Preparations for Painting

From Bondline
Jump to: navigation, search

Introduction

Is your paint job the original from the mid-70's? Don't have the minimum of $12,000 (2007 dollars) to take your Grumman to a paint shop? Then consider doing the grunt work yourself. As any good painter will tell you, painting is all about the prep work. The prep work is something most people can do on their own because it does not involve a whole lot of skill. It's mostly about time and patience, but there are a few areas where you need to use the right tool and/or practice first. Whether to paint it yourself is another question. If you have never shot paint before, seriously consider paying someone to do this part of the job unless you have a serious learning bug and are willing to practice a lot before even touching your plane. Shooting the paint is the least expensive part of the whole process.

Preparing a Grumman for painting really involves only one more step than a plane that is riveted together. This step is the protection of the bondlines with aluminum/foil tape if using chemical stripper. That's all that's different. Really! However, all of the steps are discussed and illustrated with actual Grumman pictures.

Key Steps in the Preparation Process

There are six basic steps in preparing your plane for painting.

  1. Stripping the Paint
  2. Repair Work
  3. Metal Conditioning
  4. Prime
  5. Body Filler
  6. Paint

In the past, one would normally do any filling work before priming. However, the current thinking is to do the filling work after priming, at least for aircraft structures. Since sanding is required on the filler and aluminum is a soft metal and we often work on thin sheets, it is easy to damage the skin during the sanding process and not notice it. By priming first, the primer gives you an indication about how far you've gone and how aggressive you've been. Here's a quote from Larry Matteo:

If you have no previous experience working on aluminum and you're planning on doing this yourself or with some others not trained in aluminum painting processes, I'd strongly suggest you do a little practice on something other than your plane. In my 5 years with Grumman supervising the paint shop, I've seen even experienced painters cause oil canning due to improper sanding, even by hand. I've seen several holes sanded in wings, ailerons and elevators. It don't work the same as a car body panel or a boat hull. It is an entirely different animal.

Tail Numbers

When thinking about the layout for a new paint job, consider using 2 inch tail numbers if your aircraft was manufactured at least 30 years ago. 14 CFR 45.22(b) and Advisory Circular 45-2C both specify that antique aircraft (defined as manufactured at least 30 years ago) may use 2 inch tail numbers.

(b) A small U.S.-registered aircraft built at least 30 years ago or a U.S.-registered aircraft for which an experimental certificate has been issued under §21.191(d) or 21.191(g) for operation as an exhibition aircraft or as an amateur-built aircraft and which has the same external configuration as an aircraft built at least 30 years ago may be operated without displaying marks in accordance with §§45.21 and 45.23 through 45.33 if:

(1) It displays in accordance with §45.21(c) marks at least 2 inches high on each side of the fuselage or vertical tail surface consisting of the Roman capital letter “N” followed by:

(i) The U.S. registration number of the aircraft; or

(ii) The symbol appropriate to the airworthiness certificate of the aircraft (“C”, standard; “R”, restricted; “L”, limited; or “X”, experimental) followed by the U.S. registration number of the aircraft; and

(2) It displays no other mark that begins with the letter “N” anywhere on the aircraft, unless it is the same mark that is displayed under paragraph (b)(1) of this section.

14 CFR 45.25 discusses the allowable locations for the markings. The smaller 2 inch markings are permitted to be placed on both sides of the vertical, and it seems if you are willing to use 3 inch markings, a vertical display on the vertical may be permitted.

(a) The operator of a fixed-wing aircraft shall display the required marks on either the vertical tail surfaces or the sides of the fuselage, except as provided in §45.29(f).

(b) The marks required by paragraph (a) of this section shall be displayed as follows:

(1) If displayed on the vertical tail surfaces, horizontally on both surfaces, horizontally on both surfaces of a single vertical tail or on the outer surfaces of a multivertical tail. However, on aircraft on which marks at least 3 inches high may be displayed in accordance with §45.29(b)(1), the marks may be displayed vertically on the vertical tail surfaces.

(2) If displayed on the fuselage surfaces, horizontally on both sides of the fuselage between the trailing edge of the wing and the leading edge of the horizontal stabilizer. However, if engine pods or other appurtenances are located in this area and are an integral part of the fuselage side surfaces, the operator may place the marks on those pods or appurtenances.

Finally, 14 CFR 45.29 discusses the styling of the tail numbers, for example thickness of the lines, ratios of width to height, etc. If you are still interested in using large tail numbers and are painting an AA-1, 14 CFR 45.29(f) allows you to use lettering smaller than 12 inches (the AA-1s had 10 inch lettering).

If you like the military style block letters (which meet the FAA style requirements)you can download a shareware font that you can take to a stencil cutting location (look up sign makers in the Yellow Pages) and have paint stencils created.