capt17

Hi all,

I did my usual preflight check including control surface movement and everything was ok. So I'm flying my U-Can -Do .46 today, only the second day I've had it up, and I suddenly lose contorl of my airplane at 100 ft. I know that I have an aileron issue because I'm rolling left BIG TIME but still have my other inputs. I was able to somehow get it turned and leveled but it's losing altitude quckly. By the time I hit the ground I was at about 30 degrees nose down with the wing level and an idle engine. If given the scenario five times I might have been able to fly the airplane to a softer landing but I only had about three seconds from failure to impact! Luckily I came in not TOO hard and in a bean field.

Damage wise:
Wings are great. Just two small holes in the covering.
Fuse is ok. Firewall is starting to separate from the Fuse and the gear is off. My cowl is cracked pretty good but it's cosmetic.
Engine: Didn't even break a prop. Still good compression. I'll run it later but it seems great.
The servo in question: Hitec HS-325HB. A standard size ball bearing servo.

Now to answer the question: What caused my plane to crash?!

Once I inspected the plane I notice the left aileron was almost 90 degrees upward deflection. As anticipated, all the other surfaces moved nicely still. I try to move the servo with my hand and it moves even with the RX and TX on. It's trying to fight but it's still moving. If I turn off the Rx and Tx and place the servo in a nuetral position and turn them on again, the servo jumps back to the extreme endpoint. If I move the servo with power on, as soon as I pass nuetral it will go to the other endpoint. I disconned the servo in question and hooked it directly to the reciever without my Y-harness with the same result. I got home and tried it with a different reciever and got the same result. Lastly I tried a new servo in the bad servo's original position and it is working properly. No cuts or anything could be found on the bad servo's cord. I don't want to open the servo and void a warranty. Rx Battery is at 6.4 and started at 7.1 today. Tx battery it 10.4

I bought this servo less than a month ago from TowerHobbies and the plane is brand new too. I'm satisfied I didn't do anything wrong to make this plane crash. I'm not overly ticked because my plane is repairable with some work and money but I'm disappointed with the servo. I always heard great things about Hitec servos and have used them with no difficulties before.

So, is this a bad servo? Does anything cause this that I did wrong? Will Hitec do anything? Thanks for the help and listening to me vent! [>:]

nedyob

My Feedback: (67)

Check with Hitec services and they may want you to send the servo in to them for a check up. Make a copy of the bill of sale and sned it along with the servo to Hitec. Hitec will let you know what the problem is and let you know, they may even give you a replacement servo. Hitec likes to keep there reputation for there servos and other stuff. If you know someone that might have a Hitec Servo programer. Have them put it on there and they maybe able to recreat the problem, and can tell you what might caused it. Good luck keep us posted on the out come
NEDYOB

jetmech05

servo failurers happen...it's too bad you damaged your aircraft....A friend of mine lost his twin engined Bamboo bomber due to rudder servo failure...like you, hard over....
I wish you the best getting something besides a new servo from Hitech
Good Flyin

bigedmustafa

My Feedback: (2)

Hitec's warranty most likely doesn't include incidental damage from product failure, but I'm confident that they'll replace the servo free of charge.

I lost a really nice flying Phoenix SeaBee ARF earlier this year. I had a similar problem with an aileron getting stuck on full deflection. My crash occurred when I was doing snap rolls with the plane and one of the servo extenders came loose inside the plane.

I'm glad your plane should be back up and flying soon. You have to assume the risk for a crash whenever you take off, however. Batteries lose cells in mid-flight, servos fail, engines quit running, wings fold up. It's just the nature of our hobby.

Good luck and good flying.

Gray Beard

My Feedback: (-1)

Just A thought but did you check your RX?? Did you try putting that servo in A different channel?? Just thinking. I have had Futaba and JR servos do some odd things, the only problems I have had with HT is those stupid Carbonite gears, I have has them break on heavy/hard landings A few times, easy to replace but why?? Problems happen with most any man made items, just remember that Hubble Telescope. [:-]

Mr67Stang

Probably less than a 10% chance this is your problem because it sounds like you did a fairly thourough trouble shooting on it. I know on my transmitter (JR X9303 2.4 GHz) if I set up dual aileron servos on seperate channels and do not inhibit (INH) the Aux switch for the other channel (other than standard aileron channel) and I hit that switch the aileron being controled by that channel will pop up or down (depending on servo orientation and reversal) but still move with stick input... as though the servo lost it's center position.

opjose

I've had several problems with Hitec non metal gear servos breaking teeth very easily and with the position sensor going south ( as you've experienced ).

The position sensor gear teeth breaks causing the problem you had.