Efis one flying update.

[glenmthompson]

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

[ClayR_9A]

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.

[glenmthompson]

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 **** 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

[brenthg]

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

[f1rocket]

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.

[ship]

Originally Posted by glenmthompson

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!.

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.

[L.Adamson]

Originally Posted by ship

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

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

[ship]

Originally Posted by L.Adamson

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

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)

[brenthg]

Originally Posted by ship

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)

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.

[mark manda]

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.