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HelicopterHIROBOOther › Evo 50 - 9254 Tail Failure
01-28-2007 04:09 PM  10 years agoPost 1
rudyy

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E. Amherst, NY

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The 9254 on my Evo50 failed. I am thinking it may be the oil soaking issue. I would like to check out how you guys mount your 9254 if you are using one and do not have any issue so far.

1) Do you mount the servo with the horn facing away from the muffler or on the same side as the muffler?
2) Do you use big circular horn as opposed to star shaped horn?
3) What safety measure do you have to safeguard against the failure?

Rudy

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01-28-2007 04:19 PM  10 years agoPost 2
z11355

rrMaster

New England

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infinivation makes an $$ mount that moves the servo.

I have one. It's good in that respect but it is kinda sloppy
and I probably wouldn't get another.

try using a big round arm and pointing the horn away from exhaust.

keep a log of when you changed it and maint. should be to check
the smoothness of the servo. if it starts getting waggy for no
good reason, it's a good chance it's oil soaked.

BTW, 99% sure your servo is oil-soaked.

Practice your auto-rotations and be aware of the tail servo as
a failure mode.

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01-28-2007 04:22 PM  10 years agoPost 3
rudyy

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E. Amherst, NY

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I am not 99% sure the issue is oil soaked though. Yet, I do not want to eliminate the possibility.

Rudy

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01-28-2007 06:31 PM  10 years agoPost 4
funflyer2006

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CC, Iowa

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I'm not so sure if its the oil either. I had the same thing happen to me. I think the darned servo is crap after awhile, but I did end up getting another one. It's still located on the tail.

I LOVE MY EVO!!!

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01-28-2007 07:48 PM  10 years agoPost 5
Leif

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USA

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No problems with S9254

I've been running a S9254 on my Evo for two years and it's still running strong with no problems.

- Standard Tail mount location facing exhaust side.
- Single control arm (from DuBro super strength arms for Futaba)
- Flying Wildcat YP30 (Curtis Youngblood mix with 23% oil)
- Using the Freya tail hub/grips with the MAH 90mm carbon blades.

The servo routinely gets oil on it. The only issue so far was that the label came off due to oil getting behind it and softening the adhesive. I super-glued it on a year ago and it's still holding.

I believe the PRIMARY reason for failure on these servos is running the gyro gain TOO HIGH. I run with very low gyro gain. Having learned to fly with a mechanical gyro and then flying for years with non-HH gyros I'm quite comfortable not having the gyro sitting at maximum gain.

The conventional wisdom to set your gyro gain until the tail starts to hunt back and forth and then back off is NOT good advice for the GY401/S9254. The gyro will hold quite well at gain settings MUCH lower than the hunting point.

On the Evo, I also recommend doing some modifications to improve the tail authority. At a minimum, try to get a set of Freya plastic blades instead of the stock ones. The Freya tail hub/grip upgrade also improves the tail rotor authority and minimizes the amount of throw needed on the tail servo to maintain the tail position.

Leif

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01-28-2007 09:01 PM  10 years agoPost 6
Tony-V

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Fraser Mi

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When upgrading the Evo 50 to the Freya tail hub/grips, what parts are needed?

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01-28-2007 09:26 PM  10 years agoPost 7
Leif

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USA

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To do the Freya modification you'll need to order the following part numbers.

0414-164 Freya Tail Rotor Hub
0404-662 Freya Tail Grips
2500-070 3x9x3 Bearings
2506-003 Washers
2532-028 M2x8 Screws (or re-use the ones from the Evo grips)

You will re-use the existing radial and thrust bearings from the Evo setup, with the addition of the '070 radial bearings. The finished tail is 17mm larger than the stock tail, so you'll get significantly more tail authority even using the same blades. I don't suggest running tail blades longer than 92mm with this setup.

Leif

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01-28-2007 11:37 PM  10 years agoPost 8
hootowl

rrProfessor

Garnet Valley, Pa.

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I agree with Leif. I burned up a couple of 9253/54's on my Vario Acrobatic because it likes high gain and the gasser vibrates. Put these two together and you have a recipe for burned out tail servos.

I too back off on gain as long as I have good holding and authority. The Freya setup helps alot. Not that there is anything wrong with the stock tail... it also works quite well.

I have learned a lot from Leif.

Here's the Freya hub and grip assy on my EVO50 #1

Wolves don't lose sleep over the opinions of sheep

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01-29-2007 11:57 AM  10 years agoPost 9
RICH.L

rrKey Veteran

east springfield p.a.

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i just picked up my evo 50 on sunday,and i checked it all over and looks like a very nice machine but i did notice the tailblade grips have some side to side movement.
my evo 90 has no movement at all in the tailgrips,is the side to side movement on the evo 50 normal?
is this why people are using the 90 size parts?
i already have a spare new hub and grips,all i would need is the bearings,washers and screws.
rich

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01-29-2007 12:07 PM  10 years agoPost 10
uf-engineer

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Jacksonville, Florida

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How high is to high of a gain setting?

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01-29-2007 01:13 PM  10 years agoPost 11
rudyy

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E. Amherst, NY

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I am now setting the gain to 40%. I believe anything over 60% is considered high, and will potentially damage s9254.

Rudy

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01-29-2007 01:42 PM  10 years agoPost 12
Havoc

rrElite Veteran

Ky.

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You could run the speed up pully on tail if it is stock now and then run a lower gain. Mine is around 35% avcs and holds rock solid. I also do the trick with the Zap A Dap around the case where the o-rings and screws sit and the large servo wheel. Since doing the Zap trick these servos have way outlasted my previous tail servos.

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01-29-2007 04:10 PM  10 years agoPost 13
Havoc

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Ky.

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Sorry, I meant zap a dap. Edited.

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HelicopterHIROBOOther › Evo 50 - 9254 Tail Failure
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