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HomeAircraftHelicopterMain Discussion › Trex 250 leaning to the left
04-22-2013 11:58 AM  5 years agoPost 1
Bouchah

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Willow Spring, N. Carolina USA

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I had a small misshap with my 250 yesterday, was hovering about 6 inches off the ground and then the blades hit the ground. Broke the feathering spindle which seems to be common for me to do when this bird touches the ground. I replaced the feathering spindle and put the blades back on, same blades, undamaged. When I try to hover it now I have to give a pretty good amount of right aileron / cyclic in order to keep it from going left. Before the crash it hovered rather well, the swash is level, everything looks to be ok. Ive heard of the head block going basd on these but dont remember what problems it would cause. There is not alot if any viberation so I dont think the main shaft is bent. Not sure what is going on here.

Blade 130x (5)
Trex 550 V2 (18)
Shuttle ZXX
Freya Xspec (20)

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04-22-2013 12:33 PM  5 years agoPost 2
Rotormaster

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Australia

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So the spindle is the only thing that you changed?

You haven't accidentally applied trim on your TX, or changed any other settings? Have you tried a new set of blades?

It might help if you gave us some more info... You haven't even told us if it's FB or FBL.

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04-22-2013 01:06 PM  5 years agoPost 3
dkshema

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Cedar Rapids, IA

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You are aware that helicopters with a CW rotating main rotor system (viewed from above, looking down) have a natural tendency to move to the left as a result of the horizontal thrust from the tail rotor as it counteracts torque, I hope.

Trimmed properly, at hover, you'll see about a two-degree lean to the right as the (viewed from behind the helicopter) as right aileron is required to counteract the translating tendency of the heli.

-----

Of course if the trim has changed drastically after the crash, it would be wise to make sure your servo gears are not damaged and that the push rods haven't been damaged. In the 250 it's not uncommon for pushrods to be pulled out of the tiny links.

-----
Dave

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

Team Heliproz

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04-22-2013 01:13 PM  5 years agoPost 4
Bouchah

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Willow Spring, N. Carolina USA

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Sorry, it is FB.
I will have to check the lengths of the push rods. Im at work today so I will have to check tonight.
You haven't accidentally applied trim on your TX, or changed any other settings? Have you tried a new set of blades?
No to all of the above.

Like I said, it did hover nice without correction before the crash.
Thanks for the input so far.

Blade 130x (5)
Trex 550 V2 (18)
Shuttle ZXX
Freya Xspec (20)

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04-22-2013 01:14 PM  5 years agoPost 5
Rotormaster

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Australia

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You are aware that helicopters with a CW rotating main rotor system (viewed from above, looking down) have a natural tendency to move to the left as a result of the horizontal thrust from the tail rotor as it counteracts torque, I hope.
I'm sure he is aware of this phenomenon...

Even if he wasn't, the lean is not exacerbated by swapping out the spindle.

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04-22-2013 01:27 PM  5 years agoPost 6
Rotormaster

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Australia

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Have a thorough look throughout the whole head, and make sure nothing is bent or loose.

I once had something similar happen to my clone... I was just hovering, and suddenly it develops a 6° lean to the left. It didn't drift, just hovered on the spot with a comical amount of lean. It turned out that the swash had come apart.

Also, check the aileron servos as dkshema mentioned.

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04-22-2013 02:41 PM  5 years agoPost 7
jschenck

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La Vista, NE.

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Breaking the spindle on the Trex250 is really common, it breaks easily and I've had several crashes where the spindle broke leaving the blades undamaged.

some things I'd check:

1. Flybar. They bend easily and could account for the change in trim when hovering.

2. Servo gears. Very easy to pop a tooth off one of the servo gears and have it still work but now you are way out of trim.

3. The ball link on the main blade grip is bent or stripped/pulled out of the blade grip. Also very common. I red loctite those in place when building the 250.

4. Main head block is bent on the mainshaft. another common, easily bent part. check the mainshaft itself also, they do bend just slightly and you don't see it unless you check close.

5. bearings in the head - some are fragile and fall apart causing slop with any crash.

6. check the tail grip bearings also - fragile and will cause lots of problems. not related to the issue you asked about but worth mentioning.

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04-27-2013 01:38 PM  5 years agoPost 8
Bouchah

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Willow Spring, N. Carolina USA

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I think I may have figured out the problem. Some of yOu may have seen or remember a topic I created about the washers that disappear when the feathering spindle breaks and there are only 2 in the new packages of feathering spindles. Well to remedy the washer shortage I made my own die to punch out washers. I measured the ID, OD and thickness of an original washer when I made the punch but it seems something is off. The shim stock may be a little bit too thick, it is causing the flybar to be too stiff. I loosened the screws that hold the blade grips to the feathering spindle to relax the flybar bit, hovered it for a few seconds and the drift seemed to be gone from what I could tell. I ordered a package of spindles so I can measure the stock washers to see what is wrong.

Howard

Blade 130x (5)
Trex 550 V2 (18)
Shuttle ZXX
Freya Xspec (20)

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