----[Please read http://ercoupers.com/disclaimer.htm before following any advice in this forum.]---- This service bulletin involves a lot of text and a drawing. We'll post the drawing on the website tomorrow.
DRAFT SERVICE BULLETIN NO.31 WING CENTER SECTION INSPECTION DATE: July 24, 2000 SUBJECT: Visual inspection of wing center section structure for evidence of corrosion. MODELS AFFECTED: All Ercoupe 415-C, 415-CD, 415-D, 415-E and 41 5-G aircraft. All Forney F-1 and F-lA aircraft. All Alon A-2 and A-2A aircraft. All Mooney M10 aircraft. COMPLIANCE: Inspection required within the next 25 hours of operation or at the next 100 hour or annual inspection, whichever occurs first STATEMENT OF DIFFICULTY: There have been field reports of severe corrosion in the wing center section structure of several aircraft. The most effective means of preventing corrosion damage is early identification and correction. However, the original design configuration does not provide adequate means for routine visual examination of the wing center section wing walkway boxes during periodic inspections. Undetected corrosion, if severe enough, could lead to structural failure of the wing center section, which could result in loss of control of the airplane. Consequently, this Service Bulletin provides for the installation of inspection openings to allow for visual access to the wing walkway box structure, and calls for an inspection to establish the current condition of the center section structure. The inspection openings will then allow routine inspections to be accomplished as required under FAR Part 43, Appendix 0, (f). PROCEDURE: 1. Remove the forward floorboard, seat cushion(s), seat bucket(s), and any other interior items necessary to gain clear access to the wing center section where it passes through the fuselage. 2. Remove all soundproofing in the lowest belly regions and discard. Do not replace soundproofing. Inspect and clear all drain holes. 3. Inspect front and rear spars in fuselage area and surrounding structure for corrosion, wrinkles, loose rivets, skin cracks, and unrepaired damage. 4. For Ercoupes prior to Serial Number 4869, verify that AD 59-05-04 has been complied with by the installation of the rear spar stiffener. Ercoupe Service Memorandum 53A shows the details of this reinforcement modification. If there are no rear spar reinforcements in place, install them in accordance with Ercoupe Service Memorandum 53A 5. On Ercoupes Serial Nos. 113 to 2037 inclusive, if not already done, comply with Ercoupe Service Bulletin No. 18 by installation of center section belly skin reinforcements in accordance with Ercoupe Service Bulletin No. 18. 6. On Ercoupes prior to Serial Number 5714, install drain holes and clam shell cover plates in accordance with Fornaire Service Bulletin No. 109. Univair Service Kit SK-37 contains required parts to comply with this bulletin. 7. On all Ercoupe, Forney, Alon, and Mooney M-10 aircraft accomplish the following: a. Locate eight inspection openings on the lower wing surface per the enclosed drawing, SB-31, Sheet 1, Revision None, dated 04-09-00. For aircraft with smooth bottom skins, all openings should be 4 inches in diameter. For aircraft with beaded bottom skins, four of the openings should be 4 inches in diameter and four of the openings should be 3 inches in diameter as shown on drawing SB-31. CAUTION: If the opening locations specified by the diagram interfere with any skin stiffeners, alter the opening location to clear the stiffener. Be sure also to provide clearance for installation of reinforcement rings to be installed in Step 11. 8. b. Cut inspection openings at the locations of 7(a) above and deburr. Inspection procedure - Using the openings made in Step 7 above, inspect the wing panel structure for corrosion and unrepaired damage. FAA Advisory Circular AC 43-4A, "Corrosion Control for Aircraft", dated 7/25/91 or later, should be used to identify corroded areas. Due to the extensive use of thin materials in the wing center section, any parts with corrosion beyond "light corrosion' as defined in AC 43-4A, Chapter 6, Section 4, paragraph 640 is considered unairworthy. Repair or replace any parts considered unairworthy prior to further operation. If corrosion is found on the rear side of the front spar or if corrosion is suspected for other reasons, remove wing fuel tanks in accordance with the appropriate Service Manual and inspect the front side of the wing spars for corrosion. 9. Repair -Remove all light corrosion in accordance with the procedures outlined in Chapter 6, Section 5 of AC 43-4A. Clean and apply chemical conversion coating to the corrosion rework areas as outlined in Chapter 4 of AC 43-4k For further corrosion resistance, a zinc chromate primer per MIL-P-8585A may be applied by spraying or brushing after the chemical conversion coated surfaces have thoroughly dried. Comply with safety procedures of AC 43-4A during all phases of treating the corroded areas. 10. Replacement -Replacement of unairworthy components of the wing center section may be accomplished in accordance with the Ercoupe, Forney, Alon, or Mooney M-10 Service Manual as applicable. Ercoupe Service Memorandum No. 53A provides detailed instructions for replacement of rear spar of wing center section. 11. Cover plate installation - After inspection is complete, install cover plate assemblies in each opening as shown on drawing SB-31, Sheet 2, Revision None, dated 04-09-00. Secure each cover plate with three (3) #8 machine screws and three .032 thick washers. Reinstall interior items removed in Step 1 and wing tanks, if removed. Univair Service Kit SB31-1 includes all inspection panel assemblies for aircraft with smooth center section bottom skins to comply with this Service Bulletin. Kit SB31-1 also includes rivets and cover plate attaching hardware. Univair Service Kit SB31-2 includes all inspection panel assemblies for aircraft with beaded center section bottom skins to comply with this Service Bulletin. Kit SB31-2 also includes rivets and cover plate attaching hardware. 12. Required documentation - Make log book entry stating compliance with Service Bulletin No. 31. Weight and balance change is considered negligible. 13. Continued inspections - At each 100 hour and annual inspection, remove interior components per Step I and the cover plates installed per Step 11 and inspect wing center section for corrosion or damage per Step 8 as required by FAR Part 43, Appendix D (f). Repair or replace corroded or damaged parts as required. INFORMATION AND PARTS AVAILABILITY: Copies of Ercoupe, Forney, Alon, and Mooney M-10 Service Manuals are available from Univair Aircraft Corporation. Copies of Ercoupe Service Memorandum No. 53A, Ercoupe Service Bulletin No. 18, and Fornaire Service Bulletin No. 109 are available from Univair Aircraft Corporation. Contact Univair Aircraft Corporation for availability and pricing of wing center section replacement parts and parts for complying with Service Memorandums and Bulletins. Cover plate kits SB31-1 and SB3I-2 are available from Univair Aircraft Corporation. (NOTE: None of the above is available from UNIVAIR!) ==^================================================================ This email was sent to: [EMAIL PROTECTED] EASY UNSUBSCRIBE click here: http://topica.com/u/?aVxiLm.aVzvvT Or send an email to: [EMAIL PROTECTED] T O P I C A -- Register now to manage your mail! http://www.topica.com/partner/tag02/register ==^================================================================
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