How to do a Positive Control Check?

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.

ZL wrote:

Do you do a positive control check on the towplane?



Absolutely! Every time I assemble one.


Jack

As long as JJ is confessing, I guess I can, too (especially since
there's already been at least one posting on this subject).

I've been doing solo positive control checks this season. I typically
camp at the airport for a contest and solo rig anyway, often before
anyone else arrives in the morning. I have a two-column printed
checklist. [41 assembly items, 20 cockpit equipment items, 7 task
items, 9 pre-launch items, and my old ABCCCD in-cockpit checklist just
to be sure. In addition to grouping, they're arranged so that I can do
a walkaround inspection in sequence. At the Std. Nats in Cordele this
year, Bif Huss and I compared checklists and I saw he had some
improvements based on his Navy-influenced training that I want to
incorporate.] I check everything off whether or not I have a helper. I
use a pencil so I can come back and pick up any items I skipped but
I'd just as soon not skip anything. Anyway, I lock the stick back and
centered, hard, with the lap belt, then yank/pull on the ailerons and
elevator. Then I release the stick and do several rapid full-
deflection cycles and watch the control surfaces and listen. Same
routine as JJ for the dive brakes. I think I'm safe doing it this way
with my ASW 24 with auto connections everywhere.

If I had an early ASW 20, I'd want to use a trained helper to move
each surface through its full deflection while putting a load on it,
plus some vibration testing. Plus a visual inspection to make certain
all the safety pins or sleeves were properly installed. Plus yanking
on the control rod going into the Hotelier connector itself.
Especially the elevator. Especially the elevator. Especially....

In aviation, as in life, we're all searching for absolute truths. In
the real world, a lot of things are situational or contextual. What's
safe on one glider or for one pilot or in one set of circumstances can
be dangerous when something is different. That's why we try to train
people to use judgment. Unfortunately, some pilots don't or can't seem
to exercise good judgment so we put these rules into place; e.g., the
critical assembly check at U.S. contests, which I voted for as an SSA
director but which I regularly violate by doing it myself (rather than
using a helper) because (1) I use a printed checklist (which has the
CAC items in bold) and (2) I reuse my wing tape multiple times so the
initials are on there every day regardless.

Now I'm really in trouble. But I'm a little frustrated with the
lengthy exchanges on RAS recently where various pilots argue adamantly
at length over their versions of the absolute truth: rules that should
NEVER be broken or that should ALWAYS be observed. Life isn't that
simple. If we were insistent on absolute safety, we'd never fly again.

Chip Bearden
ASW 24 "JB"
USA

Lotsa good stuff in this thread

I have a Nimbus 2C which has eight manual connections - six in the fuselage
and two in the wings. There's also an incredible number of moving
mechanical components comprising an almost incomprehensible monkey motion in
the fuselage and wings. If you move any control, pretty much everything
moves. Although I don't have a lot of experience with the N3 and N4, it
appears they are even more complicated than the N2.

I do the control hookups in overlapping stages. First, I make the outer
wing connections and safety them - then I try to take them apart again by
pulling and twisting on the connection and by pushing on the release tab.
If they fail to come apart, I figure the connection is well made. I do the
same with the six fuselage connections.

But, of course, there's more ways for the control linkage to fail. I
regularly inspect and lubricate all the control system pivot points even if
it takes a flashlight and mirror

With the ship well assembled and lubed, I do the classic positive control
check with me at the control surfaces if the helper is inexperienced or I
may wiggle the stick if the helper knows his job.

I think that a takeoff with one outer aileron connection disconnected and
positive flap would be a certain disaster. Fortunately, negative flaps for
the takeoff roll up to picking up the tailwheel and neutral flap after that
works fine.

Bill D



"ContestID67" wrote in message
...
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

On 4 Jun, 02:13, ContestID67 wrote:

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

Get someone to hold the control surfaces in place. I push the stick, s/
he tells me which way the surface is trying to move.

And I do it after towing to the launch point, to give things a chance
to fall off. At Sutton Bank it used to be mandatory to to a positive
check at the launch point before the first flight of the day, with a
column in the launch log to record this.

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

"BB" wrote

making sure the bolt is in the horizontal stab (Schleicher)

Just as a side note: in newer Schleicher designs the bolt is slightly
modified and cannot be removed from the tailplane. If you don´t fasten the
bolt its head protrudes which is easily detected during a check. Schleicher
published a TM allowing the modification of older designs in the same way.
Material and work required is negligible, it is convenient and a real
benefit in safety.

Just thought some owners might not know...

Michael

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