Letter from John Sherman (Jumpshack)

[diablopilot 2]

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Except it's NOT a base assumption if you actually read this thread, which contains a multiple posts predicated on the notion than an AAD as a integral component of a parachute deployment system. The most egregious examples of this mentality are the posts that propose changing reserve designs to accommodate an AAD.

AAD function is being discussed as if AADs are literally as necessary to the system as a pilot chute, a bridle, and a ripcord.

They aren't.

So I will bring it up one more time:

The easiest way to deal with the inherent failure rate of various AADs is to pull your effing reserve handle when you're supposed to -- and if you can't do that, then you shouldn't be skydiving.

+1 to that.

Whoa.... I'm getting dizzy.

----------------------------------------------
You're not as good as you think you are. Seriously.

[robinheid 0]

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Hi robin,

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The easiest way to deal with the inherent failure rate of various AADs is to pull your effing reserve handle when you're supposed to

Considering that the current problem is the cutter entraping the Locking Loop, and depending upon cutter location, that would not solve the current problem. You still would not get a canopy over your head.

JerryBaumchen

BINGO.

Your response to me is another one of those posts predicated on the notion that AADs are an integral component of a parachute deployment system -- and literally as necessary to that system as a pilot chute, a bridle, and a ripcord.

They aren't.

Or to put it another way: The moment you discard the absurd notiion that an AAD is an integral and necessary component of a reserve parachute system, the easiest solution to "the current problem (of) the cutter entrapping the Locking Loop, and depending upon cutter location" becomes absurdly evident: get rid of the non-essential component, the design and/or placement of which interferes with the essential function of the system.

To me, AADs are a "solution" in search of a problem and their presence in the sport has caused as many fatalities and injuries as they have prevented, and added an unnecessary level of complexity to reserve parachute systems that increases costs and the probability of error.

What a great idea.

Hi Robin,

Not to split hairs, but by your logic, an altimeter is also something we should never jump with.

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You're not splitting hairs -- you're blowing smoke: An altimeter does not interfere with the essential function of the parachute system.

Now, I agree that one shouldn't need an altimeter. Using your eyes is the best measure of altitude, and if you forget your trusty Altimaster on the ground, you should be able to jump anyway...but to suggest that we should do away with them altogether because they aren't an 'integral component' seems somewhat absurd.

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I didn't. You did, based on a false premise you thought up yourself and now attribute to me. Nice work.

In my opinion, if one doesn't want to jump with an AAD, they shouldn't jump with one. But for those who want to, I don't think it hurts to accommodate it, provided it doesn't screw with the functionality of the integral components.

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Your opinion is irrelevant given that this thread revolves around AADs that do in fact "screw with the functionality of the integral components."

Aside from AAD's, rigs also had to be changed to allow for ram-air reserves, which weren't necessarily integral to the system - they just improved the experience (admittedly, only in some ways). By the same token, accommodating something that a large number of jumpers may want to have as a last resort (i.e., in case of being incapacitated on exit or via a collision) doesn't seem to be a bad thing.

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"Provided it doesn't screw with the functionality of the integral components."

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[Full disclosure - I agree that we shouldn't be reliant on AAD's. Only one of my rigs had an AAD, until Argus was pulled out of it - I currently jump without one. But for AFF jumps (which are unpredictable by nature), I prefer to have one in the event I get clocked and knocked out by a flailing student (seen it happen). I like to have that last bit of insurance, provided it doesn't interfere with my ability to skydive & deploy my reserve on my own.]

then why did you even post this? The whole thread is about AADs that DO "interfere with (your) ability to skydive & deploy (your) reserve on (your) own."

SCR-6933 / SCS-3463 / D-5533 / BASE 44 / CCS-37 / 82d Airborne (Ret.)

"The beginning of wisdom is to first call things by their right names."

[robinheid 0]

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Except it's NOT a base assumption if you actually read this thread, which contains a multiple posts predicated on the notion than an AAD as a integral component of a parachute deployment system. The most egregious examples of this mentality are the posts that propose changing reserve designs to accommodate an AAD.

AAD function is being discussed as if AADs are literally as necessary to the system as a pilot chute, a bridle, and a ripcord.

They aren't.

So I will bring it up one more time:

The easiest way to deal with the inherent failure rate of various AADs is to pull your effing reserve handle when you're supposed to -- and if you can't do that, then you shouldn't be skydiving.

+1 to that.

Whoa.... I'm getting dizzy.

Whoa.... me too!

SCR-6933 / SCS-3463 / D-5533 / BASE 44 / CCS-37 / 82d Airborne (Ret.)

"The beginning of wisdom is to first call things by their right names."

[mjosparky 3]

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Aside from AAD's, rigs also had to be changed to allow for ram-air reserves, which weren't necessarily integral to the system - they just improved the experience (admittedly, only in some ways). By the same token, accommodating something that a large number of jumpers may want to have as a last resort (i.e., in case of being incapacitated on exit or via a collision) doesn't seem to be a bad thing.

How many rigs manufactured today do you think were around when square reserves arrived on the scene? Seeing that they are a “reserve” they would be considered “integral to the system”.
The system being the harness/container, a main canopy and a reserve or “approved” canopy. Anything else is not “integral to the system”. See Part 105.129

Sparky

My idea of a fair fight is clubbing baby seals

[LloydDobbler 2]

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Or to put it another way: The moment you discard the absurd notiion that an AAD is an integral and necessary component of a reserve parachute system, the easiest solution to "the current problem (of) the cutter entrapping the Locking Loop, and depending upon cutter location" becomes absurdly evident: get rid of the non-essential component, the design and/or placement of which interferes with the essential function of the system.

To me, AADs are a "solution" in search of a problem and their presence in the sport has caused as many fatalities and injuries as they have prevented, and added an unnecessary level of complexity to reserve parachute systems that increases costs and the probability of error.

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[Full disclosure - I agree that we shouldn't be reliant on AAD's. Only one of my rigs had an AAD, until Argus was pulled out of it - I currently jump without one. But for AFF jumps (which are unpredictable by nature), I prefer to have one in the event I get clocked and knocked out by a flailing student (seen it happen). I like to have that last bit of insurance, provided it doesn't interfere with my ability to skydive & deploy my reserve on my own.]

then why did you even post this? The whole thread is about AADs that DO "interfere with (your) ability to skydive & deploy (your) reserve on (your) own."



Robin - last I checked, no one attributed the altimeter analogy to you. I simply identified a similarity. Seems like you're more set on gunning for an argument than you are on considering that the situation may not be as black and white as you paint it.

That being said, we're in agreement on some things. As I said clearly - AADs that DO "interfere with (one's) ability to skydive & deploy (one's) reserve on (one's) own" are what's at issue.

I suppose I was confused by your statement highlighted in orange above, in which you seem to express that all AAD's are non-essential, and that the solution is to get rid of all non-essential components (and hence, all AAD's. And by my interpretation, altimeters - also non-essential components - as well). That's where I disagreed.

If I misinterpreted, my apologies.

Obviously, AAD's that interfere with the functions of a container shouldn't be in service. Case closed. But if you're moving the debate to the merits of AAD's as a whole (& whether or not someone refuses to jump without one), that's another matter.

Signatures are the new black.

[pchapman 261]

Someone passed on info about John Sherman's post on to Airtec, so Helmut Cloth of Airtec wrote a reply. Folks at SSK wondered if I might post it to add to the discussion.

Helmut's statement is quite long, and does push that CYPRES thing he manufactures, but we don't always hear from equipment designers on this site, so I figured I'd give him the courtesy of still posting it all.

I don't think Helmut is trying to get into an argument with John, but his perspective on the reasons for using the Cypres loop material instead of Kevlar (as all Racers' used to have) is a little different -- at a distance of about 20 years since they first discussed how to put a Cypres on a Racer.

I have in the past criticized Airtec for seeming to have an attitude of "just trust us", and I have heard that Helmut can get a little defensive when questioned about his wonderful product. However he expresses himself, it is interesting to see some feedback from him about Cypres cutter design and Cypres loops. Especially at a time that cutter design is on peoples' minds.

The highlighting in the text is mine, to try to pick out some of the more interesting bits of the letter.

I have also added a couple editors' comments where I think Helmut's English wasn't quite clear.

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From:
Helmut Cloth/AIRTEC/DE
Date:
27.03.2011 10:53
Subject:
WG: Fw: AAD cutter (neu)


Hello all,

Possibly I can contribute a bit and clear some things up.

After we had started to sever closing loops with a mechanical guillotine
24 years ago in order to open reserve containers, we learned a lot about
this area. E.g., that the result is different, depending where the cut is
executed. That triggered us to try to find out why this is so, then to
learn what causes those different results. Later we did trials with every
existing container model that we could find, regardless where it came from
and who had manufactured it.

Very much later that generated the "CYPRES Riggers Guide for
Installation". A thick purple binder, which showed the necessary
installation of a loop-cutting device in all these different constructions
in sketches and in worded description. To show it as easy as possible and
assure as less as possible mistakes by riggers retrofitting containers
with a set up, we even produced a video with the important contents of the
binder. The complete "Riggers Guide for Installation" kit did consist of a
Part A and a Part B. Part A was the information, the binder and the video
and a questionnaire and asked the retrofit applicant to learn and then
fill in the check questionnaire and fax it to us. If answers were
satisfying, we did ship Part B, which were tools and needed material.
Without Part B it was difficult to do retrofits. This proceeding was done
to try to achieve that people did as much correct as possible, because
this location and installation is so important.

One aspect of the location subject is the reserve container’s closing
loop. The better the loop is in terms of allowing and in supporting the
opening sequence the better. I knew three skydivers which have died (one
together with a tandem passenger) because -I for myself are absolutely
sure about it- they had a too poor reserve closing loop. These
realizations and knowledge together has born the idea to make a suitable
container closing loop. The opinion of some people that this, later called
CYPRES loop, is necessary for the CYPRES cutter is ABSOLUTELY wrong. A
CYPRES cutter can sever any dacron, spectra, kevlar, nylon, or whatever
loop or even a steel ripcord cable. Nothing causes it any problem. It
doesn’t matter if there is tension on the loop or not, it cuts clean every
time. A suitable loop is narrow, slippery, and flexible, doesn’t become
hard after a long time under strong tension, is fingertrapable and has the
necessary breaking strength, etc. We developed different generations with
a well reputed German weaving mill and tried and tested and so on. At the
end we decided for the version, that you likely know as the CYPRES loop.
To make that loop even better, we introduced a certain silicon in its
upper four centimeters. It is important to realize that the silicon does
not aid in cutting the loop, the reason for it is to further improve the
opening characteristics of the container.

I personally believe that there are skydivers still around, that would
have been dead if they haven't had this "CYPRES closing loop". Completely
independent of using an AAD or not, only due to advantage which this loop
provides to the container's opening process.

I am happy about it. That was the reason to spend the time and energy to
generate this loop system and to distribute it, mainly via our CYPRES
channels.

[Now we hardly see rigs without Cypres loop material. Before the Cypres, other loops were used. E.g., Dacron 'closing loop' line, heavier Spectra, sometimes Kevlar. -ed.]

Of the standard 1 pin loop made from this loop material and to our ideas
and treated with our silicon, we until today have manufactured more than 3
million items. We gave the vast majority of those to riggers and packers
and rig manufacturers for free.

Just on the side [as a side benefit -ed.], we also improved the holding discs with the idea to
reduce the typical and dangerous loop tearing at the washer. From our
final solution, (the three hole disc which you likely will know as
"Smiley"), we have meanwhile manufactured more than 700,000 items. The
vast majority of those we have given to riggers and packers and rig
manufacturers for free.

[He must be talking about introducing the smiley washer, vs. the standard washers that used to be used, not about the changes relating to that bad batch of washers that were produced for Airtec about a year back. - ed]

One of the side spin results [side benefits or spin-off benefits - ed] of all our work was a development which
allowed opening the reserve container of a rig like the Racer, not with a
fixed loop, but with a floatable loop. It used a channel across the pilot
chute top, which enabled the loop to run through it. The result was that a
reserve container, like the Racer reserve container, would immediately
open when only one of its two pins was pulled. In case of a loop cutting
system, the container would immediately open if only one loop cutter would
sever the loop. On a walk along Lexington Ave 20 year ago, I entered the
Jumpshack building and showed this to John. He was impressed that this
system worked always and without hesitation. But because of possible
additional packing effort he didn’t want to have it installed in the
Racer. I was a bit disappointed. Forth and back, then we negotiated a
compromise. In all countries where John’s TSO for the Racer was valid, it
was forbidden to use this running (floating) loop, in all other countries
it is permitted. You can find this regulation in every CYPRES User’s Guide
since 1991 under the Chapter "Repacking of Reserves".

Because we were interested in the most reliable system to sever a closing
loop, we searched for something which was more reliable than a mechanical
guillotine. We ended up choosing a pyrotechnic system. That is a very
sophisticated affair. There is extremely much to learn and to take care
about. We are not only used to thinking analytical and completely, but we,
when thinking about a problem, think in a ball completely around the
problem and from every angle towards the problem. And even we did run into
wrong directions several times with this pyrotechnic cutting system. That
did cost us a lot of time. Even a dummy went in. This was all long before
we did sell CYPRES. The development took 4 1/2 years and we did build 12
generations of development units. So, loop cutting (consisting of fibers)
is something really difficult. If we had not come to an absolutely
satisfying solution for the cutting action, we would have dropped the
CYPRES project.


By the way a cutter as we wanted it was not available. So we designed our
cutter and searched and found a German manufacturer who manufactured it to
our specifications and quality ideas. For example is an ex ray made of
each and every cutter, which we use to check certain things that we want
to check.

We also would have dropped the project, if we would not have found a safe
possibility for CYPRES to compensate automatically for the air pressure
changes of the weather. And for a number of other requirements too.

The guideline has always been: very very close to perfect, or nothing.

So the system which was first produced in January 1991 was safe, and this
of course included the cutting device.

Airtec feels necessary to comment about the latest conversations about
failed cutters from other AAD manufacturers. There are voices who compare
the reliability of our cutters with those of other AAD brands on the same
level concerning quality and failure rate.

We insist to completely be out of these discussions.

We have neither the same supplier, nor would we ever accept such product
for our device, as it is a low cost item not to be compared with the
CYPRES cutter. The design principle of the CYPRES cutter is especially for
our purpose and completely diverse and not to be compared with copies,
imitations, or derivatives from other suppliers.

We have proven over 20 Years to cleanly and entirely severe any loop.
More than 200,000 Cypres cutters have been manufactured.

The reliability of the CYPRES cutter is so astonishing that it has found
its way into non-CYPRES applications including satellites, rockets,
aerospace, commercial, and military.

We are investing a lot of time, money, and energy to guarantee the highest
level of safety and confidence, and we can not tolerate any misjudgment or
transfer of serious problems other manufacturers may have to our products.
Our cutters are strictly not affected by the current “lack of proper
design” discussions.

I would like to thank everyone involved over the past 20 years, especially
rig manufacturers and riggers, in helping make CYPRES one of the most
reliable pieces of skydiving equipment in use today.

Have a pleasant Sunday.
With my regards.

Helmut

[NovaTTT 1]

Might make it easier for some to read.

"Even in a world where perfection is unattainable, there's still a difference between excellence and mediocrity." Gary73

[Unstable 8]

I have this burning desire now to stick a Steel ripcord cable in an expired cypres unit and fire it off.

=========Shaun ==========

[theonlyski 3]

I could've sworn that they did that in a demo video...

Now, if it was the pin instead of the ripcord... I may be impressed a little more.

"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message

[michalm21 0]

go for it, I've seen it. it's pretty cool

[skydiverek 54]

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I have this burning desire now to stick a Steel ripcord cable in an expired cypres unit and fire it off.

Here: http://www.youtube.com/watch?v=-Jf3NV5wLWw&feature=mfu_in_order&list=UL

[pchapman 261]

The way things have gone with Argus, I'd actually be more impressed if someone took a cypres cord, put a series of knots in it, pulled each knot really tight, jammed that into a cutter, and then "pulled the trigger".

(Karel G. of Argus had complained about some in air testing a rigger, Mr. Oosterveer, did with the Argus in '06 or so, where cutters didn't cut well. The argument was that the test loops were knotted at one end and pulled partially into the cutter, making it cut a dense knot, and doing so with only one side of the circular cutter.)

Tough but flexible Spectra looks like more of a challenge than stiff steel wire.

[JohnSherman 1]

It's not about the material or the record of the CYPRES or anyother AAD or why I wouldn't allow the floating loop. It's about "if the cutter fails does it fail-safe?" "does it not interfear with the normal function of". We must make it better! We must make it fail-safe. I don't care if we use cutters which fail open or use pin pushers or pullers. Whatever we use must be fail-safe. That way we still have the oporitunity to save ourselves!

[-ftp- 0]

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It's not about the material or the record of the CYPRES or anyother AAD or why I wouldn't allow the floating loop. It's about "if the cutter fails does it fail-safe?" "does it not interfear with the normal function of". We must make it better! We must make it fail-safe. I don't care if we use cutters which fail open or use pin pushers or pullers. Whatever we use must be fail-safe. That way we still have the oporitunity to save ourselves!

wouldnt the easiest way to do this be to place the cutter at the bottom of the tray in all applications? I know it's easiser said than done, but that is a sure way to make it have no involvment in the reserve system.

The other way, is to go back to a pin pulling device instead of loop cutting.

[theonlyski 3]

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wouldnt the easiest way to do this be to place the cutter at the bottom of the tray in all applications? I know it's easiser said than done, but that is a sure way to make it have no involvment in the reserve system.

The other way, is to go back to a pin pulling device instead of loop cutting.

Yup, except Racer type containers, who's pins are located on the backpad.

Guess who makes the Racer?

"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message

[koppel 3]

would it be the biggest problem to move the cutter to one of the side flaps on a Racer?

I like my canopy...


...it lets me down.

[theonlyski 3]

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would it be the biggest problem to move the cutter to one of the side flaps on a Racer?

Then a cutter that locks the loop could keep the PC from launching.

"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message

[riggerpaul 1]

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It's not about the material or the record of the CYPRES or anyother AAD or why I wouldn't allow the floating loop. It's about "if the cutter fails does it fail-safe?" "does it not interfear with the normal function of". We must make it better! We must make it fail-safe. I don't care if we use cutters which fail open or use pin pushers or pullers. Whatever we use must be fail-safe. That way we still have the oporitunity to save ourselves!

wouldnt the easiest way to do this be to place the cutter at the bottom of the tray in all applications? I know it's easiser said than done, but that is a sure way to make it have no involvment in the reserve system.

The other way, is to go back to a pin pulling device instead of loop cutting.

(Not really directed at "-ftp-", but to all who think all cutters can be placed at the anchor end of the closing loop.)

Lest we all forget, some manufactures put the cutter above the pilot chute because putting it elsewhere created the long tail that some rigs do not tolerate well.

Now, maybe we should just say that such a rig is incompatible with current AADs, but I don't think that is going to fly so well.

We do want the rig to open after the AAD fires and completely cuts the loop, don't we?

While a failed cut that interferes with the operation of the rig is bad, a successful cut that interferes with the operation of the rig is far worse, isn't it?

[Beatnik 2]

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Yup, except Racer type containers, who's pins are located on the backpad.

Guess who makes the Racer?

Or the Reflex, Teardrop classic, Viper just to name a few.

The concern that John Sherman is expressing is valid and to try to dismiss it because of his container design is a bit obtuse thinking IMO.

[Unstable 8]

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Or the Reflex, Teardrop classic, Viper just to name a few.

The concern that John Sherman is expressing is valid and to try to dismiss it because of his container design is a bit obtuse thinking IMO.

+1. Could be acute as well, but we'd have to measure the angle.

=========Shaun ==========

[billvon 2,396]

>The concern that John Sherman is expressing is valid . . .

Agreed, but the odd thing is that he wrote that letter to explain why he dismissed a solution to that concern.

[Skybear 0]

In the good old times, which most of us in this forum including me never experienced, loops were made out of normal lines. During the Cypres development Helmu Cloth saw, that many delayed reserve container openings were caused by friction between the loop and the grommets. In his effort to create an AAD, that is as close to 100% as it can be, he developed the Cypres loop. The requirements were a minimal diameter, great strength and minimal friction. By the way, that is why we siliconize loops. To reduce friction, not to get a cleaner cut. But even with minimal friction there is still some potential for the loop to delay the container opening, when the flaps are pushed sideways by the launching PC. That is absolutely no porblem with top mounted cutters, because the length of the rest of the loop is too short to cause a problem. If the loop goes through to the bottom of the reserve container it is a totally different situation. Here the loop has to slide through all the grommets in full length. Depending on the flap design and the reserve size in the container this can lead to some delay.

We are living in free countries and can make our own choices. But why use an AAD, that needs the cutter mounted on the bottom of the reserve container when you can have something better? Whenever you are in the situation that your AAD, or that of a friend, fires, take these 1,5 seconds until the reeserve is open to think about it. If it takes longer, you might have done a bad choice.

[mjosparky 3]

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Lest we all forget, some manufactures put the cutter above the pilot chute because putting it elsewhere created the long tail that some rigs do not tolerate well.

The incidents that precipitated this action I would attribute to sloppy rigging. The loop was too long allowing the various flaps to create an “s” in the loop and lock the container. It is my opinion that the change was a rush to judgment and fix a rigging error with an equipment change.

Sparky

My idea of a fair fight is clubbing baby seals

[floormonkey 0]

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[He must be talking about introducing the smiley washer, vs. the standard washers that used to be used, not about the changes relating to that bad batch of washers that were produced for Airtec about a year back. - ed]

According to Airtec, there was not a "bad batch" of washers, but rather a batch that conformed to specs. The original manufacturer was making the washers to higher strength then required, and the new manf. made them closer to spec. Here is a letter from Airtec about it:

http://cypres-usa.com/CYPRES_disc_update.pdf

[theonlyski 3]

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Yup, except Racer type containers, who's pins are located on the backpad.

Guess who makes the Racer?

Or the Reflex, Teardrop classic, Viper just to name a few.

The concern that John Sherman is expressing is valid and to try to dismiss it because of his container design is a bit obtuse thinking IMO.

I wasn't trying to say that its not a concern, just stating (reply to -ftp-) that moving the cutters to the side flap, wouldn't make the problem go away.

"I may be a dirty pirate hooker...but I'm not about to go stand on the corner." iluvtofly
DPH -7, TDS 578, Muff 5153, SCR 14890
I'm an asshole, and I approve this message