The Turn of the Screw

I stole the blog title from the 1898 horror novella by Henry James. I never read it, but I did have to read and take a final exam on the same author’s novel Daisy Miller. Not exactly a page turner…And later it was used as the story for a 20th-century English chamber opera composed by Benjamin Britten. I never saw this version either, but I did hear the opera Billy Budd by the same composer. Not a lot of melodies or toe tapping ditties in that one. Puccini and Mozart can make me cry, but all this atonal two hours did for me was bring tears of boredom.

Still a brief lyric from the opera might ring true regarding events in the news:

Do you feel the turn of the screw?
Pushing harder, breaking through
It’s better than you ever knew
Now it gets to take care of you…

…by holding the door plug on an airline fuselage in place

We’ve all seen the pictures of the Alaska Airlines flight that lost its door plug at 16,000 feet, resulting in an explosive decompression. Thankfully no one was hurt and the plane landed safely. The FAA is on the case, and all Boeing 737 Max 9 aircraft are grounded and being inspected.

Preliminary unofficial reports are disturbing. This door plug is secured in place by 4 bolts, and inspectors found loose ones on some of the inspected aircraft. And while the door plug itself was found in a teacher’s back yard, there were no accompanying bolts. Were they loose? Were they even installed at all?

When my dad and I were farming, we had a lot of bolts to tighten, and to my knowledge none ever came loose. We both had a bad habit of ‘making assurance double sure’ and occasionally our brute strength would shear off a bolt or strip the threads. We knew how to use lock washers too, or Loctite for appropriate applications.

Today my bolt tightening is mostly limited to my bikes, and with expensive carbon frames and parts it is a good idea to follow the torque specifications. I have a torque wrench and if the spec says 5 N.m, then 5 N.m it is, and not an N.m more. By the way N.m stands for Newton Meter, which is a measure of torque, as opposed to toque, which is a chef’s hat.

Once my friend Kent brought his bike over to check the torque on some of his parts. The seat post bolt spec was 5 N.m, but the bolt was quite a bit looser than that, maybe 2 N.m. So is that what happened to the airplane door? A creaking seat post is bad enough, but a blown out door plug at 30,000 feet could be catastrophic. Window or aisle…