What to do with L-13?

Open up the wing, wrap the spar with Kevlar and carbon fiber/epoxy and
carbon rod top and bottom.
Lots of info on this at many web sites. Reassemble the wing. Do a 10G
sandbag test.
Document everything and ask for an experimental certificate from your
local FAA.
Or call it an L-13plus and go fly.

On May 3, 9:33*am, soartech wrote:
Open up the wing, wrap the spar with Kevlar and carbon fiber/epoxy and
carbon rod top and bottom.

I once designed a wing that used a carbon rod wing spar and aluminum
skins. In order to make the spar stiff enough so that the wing skins
did not yield and buckle within the limit load envelope, the spar
needed four times the amount of carbon dictated by the strength
requirements. Basically, I would have had to make the carbon spar as
stiff as the aluminum spar it was intended to replace. That carbon
spar would still have been lighter than its aluminum equivalent, but
would have been much pricier. In the end, I went with composite skins
and only twice the amount of carbon rod dictated by strength, and it
worked out great.

Regardless, designing a retrofit that uses a carbon fiber spar but
retains the aluminum parts and detail design of the rest of the
structure would be a substantial undertaking with a lot of risk and
potential for heartache. I think it would be better to invest the time
and effort into a new training sailplane design more effectively
optimized for the current realities of soaring flight training.

Thanks, Bob K.

Apart from being bad advice on many fronts with this particular wing
design....

You can't go experimental to circumvent an AD.

aerodyne

On Thursday, May 3, 2012 10:33:42 AM UTC-6, soartech wrote:
Open up the wing, wrap the spar with Kevlar and carbon fiber/epoxy and
carbon rod top and bottom.
Lots of info on this at many web sites. Reassemble the wing. Do a 10G
sandbag test.
Document everything and ask for an experimental certificate from your
local FAA.
Or call it an L-13plus and go fly.

I think an easier major modification towards an experimental certificate might be struts (which I suggested to MM long ago and was also suggest by some gent in Brazil).

It actually might look okay with struts;^)

On May 3, 9:25*pm, Frank Whiteley wrote:
On Thursday, May 3, 2012 10:33:42 AM UTC-6, soartech wrote:
Open up the wing, wrap the spar with Kevlar and carbon fiber/epoxy and
carbon rod top and bottom.
Lots of info on this at many web sites. Reassemble the wing. Do a 10G
sandbag test.
Document everything and ask for an experimental certificate from your
local FAA.
Or call it an L-13plus and go fly.

I think an easier major modification towards an experimental certificate might be struts (which I suggested to MM long ago and was also suggest by some gent in Brazil).

It actually might look okay with struts;^)

I think someone else said the FAA isn't going to allow an 'end run'
around the AD by converting it to an Experimental Airworthiness
Certificate - even with struts slapped on.

On Thursday, May 3, 2012 9:34:28 PM UTC-6, Bill D wrote:
On May 3, 9:25*pm, Frank Whiteley wrote:
On Thursday, May 3, 2012 10:33:42 AM UTC-6, soartech wrote:
Open up the wing, wrap the spar with Kevlar and carbon fiber/epoxy and
carbon rod top and bottom.
Lots of info on this at many web sites. Reassemble the wing. Do a 10G
sandbag test.
Document everything and ask for an experimental certificate from your
local FAA.
Or call it an L-13plus and go fly.

I think an easier major modification towards an experimental certificate might be struts (which I suggested to MM long ago and was also suggest by some gent in Brazil).

It actually might look okay with struts;^)

I think someone else said the FAA isn't going to allow an 'end run'
around the AD by converting it to an Experimental Airworthiness
Certificate - even with struts slapped on.

Probably not, but there are provisions for taking certified aircraft to experimental following major modifications. Auto engine conversions come to mind.

Note that there were serial changes to the L-13 wing construction as the L-13 A1. Additionally some L-13's were modified to that standard. The design change was continued into the L-23. L-13 A1's and suitably modified L-13's were returned to service with new life limits up to 5,000 hours. See the EASA section of http://sites.google.com/site/blanikspar/ The AD issued 11 July 2011 superseded the previous four AD's. The Revision 1 of the STC on 28 Feb 2012 extended the life of the L-13s modified by the STC to 5,000 hours. It requires a hands on inspection to determine an L-13A1 or partially or fully modified L-13. Would be interesting to know how many are back on flight status in EASA countries and if any other countries have followed EASA's lead.

Frank Whiteley

On May 3, 9:56*pm, Frank Whiteley wrote:
On Thursday, May 3, 2012 9:34:28 PM UTC-6, Bill D wrote:
On May 3, 9:25*pm, Frank Whiteley wrote:
On Thursday, May 3, 2012 10:33:42 AM UTC-6, soartech wrote:
Open up the wing, wrap the spar with Kevlar and carbon fiber/epoxy and
carbon rod top and bottom.
Lots of info on this at many web sites. Reassemble the wing. Do a 10G
sandbag test.
Document everything and ask for an experimental certificate from your
local FAA.
Or call it an L-13plus and go fly.

I think an easier major modification towards an experimental certificate might be struts (which I suggested to MM long ago and was also suggest by some gent in Brazil).

It actually might look okay with struts;^)

I think someone else said the FAA isn't going to allow an 'end run'
around the AD by converting it to an Experimental Airworthiness
Certificate - even with struts slapped on.

Probably not, but there are provisions for taking certified aircraft to experimental following major modifications. *Auto engine conversions come to mind.


These aren't Experimental Homebuilt or Experimental Racing &
Exhibition - they're Experimental Engineering Test. Don't expect to
use one for flight instruction. I don't think this is a realistic
option.