Wednesday, September 28, 2016

Microbial corrosion?

I was amused to read this Popular Mechanics story (via Foxtrot Alpha): 
Wash your hands, airman!
Credit: Paul Sancya/AP
...But materials specialists at the Air Force Research Laboratory (AFRL) recently have come to realize that organic contaminants—mold, mildew, fungi, bacteria—corrode aircraft surfaces more seriously than they had thought. Corrosion caused by living organisms is generated by moisture, humidity, human contact and by the increasing use of drop-in biofuels, and the microbes they bring with them are for all intents and purposes, eating airplanes. While the Air Force spends approximately $6 billion annually on corrosion issues, up to $1.2 billion of that could be spent on microbiologically-influenced corrosion. 
"Microorganisms can eat away at surface materials, and some of the worst areas affected are tight, hard-to-reach areas that maintainers have difficulty disinfecting," said AFRL Biological Materials and Processing team leader Wendy Goodson.
Apparently simple handling by maintenance staff is enough to transmit bacteria onto the surface of planes. (Gloves?) Also, it's fascinating that biofuels tend to introduce more microbial contamination. David Tracy of Foxtrot Alpha talks about the Air Force's solution:
The process is called the Joint Biological Agent Decontamination System, and it essentially just heats up the aircrafts in an oven to about 180°F to kill bio agents and viruses. According to the Wright-Patterson Airforce Base, the process “eliminates over 99.9 percent of biological contaminants on aircraft surfaces.” Plus, since it kills microbes, the chance of them regrowing is hugely decreased.
So I know 180°F isn't very hot, but doesn't this heat treatment itself introduce aging issues? (Apparently not, if they're deciding to go with it.) 


  1. The only thing I can see aging poorly might be any rubber seals around the cockpit, but there are lots of heat-resistant rubbers that would be fine at that temperature (or higher), and would imagine you'd want to use premium stuff anyway to keep your pilot breathing in case the jet were on fire. The engines get way hotter than that, I'm sure, and the rest of the plane is metal (I think, except the landing gear, but those tires are replaceable).

    I'm far from an Air Force mechanic, however.

  2. I don't know how well the mechanics can work in gloves, though - the tightest places where they would need gloves to avoid contamination might also be the hardest places to work wearing gloves.

    This makes me think of a book my father-in-law has about the alteration of civilization when a group releases a bacterium that eats plastics and oil, and also the end of Andromeda Strain.

  3. I would like to see the ovens they use for the big Bombers!

  4. Disinfectant spray will take care of that! I mean some thing like, glycol spray during icing conditions before the flight takes off!

  5. Corrosion control is a BFD in the military and a lot of time and effort is expended in keeping everything corrosion free. A nuclear powered carrier can create in excess of 400K gallons of freshwater per day and one of first priority for that water is to make sure aircraft are kept salt-free; not an easy task when you're drilling circles in the ocean. Weapon systems are under constant preventative maintenance to keep corrosion at bay.