Sunday, 19 January 2014

Glider Crisis and the Tolerance Loop Hole conspiracy

The Official position on glider mods attached below.  My knee jerk re-action is that the manufacturers can pretty much do as they please using the Tolerance Loop Hole (lets call it the TLH).  Roll on OPEN CLASS!!!!

Dear pilot,

After several meetings, here is the outcome :

Glider Checking

Some of the gliders so far tested have been found to have a trailing edge
longer than that of the glider submitted to Air Turquoise for certification.
As far as the PWCA can determine, this measurement is not specifically
mentioned in the EN norm and no tolerance is provided. In emails reproduced
below, both Alain Zoller and Harry Buntz confirm this. Alain also states that
it may not be possible to determine whether the glider conforms to
certification without further flight testing.

The PWCA is not a testing house and is not professionally qualified to
determine whether a particular glider is certified or not. Therefore there is
no option other than to continue the competition as normal, but to keep the
results provisional. The top ranked gliders from the three top manufacturers
will then be sent to the relevant testing house to verify whether they are
certified in their current configuration.

Alain Zoller Email:

That is tricky to answer, I'll say:
to have better idea of the real differences you have to compare the
measurement btw official user's manual from manufaturers, our measurement and
what you measured on the physical glider. Even check few gliders to be sure
about the production.

The consequences of such of difference can really make the glider out of the
certification, not really through the standards because I just realised is no
tolerance at all for these kind of measurements.

What is difficult to know if the tension of the glider in flight will make
the difference for to call the glider certified. I guess only the flight test
can actually show if the physcal glider have the   same behaviour as the
certified one.

My personnal point of view, this glider doesn't fit the sample how was

Harry Buntz Email:

we normally store only the tested samples. We do not measure the trailing and
leading edge in certification procedure. We store the glider as a sample that
we can compare it if there are problems, like now.

You have to ask the manufacturer which are the tolerances of the wingspans,
while we do not have anything to compare.

We could test flight the wings with different wingspans to tell you the
For sure there will be a small difference in the span, but we are not the
specialist of production tolerances.

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