Hi Peter,
I received an email update via USA. You've probably already seen the
statement from A.I. Kunovice, but the SSA's comments are interesting -
perhaps we may end up with a modified version of the eddy current
testing which we already do here in Aus.
Email copied below FYI:
As most SSA members and users of the ubiquitous L-13 Blanik know, this
glider has been the subject of a number of manufacturer's Mandatory
Service Bulletins and Airworthiness Directives issued by the European
Aviation Safety Administration EASA), and more recently by the FAA.
Currently most of the world's fleet of L-13's is grounded.
At the request of SSA and numbers of other organizations and operators
around the world, the holder of the current Type Certificate (Aircraft
Industries in Kunovice, Czech Republic) has provided the following
statement:
Kunovice September 30, 2010
OPINION Aircraft Industries, a.s. on the means to restore airworthiness
of GLIDERS L 13 and L 13 A
With regard to the accident glider L 13 sn 175117 (in Austria 12 June
2010), where the initial findings first led investigators to suspect
the fatigue cracks associated with fracture of the left wing flange
where it joins the hinge leaf; and also identified a significant strain
due to high overall acrobatic flight frequency of about 8% of the last
400 hours of operation (with the previous roughly 2000 hours of
operation not having any records at all) - to the attention of
operators and certification agencies concerned with the problem of
fatigue life of the glider and criteria for its certification.
Investigation of the accident is still not officially closed.
Aircraft Industries, as manufacturer, stresses that the service life of
L 13 gliders and other related types is based on the concept of safe
life, which was established based on fatigue tests of the glider and
fatigue tests of samples. Tests consisted of applied cyclic loading
derived from the published average operating conditions in the glider's
operational documentation. In the event that actual operating
conditions of the glider deviate towards greater burden on the glider
(the frequency of improper acrobatics, etc.), safe life of the glider
drops significantly below the standard service life.
Following the issue of Mandatory Bulletin L13/109a and EASA AD
2010-0119-E, it was revealed that many gliders L 13 have missing or
incomplete records of actual operating conditions. This situation
precludes the ability to assess what proportion of fatigue life has
been exhausted and what part remains available, which is contrary to
the concept of safe fatigue life.
In this situation, taking into account the finding that visual
inspection of the critical binding site required by Bulletin L13/109a
is unable to ensure reliable identification of all cracks, Aircraft
Industries a.s. considers that the appropriate way to restore the
airworthiness of gliders L 13 and L 13A is the development,
certification and deployment of NDT methods that can reliably identify
any incipient cracks in critical areas, together with the determination
of periodic tests and analysis of the speed of crack propagation at
critical locations to determine residual structural strength in
critical areas. Aircraft Industries a.s., in cooperation with the
Research and Testing Institute in Prague is preparing a system of
checks using the "eddy current" technique. Given that the critical
point is hidden below the two layers of sheet metal and flat head
rivets, the development of the means of processing the data is more
time consuming.
Aircraft Industries a.s. expects to restore the airworthiness of
gliders with proper operational records, by implementation of approved
NDT methods with satisfactory results. Furthermore, we assume that the
method will be verified and approved in early 2011.
Gliders with non-existent or incomplete operational records will
probably be subject to periodic checks. We expect that this will be
approved at the end of the first quarter of 2011.
The proposed way to restore the airworthiness of gliders is subject to
approval by EASA."
SSA is concerned about the reliability of Blanik L-13's since nearly
200 are owned and operated in the United States. Meanwhile, the
manufacturer, as stated above, expects to determine appropriate
inspections and methods of declaring them airworthy again. The FAA's
Small Airplane Directorate in Kansas City, MO has investigated the
matter in depth and has published a multi-page informational bulletin
which, due to its length, is published in the News Section of the SSA's
website www.SSA.org <http://www.ssa.org/>. This document is unusual in
its detail and clarity
and SSA thanks the Small Airplane Directorate, and in particular Greg
Davison the author, for their understanding and help.
The FAA Airworthiness Directives, also published on SSA's web page,
allow for proposed Alternative Methods of Compliance (AMOC's) and
provide a method for their submission. Although these AMOC's likely
also need to be approved by Aircraft Industries, they may provide an
accelerated method of getting Blaniks in the air again. SSA urges
individuals and companies with the appropriate engineering expertise to
contact the FAA and propose methods of compliance through them.
SSA will continue to publish information as it arrives on the SSA web
site in order to provide the quickest dissemination.
Jim Short,
SSA Aircraft Certification Subcommittee
October 22, 2010
On 20/11/2010 10:52 AM, Peter F Bradshaw wrote:
Hi Kym;
We have a Blanik in our club so we are all following the story closely.
I hope a fix does arrive. However, its my guess that any fix will cost
more than the aircraft is worth and this will kill the whole thing.
On Sat, 20 Nov 2010, Kym Z wrote:
Don't scrap the Blanik's yet, they are aiming for a solution by first
quarter 2011... although that doesn't help us for this soaring season :(
Regarding the trailers, I'd say that many Blanik trailers may have their
Blanik housed on them at the moment to save space while they are
grounded (ours is at RGC).
Kym Z.
On 19/11/2010 5:54 PM, Peter F Bradshaw wrote:
Hi Adam;
A Blanik trailer? How cruel. :-)
On Fri, 19 Nov 2010, Adam Webb wrote:
Hi All,
The Australian Junior GC is looking for a trailer to transport its 'new'
IS28 around this Summer (initially from Bunyan to Narromine), until we can
get a more permanent solution sorted. Does anyone know of a trailer which
could be used for this? Possibly a Blanik trailer which is sitting idle and
wouldn't require too much in the way of modification?
If anyone knows of any options, please let me know!
Cheers
Adam Webb
Pres
AJGC
Cheers
Cheers
--
-------------------------
www.riverland.net.au/~kym
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