assembly interruption a dangerous thing

Uh, that is scary... I've wondered several times while helping to put
together Schempp-Hirth planes, why the heck they've done the wing assembly
the way the have - right, it's easy to do it that way, the wings just sit
there when put into the body, but some day someone would forget the main
spar pin... I think it would be a good idea to always (well, only when the
wings aren't mounted!) let the main spar pin rest on the plane's pilot seat
(back seat on two-seater isn't good enough if it's flown by one person.

A couple of days ago, the danish news paper Politiken brought this very
relevant cartoon: http://politiken.dk/wm/article508875.ece - the text says:
"Erik, I told you to get those wings checked before we went on vacation".


Best regards,

Morten Wartou

"danlj" skrev i meddelelsen
...
Dear List,

From time to time a pilot is broken or totalled because assembly was
in some way incomplete. I'm simply writing to remind us all not to
permit ourselves to be involved in conversation, however well-
intended, during assembly.

This is motivated by the fact that I discovered that the wing root
tape IS sufficient to hold the right wing onto a Ventus when the main
spar pin is not fully engaged. This discovery was sufficiently
humiliating that I have waited for a few days to confess.

The hookups of the Ventus are brain-dead simple and foolproof, except
that the locking pins really do need to be engaged.

Sometimes I have forgotten to pull off the wing-root tape before
trying to remove the wings during disassembly, which has sparked one
of those random fantastical thoughts, "I wonder if the main spar pin
is really needed."

I normally assemble completely alone; one day last week a friend came
along to see the glider and wanted to 'help' assemble, and of course
happens to be one of those wonderfully friendly, fascinating, chatty
types.

During the latter part of the subsequent 2-hour flight, I heard a
faint low rumble from behind, making me wonder if the engine
compartment doors had fully closed.

After I landed, I discovered that the tape over the right wing root
gap was still fully covering the gap, but the gap had widened from the
usual 2mm to about 5 mm. I need hardly tell you the sense of fright
and self-abasement this inspired.

I immediately realized that I had failed to push the main spar pin
'home' - normally the sequence is to put it halfway through (into the
left spar) to hold the left wing in place while the right wing is
installed, then go straightaway and push it home. In this case an
interruption to correct wing-taping being done by my 'assistant'
caused this step to be skipped.

I recall an old suggestion that pilots should wear a red cap as a
signal not to be interrupted. But the signal won't be obeyed until
it's learned. Maybe a more effective device would be to screen-print
words on the front and back of a light vest to be worn during
assembly, perhaps
"DEAF" - or
"Shut up (please)"

But of course the real discipline is with us assemblers, to not permit
interruptions, and to say to the first person who offers to help,
"Yes, you can help by preventing anyone from talking to me until this
is done."

Dan Johnson