA to try on their servos, and WILL be installed on 331JH. Any interest, let me know and maybe Jim can make a few extra for others before BMA gets them on the market.

Comment? Questions?


Glen

I could use a picture. Japanese engineering at it's best right here. haven't installed stops yet.

edit--good news BMA turned around my CPU Three weeks to the day for the gyro upgrade. paid for it today. 420 per sec. without tumbling.

mark manda said:

I could use a picture. Japanese engineering at it's best right here. haven't installed stops yet.

edit--good news BMA turned around my CPU Three weeks to the day for the gyro upgrade. paid for it today. 420 per sec. without tumbling.

Click to expand...

Mark,

How much did they charge you for that?

Is it a change that can be done in the field?

Milt