Failed servo.
 

So I had my 60 size p51 out today. Did a full pre flight, everything was ok. Then spent 20 minutes trying to start the bastage. Finally get her started make a couple of runs down the runway and she would not lift. *** try it two more times and will not lift, finally bring her back and check my high rates, I HAVE NO ELEVATER. It worked in the pre flight.
It was a new cirrus bb601 with 6 flights on it. I am sure glad she didn't lift and then the servo failed.[:@] I will never purchase another cirrus servo.

Anybody ever have this happen?

RE: Failed servo.
 

Last time I used a cirrus was in 91

RE: Failed servo.
 

Im glad that it happened to you on the ground and not in the air. I just lost my Goldberg Ultimate a couple weeks ago due to a broken elevator half.. may she R.I.P. :)
Get you a different servo and go flying ;)
John

RE: Failed servo.
 

Wow, I haven't seen bastages since "The Meaning of Life".

I do have some Cirrus servos, though, purchased about the same time as that movie. No problems, in fact I'm still flying a World Models Ultimate 30 (preceded the Ultimate 40) with them.

Good luck,
Dave Olson

RE: Failed servo.
 

Hmmm! Lets see, I've had a bad JR, Hitec, a couple of Futaba and a no name I cant remember. Most of those lost a plane. Yeah, they do that sometimes. They do sell thousands of them.
Edwin

RE: Failed servo.
 

I had test flown my Pica p-51D and was ready to try retracts and flaps. So during the flight the retracts with sequencing doors worked flawlessly. When it was time to land I climbed to three mistake high and put the flaps down trimmed them then popped them back up and dove into a landing pattern. When the plane was in the down wind leg I popped down the LG and then the flaps. As soon as the flaps came down the plane began rolling, aileron would slow it down but not stop it. The next time it came upright I put the flaps up and it started rolling the other way. But this time it was controllable by aileron so I flew it in front of us and my buddy mike caught the problem one flap had come down 20degrees then the servo smoked. I switched control of the flap to the proportional lever and brought the good flap down till the aileron hold was gone and landed uneventfully. Giant scale servo from futaba with close to 200 in/oz torque, I new what my deploy speed had to be and did not exceed it.

Another time I had a macchi 202 from VQ I had used as my bad weather plane for two years and here we were in late nov in knew york. I was flying my pattern when I pulled E for a maneuver (which would have been placed right in front of me) and nothing happened. As the plane flew by I ran through all my options and none were good. I was about 20-30ft off the runway so I banked the plane hoping to make a slow turn. While it did turn the nose dropped more. I re-leveled the wing and reduced T to idle just before impact.

Was at a scale contest flying a flop tite bed box P-47 using split – S’s for the turn around after completing my maneuver I started a shallow climb to set up the split – S and just before I hit the Ailerons to role inverted the plane rolled over and began to spin. I went tight in to stall recovery and it did not work and as a last ditch effort I pushed hard down E and the spin stopped and it responded to the up E. after a split second behind a parked tractor trailer it came above it I called an emergency and the consensus of everyone there was that the rudder had locked full over. It was flying in a crab and I only had easy maneuvers left so I finished. Nothing would move the servo so I unplugged it readjusted the linkage to neutralize it and flew my last two flights that way.

You fly enough it will happen. found meny meny more in the work shop.

Joe

RE: Failed servo.
 

Last year I lost my Goldberg Skylane 60 ARF. My economy JR NES-537 Servo failed on me in a high speed dive last summer. When I went to pull up... well, it was the best lawn dart I have ever seen!

I looked for my plane for a week... couldn't find it anywhere. I figured it went back to China the hard way.

About two weeks later, a farmer was out cutting the hay when he saw my Lawn Dart stuck two feet in the mud, nothing left of coarse. Battery exploded... engine muffler and head was all busted etc.

When they found my plane I took it home and tried to do the FAA thing by trying to find out why. I took my elevater servo all apart and found that one of my plastic gears had striped. I ordered the new parts from Horizon and she's as good as new. (Rebuilt my motor as well) I never had a servo fail on me until that day. I'm moving up to Digital Servo's now... they seem to take more abuse. But I guess once in a while we all get one bad servo, and I guess they don't always give us a warning.

RE: Failed servo.
 

In the past 25 years, I have had 2 servos fail: both Futaba.

My first was on a 1/2A 4 channel 'stick': the aileron servo failed and it spun in (buy hadly any damage) servo was relatively new at the time, I'm thinking less than 6 flight. That was about 12 years ago.

My second was just last summer in my recently completed Top Flite Mustang ARF. The servo was a Futaba high torque digital, and I used it for the flaps (2 servos to operate 2 flaps). It happenend during the flight: I noticed an abrupt roll tendency as I was setting up for landing. Suspecting that it was a flap servo, I immediately raised the flaps and the plane flew normal. Tried to lower the flaps again and same thing, so I landed with flaps up. On the ground, I could only get it to move one way (raise the flaps. No amount of experimentaion coiuld get it to lower the flap (even when disconnected from the flap).

Thru the years, I have owned (and still own) a wide variety of servos from aftermarket companies, as well as Futaba. I would guess the the aftermarket ones out-number the Futaba ones in my inventory by about about 2 to 1 (even have some old Cirrus servos).

I have owned nothing but Futaba transmitters, and stand by Futaba, BUT as I said: they account for the only 2 servo failures that I have ever had.

Will I stop buying them? No. Every manufacturer, regardless of what they make, ships a ceratin amount of items which turn out to be defective, it's a fact of like. I didn't stop buying Futaba after the 1st failure (25 years ago), and unless I start hearing evidence that Futaba does indeed have a higher failure rate than other makes: I will continue to purchase Futaba servos when it appears that they are the best for what I need.

I don't think anyone should 'crucify' a manufacturer based on only 1 servo failure, I'm quite sure that they ALL make an occasional defective one.

RE: Failed servo.
 

I agree with Jock....I am partial to Hitec...never had a failure of ANY servo tho. Be aware of infant mortality in electrical components...no way around it.

Jeff

RE: Failed servo.
 

Thahkyou everyone, I have always been partial to airtronics. The reason I bought the cirrus servo was because it was in the red tag bin. I put a airtronics in her today and flew her 2 times, except with the last flight the ailerons were not responding properly, so I brought her in with rudder and got a nasty crosswind that I could correct without ailerons.
So she nosed in, causing no damage except a prop. The clevis on the aileron broke but I saved her once again. Shes stubborn.

RE: Failed servo.
 

I have an old crash-box arf which I use to test all of my new radio equipment. I'll put any new servos or recievers in her and take her out to the field for a few "shake down" flights. I feel a little more confident putting this used equipment in my good planes this way. I only use JR or Hitec servos without any problems so far. The Hitec 645 MG seems to be a very robust, powerful servo which do not cost too much...probably my favourite.

RE: Failed servo.
 

Sometimes I wonder if we aren't a little too quick to blame the servo(s).

A couple of years ago I had a problem on an F-86 where my flaps would either not work at all or work very slowly with no power behind them. Of course I thought I needed to replace the servos. A friend said he had something similar happen before and that the problem went away when he replaced the servo extensions. I got new extensions installed and the problem was completely solved.

Fortunately I found the problem on the ground by ALWAYS wiggling every surface before takeoff to make sure it is functioning as it should.

With the constant plugging in and unplugging of the servos and extensions, the connectors in the plug wear out after awhile. Next time you suspect a bad servo, try and replace the extension first. You may find, as I did, that it wasn't the servo at all.

RE: Failed servo.
 

I've been at this for 30 years. I am tired of losing airplanes due to electronic failures. I have failed 2 Futaba Servos, 3 Hitec Servos, 1 JR Servo, and 1 Ecologitol Servo (Thrown if for you old-timers). I have also had a Futaba 4 channel transmitter fail outright in flight. Not battery failure, an actual transmitter failure. I've even had 2 of the new 2.4 gHz Spectrum AR6100 receivers crash 2 of my electric foamies. The list of damaged or destroyed airplanes is long. Successfully flying an airplane and bringing it back in one piece is hard enough without having equipment failure. Not much I can do on the little foamies, but those don't cost that much and safety isn't as big of an issue. But on the big stuff I now insure against these losses. Here is my minimum set-up. It is cheap insurance in my opinion. Less than $100 extra per plane in most cases. The weight is little to no issue. Give me a good reason why everyone shouldn't set-up there big planes this way?

For all airplanes over 15 lbs. or $1,000 in value:

1. Dual Receivers.
2. Dual on-board battery packs.
3. Completely isolated systems one from the other.
4. Completely isolated control surfaces. Ex: LH Ail. & RH elev. to one RX. RH Ail. & LH elev. to the other RX.
5. Opto-Isolated Engine cut-off on ignitions.
6. Engine cut-off switch on magnetos.
7. Engine must idle or cut-off if transmitter is turned off.
8. Engine must idle or cut-off if both receiver switches are turned off on Electric Motors and Ignition Engines.
9. Engine throttle or cut-off control must be maintained if either one of the receiver switches are turned off on Magneto Engines.
10. Fuses installed on all servo wire leads to guard receivers against complete failure due to any servo or lead wire shorts.

An unlikely transmitter failure could still bring me down, but now I have a fighting chance against on-board failures.

Leo Spychalla

RE: Failed servo.
 

OK, I get the point.
You start with a normal 10lb model... Add all that kit and your 15lb model is good to go.
Nice one.:eek:

RE: Failed servo.
 

I agree with redundancy in items which might have a remote chance of failing, however, the chance or the reciever failing is too remote for me. If you use dual receivers, should you not also be using dual transmitters...where do you draw the line? I always use dual Rx batteries with their own switches and two elevator servos on their own channels. Never had a radio related problem.

RE: Failed servo.
 

The smart thing to do would be to get rid of the number one failure point in the system namely the guy who builds, maintains and flys the plane. :eek:.

RE: Failed servo.
 

I drew my line as above. You could keep going; no doubt. It is a few ounces of cheap insurance often times guarding a $3 - $4,000 plane.

Have you diode isolated your packs from one another or just plugged two packs into the RX? Have you considered what will happen if (when) one of those packs drops a cell or fails with a dead short as I have seen several times? How long will your second pack continue to fly the airplane with the increased load?

Leo

RE: Failed servo.
 

I'm thinking that you really should have 2 transmitters, AND a co-pilot on the second Tx just in case the 1st pilot gets a cramp in his thumb ( or something even more serious ). Furthermore, they need to be standing at least 50 ft away from each other in case a meteor strikes one of them: the other can still maintain control.

OR, install one of those ballistac parachutes on the aircraft which will deploy in any emergency, and bring the aircraft down to a safe. soft landing.

The more things that can go wrong, the more likely something WILL go wrong. It's kinda like putting 2 engines on a plane instaed of 1: it will automatically double the chances of loosing an engine. And with 1 engine running (usually full bore): a twin is quite a handful to fly (and more impotantly: LAND).

But that's just me. Even on my many planes with mechanical retracts: I have never crashed a plane due to battery failure (and/ or low battery), and not one of my planes has ever had more than 1 battery pack for the radio. Redundancy only adds more weight, which will make it crash faster and harder when/ if it crashes. But also: none of my planes are worth even 1/2 of "$3 - $4,000".

I DO like the idea of one modeler above: using a test-bed/ trainer to 'break servos in'. As suggested in a previuos post: most electronics failures are 'early in life'. Both of my servo failures where within the 1st hour or 2 of operation.

RE: Failed servo.
 

I am always amazed at the strength of the rationalization is on this issue. Pilots will say, "They must have done something wrong" or "That couldn't happen to me". Drop your guard and ask yourself, How many airplanes have you seen go in where the pilot is at the line shouting, "I don't have it!!" or "I just lost it", "I had nothing", "It just locked-up"? How many times have you said similar words. Really! How many times? Are you going to tell me never?

I have personally seen the best modelers and pilots put them in. I am sure they don't rationalize electronic failures away. ~2003 Dayton Mark Frankel blew-up a SkyRay Jet, "Didn't have it". 2004 Scale Masters demo Terry Nitch blew-up a BVM BobCat, "I had nothing, boy I sure am glad that was not toward the crowd". 2005 NATS Greg Hahn crashed his B-25 on approach. Receiver interference. 2005 NATS champion Zach Spychalla crashes his Spitfire at Warbirds over Muncie 2006. "I didn't have it!" All these were expensive top notch airplanes flown by competent top notch pilots using expensive top notch equipment. So..... can it happen? Can it happen to you?

I don't live in denial on this anymore. It can and will happen to me unless I do something about it, and I want to see more pilots insure their airplanes against the same failures. Leo Spychalla

RE: Failed servo.
 

Using a test plane to burn in electronics and sort out motors etc before comitting them to something nice is a good idea. A balance of cost, weight, complexity and other factors such as weather, pilots ability, quality of the plane to name a few, determine how long a plane will survive. Radio equipment is just part of it. The current setup most people use which appears to be quite reliable for most higher end planes would be isolated dual batteries, 2.4 ghz radio, dual elevator servos, dual aleron servos. That setup will take care of most of the common failure points without getting to heavy or complex. The FAA does this with full size planes as well. There is always a compromise between safey, cost, weight, pilot training, weather etc. Buying servos with a known reputation, flying them in somethng you don't care about for a while, is always cheap insurance.

RE: Failed servo.
 

I am glad to see that P-40 driver put "Isolated" on the description of the battery packs. That is key. Dual batteries are not much better than one stand-alone battery if they are not isolated. Failure in one pack just quickly drains the second pack down.



Here are 3 failure modes that will crash most airplanes at the field:

1. Closed circuit Servo Failure (a.k.a. Shorted-out Servo) - on most airplane set-ups this will produce more than a 20 amp current draw on the #22 gage wires and burn the traces of the Receiver in under than 10 seconds. The RX is fried and you lose complete control.

2. Closed circuit Battery Failure (a.k.a. Fried the Pack) - On a single pack system it is over. On a dual pack system that is not isolated it will quickly cook the second pack.

3. Single Cell Voltage loss / Circuit Stays Closed - On a single pack system it is over. On a dual pack system that is not isolated the second pack will try to charge the first pack until they reach equilibrium. It reduces capacity of your second pack. So depending on the mah available in the second pack and the impedance of the batteries involved will determine if the plane will survive the flight. The clock is ticking on this one.


Here is what a Closed Circuit Servo Failure looks like. It is basically an internal melt-down of the PC board due to servo overheating. Negative and positive leads end up getting connected together with solder and you have trouble. Yes this is rare, but it happens. The one in my hand destroyed an airplane valued at around $3,000. This type of failure can no longer crash one of my airplanes. It can crash yours.

Leo

RE: Failed servo.
 

What type of plane did tht come out of, I have a hard time believing that anything other then hard 3d, or bound up linkages would cause a servo to over heat to the point of melt down. I also would be careful with the fuses I selected; because, unless you are absolutely sure about your current draws, you may find them causing more problems then they solve, or doing little to prevent the problem they were set up to solve. What actually caused that plane to crash was in the set up of the plane originally, most likely. I will agree that adding another potencial failure point on a redundant system to prevent a catastrophic failure is a good idea, but being aware of the fact; that in this case, you may be increasing the risk of servo failure to decrease the chance of a catastrphic system failure. You may or may not be able to control the plane on one servo anyway, depending on what position the other servo failed in. I am a big fan of the KISS principle and have found in most cases the crash can be traced back to the owner. In 20 years of flying, I have had one receiver failure due it getting drowned in fuel, an antenna failure, one servo failure and zero battery failures. The first two could have been prevented by proper setup and maintenance. I won't tell you how many pilot failures there have been.

RE: Failed servo.
 

Well believe it. That servo ran one side of an elevator on a Ziroli Stuka for 7 years. The model expired on its 175th documented flight. It was not in an overstressed or binding application. It was just that servos day to fail. MTBF of an electronic component. You and everyone else can experience the same potential failure on any plane you are flying right now. You can either rationalize it away or plan for it.

True that you have to know what your doing when it comes to fusing. My warbird applications draw between 1.3 amp and 1.8 amp max load as measured in-line from the RX. I fuse with the 7 amp bel Type MS Slow Blow Micro. It is a more reliable electronic component than anything it is connected to. It provides a good margin for current flow yet it will still blow in 2 seconds at 10 amp. I have outfitted 4 of my 1/5th and 1/4th scale warbirds with them so far and have about 30 flights total on all the airplanes. I can sustain a direct short on any servo or any servo wire lead at any time and not effect the rest of the system.

Nobody would dream of building a car or a house without fuses. Why do you do it with your expensive and potentially dangerous airplanes?

Here are some photos of the fuses installed. It is very simple and does not take much time. Leo

RE: Failed servo.
 

This is the same thing you here from the 3d guys with all the fancy do dads, and batts, with regulators. However if you go in those forums they are all over the place asking why did my bird fall out of the sky. Any thing Can and Will happen no matter what you do you just can not escape that, some think they are adding things to lessen those chances and I guess it is whatever makes you feel best. Pre flight and maintenance is the key for me and while I certainly do not begrudge someone elses approach I will stick with what has worked for me. I do however think advocating soldering diodes here and there is a road I personally would not go down. I sure hope I know who has done this at a flyin I attend so I can keep close watch on that bird while they fly it. Kevin.

RE: Failed servo.
 

Kevin, That is exactly it. You are expressing the fatalistic attitude that plagues this hobby and one of the foundational reasons that few if any are doing anything to remedy the continual lose of airplanes. Do you realize that even those fancy power boards that the 3D guys use will not save an airplane from a shorted servo or a single pinched wire. The current draw will burn-out the system. That is the first thing I would look for when their bird goes down. I am an advocate for changing builders approach to there set-ups and it is tough to fight against the status-quo. What has been done and is being done by well intentioned and competent people is not working.

Here is my challenge: Given the on-board set-up I have described above. Tell me what component could fail that will rob me of the ability to control the plane and bring it back down for a landing? (Yes, assuming my TX still works as was pointed out earlier) Pick one. Any one. Fuse, Servo, Battery, Receiver, wire lead, switch..... Tell me how the loss of that component will effect the system. Then in contrast tell me how it will effect your set-up.

Leo