DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39 [61 FR 44157 No. 168, 8/28/96] [SN] [R20H]

[Docket No. 96-CE-36-AD; Amendment 39-9726; AD 96-18-02]
RIN 2120-AA64	American Champion
   Aircraft Corporation

Amendment 39-9726
Effective Sept. 20, 1996
Supersedes 

	
 Airworthiness Directives; American Champion Aircraft Corporation Models 8KCAB, 8GCBC, 7GCBC, 7ECA, 7GCAA, and 7KCAB Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

SUMMARY: This amendment supersedes Airworthiness Directive (AD) 96-03-11, which currently requires the following on American Champion Aircraft Corporation (American Champion) Models 8KCAB, 8GCBC, 7GCBC, and 7ECA airplanes that are equipped with metal spar wings: inspecting (one-time) the wing front strut attach fittings for cracks, scratches, or surface deformities; replacing any wing front strut attach fitting with cracks, scratches, or surface deformities; and reporting the inspection results to the Federal Aviation Administration (FAA). This action results from reports submitted as a requirement of the existing AD that reference 24 fittings with cracks, scratches, or surface deformities on 7 different airplanes, and the FAA's determination that improved wing front strut attach fittings (developed by American Champion) are not susceptible to cracks, scratches, or surface deformities. This action requires installing removable inspection hole covers for the wing front strut attach fittings, and replacing the wing front strut attach fittings with fittings of improved design. The action also provides the provision of repetitively inspecting the wing front strut attach fittings (provided no cracks, scratches, or surface deformities are found) if parts have been ordered but are not available. The actions specified by this AD are intended to prevent structural failure of a wing caused by cracked wing front strut attach fittings, which, if not detected and corrected, could result in loss of control of the airplane.

DATES: Effective September 20, 1996.
   	The incorporation by reference of American Champion Service Letter 409, Revision A, dated April 22, 1996; American Champion Service Letter 410, dated May 6, 1996; American Champion Service Letter 411, dated May 6, 1996; American Champion Service Letter 412, dated May 6, 1996; American Champion Service Letter 413, dated May 6, 1996, American Champion Service Letter 414, Revision A, dated June 25, 1996; and American Champion Service Letter 415, Revision A, dated June 25, 1996, is approved by the Director of the Federal Register as of September 20, 1996.
    	The incorporation by reference of American Champion Service Letter 408, dated January 24, 1996, was previously approved as of February 26, 1991 (61 FR 5501, February 13, 1996) by the Director of the Federal Register.
    	Comments for inclusion in the Rules Docket must be received on or before October 25, 1996.

ADDRESSES: Submit comments in triplicate to the FAA, Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket 96-CE-36-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106.
    	Service information that applies to this AD may be obtained from the American Champion Aircraft Corporation, 32032 Washington Avenue, Rochester, Wisconsin 53167. This information may also be examined at the FAA, Central Region, Office of the Assistant Chief Counsel, Attention: Rules Docket No. 96-CE-36-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: Ms. Karen Forest, Aerospace Engineer, FAA, Chicago Aircraft Certification Office, 2300 E. Devon Avenue, Des Plaines, Illinois 60018; telephone (847) 294-7697; facsimile (847) 294-7834.

SUPPLEMENTARY INFORMATION:

Events Leading to This Action

    	On January 31, 1996, the FAA issued AD 96-03-11, Amendment 39-9598 (61 FR 5501, February 13, 1996), to require the following on American Champion Models 8KCAB, 8GCBC, 7GCBC, and 7ECA airplanes that are equipped with metal spar wings:

--Inspecting (one-time) the wing front strut attach fittings for cracks, scratches, or surface deformities;

--Replacing any wing front strut attach fitting with cracks, scratches, or surface deformities; and

--Reporting the inspection results to the FAA.

    	AD 96-03-11 resulted from an investigation of an American Champion Model 8KCAB airplane accident that revealed fatigue cracking of the wing front strut attach fittings. The design of the wing and fuselage structure of this airplane is such that the outboard ends of the wing fittings for each primary strut are bolted to the web of the wing's front spar. One fitting is on the forward side of the web and one is on the aft side of the web. The fittings then transition to a wider area where the strut is attached with a bolt. On the airplane involved in the accident that resulted in AD 96-03-11, the forward fitting fractured through the transition area (approximately in the center of the fitting length), causing the fitting to separate. This wing front strut attach fitting transition area contains an aft leg that is assembled against the forward face of the wing spar web and a forward leg.
    	Investigation of the fitting from the accident aircraft revealed that small, sharp scratches in the forward edge of the shorter portion of the aft leg contributed to the fatigue cracking in the wing fitting. Metallurgical examination of the fitting indicated that these fatigue cracks formed in scratches and surface deformities that resulted during the manufacturing process, and existed prior to the accident.
    	After that accident and prior to issuing AD 96-03-11, the FAA and American Champion inspected another Model 8KCAB airplane and found fatigue cracks on two of the four wing front strut attach fittings. These fatigue cracks also originated from scratches and surface deformities in the wing front strut attach fitting. In addition, an evaluation of new uninstalled wing front strut attach fittings revealed these scratches and surface deformities. American Champion Models 8GCBC, 7GCBC, and 7ECA airplanes incorporate this same design fitting, and thus were included in the Applicability section of AD 96-03-11.
    	The results of the inspections required by AD 96-03-11 revealed 24 wing front strut attach fittings with cracks, scratches, or surface deformities. These cracked and scratched fittings were from 7 different affected airplanes that had between 103 to 666 total hours time-in-service.

Improved Design Parts and Service Information

    	American Champion has designed improved wing front strut attach fittings, part number (P/N) 3-1691 and P/N 3-1692, which, when manufactured according to design specifications, will not contain the surface deformities and scratches found on the existing design fittings. After extensive analysis, these fittings have proven to not have the cracking susceptibility of those currently in service. The following presents service information that American Champion has issued that relates to this issue:
    	* American Champion Service Letter (SL) 408, dated January 24, 1996, and American Champion SL 409, Revision A, dated April 22, 1996, which specify procedures for accessing and inspecting wing front strut attach fittings, part number (P/N) 3-1632-1 and P/N 3-1632-2; and P/N 3-1646L and 3-1646R, respectively.
    	* American Champion SL 410, dated May 6, 1996, which includes procedures for installing removable inspection hole covers for the wing front strut attach fittings on Model 8KCAB airplanes that have complied with American Champion SL 408;
    	* American Champion SL 411, dated May 6, 1996, which includes procedures for installing removable inspection hole covers for the wing front strut attach fittings on Model 8KCAB airplanes that have not complied with American Champion SL 408;
    	* American Champion SL 412, dated May 6, 1996, which specifies procedures for installing removable inspection hole covers for the wing front strut attach fittings on Models 7ECA, 7GCAA, 7GCBC, and 8GCBC airplanes that have complied with American Champion SL 409;
    	* American Champion SL 413, dated May 6, 1996, which specifies procedures for installing removable inspection hole covers for wing front strut attach fittings on Models 7ECA, 7GCAA, 7GCBC, and 8GCBC airplanes that have not complied with American Champion SL 409.
    	* American Champion SL 414, Revision A, dated June 25, 1996, which specifies procedures for replacing the wing front strut attach fittings on Model 8KCAB airplanes with improved wing front strut attach fittings, P/N 3-1691, and also includes procedures for inspecting the wing front strut attach fittings on these airplanes; and
    	* American Champion SL 415, Revision A, dated June 25, 1996, which specifies procedures for replacing the wing front strut attach fittings on Models 8GCBC, 7ECA, 7GCAA, 7GCBC, and 7KCAB airplanes with improved wing front strut attach fittings, P/N 3-1692, and also includes procedures for inspecting the wing front strut attach fittings on these airplanes.

FAA's Determination

    	After examining the circumstances and reviewing all available information related to the events described above, the FAA has determined that (1) The wing front strut attach fittings on American Champion Models 8KCAB, 8GCBC, 7ECA, 7GCAA, 7GCBC, and 7KCAB airplanes should incorporate P/N 3-1691 and 3-1692, as applicable; and (2) AD action should be taken in order to prevent structural failure of a wing caused by cracked wing front strut attach fittings, which, if not detected and corrected, could result in loss of control of the airplane.
    	In addition, based on results of an in-depth analysis of the existing wing front strut attach fittings, the FAA has determined that if the fittings were not replaced with the improved design fittings, repetitive inspections would need to be performed at intervals not to exceed 20 hours TIS. Allowing repetitive inspections of these airplanes over a long period of time goes against FAA policy, which states that if a modification exists for critical structure that could eliminate or reduce the number of short-term inspections, the modification should be incorporated. The FAA makes short-term allowances on this policy to account for parts availability provided analysis shows that an acceptable level of safety can be maintained through a short-term repetitive inspection program.

The Provisions of the Required AD Action

    	Since an unsafe condition has been identified that is likely to exist or develop in other American Champion Models 8GCBC, 7ECA, 7GCAA, 7GCBC, and 7KCAB airplanes of the same type design, this AD supersedes AD 96-03-11 with a new AD that requires installing removable inspection hole covers for the wing front strut attach fittings, and replacing the wing front strut attach fittings with P/N 3-1691 (Model 8KCAB) or P/N 3-1692 (Models 8GCBC, 7ECA, 7GCAA, 7GCBC, and 7KCAB) wing front strut attach fittings, as applicable. The FAA is including a provision of repetitively inspecting the wing front strut attach fittings (provided no cracks, scratches, or surface deformities are found) if parts have been ordered but are not available. Accomplishment of these actions is in accordance with the service information previously referenced.
    	Since a situation exists (structural failure of the wing caused by a cracked wing front strut attach fitting) that requires the immediate adoption of this regulation, it is found that notice and opportunity for prior public comment hereon are impracticable, and that good cause exists for making this amendment effective in less than 30 days.

Comments Invited

    	Although this action is in the form of a final rule that involves requirements affecting immediate flight safety and, thus, was not preceded by notice and opportunity to comment, comments are invited on this rule. Interested persons are invited to comment on this rule by submitting such written data, views, or arguments as they may desire. Communications should identify the Rules Docket number and be submitted in triplicate to the address specified above. All communications received on or before the closing date for comments will be considered, and this rule may be amended in light of the comments received. Factual information that supports the commenter's ideas and suggestions is extremely helpful in evaluating the effectiveness of the AD action and determining whether additional rulemaking action would be needed.
    	Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the rule that might suggest a need to modify the rule. All comments submitted will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested persons. A report that summarizes each FAA-public contact concerned with the substance of this AD will be filed in the Rules Docket.
    	Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this rule must submit a self-addressed, stamped postcard on which the following statement is made: "Comments to Docket No. 96-CE-36-AD." The postcard will be date stamped and returned to the commenter.

Regulatory Impact

    	The regulations adopted herein will not have substantial direct effects on the States, on the relationship between the national government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, in accordance with Executive Order 12612, it is determined that this final rule does not have sufficient federalism implications to warrant the preparation of a Federalism Assessment.
    	The FAA has determined that this regulation is an emergency regulation that must be issued immediately to correct an unsafe condition in aircraft, and is not a "significant regulatory action" under Executive Order 12866. It has been determined further that this action involves an emergency regulation under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). If it is determined that this emergency regulation otherwise would be significant under DOT Regulatory Policies and Procedures, a final regulatory evaluation will be prepared and placed in the Rules Docket (otherwise, an evaluation is not required). A copy of it, if filed, may be obtained from the Rules Docket.

List of Subjects in 14 CFR Part 39

    	Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

Adoption of the Amendment

    	Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

    	1. The authority citation for part 39 continues to read as follows:

    	Authority: 49 U.S.C. 106(g), 40113, 44701.

Sec. 39.13  [Amended]

    	2. Section 39.13 is amended by removing AD 96-03-11, Amendment 39-9598 (61 FR 5501, February 13, 1996), and by adding a new airworthiness directive (AD) to read as follows:

96-18-02  AMERICAN CHAMPION AIRCRAFT CORPORATION: Amendment 39-9726; Docket No. 96-CE-36-AD. Supersedes AD 96-03-11, Amendment 39-9598.

	Applicability: The following airplane models and serial numbers, certificated in any category, that are equipped with metal spar wings:

--	Model 8KCAB airplanes, serial numbers 643-90 through 768-96;

--	Model 8KCAB airplanes, all serial numbers, that are equipped with metal spar wings, wing assembly part number (P/N) 7-1521 (installed in accordance with American Champion Service Kit 403);

--	Model 8GCBC airplanes, serial numbers 361-91 through 377-96;

--	Model 8GCBC airplanes, all serial numbers, that are equipped with metal spar wings, wing assembly part number 7-1542;

--	Model 7GCBC airplanes, serial numbers 1200-94 through 1215-96;

--	Model 7GCBC airplanes, all serial numbers, that are equipped with metal spar wings, wing assembly part number 7-1545;

--	Model 7ECA airplanes, serial numbers 1355-95 through 1358-96; and

--	Models 7ECA, 7GCCA, and 7KCAB airplanes, all serial numbers, that are equipped with metal spar wings, wing assembly part number 7-1567.

	Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, or repaired in the area subject to the requirements of this AD. For airplanes that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (f) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and, if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it.

	Compliance: Required within the next 20 hours time-in-service (TIS) after the effective date of this AD, unless already accomplished.
	
	To prevent structural failure of a wing assembly caused by cracked wing front strut attach fittings, which, if not detected and corrected, could result in loss of control of the airplane, accomplish the following:    
   (a)	Install removable inspection hole openings for the wing front strut attach fittings in accordance with one of the following, as applicable:
	(1) 	American Champion Service Letter (SL) 410, dated May 6, 1996, for Model 8KCAB airplanes that have complied with American Champion SL 408, dated January 24, 1996;
	(2) 	American Champion SL 411, dated May 6, 1996, for Model 8KCAB airplanes that have not complied with American Champion SL 408, dated January 24, 1996;
	(3) 	American Champion SL 412, dated May 6, 1996, for Models 7ECA, 7GCAA, 7GCBC, and 8GCBC airplanes that have complied with American Champion SL 409, Revision A, dated April 22, 1996; and
	(4) 	American Champion SL 413, dated May 6, 1996, for Models 7ECA, 7GCAA, 7GCBC, and 8GCBC airplanes that have not complied with American Champion SL 409, Revision A, dated April 22, 1996.

	Note 2: American Champion SL 408 and American Champion SL 409, when complied with, incorporate permanent inspection holes for access to the wing front strut attach fittings, P/N 3-1632-1 and P/N 3-1632-2; and P/N 3-1646L and 3-1646R, respectively.

   (b) 	Replace the wing front strut attach fittings with P/N 3-1691 (Model 8KCAB) or P/N 3-1692 (Models 8GCBC, 7ECA, 7GCAA, 7GCBC, and 7KCAB) wing front strut attach fittings, as applicable. Accomplishment of these actions is required in accordance with the instructions in American Champion SL 414, Revision A, dated June 25, 1996; or American Champion SL 415, Revision A, dated June 25, 1996, as applicable.
   (c) 	If the improved design wing front strut attach fittings referenced in paragraph (b) have been ordered from the manufacturer, but are not available, repetitively inspect the wing front strut attach fittings for cracks, scratches, or surface deformities at intervals not to exceed 20 hours TIS in accordance with the instructions in American Champion SL 408, dated January 24, 1996, or American Champion SL 409, Revision A, dated April 22, 1996, as applicable. Figure 3 of these service letters depicts the crosshatched areas of the fittings that must be inspected. These service letters also specify both a visual inspection and the choice of either a dye penetrant, Zyglo test, ultrasonic, or x-ray inspection.
   (d) 	The repetitive inspections allowed in paragraph (c) of this AD may be continued until one of the following occurs at which time the replacement required by paragraph (b) of this AD must be accomplished prior to further flight:
	(1) 	Cracks, scratches, or surface deformities are found on a wing front strut attach fitting;
	(2) 	Parts become available from the American Champion Aircraft Corporation; or
	(3) 	Six repetitive inspection intervals are accomplished (120 hours TIS).
   (e) 	Special flight permits may be issued in accordance with sections 21.197 and 21.199 of the Federal Aviation Regulations (14 CFR 21.197 and 21.199) to operate the airplane to a location where the requirements of this AD can be accomplished.
   (f) 	An alternative method of compliance or adjustment of the initial or repetitive compliance time that provides an equivalent level of safety may be approved by the Manager, Chicago Aircraft Certification Office (ACO), 2300 E. Devon Avenue, Des Plaines, Illinois 60018. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Chicago ACO. Alternative methods of compliance approved in accordance with AD 96-03-11 (superseded by this action), are not considered approved as alternative methods of compliance for this AD.

	Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Chicago ACO.

   (g) 	The incorporation of certain documents referenced in this AD is as follows:    
	(1) 	The installations required by this AD shall be done in accordance with American Champion Service Letter 410, dated May 6, 1996; American Champion Service Letter 411, dated May 6, 1996; American Champion Service Letter 412, dated May 6, 1996; or American Champion Service Letter 413, dated May 6, 1996, as applicable. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
	(2) 	The replacements required by this AD shall be accomplished in accordance with American Champion Service Letter 414, Revision A, dated June 25, 1996; or American Champion Service Letter 415, Revision A, dated June 25, 1996, as applicable. This incorporation by reference was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
	(3) 	The inspections (if parts are not available) required by this AD shall be accomplished in accordance with American Champion Service Letter 408, dated January 24, 1996, or American Champion Service Letter 409, Revision A, dated April 22, 1996.
		(i) 	The incorporation by reference of American Champion Service Letter 408 reference was previously approved as of February 26, 1996 (61 FR 5501, February 13, 1996) by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
		(ii) 	The incorporation by reference of American Champion Service Letter 409 was approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
	(4) 	Copies may be obtained from the American Champion Aircraft Corporation, 32032 Washington Avenue, Rochester, Wisconsin 53167. Copies may be inspected at the FAA, Central Region, Office of the Assistant Chief Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri, or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
   (h) 	This amendment (39-9726) supersedes AD 96-03-11, Amendment 39-9598.
   (i) 	This amendment (39-9726) becomes effective on September 20, 1996.

	Issued in Kansas City, Missouri, on August 20, 1996.

Michael Gallagher, Manager, Small Airplane Directorate, Aircraft Certification Service.

FOR FURTHER INFORMATION CONTACT: Ms. Karen Forest, Aerospace Engineer, FAA, Chicago Aircraft Certification Office, 2300 E. Devon Avenue, Des Plaines, Illinois 60018; telephone (847) 294-7697; facsimile (847) 294-7834.

Manufacturer’s Service Information: -  Included below
American Champion Service Letter 408
American Champion Service Letter 409, Revision A
American Champion Service Letter 410
American Champion Service Letter 411
American Champion Service Letter 412
American Champion Service Letter 413
American Champion Service Letter 414, Revision A
American Champion Service Letter 415, Revision A

Service information that applies to this AD may be obtained from the American Champion Aircraft Corporation, 32032 Washington Avenue, Rochester, Wisconsin 53167.

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AMERICAN CHAMPION AIRCRAFT CORPORATION
PO Box 37
Rochester, WI 53167

SERVICE LETTER NO. 401
COMPLIES WITH AD 89-18-06

DATE: June 14, 1989

TITLE:
Front Folding Seat

APPLICABLE MODELS:
7ECA (S/N's All)
7GCAA (S/N's All)
7GCBC (S/N's All)
7KCAB (S/N's All)
8GCBC (S/N's All)
8KCAB (S/N's All)

DESCRIPTION:
There have been reports of failures of the folding front seat back, causing the jamming of the rear control stick and loss of control. These failures are due to high loads being applied to the seat back during aerobatic maneuvers, or by the pilot or passenger pushing or pulling on the seat back.

INSTRUCTIONS:
  1)	Before further flight
Perform a visual inspection of the front seat back hinge area for evidence of cracks using 10X magnification. Inspect the area around the hinge bolt hole on upper and lower seat assemblies. This is best accomplished by removing the hinge bolt. Determine that proper hinge bolt (AN3-7A) is installed. (See Bellanca Service Letter No. 109)

   2)	Within next 10 hours flight
	Install a placard prohibiting pulling or pushing on the upper portions of the seat back.

	WARNING: DO NOT PULL OR PUSH ON UPPER SEAT BACK

   3)	Within next 50 hours of flight
Perform a magnetic particle or dye penetrant inspection of left and right hand sides of the lower seat frame at the side-tube/side-brace area and hinge area for evidence of cracking. Any component found cracked or otherwise damaged should be repaired for replaced. This inspection is to be repeated at 50-hour intervals until item (4) is accomplished.

   4)	Within 12 months from the effective date of this service letter
	Replace front seat frame with exchange unit provided by American Champion Aircraft.
	Reference Part No. 7-1513-89 for the adjustable seat frame.
	Reference Part No. 7-1454-89 for the fixed seat frame.
	Reference Service Kit 301 for hardware kit

Contact:
AMERICAN CHAMPION AIRCRAFT CORPORATION
PO Box 37
Rochester, WI 53167
1-414-534-6315 In Wisconsin
1-800-223-9381 Outside Wisconsin 
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AMERICAN CHAMPION AIRCRAFT CORP.
P.O. Box 37
Rochester, Wisconsin 53167

SERVICE LETER: 408

DATE: January 24, 1996

WE CONSIDER THIS TO BE MANDATORY

TITLE:
Inspection of Front Strut Fittings

APPLICABLE MODELS:
All 8KCAB with serial numbers 643-90 through 754-95 and all other 8KCAB fitted with service kit 403 (Retrofit metal spar wings)

TOTAL TIME:
Aircraft with over 1000 hours total time or over 300 hours acrobatic flight.

DESCRIPTION:
There has been a report of a fatigue failure of front strut attach fittings, part numbers 3-1632-1 and 3-1632-2. This was due to a deburring abrasion that propagated under yielding loads due to the aircraft being flown repeatedly in a manner not approved under the original certification.

American Champion Aircraft warns operators of American Champion 8KCAB airplanes of the possible adverse consequences of flying the airplane in flight conditions for which it is not certified, for example, exceeding VNE, or using full or abrupt control movements above VA. Operation of the aircraft in such a manner has the potential for exceeding the maximum normal acceleration limits of the airplane and generating high stresses in key components of the aircraft structure.

The procedures in this service letter are intended to eliminate the possibility of failures by:
   1)	Reminding owners to operate the airplane within design limits
   2)	Doing an inspection of the front strut fittings for flaws or defects; namely scratches and marks from deburring.
   3)	Contacting American Champion, who is surveying the results of the inspection.

The inspection procedures described herein are not intended to be a substitute for a properly performed 100 hour/annual inspection. Refer to Advisory Circular (AC) 43.13-1: Acceptable Methods, Techniques, and Practices; Aircraft Inspection and Repair.

REMOVAL OF PARTS:
Before opening of inspection holes, support the wing tip with a large sturdy saddle. Unbolt the rear strut and the jury strut eye bolt from the front strut. Unbolt the front strut and tie down ring and remove from the front strut to wing attach fitting. The end of the strut should be supported if it is still attached to the fuselage. Cut out the two existing inspection holes behind the front spar, already provided. Also, cut out the strip of fabric between the two fitting legs. Locate the holes for the corners of the strip of the leading edge skin that must be cut out in order to remove the front attach fitting. See figure 1 for placement of the holes. The strip of material is depicted as the cross-hatched area 'A'. Note that this area will be easier to cut out later, after the fitting are loose inside the wing.

Figure 1 shows the dimensional position of all the components in the area. Use this information to determine the placement of the inspection holes. Cut 3.5 in. inspection holes in the leading edge skin on either side of the rib and forward of the spar as depicted in figure 1. The covers can be constructed after the fitting has been reinstalled.

After cutting the safety wire, remove all fitting attach hardware including the compression tube spacer. Loosen, then disconnect one of the attached dragwires from the attachment lug. If the inboard dragwire is loosened, the inspection hole by the aileron bell crank will need to be opened to loosen the jam nut. If the outboard dragwire is loosened, the wing tip will have to be removed to loosen the jam nut. When, loosening, keep track of the approximate number of turns, so that factory tension can be maintained.

While the fittings are loose, cut out the strip of leading edge material needed to remove the front fitting. Again, refer to figure 1, cross-hatched area 'A'. Also, the rib and attached gusset must be notched to allow the fitting to pass. Refer to figure 2 for dimensions. Remove the rear fitting by pushing it into the wing and pulling it out through the inboard inspection hole. Remove the front fitting by pulling it through the now relieved leading edge skin.

INSPECTION:
Inspection of the part should be done as follows:
   1)	Perform a visual inspection of the parts under magnification of at least 10X. It is important to look at the areas that are deburred. These areas are depicted in figure 3, and are shown with cross-hatching. Any marks or scratches in the reference area cannot be deeper than approximately 0.010 in.
   2)	Perform a dye-penetrant test on the depicted areas. Inspect the part for developing cracks. If the resources are available, a Zyglo test, an ultrasonic inspection, or a X-ray could also be done.
   3)	If the parts reveal no cracks or scratches, they can be reinstalled. If there is a finding in the inspection, contact American Champion concerning the replacement of the part.
   4)	Contact American Champion Aircraft Corporation to report any findings and to field any questions. American Champion is surveying the findings and greatly appreciates all responses.

REINSTALLATION OF PARTS:
Reinstall the fittings by reversing the method used to extract them. Locate the fittings into place with two bolts*. Reconnect the dragwire to the attachment lug and cotter. Install the remaining bolts through the fitting except the AN4-10H through the compression tube fitting, dragwire lug, and spacer. Place the drag wire lug on the end of the compression tube and begin to tighten the drag wire in order to gain some clearance for the spacer. Once enough clearance is gained, install the bolt and spacer. After fitting is tight, tighten the dragwire and safety wire the bolts in place again.

Normal fabric inspection hole covers can be used for the holes cut behind the spar. Construct a patch style hole cover as illustrated in figure 4. Cut the fabric back around front inspection holes 0.5 in. Methyl Ethyl Keytone, used in sparing amounts, can be used to remove localized areas of paint. Match drill hole cover to leading edge skin and blind rivet them in place such that the cover is as flush as possible.

Carefully cut out the remaining part of the acetate fabric reinforcement ring around the strut fitting without removing the rest of the fabric. Using a square fabric patch with slot shaped relief holes for the fitting legs, patch the area around the fitting. Replace the square ring with a new one or equivalent. Then, lay down another square patch on top of the ring. The geometry is depicted in figure 4. Using appropriate fabric methods, fabric cover a 5.5 to 6 inch round patch over the hole covers.

*Always use new Nyloc nuts. Use standard torque value on all bolts.

FIGURE 1
FIGURE 2
FIGURE 3
FIGURE 4
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AMERICAN CHAMPION AIRCRAFT CORP.
P.O. Box 37
Rochester, Wisconsin 53167

SERVICE LETTER NO. 409 (Revision A)

DATE: April 22, 1996 

WE CONSIDER THIS TO BE MANDATORY

TITLE:
Inspection of Front Strut Fittings

APPLICABLE MODELS:
All American Champion Aircraft 7ECA, 7GCBC, 8GCBC that were manufactured between June 1, 1990 and January 24, 1996, and 7ECA, 7GCAA, 7GCBC, 7KCAB, 8GCBC that have purchased metal spar wings before January 24, 1996. (Those that are affected by AD 96-03-11, but are not 8KCAB)

TOTAL TIME:
Within the constraints of the Airworthiness Directive

DESCRIPTION:
This service letter is a supplement to service letter 408, which details the removal and inspection of the strut attach fittings, 3-1632, on 8KCAB aircraft. Due to differences in wing design, this letter details the removal and inspection of strut attach fittings, 3-1646-1 and 3-1646-2, on the other affected models.

American Champion Aircraft warns operators of these airplanes of the possible adverse consequences of flying the airplane in flight conditions for which it is not certified, for example, exceeding Vne, or using full or abrupt control movements above VA. Operation of the aircraft in such a manner has the potential for exceeding the maximum normal acceleration limits of the airplane and generating high stresses in key components of the aircraft structure.

The procedures in this service letter are intended to eliminate the possibility of failures by:
   1)	Reminding owners to operate the airplane within design limits
   2)	Doing an inspection of the front strut fittings for flaws or defects; namely scratches and marks from deburring.
   3)	Contacting American Champion, who is surveying the results of the inspection.

The inspection procedures described herein are not intended to be a substitute for a properly performed 100 hour/annual inspection. Refer to Advisory Circular (AC) 43.13-1: Acceptable Methods, Techniques, and Practices; Aircraft Inspection and Repair.

REMOVAL OF PARTS:
Before opening of inspection holes, support the wing tip with a large sturdy saddle. Unbolt the rear strut and the jury strut eye bolt from the front strut. Unbolt the front strut and tie down ring and remove from the front strut to wing attach fitting. The end of the strut should be supported if it is still attached to the fuselage. Cut out the existing inspection hole behind the front spar, already provided.
Figure 1 shows the dimensional position of all the components in the area. Use this information to determine the placement of the inspection hole that needs to be cut in the leading edge skin. Cut the 3.5 in. inspection hole in the leading edge skin forward of the spar as depicted in Figure 1. The covers can be constructed after the fitting has been reinstalled.

After cutting the safety wire, remove all fitting attach hardware including the compression tube spacer. Loosen, then disconnect one of the attached dragwires from the attachment lug. If the inboard dragwire is loosened, the inspection hole by the aileron bell crank will need to be opened to loosen the jam nut. If the outboard dragwire is loosened, the wing tip will have to be removed to loosen the jam nut. When, loosening, keep track of the approximate number of turns, so that factory tension can be maintained. Remove the fittings by pushing them into the wing and pulling them out through the inspection hole.

INSPECTION:
Inspection of the part should be done as follows:
   1)	Perform a visual inspection of the parts under magnification of at least 10X. It is important to look at the areas that are deburred. These areas are depicted in figure 2, and are shown with cross-hatching.
   2)	Any marks, scratches, or cracks in the reference area are not acceptable. A minimal amount of scratches in the form of ScotchBriteTM scuffing is acceptable.
   3)	Perform a dye-penetrant test on the depicted areas. Inspect the part for developing cracks. If the resources are available, a Zyglo test, an ultrasonic inspection, or a X-ray could also be done.
   4)	If the parts reveal no cracks or scratches, they can be reinstalled. If there is a finding in the inspection, contact American Champion concerning the replacement of the part.
   5)	Contact American Champion Aircraft Corporation to report any findings and to field any questions. American Champion is surveying the findings and greatly appreciates all responses.

REINSTALLATION OF PARTS:
Reinstall the fittings by reversing the method used to extract them. Locate the fittings into place with two bolts*. Reconnect the dragwire to the attachment lug and cotter. Install the remaining bolts through the fitting except the AN4-10H through the compression tube fitting, dragwire lug, and spacer. Place the drag wire lug on the end of the compression tube and begin to tighten the drag wire in order to gain some clearance for the spacer. Once enough clearance is gained, install the bolt and spacer. After fitting is tight, tighten the dragwire and safety wire the bolts in place again.

Normal fabric inspection hole covers can be used for the holes cut behind the spar. Construct a patch style hole cover as illustrated in figure 1. Cut the fabric back around front inspection holes 0.5 in. Methyl Ethyl Keytone, used in sparing amounts, can be used to remove localized areas of paint. Match drill hole cover to leading edge skin and blind rivet them in place such that the cover is as flush as possible. Using appropriate fabric methods, fabric cover a 5.5 to 6 inch round patch over the hole covers. This geometry is depicted in figure 1.

APPROVAL:
Revision A to this service letter is approved by the Manager, Chicago Aircraft Certification Office, ACE-115C, by letter dated April 22, 1996, as an alternate method of compliance with AD 96-03-11, paragraph (a), for the applicable models identified herein.

*Always use new Nyloc nuts. Use standard torque value on all bolts.

FIGURE 1
FIGURE 2
======================================================================

AMERICAN CHAMPION AIRCRAFT CORP.
P.O. Box 37
32032 Washington Ave. - Hwy. D
Rochester, WI 53167
(414) 534-6315
FAX (414) 534-2395

SERVICE LETTER NO. 410

DATE: May 6, 1996

CONSIDER THIS TO BE MANDATORY 

Title:
Installation of Removable Inspection Hole Covers for Strut Fitting Removal and Repeat Inspection (already complied with service letter 408)

Applicable Models:
All 8KCAB with serial numbers 643-90 and up and all other 8KCAB fitted with service kit 403 (Retrofit metal spar wings)

Description:
This service letter details the installation of the appropriate inspection holes and cover plates for the repeat inspection of the strut attach fittings. This service letter assumes that service letter 408 has already been complied with. The hole patterns are the same between this service letter and service letter 408. If service letter 408 has not been complied with already, the procedures in service letter 411 should be used.

Procedure:
Before opening of inspection holes, support the wing tip with a large sturdy saddle. Unbolt the rear strut and the jury strut eye bolt from the front strut. Unbolt the front strut and tie down ring and remove from the front strut to wing attach fitting. The end of the strut should be supported if it is still attached to the fuselage.

With a razor blade, carefully cut the fabric around the riveted patches in the leading edge skin. Using a 1/8 in. drill, carefully drill out the blind rivets attaching the round cover plates to the leading edge skin. Remove the plates, and clean out all rivet heads and stems.

In the area where the strut fitting protrudes from the wing, cut out the fabric and acetate ring over the section where the leading edge skin was relieved for fitting removal. Remove the rest of the acetate ring. After scuffing the localized paint, fabric glue down the larger 1-10134 acetate ring as called out in figure 1*. Fabric glue 1-2444-4 patch over the top of the acetate ring as depicted in figure 1. After glue is secure, cut away excess aterial (acetate ring and fabric) that hangs over edge of inboard inspection hole and inside the acetate ring.

* Use appropriate fabric methods for all fabric work

Using the location shown in figure 1, match drill 11-0888 square cover screw attachment holes to the leading edge skin on the outside. Then, place the three Tinnerman nuts on the square cover as depicted in figure 1, and install the cover inside the wing with the screw heads exposed.

Using 11-0885 reinforcement ring, match drill the twelve attachment holes on the leading edge skin to the reinforcement ring. Then match drill the eight screw attach holes in the 11-0886 cover plate with the ring in a pattern depicted in figure 1.

Install the Tinnerman nuts on the reinforcing ring as shown in figure 1. Slide the reinforcement ring inside the wing into place. Dimple (100°) the four rivet holes that hold the ring in place. Rivet the ring in place (have Tinnermans installed) as shown in figure 1. Screw on the cover plate with the screw heads exposed. Repeat for the other inspection holes.

The following parts can be purchased from American Champion Aircraft:

	P/N		Description		Number Required   
	1-2444-4	Fabric Patch			2
	1-10134	Large Acetate Ring		2
	11-0885	Reinforcement Ring		4
	11-0886	Cover Plate			4

FIGURE 1
======================================================================

AMERICAN CHAMPION AIRCRAFT CORP.
P.O. Box 37
32032 Washington Ave. - Hwy. D
Rochester, WI 53167
(414) 534-6315
FAX (414) 534-2395

CONSIDER THIS TO BE MANDATORY

SERVICE LETTER NO. 411

Date: May 6, 1996

Title:
Installation of Removable Inspection Hole Covers for Strut Fitting Removal and Repeat Inspection

Applicable Models:
All 8KCAB with serial numbers 643-90 and up and all other 8KCAB fitted with service kit 403 (Retrofit metal spar wings)

Description: 
This service letter details the installation of the appropriate inspection holes and cover plates for the repeat inspection of the strut attach fittings. This service letter assumes that service letter 408 has not been complied with yet. The hole patterns are slightly different between this service letter and service letter 408. If service letter 408 has already been complied with, the procedures in service letter 410 should be used instead.

Procedure:
Before opening of inspection holes, support the wing tip with a large sturdy saddle. Unbolt the rear strut and the jury strut eye bolt from the front strut. Unbolt the front strut and tie down ring and remove from the front strut to wing attach fitting. The end of the strut should be supported if it is still attached to the fuselage.

Cut out the two existing inspection holes behind the front spar, already provided. Figure 1 shows the dimensional position of all the components in the area. Use this information to determine the placement of the inspection holes. Cut 3.5 in. inspection holes in the leading edge skin on either side of the rib and forward of the spar as depicted in figure 1.

Locate the holes for the corners of the strip were the leading edge skin will be relieved for fitting removal. See figure 1 for placement of the holes. The strip of material is depicted as the cross-hatched area ‘A’ (Note that this area is easier to cut out if the fitting are loose inside the wing; refer to service letter 408 or 414). Cut out the strip of leading edge material that would be needed to remove the front fitting. Again, refer to figure 1, cross-hatched area ‘A’. Remove the remaining section of the acetate ring.

The rib and attached gusset must be notched to allow the fitting to pass by the rib. Refer to figure 2 for dimensions.

After scuffing the localized paint, fabric glue down 1-10134 acetate ring as called out in figure 3*. Fabric glue 1-2444-4 patch over the top of the acetate ring as depicted in figure 3. After glue is secure, cut away excess material (acetate ring and fabric) that hangs over edge of inboard inspection hole and inside the acetate ring. Using the location shown in figure 3, match drill 11-0888 square cover screw attachment holes to the leading edge skin on the outside. Then, place the three Tinnerman nuts on the square cover as depicted in figure 3, and install the cover inside the wing with the screw heads exposed.

Using 11-0884 reinforcement ring, match drill the four holes for attaching the ring to the skin in the pattern shown in figure 3 (No. 40 drill). Then match drill the remaining eight screw attach holes in the leading edge skin (No. 30 drill). Finally, match drill the eight screw attach holes in the 11-0887 cover plate with ring.

Install the Tinnerman nuts on the reinforcing ring as shown in figure 3. Slide the reinforcement ring inside the wing into place. Dimple (100°) the four rivet holes that hold the ring in place. Rivet the ring in place (have Tinnermans installed) as shown in figure 3. Screw on the cover plate with the screw heads exposed. Repeat for the other leading edge skin inspection holes. A normal fabric inspection hole cover can be used for each of the inspection holes aft of the spar.

The following parts can be purchased from American Champion Aircraft:

	P/N		Description		Number Required
	1-2444-4	Fabric Patch			2
	1-10134	Large Acetate Ring		2
	11-0884	Reinforcement Ring		4
	11-0087	Cover Plate			4

*Use appropriate fabric methods for all fabric work

FIGURE 1
FIGURE 2
FIGURE 3
======================================================================

AMERICAN CHAMPION AIRCRAFT
P.O. Box 37
32032 Washington Ave. - Hwy. D
Rochester, WI 53167
(414) 534-6315
FAX (414) 534-2395

CONSIDER THIS TO BE MANDATORY

SERVICE LETTER NO. 412

Date: May 6, 1996

Title:
Installation of Removable Inspection Hole Covers for Strut Fitting Removal and Repeat Inspection (already complied with service letter 409)

Applicable Models:
All American Champion Aircraft 7ECA, 7GCAA, 7GCBC, and 8GCBC that were manufactured after June of 1991, and 7ECA, 7GCAA, 7GCBC, 7KCAB, and 8GCBC that have purchased metal spar wings. (i.e. those that are affected by AD 96-03-11, but are not 8KCAB)

Description:
This service letter details the installation of the appropriate inspection holes and cover plates for the repeat inspection of the strut attach fittings. This service letter assumes that service letter 409 has already been complied with. The hole patterns are the same between this service letter and service letter 409. If service letter 409 has not been complied with already, the procedures in service letter 413 should be used.

Procedure:
With a razor blade, carefully cut the fabric around the riveted patches in the leading edge skin. Using a 1/8 in. drill, carefully drill out the blind rivets attaching the round cover plates to the leading edge skin. Remove the plates, and clean out all rivet heads and stems.

Using 11-0885 reinforcement ring, match drill the twelve attachment holes on the leading edge skin to the reinforcement ring. Then match drill the eight screw attach holes in the 11-0886 cover plate with the ring in a pattern depicted in figure 1. The reinforcement ring (11-0885) and the cover plate (11-0886) can be purchased from American Champion Aircraft.

Install the Tinnerman nuts on the reinforcing ring as shown in figure 1. Slide the reinforcement ring inside the wing into place. Dimple (100°) the four rivet holes that hold the ring in place. Rivet the ring in place (have Tinnermans installed) as shown in figure 1. Screw on the cover plate with the screw heads exposed. Repeat for the other wing.

FIGURE 1
======================================================================

AMERICAN CHAMPION AIRCRAFT CORP.
P.O. Box 37
32032 Washington Ave. - Hwy. D
Rochester, WI 53167
(414) 534-6315
FAX (414) 534-2395

CONSIDER THIS TO BE MANDATORY

SERVICE LETTER NO. 413

DATE: May 6, 1996

Title:
Installation of Removable Inspection Hole Covers for Strut Fitting Removal and Repeat Inspection

Applicable Models:
All American Champion Aircraft 7ECA, 7GCAA, 7GCBC, and 8GCBC that were manufactured after June of 1991, and 7ECA, 7GCAA, 7GCBC, 7KCAB, and 8GCBC that have purchased metal spar wings. (i.e. those that are affected by AD 96-03-11, but are not 8KCAB)

Description:
This service letter details the installation of the appropriate inspection holes and cover plates for the repeat inspection of the strut attach fittings. This service letter assumes that service letter 409 has not been complied with yet. The hole patterns are slightly different between this service letter and service letter 409. If service letter 409 has already been complied with, the procedures in service letter 412 should be used instead.

Procedure:
Cut out the existing inspection hole behind the front spar, already provided. Figure 1 shows the dimensional position of all the components in the area. Use this information to determine the placement of the inspection hole in the leading edge skin. Cut a 3.5 in. inspection holes in the leading edge skin forward of the spar as depicted in figure 1.

Using 11-0884 reinforcement ring, match drill the four holes for attaching the ring to the skin in the pattern shown in figure 1 (No. 40 drill). Then match drill the remaining eight screw attach holes in the leading edge skin (No. 30 drill). Finally, match drill the eight screw attach holes in the 11-0887 cover plate with ring. The reinforcement ring (11-0884) and the cover plate (11-0887) can be purchased from American Champion Aircraft.

Install the Tinnerman nuts on the reinforcing ring as shown in figure 1. Slide the reinforcement ring inside the wing into place. Dimple (100°) the four rivet holes that hold the ring in place. Rivet the ring in place (have Tinnermans installed) as shown in figure 1. Screw on the cover plate with the screw heads exposed. Repeat for the other wing. A normal fabric inspection hole cover can be used for each of the inspection holes aft of the spar.

FIGURE 1
======================================================================

AMERICAN CHAMPION AIRCRAFT CORP.
American Champion Aircraft
P.O. Box 37
32032 Washington Ave. - Hwy. D
Rochester, WI 53167
(414) 534-6315
FAX (414) 534-2395

CONSIDER THIS TO BE MANDATORY

SERVICE LETTER NO. 414 (revision A)

DATE: June 25, 1996

Title:
Repeat Inspection of Front Strut Fittings 3-1691
{Replacement of 3-1632 Fittings with 3-1691 Fittings}

Applicable Models:
All 8 KCAB with serial numbers 643-90 and up; also all other 8KCAB fitted with service kit 403 (Retrofit metal spar wings)

Inspection Interval:
1000 hours of flight time after installation of Fittings P/N 3-1691, and at 1000 flight hour intervals thereafter.

Note: These inspections are mandatory per American Champion Aircraft Corp. Airworthiness Limitations section of the Decathlon Model 8KCAB Service Manual.

Description:
The 3-1691 strut attach fitting has a damage tolerance inspection interval of 1000 hours. This service letter describes the removal and inspection of these fittings. However, this service letter assumes that inspection access holes have been installed in accordance with Service Letter 410 or 411, "Installation of Removable Inspection Hole Covers For Strut Fitting Removal and Repeat Inspection", or in accordance with an alternate means of compliance. Installation of removable covers (such as the above service letters) must be done before this inspection.

The removal and installation procedures contained herein can be used to replace 3-1632 fittings with 3-1691 fittings as well. Key differences and important notes are described within the text and are surrounded with brackets: { }. Newly installed 3-1691 fittings do not have to go through the inspection procedures during initial installation.

The inspection procedures described herein are not intended to be a substitute for a properly performed 100 hour/annual inspection.

Removal of Parts:
Before opening of inspection holes, support the wing tip with a large sturdy saddle. Unbolt the rear strut and the jury strut eye bolt from the front strut. Unbolt the front strut and tie down ring and remove from the front strut to wing attach fitting. The end of the strut should be supported if it is still attached to the fuselage. Remove the four round inspection hole covers by the strut attach fitting. Then, remove the small square cover plate next to the strut attach fitting.

After cutting the safety wire, remove all fitting attach hardware including the compression tube spacer. {If the 3-1691 fittings are replacing previously installed 3-1632-1 and 3-1632-2 fittings, the spacer is no longer necessary.} Tighten one of the attached dragwires on the attachment lug to gain some clearance. If the inboard dragwire is tightened, the inspection hole by the aileron bell crank will need to be opened to loosen the jam nut. If the outboard dragwire is tightened, the wing tip will have to be removed to loosen the jam nut. When tightening dragwire, keep track of the number of turns, so that upon reassembly, factory tension can be restored. {Remove the 3-1632 aft fitting by pushing it into the wing and pulling it out through the inboard inspection hole.} Remove the 3-1691 aft fitting by pulling it through the loose area of fabric inside the acetate ring. Remove the front fitting by pulling it through the relieved section of the leading edge skin.

Inspection:
Inspection of the part should be done as follows:
   1)	Perform a visual inspection of the entire part under magnification of at least 10X.
   2)	Perform a 100% fluorescent liquid dye penetrant inspection of each fitting. Both sides of the fitting must be inspected with particular attention paid to the bores of each hole.

	Notes:
	(1)	The penetrant used must meet Specification MIL-I-25135.
	(2)	The inspection procedure must comply with MIL-STD-6866.
	(3)	The inspection must satisfy the requirements of the appropriate portions of MIL-STD-410.

   3)	Optional recommended additional inspection are eddy current, ultrasonic, and X-ray.

Rejection Criteria:
   1)	Any fitting found to have a crack, no matter how small, is unairworthy. It must be replaced with an airworthy part before further flight.
   2)	Any fitting found to be corroded or to have elongated bolt holes is unairworthy. It must be replaced with an airworthy part before further flight.

Note: Notify American Champion Aircraft of any fitting found to be unairworthy, or to answer any questions regarding fitting removal, inspection, and reinstallation. American Champion Aircraft is surveying service experience, and greatly appreciates all responses.

Reinstallation of Parts:
Reinstall the fittings by reversing the method used to extract them. {When replacing 3-1632 aft fittings with 3-1691 fittings, fabric may have to be relieved with a ¼" cut; slide fittings through the slots that they protrude from.} Install the attach bolts* through the fittings except for the AN4H-10A through the compression tube fitting and dragwire lug. {Replace the two inboard spar to fitting bolts (AN4-7A) with AN4-10A bolts (requiring AN960-416L thin washers).} Loosen the previously tightened dragwire back to factory tension such that it lines up with the bolt hole and reinstall bolt. Retighten the jam nuts on the dragwire. Safety wire the bolts in place again. Using the open inspection covers, reinstall the square fitting cover plate first. Then reinstall all the remaining inspection hole covers.

Log Book Entry:
At the completion of each required inspection, record in the airplane’s log book, the results of the inspection as required by the Airworthiness Limitations Section of the Decathlon Model 8KCAB Service Manual.

*Always use new Nyloc nuts. Use torque values per AC 43.13-1A.
======================================================================

AMERICAN CHAMPION AIRCRAFT CORP.
P.O. Box 37
32032 Washington Ave. - Hwy. D
Rochester, WI 53167
(414) 534-6315
FAX (414) 534-2395

CONSIDER THIS TO BE MANDATORY

SERVICE LETTER NO. 415 (revision A)

DATE: June 25, 1996 

Title:
Repeat Inspection of Front Strut Fittings 3-1692
{Replacement of 3-1646 Fittings with 3-1692 Fittings}

Applicable Models:
All American Champion Aircraft 7ECA, 7GCAA, 7GCBC, and 8GCBC that were manufactured after June of 1991, and 7ECA, 7GCAA, 7GCBC, 7KCAB, and 8GCBC that have retrofitted with metal spar wings. (i.e. those that are affected by AD 96-03-11, but are not 8KCAB)

Inspection Interval:
1000 hours of flight time after installation of Fittings P/N 3-1692, and at 1000 flight hour intervals thereafter.

Note: These inspections are mandatory per American Champion Aircraft Corp. Airworthiness Limitations Section of the Service Manuals for airplanes: Citabria Model 7ECA, 7GCAA, 7GCBC, and 7KCAB; Scout Model 8GCBC.

Description:
The 3-1692 strut attach fitting has a damage tolerance inspection interval of 1000 hours. This service letter describes the removal and inspection of these fittings. However, this service letter assumes that inspection access holes have been installed in accordance with Service Letter 412 or 413 "Installation of Removable Inspection Hole Covers For Strut Fitting Removal and Repeat Inspection", or in accordance with an alternate means of compliance. Installation of removable covers (such as the above service letters) must be done before this inspection.

The removal and installation procedures contained herein can be used to replace 3-1646 fittings with 3-1692 fittings as well. Key differences and important notes are described within the text and are surrounded with brackets: { }. Newly installed 3-1692 fittings do not have to go through the inspection procedures during initial installation.

The inspection procedures described herein are not intended to be a substitute for a properly performed 100 hour/annual inspection.

Removal of Parts:
Before opening of inspection holes, support the wing tip with a large sturdy saddle. Unbolt the rear strut and the jury strut eye bolt from the front strut. Unbolt the front strut and tie down ring and remove from the front strut to wing attach fitting. The end of the strut should be supported if it is still attached to the fuselage. Remove the two round inspection hole covers by the strut attach fitting.

After cutting the safety wire, remove all fitting attach hardware including the compression tube spacer. {If the 3-1692 fittings are replacing previously installed 3-1646 L/R fittings, the spacer is no longer necessary.} Tighten one of the attached dragwires on the attachment lug to gain some clearance. If the inboard dragwire is tightened, the inspection hole by the aileron bell crank will need to be opened to loosen the jam nut. If the outboard dragwire is tightened, the wing tip will have to be removed to loosen the jam nut. When, tightening dragwire, keep track of the number of turns, so that upon reassembly, factory tension can be restored. Remove the fittings by pushing it into the wing and pulling it out through the inspection hole.

Inspection:
Inspection of the part should be done as follows:
   1)	Perform a visual inspection of the entire part under magnification of at least 10X.
   2)	Perform a 100% fluorescent liquid dye penetrant inspection of each fitting. Both sides of the fitting must be inspected with particular attention paid to the bores of each hole.

	Notes:
	   (1)	The penetrant used must meet Specification MIL-I-25135.
	   (2)	The inspection procedure must comply with MIL-STD-6866.
	   (3)	The inspection must satisfy the requirements of the appropriate portions of MIL-STD-410.

   3)	Optional recommended additional inspection are eddy current, ultrasonic, and X-ray.

Rejection Criteria:
   1)	Any fitting found to have a crack, no matter how small, is unairworthy. It must be replaced with an airworthy part before further flight.
   2)	Any fitting found to be corroded or to have elongated bolt holes is unairworthy. It must be replaced with an airworthy part before further flight.

Note: Notify American Champion Aircraft of any fitting found to be unairworthy, or to answer any questions regarding fitting removal, inspection, and reinstallation. American Champion Aircraft is surveying service experience, and greatly appreciates all responses.

Reinstallation of Parts:
Reinstall the fittings by reversing the method used to extract them. Install all attach bolts* through the fittings except for the AN4H-10A through the compression tube fitting and dragwire lug. {Replace the two inboard spar to fitting bolts (AN4-7A) with AN4-10A bolts (requiring AN960-416L thin washers).} Loosen the previously tightened dragwire back to factory tension so that it lines up with the bolt hole and reinstall the bolt. Retighten the jam nuts on the dragwire. Safety wire the bolts in place again. Reinstall inspection hole covers.

Log Book Entry:
At the completion of each required inspection, record in the airplane’s log book, the results of the inspection as required by the Airworthiness Limitations Section of the appropriate (Citabria Model Series, or Scout Model Series) Service Manual.

*Always use new Nyloc nuts. Use torque value per AC 43.13-1A