I had a feeling it was not going to take long for the feds to solve the riddle of the damaged Chinook helicopter at Boeing.

I wasn’t wrong. Yesterday the feds filed charges against a Boeing production line worker in connection with severed lines discovered on a Chinoook under production at the Ridley plant.

Case closed. Or at least half of it. Still unsolved is the second act of what the feds are calling “deliberate vandalism,” a misplaced washer found in another copter.

Federal investigators say the worker, Matthew Montgomery, 33, of Trevose, admitted to the one act of sabotage. Why is a little more tricky. Montgomery may have been upset with a recent transfer from the Chinook line to working on the V-22 Osprey project.

The $5,000 reward for information remains on the table, and U.S. Attorney Pat Meehan stressed yesterday that this is still very much an open investigation.

Still unsolved is who is responsible for putting the wrong washer inside the transmission of a Chinook that was almost ready to roll off the production line.

Just as I did on the first case, I don’t think it’s going to take long to solve the second part of this riddle, either. You’d be surprised how quickly people start talking when you put $5,000 on the table.

There is also the matter of the other 5,200 workers at the plant. Union officials say their rank-and-file have been extremely upset at the acts of vandalism, which put their livelihoods in jeopardy. They’re proud of the copters they produce, and realize the last thing they want to deal with now is an image issue that could make the Defense Department look elsewhere when it comes to new work.

Stay tuned. My guess is that the other vandal in this case will be flushed out soon.