PCC Presentation

Jim Vincent wrote:
(DG's) have an elevator pushrod that
terminates in a 'C' shaped fitting. A roller bearing on the elevator fits
snugly into the open 'C', a reliable automatic hookup but does need
attention at assembly time.


Wrong there, my friend. The standard Cirrus accident where the elevator
disconnected failed because the pushrod did not catch in the "C". Admittingly,
it is very difficult to make it happen, but it can and did. Had he done a
proper inspection, he would have caught it. This is proven by tests Tom Knauff
did on a standard Cirrus. After much effort, he was able to invoke the failure
mode.

After the glider is assembled, and before the pilot does the PCC,
doesn't he walk around the glider and inspect the control surfaces and
move them through their full deflections, in addition to other
inspections? Isn't the improperly assembled elevator noticable during
this inspection?

When the Std Cirrus elevator is connected improperly in this fashion,
isn't the front of the elevator quite high and easily visible to pilot
standing near the cockpit while doing the PCC?

It's been a long time since I've had my Std Cirrus, but I think a pilot
that does a proper inspection has as least 3 chances (including looking
in the little window right after assembly) to notice an improperly
assembled elevator without the need to be at the control surfaces during
the PCC.

I'm with Ramy on this one: keep it simple. This one unfortunate case is
not a good argument for everyone to have the pilot at the control
surfaces during the PCC.

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Eric Greenwell
Washington State
USA

After the glider is assembled, and before the pilot does the PCC,
doesn't he walk around the glider and inspect the control surfaces and
move them through their full deflections, in addition to other
inspections? Isn't the improperly assembled elevator noticable during
this inspection?


Apparently not. A Twin DG at out club has a small storyboard attached to the
top of the fin leaving no doubt in the riggers mind exactly how , where and
when to put things when rigging. I helped with the stab assembly once and
when it didn't go together easily. I suggested the pilot read the list on
the tail, we removed and refitted the stab discovering in the process that
it had gone together wrong first time round! Everything worked OK but the
travels were all out of kilter.

Ian

Eric Greenwell wrote in message ...
Jim Vincent wrote:
(DG's) have an elevator pushrod that
terminates in a 'C' shaped fitting. A roller bearing on the elevator fits
snugly into the open 'C', a reliable automatic hookup but does need
attention at assembly time.


Wrong there, my friend. The standard Cirrus accident where the elevator
disconnected failed because the pushrod did not catch in the "C". Admittingly,
it is very difficult to make it happen, but it can and did. Had he done a
proper inspection, he would have caught it. This is proven by tests Tom Knauff
did on a standard Cirrus. After much effort, he was able to invoke the failure
mode.

After the glider is assembled, and before the pilot does the PCC,
doesn't he walk around the glider and inspect the control surfaces and
move them through their full deflections, in addition to other
inspections? Isn't the improperly assembled elevator noticable during
this inspection?


Eric,

I did misassemble my Std. Cirrus tailplane once. Just once.
The person that showed me how to assemble didn't know that it could go
together wrong. I guess I didn't either, until I did it.

When the Std Cirrus elevator is connected improperly in this fashion,
isn't the front of the elevator quite high and easily visible to pilot
standing near the cockpit while doing the PCC?


Not if the pilot is sitting in the ship!! And the trim is all the way
forward to ease assembly, so the tailplane is normally high at this
point anyway.

It's been a long time since I've had my Std Cirrus, but I think a pilot
that does a proper inspection has as least 3 chances (including looking
in the little window right after assembly) to notice an improperly
assembled elevator without the need to be at the control surfaces during
the PCC.

The window gets dirty easily and is not very big. It should be cleaned
every year (at least) at annual time. Even then, the plastic yellows,
and it is dark in there

I'm with Ramy on this one: keep it simple. This one unfortunate case is
not a good argument for everyone to have the pilot at the control
surfaces during the PCC.

My misassembly was caught at the PCC stage. I have since changed my
assembly procedure to recheck two different ways for tailplane
assembly immediately after installing the tailplane. The manual says
to look for the hook through the little window. But, the most obvious
way is to examine the range of motion of the tailplane for correct,
full travel. The PCC catches it also, with some obvious banging.

After assembly, I corral someone and teach them how to do a Critical
Assembly Check on my ship (and offer to do theirs!). There is actually
a Critical Assembly Checklist in the manual. Then of course I tell
them all the ways the tailplane will look wrong when not put together
correctly. Then we do a PCC. Then I feel like I have a properly
assembled ship.

There are many ways improper assemblies can be caught, I like to use
as many as possible to decrease the odds that any mistakes I make get
through.

Assembly (me)
Check each system after assembled, wing pin & safety pin, spoiler
l'Hotelliers and safety pins, ailerons and safety pins, tailplane.
(me)
Critical Assembly Check (someone else)
Positive Control Check (someone else with me)

Regards,
John Gilbert
Std. Cirrus s/n 266 PY
Seattle, WA, USA