A aviation & planes forum. AviationBanter

If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below.

Go Back   Home » AviationBanter forum » rec.aviation newsgroups » Soaring
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

L13 Blanik Mandatory Bulletin



 
 
Thread Tools Display Modes
  #1  
Old June 22nd 10, 11:50 PM posted to rec.aviation.soaring
Ernst
external usenet poster
 
Posts: 49
Default L13 Blanik Mandatory Bulletin

After a fatal accident in Austria LET issued a Mandatory Bulletin:
http://www.let.cz/files/bulletines/M...9a_english.pdf

EASA issued an Emergency Airworthiness Directive:
http://www.caa.co.uk/docs/33/easa_ad_2010_0119_E.pdf
  #2  
Old June 23rd 10, 02:47 AM posted to rec.aviation.soaring
alautert
external usenet poster
 
Posts: 2
Default L13 Blanik Mandatory Bulletin

On Jun 22, 7:50*pm, Ernst wrote:
After a fatal accident in Austria LET issued a Mandatory Bulletin:http://www.let.cz/files/bulletines/M...9a_english.pdf

EASA issued an Emergency Airworthiness Directive:http://www.caa.co.uk/docs/33/easa_ad_2010_0119_E.pdf


Does anyone know if the L23 could have similar problem?
  #3  
Old June 23rd 10, 03:23 AM posted to rec.aviation.soaring
BT[_3_]
external usenet poster
 
Posts: 59
Default L13 Blanik Mandatory Bulletin

Reading the MB, It appears that based on the "flight data" of the aircraft,
and high number of launches per flight hour, the concern is overstressing
from repeated winch launches. LET is requesting all users submit flight
statistics for further evaluation plus a one time inspection of the load
bearing aft spar cap in the fuselage carry through structure.

I do not know if the L-23 and the L-13 have the same construction for the
aft spar cap.

"Ernst" wrote in message
...
After a fatal accident in Austria LET issued a Mandatory Bulletin:
http://www.let.cz/files/bulletines/M...9a_english.pdf

EASA issued an Emergency Airworthiness Directive:
http://www.caa.co.uk/docs/33/easa_ad_2010_0119_E.pdf


  #4  
Old June 23rd 10, 02:24 PM posted to rec.aviation.soaring
Derek C
external usenet poster
 
Posts: 114
Default L13 Blanik Mandatory Bulletin

Provided that the correct weak link is always used, it should not be
easily possible to damage a glider by winch launching it. What
aerobatics had this glider done?

Derek C


On Jun 23, 3:23*am, "BT" wrote:
Reading the MB, It appears that based on the "flight data" of the aircraft,
and high number of launches per flight hour, the concern is overstressing
from repeated winch launches. LET is requesting all users submit flight
statistics for further evaluation plus a one time inspection of the load
bearing aft spar cap in the fuselage carry through structure.

I do not know if the L-23 and the L-13 have the same construction for the
aft spar cap.

"Ernst" wrote in message

...



After a fatal accident in Austria LET issued a Mandatory Bulletin:
http://www.let.cz/files/bulletines/M...9a_english.pdf


EASA issued an Emergency Airworthiness Directive:
http://www.caa.co.uk/docs/33/easa_ad_2010_0119_E.pdf- Hide quoted text -


- Show quoted text -


  #5  
Old June 23rd 10, 02:58 PM posted to rec.aviation.soaring
John Smith
external usenet poster
 
Posts: 195
Default L13 Blanik Mandatory Bulletin

Am 23.06.10 04:23, schrieb BT:
Reading the MB, It appears that based on the "flight data" of the
aircraft, and high number of launches per flight hour, the concern is
overstressing from repeated winch launches. LET is requesting all users


Sigh. The urban legend lives.
  #6  
Old June 23rd 10, 03:47 PM posted to rec.aviation.soaring
Bob Kuykendall
external usenet poster
 
Posts: 1,345
Default L13 Blanik Mandatory Bulletin

On Jun 23, 6:58*am, John Smith wrote:
Am 23.06.10 04:23, schrieb BT:

Reading the MB, It appears that based on the "flight data" of the
aircraft, and high number of launches per flight hour, the concern is
overstressing from repeated winch launches. LET is requesting all users


Sigh. The urban legend lives.


Can you please clarify that remark? I don't see any urban legendry
here.

Winch launching inherently load the wings in bending more than
aerotow. Maybe not enough to actually exceed the design load of the
wings. But certainly enough to contribute a substantial amount of
fatigue and to make a measurable difference in long-term service
life.

When fatigue has weakened a structure, and then you apply a load that
exceeds the diminished capacity of that structure, it will fail. You
can say that it was overstressed, or you can say that it wasn't
overstressed and that it just exhibited a fatigue failure. Whatever
you call it, you still have a broken structure.

Thanks, Bob K.
  #7  
Old June 23rd 10, 03:58 PM posted to rec.aviation.soaring
John Smith
external usenet poster
 
Posts: 195
Default L13 Blanik Mandatory Bulletin

Bob Kuykendall wrote:
Can you please clarify that remark? I don't see any urban legendry
here.

Winch launching inherently load the wings in bending more than
aerotow. Maybe not enough to actually exceed the design load of the
wings. But certainly enough to contribute a substantial amount of


Provided the correct weak link is used, the wing load during a winch
launch never exceeds 2g. Each turbulence stresses the structure more
than that. But as I've already said: Urban legends are here to stay.
  #8  
Old June 23rd 10, 04:17 PM posted to rec.aviation.soaring
Derek C
external usenet poster
 
Posts: 114
Default L13 Blanik Mandatory Bulletin

On Jun 23, 3:58*pm, John Smith wrote:
Bob Kuykendall wrote:
Can you please clarify that remark? I don't see any urban legendry
here.


Winch launching inherently load the wings in bending more than
aerotow. Maybe not enough to actually exceed the design load of the
wings. But certainly enough to contribute a substantial amount of


Provided the correct weak link is used, the wing load during a winch
launch never exceeds 2g. Each turbulence stresses the structure more
than that. But as I've already said: Urban legends are here to stay.


Actually the maximum bending load on the wingspar during a winch is
equivalent to about 3 g, due to the point loading on the fuselage and
the lack of g unloading on the wings, but that still shouldn't cause a
failure. I have looked at the newspaper reports on this accident, but
they don't state which phase of flight the glider was in when it broke
up. They say that it crashed into a forest, which sounds as though it
was in free flight, rather on a winch launch when it would have been
over the airfield. Does anyone have any better information?

Derek C
  #9  
Old June 23rd 10, 04:30 PM posted to rec.aviation.soaring
John Smith
external usenet poster
 
Posts: 195
Default L13 Blanik Mandatory Bulletin

Derek C wrote:
failure. I have looked at the newspaper reports on this accident, but
they don't state which phase of flight the glider was in when it broke


To my knowledge, the Blanik was aerotowed to about 1200m AGL, from where
an aerobatics program was flown. The wing broke only after the
aerobatics had been finished. It was too low for the two pilots to bail out.
  #10  
Old June 23rd 10, 06:45 PM posted to rec.aviation.soaring
Bob Kuykendall
external usenet poster
 
Posts: 1,345
Default L13 Blanik Mandatory Bulletin

On Jun 23, 8:17*am, Derek C wrote:

Actually the maximum bending load on the wingspar during a winch is
equivalent to about 3 g, due to the point loading on the fuselage and
the lack of g unloading on the wings, but that still shouldn't cause a
failure...


I think that 3g equivalent load is a large enough percentage of the
limit load to constitute a fatigue concern. If I were assessing
service histories, I would definitely want to know the cycle count on
activities likely to cause that kind of load.

Thanks, Bob K.

 




Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Blanik L-23 Super Blanik Manual -F.C.F.S. Joel Flamenbaum Soaring 2 April 14th 10 03:29 PM
Mandatory ELT [email protected] Soaring 9 March 8th 05 04:01 PM
ELT Mandatory ? Jim Culp Soaring 20 June 19th 04 06:40 PM
New security bulletin gatt Piloting 28 June 9th 04 10:33 PM
Grob 103 bulletin becomes AD Mike Borgelt Soaring 0 October 3rd 03 12:47 AM


All times are GMT +1. The time now is 03:42 PM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 AviationBanter.
The comments are property of their posters.