How to do a Positive Control Check?

wrote:
For ships with *auto hookups* positive control checks are a waste of
time, and in fact do more harm then good. I have never heard of a

PCC should also cover whether the stabilizer is actually bolted on and
bolted all the way. Good luck flying a glider with stabilizer
flapping up and down, regardless of whether it has auto hookup or
manual. Reminds me of the discussion about the wing pins being in
all the way.

Do you do a positive control check on the towplane? I mean the 2-man
yank on the controls from both ends check. Not the normal pre-flight
walk around, controls free and correct check.

Probably not.

The critical assembly check (everything critical installed, tightened,
saftied, etc. tailored to the specific glider) makes sense as does the
normal pre-flight. I'm not sure the positive control check does.

What's the fundamental difference between the towplane's controls and a
properly assembled glider's controls?

Do you really know how much load is safe to apply to a control surface?
Is it in your operators manual? Airloads on modern tiny control surfaces
can be quite small in comparison to what an enthusiastic human hand can
apply. Is your control system designed for airloads or positive control
check loads? Are you sure you can tell if you pushed too hard?

-Dave

On Jun 4, 5:23*pm, ZL wrote:

What's the fundamental difference between the towplane's controls and a
properly assembled glider's controls?

The fundamental difference is that the tow-plane isn't being
disassembled and reassembled all the time. And the tow-planes control
systems aren't designed with disassembly in mind; whereas a glider's
are. It creates some fundamental differences in the engineering...

Do you really know how much load is safe to apply to a control surface?

Ok, so let me get this straight - you'd rather risk your LIFE (and the
lives of those around you) instead of risking damage to your control
surface?

Common sense should work for figuring out how to do the PCC without
damage, just as common sense should encourage us to DO a PCC in the
first place.

--Noel

On Jun 4, 5:23*pm, ZL wrote:

Do you really know how much load is safe to apply to a control surface?
Is it in your operators manual? Airloads on modern tiny control surfaces
can be quite small in comparison to what an enthusiastic human hand can
apply...

Actually, it's not that hard to reverse-engineer estimated maximum
hinge moments from (rho*v^2)/2 and the suggested loading schedules in
the old FAA pub "Basic Glider Criteria." The total forces can be
pretty great, especially the accumulated torsion for something like a
c*.17, 2-drive full-span flaperon like yours.

As you observe, the maximum hinge moment and normal loading on
something like your LS6 elevator is pretty small. However, JAR22 and
FAR23 both require a fair bit of margin over the flight loads. They
also specify some pretty hefty minimum input loads between the control
stick and the stops, though by the looks of the European marques they
tend to weasel out of the default input forces with the "unless lower
can be rationally justified" clause.

Thanks, Bob K.

Guys you are missing the point! There is a difference between a
Critical Assembly Check and a Positive Control Check. A PCC would NOT
have helped Clem. With the elevator connecting bolt taped over, the
glider would have most likely passed the PCC! I am all in favor of
doing the Critical Assembly Check. I always do mine twice, first after
rigging, second before launch. Of all of the accidents described, most
would have been avoided by doing a proper CAC, not PCC!

On Jun 4, 8:56*am, Andreas Maurer wrote:
On Tue, 3 Jun 2008 19:43:51 -0700 (PDT), wrote:
Please name one accident of a glider with auto hookups that could have
been prevented by a positive control check. I sure don't know any. A
seized bearing will be detected by simply moving the stick. In all
gliders I know there is no scenario of control failure that would
necessitate a positive control check for detection.

There have been SEVERAL incidents and accidents of DG gliders where
the automatic hookup of the elevator was not connected correctly.

Not to mention several (unfortunately usually fatal) crashes of
gliders where the auto hookups were connected correctly, but the
horizontal tail was not. Ernst-Gernot Peter and Clem Bowman come to my
mind...

You are making a slippery slope argument. Should we mandate annual
stress tests of wings in the name of safety? Overhaul all tost
releases every 100 cycles?

Nope... but to do a simple 2 minute check before the flight...

Bye
Andreas

On 4 Jun, 20:27, "noel.wade" wrote:
On Jun 3, 7:18*pm, wrote:

After all, he's going to be the one in trouble if he's wrong. But it

Let's tackle that statement once and for all, shall we?

I know this wasn't Ian's main point in his post - but its important to
mull this over before you think that "its OK becuase I'm the one who
will pay if I screw up". *You can't be that certain.

OK, I will happily amend that to "He's the one person who will
certainly be in trouble if he screws up..."

P.S. *Contrary to popular belief, its possible to be safe AND still
have a ton of fun. *Being safe doesn't mean being nasty or boring - it
just means taking 5 minutes to be responsible!

Of course. That's why I do positive control checks. But one of the
best ways to reduce safety is to make checks and routines /too/
automatic. I think it is much better to have people follow routines
they've thought about than follow a checklist blindly.

I think, for example, of all the pilots trained by BGA instructors in
K21s (or K13s or Bocians or ...) to say
"...strapstightinstrumentsoknoflapsfittedcanopyclo sed..." pre take-off
or
"windslightlycrossfromtherightundercarriagefixeddo wnspeedappropriate ...."
while downwind.

Ian

On Jun 3, 8:13 pm, ContestID67 wrote:
A recent accident (disconnected aileron) got me thinking about
positive control checks. I searched the RAS archives and didn't find
any details on how people do this.

I was trained by my CFIG, like most of you I hope, to do a positive
control check every day. Actually it was more like it was drilled
into me. This was even done on club ships that remain assembled for
the season.

As a beginning pilot I would sit in the cockpit and move the controls
as someone more experienced put their hands on the flight surfaces.
Later I found that anyone can handle the controls, it's the hands on
the surfaces that was much more telling if things were connected
properly or not. My ship does not have automatic hookups so this is
especially important to me.

I got into the habit of having my assistant move the control one way,
then the other, then back again with full deflection. All the while I
was putting pressure on the surface and, at the same time, wiggling
the surface to simulate take off vibration. So far, no incidents,
knock on wood.

So, the question is, how do *YOU* do your positive control check?

John "67" DeRosa

John,

Your topic is an old favorite of mine. When starting glider flying in
this country many years ago I was appalled by the way positive control
checks were done. The pilot was in the cockpit, in line for getting
towed and a more or less hapless assistant was asked to lock a
particular control surface or the airbrakes with their hands. The
pilot would then bang the stick around and declare the airplane safe
for flight (leaving the assistant with pinched and bruised fingers).
You already described well a better way to do this. Put the assistant
into the cockpit, yes, sitting in it, not just standing outside. Have
her move control surfaces on your command, slowly and deliberately.
The pilot will put pressure on those surfaces simulating in-flight
forces around the center position but also test full deflections.
Walking around the glider doing this also allows for a full assembly
check, looking for mylar seals, hinge conditions, gap tape, tire
inflation etc.
My wife and I have done this for many years with me calling out the
control movements (in German) and her repeating them and executing.
It's been a source for amusement for many bystanders but I believe it
kept me safe.
Now, I can teach you to do this in German (with a Colonel Klink voice)
but that's not really necessary...

Herb, J7

Now, I can teach you to do this in German (with a Colonel Klink voice)
but that's not really necessary...

Herb, J7-

Please, Herb! That would make it much more fun.

More seriously, missing in much of this discussion is the approach
that US contests have taken to this whole question. We don't call it a
"posiitve control" check, we call it a "critical assembly" check.
Whatever you think of the value of pushing around control surfaces on
gliders with automatic hookups, "critical assembly" includes making
sure the bolt is in the horizontal stab (Schleicher) or stub pushed in
(Schempp), the mylar isn't falling off the tail, the main pins are in
and locked.

John Cochrane

My wife and I have done this for many years with me calling out the
control movements

Just had a terrible thought, check out this scenario.........

My whife doesn't come to the airport much anymore, so I ask the pretty
little thing who's been interrupting my assembly to help with a
control check. She says sure and jumps in the cockpit (like Herb
recommends). We go through the left aileron, left spoiler, elevator,
right spoiler, right aileron...................she hasn't missed a
beat. Then I say, Oh I forgot the flaps. Which one of these handles
does that, she asks sweetly? It's that little black one down on the
left side.................BAM the ships alams to the ramp as the
landing gear retracts!

Errrrrr, the OTHER little black handle down there on your left!!!!

Here's how I handle the control check (solo for above reasons) I have
automatic hook-ups.

I assemble with the aileron control locks in place. When she's
together, I attach a stiff bungee from the stick to the left rudder
pedal, which keeps the stick full forward and rudder full left. Then I
move out to the left aileron, remove the control lock and try to move
the aileron. If I can't move the aileron, it's connected. I then
replace the control lock and try the same thing with the right
aileron, If I can't move it, it's hooked up also. Next I pull full
spoilers and check to see they're both wide open and that the wheel
brake is locked. Then I close and lock the spoilers and check to see
that both spoiler caps are down and flush, indicating ther're hooked
up. Then I go to the rear and try to move the elevator and rudder. If
I can't move them, ther're hooked up also.
JJ
PS, I have seen a pilot retract the gear when asked to do a control
check.........it can happen!

JJ Sinclair wrote:
....
PS, I have seen a pilot retract the gear when asked to do a control
check.........it can happen!

Interesting, thanks for that detail. I've always wondered if it's possible to retract the gear
with weight on the wheel - that is, on the ground. One'd think it possible to design an over-center
mechanism that would make that impossible, or at least *really* hard to do.
But it is experiment I've never been willing to try.

Sarah

On Jun 5, 7:54*pm, Sarah Anderson wrote:
JJ Sinclair wrote:

...

PS, I have seen a pilot retract the gear when asked to do a control
check.........it can happen!

Interesting, thanks for that detail. *I've always wondered if it's possible to retract the gear
with weight on the wheel - that is, on the ground. * One'd think it possible to design an over-center
mechanism that would make that impossible, or at least *really* hard to do..
But it is experiment I've never been willing to try.

Sarah

I have tried it. With the plane assembled, but still in the 'cradle',
extend the undercarriage, then lower the cradle until the weight is
all on the wheel, but it can only drop an inch (or less). Get in, and
try to retract the gear. In the Speed Astir, I can't do it with a
very firm pull on the gear handle.