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Tsb Report: Aug 2008 B206l Crash Near Terrace


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Wow, I find that incredible. We teach AME student apprentices about collective bounce and min friction.

 

Why is this incredible. Not all aircraft react like a bells. Not all aircraft require any minimal friction on the colective for flight. Last bell I put a wench to was at SAIT about a decade ago. I guesse that was the last time I had ever heard of colective bounce. There is a reason that we type endorse AME's before we give them ACA. I asked 2 pilots to explain (not bell pilots) and they could not either. I did not know if it was just a phanominum that occured in this type of rotor head. There was a post about how pilots would ask there engineer to reduce the friction on the machine they were flying. Maybe now someone will read this and know that maybee thats not the best idea. Im glad you still remember every detail about every aircraft type and system you learned about in school. I guesse you're a better engineer than I. If I ever have any questions about Mag timming i will drop you a line. I think that this thread has been very informative and personally I learned from it. I sure the guys that put out this TSB report would be happy to know that there were people from all over the industry discussing it in an open form and educating people in hopes to one day prevent an accident like this from happining. I think the whole point of the reports being published is so we all can get closure and learn from others mistakes.

 

Oh ya pretty sure we're also taught to use the Maintenance Manual when perfoming maintenance on an aircraft. I pretty much stick with that and its worked for the past decade. I guesse I did remember something.

 

Cheers

 

 

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I sure the guys that put out this TSB report would be happy to know that there were people from all over the industry discussing it in an open form and educating people in hopes to one day prevent an accident like this from happining. I think the whole point of the reports being published is so we all can get closure and learn from others mistakes.

 

The TSB are keenly aware of the discussion here and support any education that will encourage prevention of this happening again.

HB

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Having been in a S58T that got into collective bounce is an experience that I "never" want duplicated (extremely violent).......it is not just related to Bell products.

 

It is an oscillation that can happen in various flight regimes (turbulence for example). The oscillations resonate between blade phasing (and track), hydraulic pressures and airframe bounce.

 

I had bruises on my shoulders for weeks and a sprained thumb trying to get to the collective friction lock to arrest it wild movements.

 

Not sure why the tail was not severed in flight, as I know blades passed below the front windshields and the m/r head stops were hammered several times......the aircraft was totally out of control for a few seconds as the aircraft would not respond to control inputs by the left seat (logging) pilot.

 

All Sikorsky (and Bell) products I fly, include a fair measure of collective friction!

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Due and careful note should be taken of what "Helilog56" had to say. His point about staying away from Bell products will NOT keep you out of harm's way once again very true. I had also mentioned that I had almost encountered same in a multi-bladed M/R system and I say again "almost". The "almost' part was because the a/c 'talked' to me and I felt the onset enough to already be entering forward speed before it arrived, stayed momentary seconds and then was gone. To be absolutely particular that a/c was an Allouette II and if you landed on a wrongly constructed pad that had any spring to it whatsoever, you best paid close attention. This all was further aggrevated by the fact that there were shocks between the A/F and the skids + other 'amentities' on the 3-bladed head that all had to be in good condition and working perfectly or I hope you packed lots of clean underwear with you. Could you push down on the collective and have the a/c try to left off the pad and have the opposite occur also......you betchem'.

 

Once again, fly the thing the way it's supposed to be flown, focus on what the He*ll is happening and slow-down. Do all that and 'collective-bounce' will never come calling at your door. There's pilots that have flown all types of R/W for a whole career and never ever encountered what we've been talking about here......and you'll find that they all fly a certain way that keeps them from having had it happen......so duplicate them. Still doesn't mean that it shouldn't be experienced in flight schools rather than on the side of a mountain some day in 'the Rock pile'.

 

 

CMJ91 -------- the term is "Drill-o-grams". The folks who caused that phrase to be coined also have special weights for dry and wet plywood of different thicknesses (thicknesses of each piece make no difference because a stack of 4 x 8's that is 12"" thick is 1,200lbs DRY). They have the same for 45 gal drums of JP-4 and the average weights for them over the eons has been anywhere from 150-300 lbs at most. Very few of the drillers weigh more than 148lbs by the way and if you dodn't believe that just ask the other excellent pilot who also works for your company and lifted all those previous loads with no bitchin'. Explain all you wish and trust that it works. After you've been around for awhile your very appearance on a jobsite let's them know that their moments of B.S. have come to a resounding STOP. If however, you've been in the habit of only looking at the load, only exercising your left bicept muscle and disregarding your power guages completely, then you train this crew improperly and set the tone for the poor s.o.b. following you who just maybe a newbie.

 

 

Sorry 'bout that Skids Up Had to get serious for a moment there.

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Surely we realize that if we do not know what the charts say, it doesn't matter where they are...

 

(You know I couldn't resist...) :D

Who cares where the performance data is located? Performance data is REAL. Any pilot who ignores the hover-out-of-ground-effect chart in the mountains, or anywhere, is flying in uncharted waters. However, everyone who has flown drills knows that all kinds of crap gets added after the first loads. You can get an overgross load up under good conditions, not learn that you have a tiger by the tail until it too late to put it back down, and be way over your head putting it down under bad conditions.

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Heli500- I mention that I found that increadable because collective bounce and minumum friction settings are on the basic curriculm for AME's. I was suprised that a pilot would not be exposed to the same education regardless of the model or type of helicopter they are training or working on. I also meant no disrespect in my comments.

 

I guesse you're a better engineer than I. If I ever have any questions about Mag timming i will drop you a line. I think that this thread has been very informative and personally I learned from it.

 

Where the eff, did that come from?? I never stated that I was gods gift to engineering, (and I never will) I do not know it all, never will, and yes this has been an excellent thread in relation to the TSB report which I am going to use to reinforce to my students the reason for proper min friction adjustments.

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CMJ91 ... Explain all you wish and trust that it works. After you've been around for awhile your very appearance on a jobsite let's them know that their moments of B.S. have come to a resounding STOP. If however, you've been in the habit of only looking at the load, only exercising your left bicept muscle and disregarding your power guages completely, then you train this crew improperly and set the tone for the poor s.o.b. following you who just maybe a newbie.

...

 

Good concept but it seems that there's more of the latter than the former. Don't know how you get everyone on the same page - someone has to set a standard and stick with it in the face of customer pressure and peer pressure. Any thoughts? Not every pilot can automatically command the respect of the drill crew, especially if the pilot is young, low on experience and being asked to "fill the big shoes".

 

"... if you landed on a wrongly constructed pad that had any spring to it whatsoever, you best paid close attention". I think this refers to ground resonance which I think is a different problem.

 

As for the performance charts, it shouldn't matter where they are. The Gross Weight limit is already in the Limitations Section. I don't think that the Performance Charts could be considered limiting as there are other local site variables that are difficult to quantify or change from load to load (wind, humidity, etc.). They certainly should be a guide, though.

 

Thanks for the great responses, cheers . . . . .

 

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