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Q-talk 11 - ODDS and ENDS


THE AVIATION CONSUMER has had this to say: "There's no doubt among knowledgeable firefighters as to the value of using Halon -any kind- to fight an aircraft fire (but) the particular formulation is...far less important than the size of the extinguisher...we are not convinced Halonite is really any better than 1211 or 1301...We'd feel a bit more confident using the less toxic 1301 in a small-aircraft cockpit."

Mike Conlin sent a company Material Data Safety Sheet which advises that small chips, fine turnings and dust created from working with aluminum may ignite readily and that halogen acids and sodium hydroxide in contact with such finely divided aluminum may generate explosive mixtures of hydrogen. So...? Did you ever think that just behind the firewall you might have just such small chips in the creases? Get the ol' vacuum out boys.

Sam Hoskins got a data sheet from a local fire extinguisher shop. Part of what it says: "When Halon 1211 is discharged onto a fire, it decomposes above 900 degrees F releasing bromide ions, the extinguishing agent." Halogen compounds such as halogen acids are formed. These are harmful if inhaled but are easily detected by an unpleasant, acrid odor. Vacate or ventilate as soon as possible. In susceptible individuals, cardiac sensitization to circulating epinephrine compounds can result in potentially fatal heart arrhythmias.

It seems to me that nothing is perfect, even Halon, but don't let a minimal risk cause you to choose frying in a fire as a better alternative...you won't be pleased with your decision.

Now here's an UNUSUAL item from KITPLANES' October issue, unusual enough to get 2 full pages of space. Rex Taylor admirably handled a builder's in-flight crankshaft failure of one of his new 82 hp Magnum Plus engines by not only an immediate teardown inspection of his own prototype but by quickly sending out a certified mail factory airworthiness directive to the other 13 owners of the type: "The new prop hub and machine work to the crankcase will be provided by HAPI (Engines) at no cost to you for parts or labor..."

I'm happy HAPI took this quick and responsible action and I'll be just as happy as a pig in mud when such quick and reasonable action becomes standard operating practice for all sportplane kit/parts suppliers.

From Max Kroll/Jim Casey, St. Paul, MN

We've found a feather fill called Awl-Fair from U.S. Paint. It's a 2 part, 1:1 mix that takes a day or two to set up (temp. dependent) but it sands well and sticks to the epoxy like crazy. It doesn't seem to get as brittle as some of the other material I've seen, therefore, you shouldn't see the cracks in the flex paints. It works best when used with a hair dryer to keep it from pulling.

Tom Moore wrote Michael Engineering Company about rebuilding his Sticky Stuff Dispenser. ME responded with a parts list for a rebuild kit they offer for $32.30 or $48.30 if new intake valves are desired. A note said "...some have had success with hot water on hardener or a propane torch to heat and then scrape off partially cured material. There are chemical strippers that eat the metal - then the epoxy falls off...intake valves...are generally OK if cleaned a little." Michael Engineering Company, 4997 S .Crawford Road, Mt. Pleasant, MI 48858.

Mike Conlin of Conroe, TX is a constant and keen-eyed reader of catalogs and technical journals. Somewhere in his house he keeps a stash of clippings and scratchings that he sends to me when it gets high enough. Here's some of what he's found of interest:

1. Available in October from Radio Shack is a $49.95 hi-accuracy compass as an accessory for your car. "Flux Gate Technology Similar to That Used in Jet Airliners, " trumpets the ad. Approx. 2x3x3, it looks similar to a Hamilton card compass.

2. This write-up on Cleveland brakes in LIGHT PLANE MAINTENANCE also has application to the Rosenhans: "A non-floating caliper is bad for 2 reasons. Number one, braking effectiveness is lessened, because only the piston-side brake pad is applying pressure to the disc - the "back plate" pad is not snuggling up (by equal and opposite reaction) against the other side of the disc - (Newton's law only works if the anchor pins are sliding freely in and out.) Number two, huge bending forces are applied to the root of each anchor pin when you step on the brake and force the piston out against the pad and disc. In other words, the pressure of the piston causes the whole brake to want to cock over against the anchor pins. If the pins were free to slide, this wouldn't happen." You should "Periodically aim a blast of dry-slide (not oil or WD-40; they'll only attract dirt) at the anchor pins on walk around," to decrease chances that the pins may rust up and freeze in one place, rendering the caliper NON-floating. Add this to your pre-flight check.

You can order a PDF or printed copy of Q-talk #11 by using the Q-talk Back Issue Order Page.