Aviation From My Rocking Chair: What’s This Gray and Orange Stuff?

Hello again, gang. This month I’d like to start with a little problem, and then preach AC43.13-1b a bit. (We all remember 43.13-1b, don’t we?)

Suppose for a moment you are tired of wheels, and decide to install floats on the old “Whiz-bang 150”. You happily fly for 6 months or so, until one day to your utter horror, the above-mentioned airplane has just added to the worlds bauxite supply. What went wrong? Welllll… the answer can be found…where? That’s right; Chap.6, section 13 of AC43.13-1b! Titled “Corrosion proofing of land planes converted to sea planes,” it lists two classes of corrosion-proofing standards: Necessary minimum precautions, and Recommended precautions. Just for drill, let’s go through these, starting with:

(1) Necessary Minimum Precautions - These procedures are considered minimum to safeguard the airworthiness of converted aircraft and are not in themselves intended to maintain them for an indefinite period. a) Treat exposed fittings or fittings that can be reached through inspection openings with 2 coats of Zinc Chromate, Paralketone, non-water soluble heavy grease, or comparable materials. b) Coat non-stainless control cables with grease or Paralketone if not replace with corrosion-resistant cables.

c) Inspect accessible aircraft structure. Clean structural parts showing corrosion and refinish if attack is superficial. If corrosion is severe, replace part with corrosion-proofed one. (2) Recommended Precautions - Are those which are suggested as a means of maintaining such aircraft over extended periods.

a) Provide additional inspection openings to help detect corrosion, especially in the lower/rear part of the fuselage.

b) Install additional provisions for free drainage and ventilation of all interior surfaces (i.e. Seaplane grommets, etc.)

c) On fabric covered aircraft, slit fabric longitudinally on fuselage lower surface and tail for access. Coat lower structural members with 2 of Zinc Chromate primer, followed by 1 coat of dope-proof paint, and rejoin fabric. This precaution should be done within a few months after starting sea plane operations. d) Protect the interior of structural steel tubing by air and water tight, or hot linseed oil and plugging openings.

e) Spray interior of metal covered wings and fuselages with an adherent corrosion inhibitor. f) Place bags of Potassium or Sodium Dichromate in the bottom of floats or boat hulls to inhibit corrosion. g) Prevent the entry of water by sealing as completely as possible, all openings in wings, fuselage, control surfaces, control cable openings, etc.

As this excerpt shows, there is just a wealth of information in this book. Whether you need rivet spacing data, welding repairs, wood repairs, composite repairs, weight and balance or windshield repair/installation help, you can find it here. Do yourself a favor and add AC43.13-1b and 2a to your library soon. O.K., Troopers. My mind and my backside are numb, so y’all need to take it from here. Enjoy the Fall Leaf Extravaganza.

Rick Vaux TC4130