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XHELI.COM . Autography FlightPower . Advantage Hobby

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e-Ark X-400 - MX400 > MX-400 Service report
 
 
celihopter
Senior Heliman
Location: Planet Earth first on the left..

I love my MX-400.
I log all flights and some related data.
Have now 84 flights and 11.8 hour total time with virtually no wear to really speak off on any components.
Here is how my heli is equipped:
• Aluminum center hub (is a must do not fly without it)
• Aluminum swash plate
• Aluminum tail blade grips
• Pro linkage set
• T-REX tail-pitch slider assembly (double fork design from plastic), fits right on and is absolutely play free.
• Helimax recommended 6 pole motor
• Helimax 25 A speed control
• JR- PCM receiver
• Futaba 3107 servos with the pitch servo arm extended
• GWS PG-03 gyro – works no problems
• TP 2100 3 cell battery slightly raised in front to allow fit in canopy.

It is a working package.

Here some data which might be of interest for some guys.
All data are related to sport type flying with occasional mild aerobatic included.
• Lowest temp flown 26F; highest temp 74 F – (no problems.)
• Average amp draw is about 9.3. I have seen between 7.5 and 11.3 in flight (average based on flight time and charge input after flight).
• Highest wind flown was 21 mph and very gusty (no problems).
• My typical flight time is on average 8.5 minutes (self selected for safety), with about 1350 ma charge required.
• Longest flight was 12.4 minutes with 1936 ma charge after that flight.

I encountered the following problems:

1. The first flight ended with a slight tip over causing the rotor head entirely to twist off. All linkages gone and so on.
That was with the plastic center hub which I replaced immediately.
2. After 13 flights and 1.8 hours. The Helimax motor shaft migrated out towards the top. Doing so, the lower (thicker) part of the pinion with the setscrew contacted the main gear and blocked it enough to cause the rotor to slow down and the helicopter to crash. I could hear a grinding sound for about 2 s.
The helicopter crashed on its skids from about 6 ft. No damage except the skids.
Shaft was retained with sleeve retainer.
3. After 60 flights a full speed tree encounter caused by tunnel vision. I thought there is nothing left based on the sound of impact. Damage: skids (my already glued ones); one blade broken at tip; lost the two bushings and screws inside the seesaw assembly; vertical fin broken, main drive gear lost some teeth’s but is still in use today– that was it – unbelievable.
4. After 73 flights an uncontrolled drop from about 30 ft min on short grass. I think a glitch caused it. Damage: my already glued skids again, one blade covering cracked; one tail blade – no other damage. I still can’t believe it. Not even the frame is bent.
5. Flight # 80 ended with impact on some industrial furniture during slow inside maneuvering causing the heli to drop from at least 6 ft sideways on concrete.
I just crossed a table causing paper to fly – looked at the paper and ……….
Damage: One blade, my home made skids, small crack in canopy – that’s it – no further damage.

The following wear is observable after all that and 11.8 hours of flying. Parts in question are never replaced.
• Radius arms on washout assembly – ball joints seem to get a little loose at the swash plate attach points, but still ok.
• The aluminum swash plate plastic insert is loose – slight movement possible – still ok – I hope.
• Main drive gear is in bad shape – I believe that is crash related.

Guess all I am saying is –that is one though bird!
01-19-2006 Over year old.
 
 
BoneDoc
Senior Heliman
Location: San Antonio, TX

That is one awesome report. Thanks for posting your experience with the MX400. I think most of the damage I sustained in my crash is related to the plastic hub. as it comes off, it tears the washout arm and a couple of other things.

So is the stock TRex slider a lot better than the MX400 ones?

**If you ain't crashing, you ain't flying hard enough**
01-19-2006 Over year old.
HOMEPAGE  
 
 
celihopter
Senior Heliman
Location: Planet Earth first on the left..

Absolutely.
The stock one worked fine - just had a lot of play at the ball joint after flying it for 5.7 hours. The TREX fits right on the shaft. The bell crank has ball bearings, comes with it and fits also.
The slider binds a little bit with my X-400 red tail blade grips - but very little. This works fine already for 6.1 hours without any increase in play.
It probably would make sense to also change to the TREX tail blade grips.
01-19-2006 Over year old.
 
 
RC-J
Heliman
Location: Lexington Ky

Very thorough report! Nicely done and thanks for taking the time.
01-19-2006 Over year old.
 
 
Squirrlybird
Veteran
Location: Suffolk, Va US

Beautiful report and thanks!

I am going to have to get that trex slider.

I have also been impressed with the durability of this bird (with the cnc hub).
01-19-2006 Over year old.
 
 
Mark C
Key Veteran
Location: Houston, TX - USA

Many thanks on the heads up. Great report! The only issues I have yet to hear on this nice little heli is the easy-to-break plastic rotorheads. I put an aliminum one on mine before I ever flew it for the first time ... which was today!!!

I really like it so far. Pretty stable. I will try to get it upsidedown pretty soon for some inverted circuits.

Mark C.
01-19-2006 Over year old.
 
 
BoneDoc
Senior Heliman
Location: San Antonio, TX

Keep us updated on that too. My skills so far prevents me from doing that .

**If you ain't crashing, you ain't flying hard enough**
01-19-2006 Over year old.
HOMEPAGE  
 
 
crusader4u
Heliman
Location: St.Kitts. Canada

Hi glad to see a great report like this, I just was wondering.
Where is your rx and speed controller mounted.

Thanks.
01-19-2006 Over year old.
 
 
T-Yo
Heliman
Location: Hoogezand, the Netherlands

Thx for the report, I'm building the X-400 at this moment. Its cool to read your experience!

T-Yo
01-19-2006 Over year old.
 
 
celihopter
Senior Heliman
Location: Planet Earth first on the left..

Crusader4u,
I mounted the receiver in the frame compartment below the main shaft.
The ESC is attached via velcro to the left side of the batt (used the cool side of the ESC.
I did cut a hole in the left side of the canopy for ESC cooling. Also opened the canopy nose to allow air to circulate around the batt.
Batt. is located forward of the motor. The GWS gyro is double stick taped to the frame just behind the antirotation bracket.
01-19-2006 Over year old.
 
 
celihopter
Senior Heliman
Location: Planet Earth first on the left..

Now at 91 flights and 12.75 hours. No problems.
Finally mounted new skids. I did put them in cooking water for 10 minutes as suggested in one of the forums. They are noticable more flexible after that.
01-21-2006 Over year old.
 
 
celihopter
Senior Heliman
Location: Planet Earth first on the left..

Now at 101 flights and 14.37 hours.
Everything seems to hold up very well.
No further parts changes besides a new set of blades.
The old one was glued together and taped causing some tracking issues.
Love that T-REX tail pitch slider.
01-24-2006 Over year old.
 
 
BoneDoc
Senior Heliman
Location: San Antonio, TX

I thought about getting the Ark one, but it looks like the ball is also plastic... not good

**If you ain't crashing, you ain't flying hard enough**
01-25-2006 Over year old.
HOMEPAGE  
 
 
celihopter
Senior Heliman
Location: Planet Earth first on the left..

Update:
I have now 109 flights and 15.38 hours.
I had no more accidents and expanded the flight envelope to a flight at winds gusting to 25 mph.
My flying has become a little more aggressive over the last 4 hours with frequent loops but it is certainly not 3D yet.
Yesterday I finally changed my main gear to a new one (missed some teeth after all kinds of abuse).
At this occasion, I disassembled the entire rotor head – shaft and gear assembly to inspect for wear and tear (all stock except for the metal center hub). Just thought it would be good to check everything and trace the source of some play.
Here what I found:
• The screws holding the center hub and the autorotation gear set to the main shaft are both bent. This is most probably related to the crash history listed in detail above. I replaced them with new screws.
• On one of the links, the rod end was loose on the push rod. I decided to CA that rod end to the push rod.
• Everything else is in good condition and still usable.
• The play in the rotor head assembly was traced to 4 points:
o Increased play in my servos due to service time
o Washout arms and mixing arms can tilt sideways under load. This is caused due to play in the bearing and between screw and bearing (single bearing design). This play has increased over time.
o Radius arms (rod end side) are able to move on the swash plate ball along the ball axis. That allows for some slop. I thought that was caused by wear of the plastic radius arm. It is not. I checked two new arms and both are also able to move along the ball axis.
o Increased play in my metal swash plate. The plastic insert is a little loose.
I am surprised to find my main shaft and feathering shaft perfectly straight.
I did not change anything except for the two bent screws and the main gear.
All the parts are original.

I also checked my tail drive visual. Everything turns freely and looks good. The drive gears and the belt are also in good shape.
The T-REX plastic tail pitch slider (double fork design) is as solid as the day I mounted it – about 10 hours ago. It has virtually no play.
Here is a list of the parts I changed over the service time of my helicopter:
• Main blades (twice)
• Tail blades (ones)
• Vertical fin and horizontal fin (ones)
• Skids (ones)
• Main drive gear(ones)
• Screws and bushings holding the seesaw arm inside the center hub (ones)
• Fly bar paddles (ones)
• Canopy holder (ones)
Here is a list of none stock parts:
• Metal center hub
• Metal swash plate
• Metal tail blade grips
• T-REX tail pitch slider
• T-REX fins ( liked the style better)
That’s it.
The MX-400 has been an excellent helicopter for me so far.
01-27-2006 Over year old.
 
 
Dave588
Senior Heliman
Location: ST. George UT. USA

I looked at one of your prevous posts and noticed that you said: you need a aluminum center hub,

why do you need it, I asking cause I am about to fly mine for the first time.
Thank you
by the way, awsome report!!!!

www.rcdudes.com
Another^Great^Form
01-27-2006 Over year old.
HOMEPAGE  
 
 
BoneDoc
Senior Heliman
Location: San Antonio, TX

It's the weakest part of the whole head. It will break even in a boom strike and one / two people has had theirs fail in flight. When it breaks, it'll take the rest of the linkages out with it.

It's a cheap 15 dollar upgrade anyway

**If you ain't crashing, you ain't flying hard enough**
01-27-2006 Over year old.
HOMEPAGE  
 
 
Dave588
Senior Heliman
Location: ST. George UT. USA

ok....Thanks
I'll do that, do you think it will be ok for hovering till the alunimun one gets here?

www.rcdudes.com
Another^Great^Form
01-27-2006 Over year old.
HOMEPAGE  
 
 
Squirrlybird
Veteran
Location: Suffolk, Va US

It should be fine, I do recommend replacing it as soon as possible. Just dont scuff the blades on that inverted hover.
01-27-2006 Over year old.
 
 
BoneDoc
Senior Heliman
Location: San Antonio, TX

lol

If you're new and still learning how to hover, invest yourself in soem training gear. That will save you tons in broken parts. With a training gear, you can hover 3 ft off the ground, and then land it real quick when things gets real squirly. Just make sure your pitch doesn't go below -2 degrees or so, or else you'll get a boom strike from the sudden pitch change.

**If you ain't crashing, you ain't flying hard enough**
01-27-2006 Over year old.
HOMEPAGE  
 
 
celihopter
Senior Heliman
Location: Planet Earth first on the left..

Same here.
My plastic center hub failed on my very first flight on a minor blade strike.
01-27-2006 Over year old.
 
 
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