duanefamly(at)aol.com
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 Posted: Mon Jul 11, 2016 7:52 pm Post subject: Europa-List: Do you recognize this cockpit mod |
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Nice write-up. I will have to investigate this more when I get to your shop. Did you get my email with the pix attached?
Mike
Sent from Windows Mail
From: budyerly(at)msn.com (budyerly(at)msn.com)
Sent: ‎Monday‎, ‎July‎ ‎11‎, ‎2016 ‎2‎:‎40‎ ‎PM
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Graeme,
That was a Flight Crafters mod for the trigear only. However the Berube’ conventional often had it also. The flange was done in four layers. The cover was normally done in a four layer, however, that is a structural member and in a front end impact the aircraft with this mod will buckle right across the canopy bow area if the area is cut down considerably like flat from the back to the panel face.
I have made this cutout myself on many aircraft but frown on cutting the tunnel lower.
To add structure back, I made the center console cover and the flanges out of a compressed 6 layer piece of high density 8oz. glass. The cutout has to be reinforced with a flange of considerable strength to maintain the beam strength of the top. The flange must be six plies in my opinion and run down on to the inside of the tunnel at least 3-4 inches overlapping each two plies over each other to take the shear of an impact. The cover plate is screwed in using #8 or 10 screws about 3 inches apart down the sides. That makes for a robust part but it is considerably heavier than the original couple of plies and some 3 mm foam.
Note each engineering test firm has slightly different criteria ( I use USAF Wright Patterson Data mostly), but a .009 thick glass ply has very little compressive strength capability. If you layer say, six compressed layers (i.e. no voids), at 15,000 psi for a thin flat hand laid plate you only have .050 inches of glass and over three inches, the math says it will hold 750 pounds, but it has little compressive rigidness and will buckle under load unless built like an angle iron. So make it thicker right! Well a uniform thickness with a glass to epoxy ratio of about even may get you 100,000 PSI in a perfect sample built to nearly a 90 degree angle, which is quite strong (it is now a longeron), but every hole and cut you put into that cover and flange will in fact weaken it. Fiberglass peels in bending shear so pay attention to your molding. I’ve seen some ugly voids which basically makes the structure suspect...
I feel comfortable with a full ring of six plies well lapped onto the tunnel wall all the way around and screws every three inches or so. The cover plate should be at least 6 plies but it has to be esthetically about the same as the piece you took out so it gets a bit thick. If you compress the piece you took out to bending failure and you test your filler piece and it is stronger, you did your job. I rely on the flanges being considerably stronger than the original C section and assume the plate is only a shear load. One must not forget to tie the original glass to the new glass by hollowing out the edge and filling with flox and assure there are no voids. Once complete, you can lift the plane with the panel cutout. It is very rigid, and analytically should take the force of a modest impact better than original.
I also recommend that Trigear owners and those conventional conversions consider a beam be added from wall to wall to make the seat areas connect with one another if cutting out the tunnel. That makes a brutally strong beam across the cockpit. Not really essential to the Trigear but worth considering on the conventional conversion. After all, one does not care to have his ’arse be the first item on the scene of the gear collapse.
Does my reinforcing work. A nameless client on a cross country impacted the runway some 25 degrees nose low and porpoised some 4 times before ramming the nose into the tarmac at a 30 degree angle and pushed the nose gear leg into the center tunnel. The fuselage was completely intact but all three gear were pretzels. Airport observers (mechanics watching the approach and bounces) were astounded the aircraft was in such good shape. No main structure was damaged. Yes the gear,were changed out and the engine frame and nose gear, but more damage to the plane was done grinding off paint and inspecting it than was done by the “crash”. This is one tough little airplane. If you want to stiffen the nose a bit more, lay a 2mm or 1/8 inch foam and glass over with two layers to the area between the seat and the footwell step. That is the common impact failure area due to buckling I’ve seen which puts more stress on the center tunnel.
Nigel is correct. Unless you can prove your mod is as strong as the original structure, don’t fool with it. Put an access panel in the belly for the center tunnel and leave it alone. If you do cut it out, do your homework. I did and I feel confident in my construction and am pleased with its performance. I am as a builder my own inspector in the US, and frankly the FAA rep just rolled his eyes and said you damn engineers, it feels really strong to me so here is your airworthiness certificate. Heck of a thing we put up with. 419 PL was originally built in 2004, still going strong. 12AY has bottom access only because it was faster lighter and easier to do.
Why avoid this mod, well it is a pain to sit in the seat and undo a zillion screws to get to an item in the tunnel, then drop something and try to bend over to feel around for it. The underbelly pan is a bit more relaxing on a flat floor with a nice creeper to lay on. However it is really dark in there and since gravity works 24/7 wear safety glasses as every nut and bolt hits you in the face. It makes for great stomach muscles as you continually cycle from the belly to the cockpit unscrewing things. I have a love hate relationship with everything in an airplane so keep it light and simple.
Note that the Europa Trigear mod which cuts out 1/3 of the side of the tunnel has less glass than what I do and that was approved. There was also an approved foam and glass modification to cut down a tunnel approved but it did not have a large removable panel.
On the original mono I was always amazed how thin the glass was on the center tunnel and as seen in crash photo’s the tunnel will fail on a mono. Of course it fails on a very severe impact only. One cannot build to an impact resistant aircraft as it would never get off the ground would it.
That’s my two cents of boring info.
Best Regards,
Bud Yerly
Custom Flight Creations, Inc.
US Europa Dealer
Best Regards,
Bud Yerly
Custom Flight Creations.
From: Graeme Hart (graeme.hart(at)onecoolkat.com)
Sent: Thursday, July 07, 2016 7:16 PM
To: europa-list(at)matronics.com (europa-list(at)matronics.com)
Subject: Re: Fwd: Europa-List: Do you recognise this cockpit mod
Thanks Nigel
While that is bad news it is also good news in that I'm only starting the build so it shouldn't be too hard to fix compared with attempting to fix when ready to fly.
I am in New Zealand and with our smaller population it is a little harder to find people with the experience your inspectors have. We also have a much simpler inspection regime.
I'll contact the Europa factory and get their advice on how to reinstate the structure. Hopefully it will just be a matter of reinstating the missing structure with a flat panel with an appropriate number of plys and a suitable overlap/bonding to the edges.
On Fri, Jul 8, 2016 at 10:48 AM, nigel_graham(at)m-tecque.co.uk (nigel_graham(at)m-tecque.co.uk) <nigel_graham(at)m-tecque.co.uk (nigel_graham(at)m-tecque.co.uk)> wrote:
| Quote: |
Hi Graeme,
I don't like to be the bearer of bad news but that mod was not (and never will be) approved in the UK. The centre tunnel is a critical structural component and by removing such a huge area of the box section, most of the strength will have been removed with it. If it is your intention to build the airframe to flying condition, I would suggest involving your inspector (one with proven composite skills) to advise on reconstructing the tunnel.
The Europa has no longeron like structures forward of the seat moulding and it is only the tunnel that prevents the fuselage snapping off in the event of a high "G" arrival. Typically, the fracture initiates at the sharp corner at the lower edge of the windscreen, propagates down the fuselage sides and across the floor. I have attached a picture of such a failure to help concentrate the mind (I have more!).
Nigel
On 07/07/2016 21:51, Graeme Hart wrote:
| Quote: | Hi Alan
It is a trigear and came as a trigear from the factory.
It looks to me like the plan was to put a removable panel on the top.
I have attached a better picture. On 7/07/2016 11:14 pm, "Alan Burrill" <alanb(at)dpy01.co.uk (alanb(at)dpy01.co.uk)> wrote:
| Quote: | --> Europa-List message posted by: Alan Burrill <alanb(at)dpy01.co.uk (alanb(at)dpy01.co.uk)>
Tri-Gear or Monowheel?
Alan
GOBJT
| Quote: | On 7 Jul 2016, at 11:35, Graeme Hart <graeme.hart(at)onecoolkat.com (graeme.hart(at)onecoolkat.com)> wrote:
Hi All
I have a kit that started out around 1999 and has been worked on by a number of builder since them.
Does anyone recognise the mod that has been done to the cockpit. A lot of the top of the centre console has been cut out and reinforced around the edges.
I'm hoping that this is a recognised mod and someone can point me at documentation on what was intended.
A picture of part of the cutout section is below (sorry I don't have one of the entire cutout)
I'd appreciate any leads on how this mod is intended to work. Also, with this large hole in the top do you still need the fuel valve access panel?
Thanks
Graeme
<20160705_174300.jpg>
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