Thursday, October 08, 2009

Specialized Substances

I went as directed to a back room to look for a particular can of glue approved for securing loose carpeting to the walls (I only replaced the floor carpeting, because the stuff on the bottom of the walls is fine, just that some of it is loose). I didn't find it at first, but was amused by the very specialized products on the shelves.

  • Deicer conductive cement - I think this is for the strips on the leading edges of electrically heated propellers
  • Spar varnish - I assume it works on wing and tail spars, but don't use it on the ribs?
  • Cessna flap screw and trim tab grease - disaster befalls you if you use it on Piper flaps?
  • a roll of wire labelled "turbine only" - it looked like lockwire. What possible difference could the type of fuel make to wire?
  • a can of ordinary baby powder - I laughed at the incongruity

Oh and here's the broken cable.

14 comments:

Jimmy Mack said...

baby powder... the best thing for putting tubes into tires.

Angus said...

Spar varnish...predates the aeroplane, used on ship's spars.

Critical Alpha said...

Spar varnish is, as Angus said, used on ship's spars and even boats spars.

It's used more generally on exterior surfaces because it has UV protectors in it. In contrast interior varnishes would break down rapidly if used in full sunlight as they don't tend to have the same UV protectors in them.

The question is what situation would require varnish, and in particular spar varnish on or in an aircraft? Maybe it's there for the Tiger Moths.

CA

Angus said...

All wooden components in an aircraft require a protective coating, primarily for waterproofing. I suspect the reason spar varnish usually gets the nod for US aircraft is that it meets a federal specification outlined in the FAA publication AC 43.13.

A Squared said...

Critical alpha wrote: The question is what situation would require varnish, and in particular spar varnish on or in an aircraft?

Aircraft of the Cub/Champ/Taylorcraft sort have a substantial amount of wood. A Citabria, (updated champ) for example has a plywood floor, plywood fuselage formers, wood stringers, and if it is pre American Champion (or hasn't been converted) it has wood wing spars.

The Mudry CAP 10's and CAP 235's (French aerobatic plane) are almost entirely wood.

Most of the wing of a Bellanca Viking is wood.

SwL_Wildcat said...

"I assume it works on wing and tail spars, but don't use it on the ribs?" Since your having fun poking around I will comment that I wouldn't use it on the ribs, I would use this instead...

viennatech said...

mmmmmmm ribs.

Aviatrix said...

SwL_Wildcat: should I use honey-garlic or mesquite?

Kevin said...

The spar varnish is probably for wooden propellers, and as Angus said, other wooden components exposed to air or weather.

Baby powder is often used for tires, but it shouldn't be. There is specific tire/tyre talc which should be used instead. The reason is that baby powder contains compounds to soften widdle babies' bottoms and make them smell nice; these same compounds dry out and ruin tire tubes. Tubes fitted with proper tire talc vs. baby powder will last more than twice as long (on average).

I wonder, Aviatrix: did you find the glass hammer, the bucket of prop wash and the long stand? :-)

Mechanics can be such d*cks at times... ;-)

Kevin said...

Oh, I forgot. Lockwire comes in different thicknesses. Turbine lockwire is thicker than the lockwire we use on piston engines, and is of a different, less stretchy alloy of steel.

Anonymous said...

Interesting... nobody dared comment on the previous post!

Anonymous said...

Interesting... nobody dared comment on the previous post!

Not even anonymously.

I would like to complain all this speculation about the use of baby powder outrages my modesty.

Sarah

(oops!)

Big Steve said...

An interesting one is Swiss Navy Lube....yes there is a Swiss Navy, it patrols Lac Leman (Lake Geneva) and the Bodensee, both of which are sizeable lakes with international borders.

See http://www.swissnavylube.com/. Incidentally, I was driving over a mountain pass in Switzerland and found a a large level area at the top, where the "road" suddenly widened dramatically. I then noticed PAPIs at the roadside and a very large turning straight into a hangar door built into the mountainside! Presumably there are aircraft hangared in there....

Critical Alpha said...

Getting right away from uses for baby powder...

I think the only use that demands the UV protection available in spar varnish (leave aside the regs) is the one suggested by Kevin. Props are out in the sun, they need their sunscreen ;-)

However if I was going to varnish a prop I'd be tempted to use a two pack product. They are much tougher than spar varnish and would be less inclined to be removed by the rain.

I hate it when you can't fly in the rain and many wooden props have that restriction because the rain strips the varnish and then damages the bare wood.

Better go...off to varnish the mast of my boat with...spar varnish.