On 4/7/2013 10:16 AM, son_of_flubber wrote:
On Saturday, April 6, 2013 10:50:52 PM UTC-4, Bill T wrote:
I do not see how you correlate a failure of a wood spar glider with the
potential grounding of metal spar SGS-2-33s. That is a reach.

I do not draw any correlation between the failure of a wood spar glider
with a potential SGS-2-33 failure other than the fact that all gliders are
subject to age, the occasional hard landing, wear and tear, and unevenness
of inspection.

Consider the most hard-landed, abused and/or poorly inspected SGS 2-33 in
use. That's the one that is the most relevant. As time passes this crappy
glider deteriorates more and becomes more likely to fail catastrophically.
No one really knows when/if it will actually fail. We just don't know.
You can't really inspect it completely without taking it apart and if it
fails, the FAA will take some action. Sure, it is engineered and built to
last from the start. But those engineering calculations become less
reliable predictors as the glider accrues unpredictable and unquantifiable
experience and neglect.

A while back, the Australian's tested a couple of Blaniks that had used up
their factory authorized "service life". They took them apart and did all
sorts of inspection and materials testing. On the basis of that
evaluation, they extended the allowable service life of that type in
Australia.

Will that sort of rigorous pre-fatality evaluation ever happen to an SGS
2-33? Probably not. So we are all just keeping our fingers crossed. Are
there hidden problems? Who the heck knows? But everything gets old and
wears out.

My point is not to push a panic button about the 2-33s. I just wanted to
restart the conversation about updating the fleet. The current non-plan is
pathetic, (plus I've gotten tired of reading about stupid narcissistic s--t
on RAS and my glider is still snowed in.)

I'm not an aeronautical engineer and I welcome anyone who can correct me if
I'm wrong about how this is going to unfold over the next ten years.


Heh. It can be painful to have future vision..especially when you're likely to
be correct!

FWIW, this degreed aerospace engineer (wanted to be an aeronautical one, but
the space race of the '60s led to "aeronautical" being "upgraded to aerospace,
in curriculum naming terms), doesn't sense any points of disagreement with
your assessment.

Nor do I disagree with Bill T''s prior point of how *individual* aircraft in
the U.S. are likely to be determined non-airworthy, i.e. "If you maintain your
aircraft, metal or wood spar, make the decision yourself, or the mechanic will
decide for you, when it's time to retire an aircraft.
Not the Feds."

However, should a 2-33 suffer a catastrophic in-flight failure, we've plenty
of FAA history to surmise how they might react...and grounding the fleet is
always a possibility (e.g. L-13, T-34 spar AD, various other older birds with
expensive [effectively, grounding] AD's, etc.).

The U.S. 2-seat glider training fleet is - IMO - definitely ripe for "a
universal upgrade"...which doesn't - in my mind - necessarily mean a wholesale
scrapping of currently flightworthy 2-seaters. Lots of ways to skin cats...and
"capital action" of this nature generally begins with discussion, mental
effort, etc. Keep at it!

Bob W.