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HelicopterMain Discussion › Help to find crash reason????
12-02-2007 11:00 PM  10 years agoPost 1
ferincr

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From Argentina now in Costa Rica

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Hi, just a long story short, I was hovering my R90SE doing some engine tunning when all of a sudden I got like a glitch and it went full throttle and right aileron into the ground.
Batteries (both Tx &Rx were full) no one else at the field, range check ok.
The only difference I had in the heli since last weekend (when I lost a screw from the exhaust was that I put extra nut at the end of the exhaust screw.
Now, this nut was touching the carbon base plate. Can metal to carbon rub create radio interference?????? Or just metal to metal.
The funny thing is that I hit T hold before the crash and nothing happened neither the F/S kicked in (which it's at 28% throttle)


Otherwise I have no clue as what did happen, and I hate to rebuild not knowing what to expect next time...
Thanks for any input on this.
Fernando

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12-02-2007 11:06 PM  10 years agoPost 2
ckoelliker

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St. Simons, GA

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Probably a long shot, but try to wiggle or squeeze the battery pack. Sometimes the tabs that are soldered to connect the cells get damaged. That happened to me recently, and I really had squeeze the pack together in the right spot to get it to fail. You might also want to check the battery connections, the leads from the receiver, leads from the regulator, etc.

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12-02-2007 11:12 PM  10 years agoPost 3
MMike

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Holland,Mi-USA

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CK has a good idea.

I would put a volt meter on your receiver and wiggle everthing.

Move the sticks on your radio.

How old are you batteries?

MMike

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12-03-2007 12:12 AM  10 years agoPost 4
ferincr

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From Argentina now in Costa Rica

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I'll try that.
The battery is about a year or less, I'll try the connectors thing.
After I crashed I did check the voltage again and it was at 5.2v and since it shows it at the gyro screen (Logitech 6100)I also tried to force a servo to overload it and I only managed to drop the voltage to 4.9v
It seems like no one think it might be the carbon to metal rub, bummer since I had put all my hopes on that one.
I hate not knowing what happened
Keep them coming (please)all suggestions are welcome.
Fernando

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12-03-2007 12:19 AM  10 years agoPost 5
Yug

rrMaster

UK. Herts

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Carbon is nearly as good a conductor as metal. On the R90SE you have to be careful with the 4 screws at the top of the upper start shaft bearing as these can rub against the inside sides of the carbon pitch tray. Use THIN washers or none at all.
As others have said, have a wiggle and you may find something.

Vegetable rights and Peace

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12-03-2007 12:23 AM  10 years agoPost 6
Jeff polisena

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westpalmbeachflorida usa

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I would go with yug this is always the culprit also if you have a carbon boom look at boom braces mounting to fin mount if loose and horizontal fin is not rubbing tail case

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12-03-2007 12:52 AM  10 years agoPost 7
Wyn

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Oregon, USA

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What's the setup on this bird (radio, servos, battery, switch, reg?)

Wyn
VoltMagic

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12-03-2007 02:52 AM  10 years agoPost 8
ferincr

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From Argentina now in Costa Rica

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I have a 4300mha Sub C Nimh batt
Futaba 3x S9351's for swash
1x S9252 Throttle
Logitech 6100 gyro with it's Servo
CSM Revlock 20 (bypassed today since I was engine tunning)
Hitec Heavy duty switch
All in a Futaba 9CHP,
Rx futaba 9ch PCM

It's good (in a weird sense) that carbon to metal could be the case here.
Anyway, the boom and fins are all good. The screws at the top of the start shaft are good (I remember having a hard time when I put the bird together, but I checked now and they are clear and no markings on the inside of the tray).
Did the wiggle and I made it fail on the connector from the battery to the switch, unfortunately I'm stupid enough to have the battery unplugged before I took a good look at the status of the connection.
I decided to move the hanging battery in a more comfortable position and didn't realize what I was actually doing.
I tried many more times and it seems like if the plug is not all the way in (like 1/2 to 1mm out)it might fail.
I'm not 100% sold on this but at least it's something.
Tomorrow I'll do more tests with a fresh start, I'm a bit tired tonight and when you don't have any IQ to spare under normal conditions that doesn't help.
Thanks for all the inputs, I'll post a follow up tomorrow.
Fernando

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12-03-2007 03:34 AM  10 years agoPost 9
wannabfishin02

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barnhart, Mo-63012

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If fail safe was set, and it didnt kick in, I would rule out the carbon to metal or any glitch problem.

A bad day of flying is better than a good day of work

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12-03-2007 04:27 AM  10 years agoPost 10
ferincr

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From Argentina now in Costa Rica

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Actually I thought of that too. So I guess I'm more inclined now to what most of you suggested, some dodgy connection.
I did attach my orbital random sander to it (fortunately I was smart enough to get the sandpaper off before that)and turned both on but no glitches, so may be was that battery to switch conection.
I'll keep pushing it tomorrow.

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12-03-2007 04:38 AM  10 years agoPost 11
wannabfishin02

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barnhart, Mo-63012

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I'd bet on the battery problem of some sort. Sounds like you lost power with the throttle going all the way up and such. That would explain throttle hold and fail safe not working at all. Good luck, I know what a pain it can be to find those problems.

A bad day of flying is better than a good day of work

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12-03-2007 04:56 AM  10 years agoPost 12
ferincr

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From Argentina now in Costa Rica

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One weird thing is that I was at hover speed and the throttle went up by itself, that is why I thought of radio glitch and not power loss.
I'm not sure if a bad connection can bump the throttle servo up. I'll try to reproduce that too.

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12-03-2007 09:01 AM  10 years agoPost 13
classic

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All over the place!

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Just a sugestion, but I use heat shrink on All rc connections, battery plugs, servo extentions I had a battery plug come loose few years back an my heli did the same thing. If you had a JR radio then I would also recommend using a rubber band to hold the crystal in as that has been a culprit in many crashes.

Which is worse, ignorance or apathy? I don't know and I don't care!

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12-03-2007 09:17 AM  10 years agoPost 14
subarus

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South East Asia

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Have you rule out frequency clash?

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12-03-2007 10:05 AM  10 years agoPost 15
Jeff polisena

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westpalmbeachflorida usa

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what radio are you using ? throttle up seems like a glitch without fail safe

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12-03-2007 02:00 PM  10 years agoPost 16
pavan_mex

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Leon, Mexico

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Sometimes just stop looking...

Yup..sometimes it just makes more sense than to become a detective.

Change / fix all that you think might think would have been the culprit and............keep on going. Don't let it scare you. I know it means a few dollars here and there, but hey, you only live once.

Cheers

So many years wasted on plankers...!!!!

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12-03-2007 02:28 PM  10 years agoPost 17
ferincr

rrVeteran

From Argentina now in Costa Rica

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Just a sugestion, but I use heat shrink on All rc connections, battery plugs
I used to do that but once in a crash the battery got loose and pulled everything with it, so I didn't put anything on the battery pack to allow it to fly free in an event of a crash, I guess I'm going back to secure ALL connections now.

Have you rule out frequency clash
I guess you referring to if somebody else was on my frec. if that is what you meant I was the only one at the field at that time and there is only one other guy on my same channel that he didn't even showed up yesterday.

what radio are you using ? throttle up seems like a glitch without fail safe
I have a 9CHP. Stupid me when Ilanded to adjust the needle the previous time the engine reved up a couple of time for just milliseconds, I thought of a glitch but since I was doing pinch tests to it I though, nah it must have been an air bubble and started it once again.

Change / fix all that you think might think would have been the culprit and............keep on going. Don't let it scare you.
Well, I hate when it is not my fault and not knowing what it was does scare me, I don't need any help to crash my helis (believe me I do a pretty good job by myself)
I don't know what the situation is in MX but here there are no heli shops, so all my parts need to come from the US so it's not just the money (for which I pay 50% custom tax on every order I make) but also that I get grounded every time I don't have the specific part. I just have a big spares order coming now, but I broke one of the A links (which of course I don't have any)So I guess I'll need to keep stashing parts. Well, I might be able to open shop in a few years
Anyway, today I'm a bit more relaxed (read resigned) so we'll see where do I end up.
Thanks for everybody's posts, have been of great help to organize all my thoughts and procedures, I guess may be pavan is right after all.
Another call to the US, another order, another zap zap on the CC, and hopefully I don't get grounded for too long.
Fernando

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HelicopterMain Discussion › Help to find crash reason????
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