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Audacity Models Pantera 50 - Tiger 50 > Exploding Pantera!
 
 
rotaryfalcon
Senior Heliman
Location: Social Circle, Ga. USA

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Gee guys I hate to interupt the drama unfolding here in this forum, but today I witnessed a Pantera self destruct while in hover. This was a very recent build which had been hovered and flown briefly before. The owner had just installed a new set of carbon blades and I was enlisted to help get them in track. They were only slightly out and one turn set them perfectly. After hovering( perfectly smooth by the way)for a bit checking trim and engine tune he initated foward flight from about 15ft. of altltude. Before he got more than the departure turn started, the heli started a bad vibration. Before I could say get it down, It shed the entire tail boom, followed by the canopy then the battery tray seperated with the battery and radio receivers. The still sort of flying main frame finally hit the ground, and it was over. Upon examing the carnage the boom was totally free of any contact(no boom strike) the main shaft was bent 90 degrees to the main frame and the only blade contact was with the battery in mid-air. The fuel tank was shattered into many small pieces found in varying distances from the heli, yet the frame and skids were intact, ie the frame hadnt opened. The swash was destroyed along with the gyro, but the head was intact with a bent spindle, but strangely the flybar was basically unhurt. I have seen many failures and crashes but never one as spectacular or with such complete destruction, especially in a hover!! The head speed was only around 1850. The whole club heli contingent witnessed this and we could not come to a consenus as to exactly what happened. Any thoughts? Disregard the pic.

10-12-2009 03:00 AM
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pertti
Heliman
Location: deltona,FL

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Answer most probably lies in what was changed between previous successful flight and the crashing one, however small the
change.
10-12-2009 03:57 AM
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jbeech
Elite Veteran
Location: Sanford, FL (Orlando area)

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What about the bolts securing the spindle? Any chance one came loose? It would lead to a massive imbalance. Changing blades seem innocuous in and of itself, but this may be a clue hidden within the narrative. I dunno other than perhaps a link came off (mostly wondering since that was the last thing you guys dealth with).


John Beech - GM (and janitor)
Audacity Models
AMA # 47381
IRCHA #745
10-12-2009 04:11 AM
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AzHyper
Veteran
Location: Peoria, Az.

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Just out of curiosity
Quote 
The owner had just installed a new set of carbon blades
what brand of blades were these?
10-12-2009 04:17 AM
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MartyH
Elite Veteran
Location: Cincinnati

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Oh, you probably experienced another one of those isolated incidents that never happens to a Pantera.

Ok, seriously, what sort of blades were these? Some of the off brand stuff you can buy cheap online have had the bushings pull out of the roots of the blades. You can imagine what happens next.

Marty,
Raptor 90 3D, Freya and more
10-12-2009 11:20 AM
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rotaryfalcon
Senior Heliman
Location: Social Circle, Ga. USA

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The blades were Maverick G5s which many of us fly with no problems. The only failure on the blade was where it hit the battery top, which also totally obliterated the AR7100. The only thing changed at all were the blades, an upgrade from woodies. The link used to track the blades was still in place. The grips were intact, and no play was found(no loose spindle bolt) I experienced a bolt that holds the seesaw coming out in flight, which caused a bad out of track situation, but the heli flew on home and landed. These are not locktited by the way and this builder was told about this. A quick spin of the blade bolts found them not bent. The engine turned over through the one-way meaning the clutch/hub was probably OK. The tail boom broke off( did not just come off). I figured the vibes were so bad that the boom hit a resonance which caused it to fail starting the whole crash process. The heli was in smooth stable hover, when the vibes started. The fins, canopy, and skids(just about anything that could move) started shaking badly, less than 10 secs. later it was history! A club member that was shooting vids of the heli flying had just left(dang!) It would have been a vid to see! There was quite a bit of long time heli experience viewing this, and we were all kinda puzzled. The builder is a very meticulous,and a multi eyed look over turned up no problems. We are not really faulting the Pantera as we have been wringing out the several on the field for quite a while now and the only problems have been thumb induced. We are waiting for a tear down by the builder for a further inspection. Maybe we will find the cause, its in there some where.
10-12-2009 02:35 PM
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rotaryfalcon
Senior Heliman
Location: Social Circle, Ga. USA

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BTW, save for the usual breaking off of the rear canopy mounts and the trashing of the upper bearing block when the main shaft decided to make a 90 degree turn, the anvil tough main frames are undamaged. I know my Titan or 600N would not have made it out as well.
10-12-2009 02:41 PM
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CoastalTom
Senior Heliman
Location: Foley, AL (7 miles N of Gulf Shores/Orange Beach)

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You said the tail boom broke off, not just came off. Exactly what does that mean? Length wise, did it break just after the main frames or somewhere else? Just trying to help analyze. I've been flying helis a loooong time but just bought a Pantera and so far I'm pleased.

Tommy Patterson - Gulf Coast Aerials
10-12-2009 04:00 PM
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MartyH
Elite Veteran
Location: Cincinnati

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the vibes came on slowly and built up or they just hit and then she was all tore up? If it came on instantly and the tail boom is broke, maybe it threw a tail blade. Does anyone remember an issue with the tail boom developing cracks right where it exits the main frames. I vaguely remember some discussion on that a year or so ago.

Marty,
Raptor 90 3D, Freya and more
10-12-2009 06:10 PM
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wthford
Veteran
Location: Monticello, Illinois

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Did this helicopter have the tail supports installed? I know there are some that think they are not needed. I am also wondering if the flybar came loose, causing the head to become imbalanced. That would produce a horrible vibration that could cause the damage.

How can I soar with the Eagles when I work with turkeys??
10-12-2009 08:04 PM
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rotaryfalcon
Senior Heliman
Location: Social Circle, Ga. USA

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The vibes built very fast, this was all over in about 10 secs. or less. The tail boom broke at the main frame, the boom supports remained attatched to the boom, the plastic eyelets on the supports broke at the frame. The entire tail boom assembly including the belt departed together save for the piece in the main frame. The tail rotor assembly was unharmed, the shaft is even true, no damage to the blades or grips either. The builder had painted the boom day-glo orange and there were no contact marks any where in the paint. The vibes were so bad that the canopy, battery and receiver departed in mid air leaving the main frame and blades spirialing in by itself. The fuel tank even shattered before it left the heli. The conclusion that is probably going to be arrived at is a popped linkage somewhere. The only link removed to track the blades was still attatched. We may never know, hopefully we can examine the heli again in detail.
10-12-2009 11:16 PM
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pertti
Heliman
Location: deltona,FL

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Was it like this:
http://www.youtube.com/watch?v=rpFFp2A9saU
10-12-2009 11:43 PM
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rotaryfalcon
Senior Heliman
Location: Social Circle, Ga. USA

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Ahh the old training gear resonance, great example! This incident was about 4x faster with a much more complete destruction. The latest from the Club Council on Crashes is that more than likely it was a blade failure. We found about 8" of delamination near the tip of one blade, with about 6" of the leading edge deflected downward. Our original conclusion was blade failure. This was based on the fact that there were absolutely no contact marks on the blade any where. later when the foam wrapped receiver was found destroyed, the conclusion was drawn that the blade must have hit the battery tray in mid air, trashing the blade. The almost instant destruction of the poor old Pantera, however is consistant with blade failure. The blades are being sent to the vendor for their take on it. A few discussions with blade failure victims revealed similar blade damage. So the offical verdict vindicates the Pantera. You have to witness something like this to understand how much energy is stored in those blades!!
10-13-2009 12:29 AM
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billm
Elite Veteran
Location: Liberty Lake, WA

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It does look like a blade failure. I must ask.
Do you know the head speed (or a WAG) when things went bonkers?
If the pantera had a tail blade failure the ship would of spun and not explode Marty!

My name is Billm. Cough, and I'm a Heli Holic
10-13-2009 03:13 AM
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MartyH
Elite Veteran
Location: Cincinnati

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I only suggested that because he said the boom broke off at the frame Bill. Something a severely out of balance tail could do just prior to the spinning.

Marty,
Raptor 90 3D, Freya and more
10-13-2009 11:36 AM
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jbeech
Elite Veteran
Location: Sanford, FL (Orlando area)

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We went through a horrible situation with blades, which I had purchased out of China, several years ago. Perhaps some of the old hands will recall the unfortunate events.

Anyway, in a nutshell, I was excited to discover a manufacturer of blades (who was making blades for a rather well known manufacturer of model helicopters) who offered me an attractive pricing schedule. After extensive testing here, everything looked golden and thus, we placed a substantial order. We, in turn, offered what we thought were decent blades for a decent price but it wasn't meant to be. We quickly sold about 100 sets (in a matter of days) but before long things started to go south. In short, complaints started to come in (ultimately, about 60 customers called to complain), mostly with issues of delamination in one form, or another.

Frankly, I felt a sense of dread each time the phone rang. After some initial angst, I knew there was really only one right thing to do. I immediately issued a recall, e.g. we contacted every single customer and whether they were experiencing problems, or not, asked them to return the blades to us for a refund. Meanwhile, my vendor, exhibiting the lack of responsability I've subsequently learned is somewhat typical of Chinese manfacturers, refused to so much as acknowledge the problems, much less offer warranty replacement, or take care of us in any manner whatsoever.

Moreover, as you read this account, reflect on one thing. Basically, we're not a giant conglomerate manufacturer based in the Orient, or the largest and most influential mail order vendor in the country. Instead, we're merely a handful of folks in central Florida, e.g. one of the smallest players in the market. Yet ultimately, there was really only one right thing to do - right in my view meaning doing what lets me continue to sleep well at night.

Hence, instead of simply eBaying them off on unsuspecting customers, or offering them as blems to people desperate to save a few bucks and willing to knowingly fly something known to be less than 'right', I knew from the get go I couldn't offer them to anybody - certainly not in good concience. Our course of action was, predicatably if you know me, straightforward, e.g. we took almost 1000 sets of blades to the landfill. To date, quite frankly, this remains the single biggest test of my business ethics because it was a huge financial hit. Believe me, the temptation to take advantage of folks desperate for a deal was huge, but it didn't matter, if you want to be taken seriously you have to do what's right.

Ultimately, I hope whomever is responsible for the blades in question has the integrity to do the right thing. The simple fact is, this could, and may still for someone else in the future, have tragic consequences. Folks be careful in buying blades you don't either know something about, or know someone reputable has your back on the product, the consequences are too grave to risk your safety on a quick buck artist.


John Beech - GM (and janitor)
Audacity Models
AMA # 47381
IRCHA #745
10-13-2009 03:38 PM
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Audacity Models Pantera 50 - Tiger 50 > Exploding Pantera!
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