Help with my crash analysis! - HeliFreak
Fun, Learning, Friendship and Mutual Respect START  HERE


Unregistered
Go Back   HeliFreak > R/C Helicopter Support > 500 Class Electric Helicopters > 500 Pro Class Electric Helicopters


500 Pro Class Electric Helicopters 500 Pro Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


Reply
 
LinkBack Thread Tools Display Modes
Old 04-22-2012, 09:22 PM   #1 (permalink)
Registered Users
 
Posts: 77
 

Join Date: Dec 2011
Location: Manitoba, Canada
Default Help with my crash analysis!

If only my helicopter had a flight data recorder....

Finally the weather was nice enough and time permitted to finally maiden my 500EFL. I was in awe at how fantastic it flew even with my relative inexperience. Rock solid. I was on my fourth pack and augered it in due to something beyond my control.

Something started to feel wrong with the tail, like I lost control of it then shortly followed by the wobbles and that was all she wrote. Below is the video link. At about 1:23 is where I felt something wrong and tried to start bringing it back to earth. Didn't seem to be any power loss just controllability went all to heck.

http://youtu.be/GHKwPN0_Mj4

Here is my setup which is stock except:

AR7200BX
DSMX Satellite
TM1000
DX8
CC ICE 75 ESC, Governed Mode, Internal BEC 6.0V

Post crash no evidence of mechanical failure, everything together and working. In the heat of the moment I went and turned my TX off so I lost any useful flight log data for voltages and frame loss from the TM1000. I did pull the castle logs and everything looks normal, running nice and cool. I had progressively been increasing the gyro gain in HH mode each flight and this particular flight was at 65% in the DX8.

So now I'm at a loss for what went wrong. In my mind the two possibilities are reception loss or brownout to the AR7200BX? Reception loss seems unrealistic because the helicopter was very near when this occurred. If the AR7200BX reset then you would think the throttle would have gone to failsafe.

What does it look like to everyone else?
barefootlifter is offline        Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
Old 04-22-2012, 09:59 PM   #2 (permalink)
Registered Users
 
Posts: 1,853
 

Join Date: Dec 2006
Location: Sydney, Australia
Default

Doesn't look like it was a reset as the heli was still changing attitude - like a "drunk" heli thou..

possibly something loose - but you say not and anything loose effecting tail (the first symptom you noticed) would generally not effect cyclic.

Any chance something happened to the gain setting to make it extremely low? ie: you flicked a switch that effected gain, etc ?

Very hard to say - a very unusual crash indeed.
__________________
DX7 Mode-1 | 450 pro 6s | 450 pro | Schweizer 300C Gasser Scale | T-Rex550e | Aeolus 50 | HeliX T-Rex700 fbl Gasser | HWC600 Gasser | Henseleit MPXLe | Henseleit 3DNT | Suzi-Janis 700 | Gaui NX4 | Gaui X5 | Blade 350QX
jockstrap is offline        Reply With Quote Quick reply to this message
Old 04-22-2012, 11:45 PM   #3 (permalink)
Registered Users
 
Posts: 77
Thread Starter Thread Starter
 

Join Date: Dec 2011
Location: Manitoba, Canada
Default

No switches flicked for sure. When doing some pitch pumps earlier in the flight the tail did blow out. But the cyclic did go all to heck on me as well.

Sent from my Galaxy Nexus using Tapatalk 2
barefootlifter is offline        Reply With Quote Quick reply to this message
Old 04-23-2012, 12:05 AM   #4 (permalink)
Registered Users
 
Posts: 1,002
 
My HF Map location
Join Date: Feb 2012
Location: New Mexico
Default

wow that stinks! im getting the 7200bx is thursday. Did you have a good bind?
__________________

Slow & Steady!
nmdesertracer is offline        Reply With Quote Quick reply to this message
Old 04-23-2012, 08:17 AM   #5 (permalink)
Registered Users
 
Posts: 3,951
 

Join Date: Mar 2010
Location: greenville,nc
Default

The bearings on my 500 mx went out and caused my Beast X to have a pretty bad aileron twitch. The flight characteristics were very similar to what you witnessed but not as severe.

To diagnose I spooled it up with the mainshaft and tail blades removed and witnessed the aileron servo going nuts. If no other obvious items are discovered, I would do a spool up with only the motor and keep adding components till you find the problem.

Let us know what you find.
__________________
Team HeliDirect
Flying Align - Powered by Pulse
tomd27858 is offline        Reply With Quote Quick reply to this message
Old 04-23-2012, 10:26 AM   #6 (permalink)
Registered Users
 
Posts: 77
Thread Starter Thread Starter
 

Join Date: Dec 2011
Location: Manitoba, Canada
Default

Ok I'll try that. While I was making a parts list I did run the motor for a bit and it did sound a bit noisier than before the crash but it could have the impact. I will get Humpty Dumpty back together and try as you suggested.

I only had like 12 min of run time on the motor. How long before your bearings caused the problem?

Thanks

Sent from my Galaxy Nexus using Tapatalk 2
barefootlifter is offline        Reply With Quote Quick reply to this message
Old 04-23-2012, 11:57 AM   #7 (permalink)
Registered Users
 
Posts: 3,951
 

Join Date: Mar 2010
Location: greenville,nc
Default

Mine quit at around 30 flights or so.

I wish you luck.
__________________
Team HeliDirect
Flying Align - Powered by Pulse
tomd27858 is offline        Reply With Quote Quick reply to this message
Old 04-24-2012, 12:22 AM   #8 (permalink)
Registered Users
 
Posts: 77
Thread Starter Thread Starter
 

Join Date: Dec 2011
Location: Manitoba, Canada
Default

You may have been right.

I did some more dry motor runs and found it quite noisy. It also was sending a very high frequency vibration through the frame. When putting a finger on the AR7200BX it almost tickles your finger (for lack of a better description). I wasn't able to reproduce any servo twitching though.

http://youtu.be/GnIbsMmgmao

I took apart the 500MX and found the bottom (small) bearing to be very rough. Going to solve that with some new all ceramic BOCA bearings. I noticed the main shaft bearings down right suck as well, whether they were better before the crash who knows but I'm going to replace with BOCA as well.

Could that be it, one little bearing that failed after a few test runs and like 8 total minutes of flying time, and send the AR7200BX into a death wobble? I have read the 500MX bearings were sometimes questionable but really, that bad?
barefootlifter is offline        Reply With Quote Quick reply to this message
Old 04-24-2012, 08:08 AM   #9 (permalink)
Registered Users
 
Posts: 3,951
 

Join Date: Mar 2010
Location: greenville,nc
Default

It sounds like you may be on to something. Vibrations will definitely cause a fbl unit to do strange things. Your death wobble was very similar to what happened to mine. I think you found your problem.
__________________
Team HeliDirect
Flying Align - Powered by Pulse
tomd27858 is offline        Reply With Quote Quick reply to this message
Old 04-24-2012, 10:06 AM   #10 (permalink)
Registered Users
 
Posts: 10,647
 

Join Date: Feb 2011
Location: Austin, TX
Default

The motor acting up will definitely reek havoc with the FBL units. I had a magnet seperation in the stock MX on my fourth flight or so that resulted in some funky behaviour and an unplanned auto. Sounds like you have found your gremlin.

Good luck in getting back in the air!
__________________
Nano CP X, mCP X BL, 130 X (Love the little ones)T-REX 500 Efl Pro DFC
Phoenix Sim, DX8, Gibson Les Paul, AMA #987871
"If a law is unjust, a man is not only right to disobey it, he is obligated to do so." Thomas Jefferson
Maypole is online now        Reply With Quote Quick reply to this message
Old 04-24-2012, 10:57 PM   #11 (permalink)
Registered Users
 
Posts: 182
 

Join Date: Sep 2011
Location: Northern Colorado
Default

The only thing I can add is that it doesn't sound right at 1:30 when you were bringing it in. There's a whining... it's subtle and the only reason I noticed it was b/c my 450 started doing it last time I ran it. I've yet to tear it down but I bet it's a shot bearing.

Good luck getting her fixed!
__________________
Tim

Blade MCPX BL stretched, full Rakon upgrades
mombawamba is offline        Reply With Quote Quick reply to this message
Old 04-25-2012, 12:51 AM   #12 (permalink)
Registered Users
 
My HF Map location
Join Date: Sep 2011
Location: Lower Lake, CA
Default

I had a similar problem with a 500esp. I thought motor bearings would solve it (500esp, but the similarity is the Servo's (DS510's), not the frame or FBL unit) In my case I was lucky enough to have it happen right after hitting idle up and was able to recognize the death wobble in time to hit TH.

Here is a link to Bad007's servo mod that fixed my 500 after hours of trying and buying everything else. He'd probably send you pictures if you PM him, nice guy.

https://www.helifreak.com/showthread.php?t=381030

I would never have believed that a piece of packing tape would fix this issue, It's come back again and I've had to replace the tape to fix again (about every 50 flights)

You're issue could be different, it could be bearings, but keep this in mind if you can't find anything else. (and if you have DS510's, MG or not) I've had the issue happen with several FBL units and the piece of packing tape fixed it every time.

Sorry about your crash and good luck with the diagnosis
phranticness is offline        Reply With Quote Quick reply to this message
Old 04-25-2012, 06:05 PM   #13 (permalink)
Registered Users
 
Posts: 77
Thread Starter Thread Starter
 

Join Date: Dec 2011
Location: Manitoba, Canada
Default

Thanks everyone for the input.

Sent from my Galaxy Nexus using Tapatalk 2
barefootlifter is offline        Reply With Quote Quick reply to this message
Old 05-12-2012, 08:58 PM   #14 (permalink)
Registered Users
 
Posts: 77
Thread Starter Thread Starter
 

Join Date: Dec 2011
Location: Manitoba, Canada
Default

First flights after the crash complete. Installed ceramic bearings in the 500MX, ABEC 3 throughout the rest of the heli. Installed second bearing on torque tube, balanced the blades, expoxied in the gyro tray and put the AR7200BX on some 4011. Gave it some good runs with no blades and very smooth now.

Had four great flights. Set up the tail in rate mode. Ending up going to 100% flat from 2850 governed and it is WAY better, tail is so much more locked in.

Switched to TX mode as well from the presets and that really sets the beast loose.

Fingers crossed.....

Sent from my Galaxy Nexus using Tapatalk 2
barefootlifter is offline        Reply With Quote Quick reply to this message
Old 05-12-2012, 09:28 PM   #15 (permalink)
Registered Users
 
Posts: 3,951
 

Join Date: Mar 2010
Location: greenville,nc
Default

Glad you got it fixed. It was scary for us when the MX gave up the bearings as well.

Nothing better than finding the problem and having some good flights. The benefits of fbl are obvious but the fbl systems sure don't like odd vibrations.

Thanks for the report and follow up!
__________________
Team HeliDirect
Flying Align - Powered by Pulse
tomd27858 is offline        Reply With Quote Quick reply to this message
Reply




Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the HeliFreak forums, you must first register.
Please enter your desired user name, your REAL and WORKING email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself. Use a real email address or you will not be granted access to the site. Thank you.
Email Address:
Location
Where do you live? ie: Country, State, City or General Geographic Location please.
Name and Lastname
Enter name and last name here. (This information is not shown to the general public. Optional)
Helicopter #1
Enter Helicopter #1 type and equipment.
Insurance
Please select your insurance company (Optional)
Helicopter #2
Enter Helicopter #2 type and equipment.
Helicopter #3
Enter Helicopter #3 type and equipment.
Helicopter #4
Enter Helicopter #4 type and equipment.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools
Display Modes

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On




Copyright © VerticalScope Inc. All rights reserved.
 

SEO by vBSEO 3.6.1