Sunday, January 15, 2006

Aluminum Cans versus Plastic Bottles

Airbus is trying to stem the flow of sales going to Boeing, by bashing the B787's all-composite airframe. Not literally, by driving a catering truck into it, but by questioning what would happen if someone did drive a catering truck into it--and maybe even didn't report it. Aluminum (or "aluminium" as my British readers insist on calling it) dents and tears on impact, while a composite could potentially accumulate invisible damage until it shatters, like an Airbus rudder.

I'm thinking of the plastic or composite components on airplanes I have flown. Many use plastic for cosmetic details in the interior, and those are prone to cracking and embrittlement. The main structural elements of all the airplanes I have flown have been aluminum (or wood and steel wires if you want to count some of the sketchier non-commercial aircraft I've decided to pilot), but many have exterior fairings made out of plastic. And I can't think of a single plastic component that I haven't flown around knowing was cracked. I remember being questioned by a Transport Canada safety inspector who wanted to know why our wing strut was wrapped in duct tape. We were able to show him a properly formatted, signed and stamped logbook entry documenting the "temporary fairing repair" effected by our maintenance department. And this was a commercial passenger airplane.

It's not really duct tape, it's speed tape a similar silvery-grey sticky tape that I'm sure costs at least ten times as much. I've done a field repair myself, using speed tape for temporary damage control.

Comparing the plastic components on airplanes as old as I am to the all-composite airframe of the new 787s is a bit like saying "Metal? They make airplanes out of metal? My car is made out of metal and it fell apart after five years of winter driving!"

Looks like duct tape, but isn't. Sounds like plastic, but isn't. Different kinds of metals ... I'm a pilot, not a materials scientist. But if you're looking for a career in aviation maintenance, I'm thinking that experienced non-destructive testing technicians are going to be in high demand before too long. Also you don't have to wield a rivet gun.

5 comments:

Lord Hutton said...

Are you a Yank???? Aluminum. Gah!
It does make you wonder what bodges are carried out though.

Greybeard said...

Yes, aluminum!
(Shorter, more efficient word for the same material!

Composites have been used on rotor blades for years, and the French were the pioneers there. They are by FAR stronger than the aluminium (Gah?) rotors I had been flying under!

Composite rotors actually get stronger as they age. I'll take one any day, thank you.

Aviatrix said...

Read the top, Lord Hutton. I'm Canadian. Our lexicon is unique in the world, but Microsoft will not believe us. There is no spellchecker that won't flag "organized labour" -- the correct Canadian spelling.

dph said...

Aluminum, Aluminium... interesting discussion not at all related to the original post.

Here is the real story as I understand it:
-It was named Aluminium originally but changed officially to aluminum to relfect latin root. The same year the discoverer named made it 'aluminum', someone (anonymous) wrote into a journal and said 'ium' sounds better (ie: more impressive).
-Was aluminium everywhere until a spelling mistake (one version I have heard) in what was to become a dominant product in north america changed it back to Aluminum (which incidently fits well with platinum, molybdenum a point that the aluminium adherents seem to forget).

-In canada, both spellings are common, in the US Aluminium is rare, and

-I was reading someone who felt that the more militant insistance on aluminium was an example of anti-americanism in other english speaking parts of the world.

Yes, I really do need to get a life.

dph said...

I feel I should follow-up and point out that being Canadian rocks.

Where else can you have a colourful story about changing a tire on your way to buy a two-four of brew and why you were glad to have your toque cause it was cold out and you just finished playing shinny.