Thoughts on Daily Assembly and Pre-Flight Routines

The following story I picked off from rec.aviation.soaring -- a near disaster story of a botched assembly which is blamed on interruptions.

My $0.02: Interruptions happen. This cannot be prevented**. My take on the story is that the failure was not caused by an interruption in the assembly routine, but by failure to conduct a proper pre-flight inspection.

All of you new private owners (& 304 pilots) need to understand this: Assembly and Pre-Flight Inspection are two separate, non-interchangeable tasks which may not be done simultaneously. Yes, I inspect as I assemble: I inspect for wear, abuse, insects, etc. I inspect every connection I make as it is made, and I inspect the safeties after they are made. And after the assembly is finished, I do a preflight walk around and look over every single connection again. After all that, I tape.

**All this said, we should probably save the social banter for when we aren't in the middle of safety critical tasks like assembly and pre-flight.

Article Follows:

" 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