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Home✈️Aircraft🚁Helicoptere-AlignT-REX 450 › HS-65 In-Flight Failure
05-21-2007 12:54 PM  13 years ago
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Darren Lee

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Woodstock, GA

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HS-65 In-Flight Failure
Anyone had this happen? I just finished rebuilding from the last crash (motor bolts departed) and damned if I didn't stick it in the dirt on the first flight out.

I was having a nice controlled flight when all of a sudden the cyclic control went to hell. Just started flopping around like a fish out of water. So I hit throttle hold and watch her go in.

Back on the bench, my front right cyclic servo was unresponsive. I removed it and checked the gears, nothing stripped. This would lead me to believe that it failed in-flight and was the cause of the crash.

Oddly enough, the servo came back to life briefly while I was messing with it but now it seems to be dead again. How often does a servo just die with no warning signs? How can I be sure the other two aren't about to go? These have about 275 flights on them with no crash damage (never stripped any gears).
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05-21-2007 01:36 PM  13 years ago
helimatt

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Lafayette, IN

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I know of some fliers who replace servos every season. I don't know how long it took you to accumulate that many flights, but perhaps it would be cheap-ish insurance to put servos out to pasture after 200 flights or so. Vibration is a killer, and most of us mount them without any dampers in the tabs. There always seems to be some level of high frequency vibration on the heli though we work hard to eliminate the causes. Even the main motor will cause vibration- even the better motors to some degree.

Anyhow, I have gone through several gear sets, but otherwise my Hitecs are running great (both HS-56's and -65's with karbonite gears). I have only been flying them since late last fall though, maybe 100 flight on each set (two differnt helis).

Also, are you running a 6V BEC? Don't know if it could be part of the story or not.
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05-21-2007 01:42 PM  13 years ago
Darren Lee

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Woodstock, GA

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The 275 flights have accumulated since New Years (this year). I am running the new BL35X, which does have a 6V BEC.
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05-21-2007 02:17 PM  13 years ago
cbflys

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Nesconset, NY - USA

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If your servo came back to life briefly, the problem is most likely an intermittent open somewhere. Could be in the servo lead, which can be easily replaced. If not there it could be anywhere internal such as a cracked circuit board or failed solder joint. In that case, it's probably not worth the time to troubleshoot it (unless you're into that).
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05-21-2007 02:53 PM  13 years ago
markgca

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Los Gatos, CA 95032

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i had exactly the same thing happen last month with a hs65.

so i put it on a servo tester, and it would work for a bit, then stop.

found out if i turned it manually, it would start up again, work for a bit then stop. now its just dead.

perhaps they had a bad batch?
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05-21-2007 02:56 PM  13 years ago
Darren Lee

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Woodstock, GA

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found out if i turned it manually, it would start up again, work for a bit then stop
That's what I did to get it working. I am definetely going to replace it but I just have to decide about the other two.
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05-21-2007 03:51 PM  13 years ago
helimatt

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Lafayette, IN

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Okay, you fly a lot!

Just thinking about what you said concerning turning it by hand to "start it back up". Could be some grease or oxidation on the pot wipers- try cleaning with an electronics spray cleaner and see if you can get it 100% working.

Also you've had a crash or two- did you check the gears under magnification? A tooth or two may be cracked, and it causes binding so the geartrain binds until you give it a little push. I had a servo do that. If it continues to bind you may burn out the IC (overcurrent from stalled motor). Just a thought.
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05-21-2007 04:22 PM  13 years ago
Darren Lee

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Woodstock, GA

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Haven't used a magnifier, but my eyes are pretty good and I didn't see any gear damage whatsoever. I hate to risk my bird again by trying to "fix" the problem. I don't trust the servo. It would be difficult to know if it's 100% working.
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05-21-2007 04:26 PM  13 years ago
lsurber

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Fort Worth, Texas - US

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Helimatt hit it with high frequency killing electronics....I now mount every servo using gromets!

I would only dissagree with observation of bieng able to start it by hand be a pot wiper......It is most likely caused by intermitent open in brush/commutator.

Go coreless!

Lee
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05-21-2007 05:48 PM  13 years ago
helimatt

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Lafayette, IN

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In any case may be time to retire those servos per all these concerns.

Good coreless servos for the 450 sized? Waypoint makes one, 068PB and I have flown one as a tail servo with pretty good success. Only 14oz-in of torque, but its light. Nylon gears though, so not durable in a crash.

Other coreless options?
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05-21-2007 06:55 PM  13 years ago
airboss

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OC ,california

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crash
after every crash,i had many,i would replace any questionable servos or gyros,its much cheaper than repairing the whole heli.
Urukay HPS3 KSE 700 HPS3
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05-21-2007 07:00 PM  13 years ago
lsurber

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Fort Worth, Texas - US

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helimatt,

Exactly, W-068PB corless BB all the way around!!!!!!! I think I like the way you think! LOL!

Lee
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05-21-2007 07:02 PM  13 years ago
lsurber

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Fort Worth, Texas - US

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Just keep head speed up, balance good, choke down on servo arm for more leverage......... all is well!
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05-21-2007 07:11 PM  13 years ago
MJWS

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Airdrie, AB - Canada

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The HS65's are pretty much bullet proof. You smacked it in a crash and likely have an intermittent open as suggested above. Just because you didn't strip gears doesn't mean it didn't take a beating. It's not a bad batch, not a conspiracy, you don't need to change them all out.

Swap it out for a new HS65 and don't think twice. If you send it in to Hitec they'll send you a new one (at least they always have for me). Often only takes a few days. If you'll feel better swap out all 3 and send them in.

It's hard to even estimate how many of these are running in trexes. Must be in the 100's of thousands. They are the defacto standard for a reason. Performance is fantastic. Failure rates are miniscule.

Good luck,

Mike
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05-21-2007 07:29 PM  13 years ago
airboss

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OC ,california

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???
always carry spares,hs 65 are not to expensive so having one spare and a gear set will keep you flying.
Urukay HPS3 KSE 700 HPS3
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05-21-2007 07:34 PM  13 years ago
Darren Lee

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Woodstock, GA

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always carry spares,hs 65 are not to expensive so having one spare and a gear set will keep you flying.
Unless the servo failure causes a crash and takes your Hyperion blades, fiberglass canopy, mainshaft, maingear, tailboom, skids, flybar and paddles...
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05-21-2007 08:36 PM  13 years ago
MJWS

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Airdrie, AB - Canada

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A single screw loosening could cost the same.

Your component choice is fine. You just happened to smack that one in a bizzare way. Normally they work or they don't. If you can't trust them buy something else.

The JR 285's are about the only thing that comes close and you can brag about 'digitals'

Mike
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01-08-2008 01:49 AM  13 years ago
da_man

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Central NC

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I just had a hs 65 fail today. NEVER before have I ever had a servo failure. I even have 15 year old servos in stuff. Same problem. I lost my carbon frame, radix blades, main shaft, carbon boom, belt, skids, spindle and probably some other odds and ends. This hobby S!CKS !!
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01-08-2008 02:11 AM  13 years ago
Rick

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ny, ny

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How often does a servo just die with no warning signs?
I think the crash was the warning sign.
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01-08-2008 03:00 AM  13 years ago
dkshema

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Cedar Rapids, IA

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If you have a broken winding inside the servo motor, it will have a dead spot. As long as the servo has enough momentum for the motor to spin past the dead spot, it will seem to work just fine. But if you are moving slowly and come upon the dead spot, the servo will just sit there unless there is some outside force that moves the servo arm (and in turn, the motor) until the brushes move off the commutator pair that is dead. IF you give the servo arm a little push, it should move normally until you come to rest back on the dead spot.

I have an HS-55 that died that way about a year ago. Makes for a wild ride, it was on elevator. I did manage to land in one piece without damage.

It also happened many years ago on a couple of differend servos that had been in a heli for quite a few years. Vibration eventually fractured one of the motor winding wires. One was a JR servo, the other a Futaba.

But then, you also just got finished rebuilding from a crash. Perhaps the crash damaged the servo.
-----
Dave

* Making the World Better -- One Helicopter at a time! *

Team Heliproz
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