## Burl’s Aircraft, LLC **P.O. Box 671487 Chugiak** **, Alask a 99567**  **- 1487**  **(907)688 -**  **3715 (907)688 -**  **5031 fax Email~**  burl@biginalaska.com **web :**  **www.burlac.com** “Serving the aviation community since 1982” September 9 , 2011 

## Installation Instruction No.

SB 15AC06 - 08 - 10 To be used in conjunction with Installation Sketch No. SB 15AC06 - 08 - 10 **Introduction** The following instructions are for installing the 2 - 1272 reinforcement doubler and 2 - 1285 inspection cover assemblies into the Rogers (Aeronca) 15AC and S15AC Sedan airplanes with the wings still attached to the fuselage AND if the wings are removed from the fuselage . If, in the course of installing the inspection cover and doublers, slight corrosion is enco untered in the upper and/or lower wing spar cap angles , determine if the corrosion can be dealt with at this level of inspection. If m oderate to severe corrosion is detected then the aircraft must be removed from service to determine the extent of damage to the spar cap angles. This would probably require the removal of the wings and skins to do a more detailed inspection. This could possibly include replacing the spar cap angles with new parts. Also, c orrosion may

have spread to the adjoining wing skins and main spar webs. These components must be inspected as well and repaired or replaced as necessary . **Installation** 1) Study the enclosed installation sketch thoroughl y before drilling or cutting any holes in the wings. 2) Lay out the pattern on the appropriat e wing bottom skins acco rding to the sketch. If there is any conflict with any stiffeners that were installed by Aeronca that interfere with the exact placement of the doublers in the sketch, it is permissible to relocate that doubler in that bay

to not interfere with the stiffener. 3) Locate the center of each hole to be cut into the wing skin. Using a compass or a set of dividers, lightly

scribe a 3.5” diameter circle onto the wing skin. NOTE: this is the I .D. of the doubler; use this circle to center the doubler on the hole. **Do not cut any center holes in the wing yet .**  4) Referring to Sketch No. SB 15AC06 - 08 - 10 for proper placement/dimensions, locate the doubler centers on the wings. M atch - drill the wing skin s with a #40 pilot drill using each doubler as a template for that hole . (1 of 4 )In stallation Instruction No. SB 15AC06 - 08 - 10 , continued 5) Upon completing Step 4 for all the doublers, go back to all the centers and re - scribe the wing skins to a 4.00” diameter circle. 6) Drill a #30 pilot hole in the wing skin. Enlarge the hole to whatever size the pilot is on yo ur fly cutter or hole saw. 7) Either invert the pilot drill on the fly cutter or hole saw or use a replacement drill blank of the same diameter to use as a smooth pilot to cut the 4.00” diameter hole s in the wing s . This will keep the center constant and not allow the cutter or saw to wander and enlarge the hole. **Exact hole size is critical for the cover to fit properly.** 8) When cutting the 4.00” diameter hole, it is recommended that the center be set first. I f using a fl y cutter, use a variable speed drill to power the cutter at a very slow speed. Even better yet , turn the fly cutter b y hand. Most of the skins are either .020” or .025” thick. Only

the skin directly

aft of the main fuel cell is .032 ” thick. 9) Once the holes are all cut and deburred, proceed with the further inspection of the wing spar cap angles , main spar web, rib attaching flanges and skins . 10) Refer to AC43.13 - 1B, Chapter 6, Corrosion Inspection &Correction, Section 2, Types of C orrosion, Section 6, Corrosion Removal Procedures, Section 7, Basic Corrosion Removal Techniques, & Section 8, Aluminum & Aluminum Alloys for guide lines on their appropriate topics. These parts of the AC43.13 - 1B are taken directly from AC43 - 4A, Corrosion Control for Aircraft. For more detailed information go online to the original document : AC4 3 - 4A, Corrosion Control for Aircraft, Dated 07/25/1991 http://rgl.faa.gov/Regulatory _and_Guidance_Library

/rgAdvisoryCircular.nsf/0/a7ffc0f8 b6216a43862569b5005081ed/$FILE/AC%2043 - 4a%20.pdf 11) If only light or slight corrosion is encountered, clean the affected areas as per AC43.13 - 1B , Chapter 6, Section 6, page 6 - 22, Table 6 - 1, ref. Aluminum Alloys except Clad Aluminum and Clad Aluminum. Also reference page 6 - 23, Figure 6 - 14 and para. 6 - 118 for methods of removal of corrosion. If any intergranular or exfoliation corrosion is found, especiall y on the upper or lower (or both) spar cap angles, then the aircraft must be removed from service and the affected cap angle(s) and any other damaged parts must be replaced with new parts. **This situation indicates the extreme extent that the corrosion has advanced and thus**  **renders the aircraft unairworthy.** (2 of 4 )In stallation Instruction No. SB 15AC06 - 08 - 10 , continued 12) On ce any corrosion has been dealt with properly, prime the doublers with zinc phosphate (Federal Spec. TT - P - 1757A) and install them in their respective locations using the following method to insert the doublers into the wing if the wing is fully assembled whether or not it is installed on the aircraft. **UNDER NO CIRCUMSTANCES ARE THE DOUBLER RINGS TO BE CUT**  **OR SPLIT UNLESS ALTERNATE INSTALLATION**  **INSTRUCTIONS ARE FOLLOWED IN DRAWING NO. 2**  **- 1272 SPLICE**  **.** A) For the doublers aft of the main spar , remove the lower wi ng root fairings and pass the three (3) pre - primed doublers through the 2 nd lightening hole in the intermediate butt rib and the second rib outboard, dropping one of the doublers in the second rib bay . Progressivel y pass the remaining two (2) doublers into their respective bay s by

using the inspection holes cut in the wing skins to pass the doublers further out into the wing. B) Another method that may be used is to remove the aileron push - pull rod from the aileron control horn and mov e the push - pull rod to the side. P ass the pre primed doublers through the push - pull rod slot in the wing forward toward the aileron bell crank. P ass the three (3) primed doublers inboard using the already installed aileron bell crank in stallation and inspection cover through the intermediate rib 2 nd lightening hole, dropping one of the doublers in the 6 th rib bay and passing the remaining doublers inboard to their respective rib bay s using the pre - cut holes for access to move the doublers . C) To install the pre - primed doublers forw ard of the main spar: On the outboard end of the wing at STA. 137.02, ref. Sketch No. SB 15AC06 - 08 - 10, measuring from the aft e dge of the leading edge nose skin, bottom of wing, drill out and remove nose rib rivets at 5.6”, 7.7”, 9.8” and if necessary at 11.9” to allow separation of the wing skins to slip the doublers between the skins . Insert 5 each for the right wing, 4 each for the left wing , into the rib bay between STA. 137.02 and STA. 124.25 between the - 5 L/R and - 6 L/R skins . Pass the doublers through the first lightening hole in each nose rib , into each rib bay , to drop a doubler at its required location. Replace the rivets at STA. 137.02 that were removed to perform this operation immediately . NOTE: The first lightening hole in the nose rib i s the same diameter as the O.D. of the doubler . The doubler has been slightl y modified with 2 opposing “flats” sheared from the edges to allow ease of passage of the doubler through the hole in the nose rib. **DO NOT FORCE THE DOUBLER THROUGH THE NOSE RIB HOLE; IT WILL**  **DESTROY THE INTEGRETY OF THE NOSE RIB. ROTATE THE**  **DOUBLER UNTIL IT PASSES THROUGH THE LIGHTENING HOLE EASILY.**  (3 of 4 )In stallation Instruction No. SB 15AC06 - 08 - 10 , continued 13) Once all the doublers are in place, use 3/32” cleco s in ev ery other hole and re - drill the skins and do ublers to a #30 hole. Install the supplied MS20470AD4 - 4.5 rivets. Remove the clecos and install the remaining rivets. 14) Itis recommended that, if the wing is to be disassembled for replacement of skins and / or wing spar cap angles, the location of the doubler centers and rivet patterns be completed in the old skins prior to disassembly so that the pattern may be accurately transferred to the new skins with a minimum of effort . Upon reassembly of the win g, the skins and doublers can then be primed with zinc phosphate and the doublers installed onto the skins using the supplied M20470AD4 - 4.5 rivets before the skins are attached/re - attached to the ribs and spars. 15 ) Upon completion of the installation of the doublers or replacement of spar cap angles, doublers and skins , repaint the wings and the new inspection covers as necessary . It is required that the inner surfaces of the wing be treated with ACF - 50 (or equivalent) anti - corrosion compound. This treatment must be done after the wings are finished and repainted. The anti - corrosion compound is an oil based material and w ill interfere with paint adhesion should it leak out from the lap seams of the wing skins. Make the following entry into the aircraft logbooks or permanent records: “This aircraft has been modified and repaired in accordance with Rogers Service Bulletin No. SB 15AC06 - 08 - 10 as applicable to Rogers (Aeronca) Model 15AC & S15AC Sedan airplanes. At minimum, this requi red the installation of 15 new 2 - 1285 inspection covers and 2 - 1272 doublers in the wings fore and aft of the main spar assembly . Weight change is negligible.” NOTE: If skins and spar caps were replaced, enumerate which skins and which cap angles were rep laced in the aircraft records . This is FAA Accepted Data; no 337 is required for compliance with this Service Bulletin ; it is a logbook or permanent records entry onl y . ______________________________________END__________________________________

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