DO YOUR CONTOL CHECKS!

Mark James Boyd wrote: [snip] " . . . during a PCC a bellcrank broke and
this was caused by the pressure exerted by the "helper."
Nice to have this happen on the ground, and I can't
think of how this could have been detected without
a PCC. So now I think a PCC is useful too..."

Having a helper exert this much force is good???

I retain my renegade attitude to PCC's - they may be suitable for some
things if done right (and breaking gliders is not doing it right in my
book - the above is not an isolated example) but other checks are far
more useful, and less damaging, for some gliders, e.g. my Ka6E.

Chris N.

I'm going to guess that the 10,000 repetitions of
opening and closing the dive brakes were what really caused the
bellcrank problem in this case. On the other hand, I'm
not a dig fan of manhandling and potentially
deforming the spoilers on the glass ships either.
If I was smarter and I owned my own ship, I'd
likely investigate the best places to apply pressure which
would't damage anything even when repeated 10000 times...

In article ,
Chris Nicholas wrote:
Mark James Boyd wrote: [snip] " . . . during a PCC a bellcrank broke and
this was caused by the pressure exerted by the "helper."
Nice to have this happen on the ground, and I can't
think of how this could have been detected without
a PCC. So now I think a PCC is useful too..."

Having a helper exert this much force is good???

How much is too much? There's really no manual for this, and
the POH doesn't even mention PCC... This area could
use a bit of advice from sailplane manufacturers/materials
engineers...


I retain my renegade attitude to PCC's - they may be suitable for some
things if done right (and breaking gliders is not doing it right in my
book - the above is not an isolated example) but other checks are far
more useful, and less damaging, for some gliders, e.g. my Ka6E.
--

------------+
Mark Boyd
Avenal, California, USA

A Positive Control Check is a means to an end, not an end in itself.

What is required is a Critical Assembly Check, of which the PCC may form a
part.

It is not possible to do a CAC unless the way the particular glider is
rigged is understood, and there may be variations between different versions
of the same type of glider, e.g. the elevator control connection on the
ASK21.

I know of several cases where gliders have flown mis-rigged and got away
with it, e.g.:
K13 with the drag spar pins not in safety.
K21 with the drag spar pins missing.
K13 with the aileron and brake safety pins missing (discovered when one
aileron disconnected itself while flying).
ASW20 with the elevator bolt missing.
ASW24 with the elevator bolt missing.

All these things happened to people I know, none of them would have been
found by a PCC, indeed in many cases a PCC was done.

Of course, there have been many cases where the pilot did not get away with
it.

I also know one club with several K23s, where the elevator control is
automatic when the tailplane is rigged. After PCCs were made compulsory at
that club, at the subsequent annual inspection damage was found to several
elevators almost certainly caused by too much force during the PCC.

I am sure the method of PCC recommended by Jim Vincent is correct, (posting
5th April 04.53 above), and his presentation
http://www.mymedtrans.com/personal.htm looks ideal to me. However this is
only part of a Critical Assembly Check, and if that is done properly the PCC
is not the most important part.

I am sure that a PCC should be done with the pilot at the control surfaces,
and the helper at the cockpit controls.

When Hotelier connections were first used it was not considered necessary
to use safety pins, indeed some were provided with check holes so small that
the use of pins was not possible.

It was subsequently found that it was possible for Hoteliers to come undone
UNDER NORMAL FLIGHT LOADS, and EVEN WHEN CORRECTLY RIGGED. This was why
the use of locking wire, pins or some other safety device was made
compulsory, and those connectors manufactured with small holes had to have
them drilled larger.

W.J. (Bill) Dean (U.K.).
Remove "ic" to reply.


"Chris Nicholas" wrote in message
...

Mark James Boyd wrote: [snip]
" . . . during a PCC a bellcrank broke and this was caused by the pressure
exerted by the "helper."
Nice to have this happen on the ground, and I can't
think of how this could have been detected without
a PCC. So now I think a PCC is useful too..."

Having a helper exert this much force is good???

I retain my renegade attitude to PCC's - they may be suitable for some
things if done right (and breaking gliders is not doing it right in my
book - the above is not an isolated example) but other checks are far
more useful, and less damaging, for some gliders, e.g. my Ka6E.

Chris N.

Bill,

I'm under the impression that you haven't looked at the presentation and are
just evaluating it based on the title itself..if you have, my apologies.

Some points I would like to make:

What is required is a Critical Assembly Check, of which the PCC may form a
part

I fully agree with you. Not only is a PCC and CAC needed, but also takeoff
checklists and landing checklists. The presentation does cover the
requirements to do a PCC, CAC, as well as L'Hotelier connectors, the
requirement for pins or LH connectors, preflight checks, landing checks....you
get the picture.

After PCCs were made compulsory at
that club, at the subsequent annual inspection damage was found to several
elevators almost certainly caused by too much force during the PCC.

In addition, regarding avoiding damage to gliders, it does have a detail slide
adressing this, points mentioned he

* Don’t bang stick or control surfaces against the stops
* Use light pressure on control surface… perhaps equal to weight of forearm
* Control surfaces and trailing edges are damaged easily…apply pressure with
open hand to avoid point loads
* Apply pressure at control surface strong point…typically near pushrod
attach point
* For elevator, one hand on left elevator, one hand on right elevator
* For spoilers, hold by spoiler plate, not spoiler cap…be careful of your
fingers

Regards!







Jim Vincent
CFIG
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