AD 96-03-11

This amendment adopts a new airworthiness directive (AD) that applies to American Champion Aircraft Corporation (American Champion) Models 8KCAB, 8GCBC, 7GCBC, and 7ECA airplanes that are equipped with metal spar wings. This action requires inspecting (one-time) the wing front strut fittings for cracks or scratches, replacing any wing front strut fittings found cracked or scratched, and reporting the inspection results to the Federal Aviation Administration (FAA). Fatigue cracks found on the wing front strut fittings on two Model 8KCAB airplanes prompted this action. The actions specified by this AD are intended to prevent structural failure of a wing assembly caused by cracked or scratched wing front strut fittings, which, if not detected and corrected, could result in loss of control of the airplane.

Final rule; request for comments.

96-03-11 AMERICAN CHAMPION AIRCRAFT CORPORATION: Amendment 39-9508; Docket No. 96-CE-08-AD.

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 762-95;

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

- Model 8GCBC airplanes, serial numbers 361-91 through 374-95;

- 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 1212-95;

- Model 7GCBC airplanes, all serial numbers, that are equipped with metal spar wings, wing assembly part number 7-1541;

- Model 7ECA airplanes, serial numbers 1355-95 through 1357-95; and

- Model 7ECA 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 (d) 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 as follows:

- Within the next 50 hours time-in-service after the effective date of this AD, unless already accomplished; and

- Upon the installation of metal spar wings, unless the replacement wings have been inspected in accordance with this AD prior to installation.

To prevent structural failure of a wing assembly caused by cracked or scratched wing front strut fittings, which, if not detected and corrected, could result in loss of control of the airplane, accomplish the following:

(a) Inspect the wing front strut fittings for cracks, scratches, or surface deformities in accordance with the instructions in American Champion Aircraft Corporation Service Letter 408, dated January 24, 1996. Figure 3 of Service Letter 408 depicts the crosshatched areas of the fittings that must be inspected. This service letter specifies both a visual inspection and the choice of either a dye penetrant, Zyglo test, ultrasonic, or x-ray inspection. Prior to further flight, replace any wing front strut fitting that has any crack, scratch, or surface deformity, with a wing front strut fitting that is found to be free of cracks, scratches, and surface deformities. Accomplish this replacement in accordance with the instructions in the applicable maintenance manual.

NOTE 2: American Champion Aircraft Corporation Service Letter 408 specifies replacing the wing strut fitting if scratches are found that are deeper than 0.010 inch. This AD requires replacing the wing strut fitting if any scratch is found and takes precedence over that specified in the service letter.

NOTE 3: American Champion Service Letter 408 only references wing front strut fittings, part numbers 3-1632-1 and 3-1632-2. Certain airplanes will incorporate wing front strut fittings, part numbers 3-1646R and 3-1646L, depending on the specific airplane design. The design of the critical area of the strut is the same and the inspection procedures apply to all of the above-referenced wing front strut fitting part numbers.

(b) Send the results of the inspection required by paragraph (a) of this AD within 10 calendar days after the inspection to the Manager, Chicago Aircraft Certification Office (ACO), 2300 E. Devon, room 232, Des Plaines, Illinois 60018. Include the airplane serial number, and the condition and number of hours time-in-service of each cracked or scratched wing front strut fitting at the time of inspection. (Reporting approved by the Office of Management and Budget under OMB no. 2120-0056.)

(c) 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.

(d) An alternative method of compliance or adjustment of the compliance time that provides an equivalent level of safety may be approved by the Manager, Chicago ACO, at the address specified in paragraph (b) of this AD. The request shall be forwarded through an appropriate FAA Maintenance Inspector, who may add comments and then send it to the Manager, Chicago ACO.NOTE 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Chicago ACO.

(e) The inspections required by this AD shall be done in accordance with American Champion Aircraft Corporation Service Letter 408, dated January 24, 1996. 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. Copies may be obtained from 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., 7th Floor, suite 700, Washington, DC.

(f) This amendment becomes effective on February 26, 1996.

The FAA has received a report of an American Champion Model 8KCAB airplane breaking apart in flight and resulting in a fatal accident. The cause of the accident is attributed to the pilot operating the airplane outside of its approved flight envelope during aerobatic instruction. During the accident investigation, the National Transportation Safety Board (NTSB), American Champion, and the FAA examined the remains of the accident airplane, including the separated pieces of the wing and fuselage structure. This examination revealed fatigue cracking of the wing front strut fittings.

The design of the wing and fuselage structure 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. In the above-referenced accident,the forward fitting fractured through the transition area (approximately in the center of the fitting length), causing the fitting to separate. This wing strut 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 indicates that these fatigue cracks formed in scratches and surface deformities that resulted during the manufacturing process, and existed prior to the accident.

Since the accident, the FAA and American Champion have inspected another Model 8KCAB airplane and found fatigue cracks on two of the four wing strut fittings. These fatigue cracks also originated from scratches and surface deformities in the wing front strut fitting. In addition, evaluation of new uninstalled wing front strut fittings reveal these scratches and surface deformities.

American Champion Models 8GCBC, 7GCBC, and 7ECA airplanes incorporate the same design fitting that the Model 8KCAB airplanes incorporate. The fittings of these airplanes do incur lower stress levels compared to the fittings of the Model 8KCAB airplanes; however, the FAA does not know at what stress levels fatigue cracks will form in the area of scratches or surface deformities of these fittings, and how many or which fittings have scratches or surface deformities as a result of the manufacturing process.

The FAA does know that the accident airplane had accumulated approximately 890 hours time-in-service (TIS) and the airplane inspected that had fatigue cracks in two of the four wing front strut fittings had accumulated about 200 hours TIS. While a full analysis of the fatigue crack growth on these fittings is currently taking place, the FAA feels that the above range of hours TIS on the two aircraft found with fatigue cracks presents an immediate unsafe condition on the American Champion Models 8KCAB, 8GCBC, 7GCBC, and 7ECA airplanes that may have scratches or surface deformities on any wing front strut fitting.

American Champion has issued Service Letter 408, dated January 24, 1996, which specifies procedures for inspecting the wing front strut fittings for cracks or scratches. This service letter includes a figure that depicts the crosshatched areas of the wing front strut fittings to be inspected.

After examining the circumstances and reviewing all available information related to the incidents described above including the referenced service letter, the FAA has determined that (1) the wing fittings of all American Champion airplane models that incorporate metal wing spars should be inspected to detect and correct any cracks, scratches, or surface deformities; and (2) AD action should be taken to prevent structural failure of a wing assembly caused by cracked or scratched wing front strut fittings, which, if not detected and corrected, could result in loss of control of the airplane.

Since an unsafe condition has been identified that is likely to exist or develop in other American Champion Models 8KCAB, 8GCBC, 7GCBC, and 7ECA airplanes of the same type design that are equipped with metal spar wings, this AD requires inspecting (one-time) the wing front strut fittings for cracks, scratches, or surface deformities, and replacing any wing front strut fittings found with cracks, scratches, or surface deformities. The proposed AD would also require the owners/operators of the affected airplanes to report the results of the one-time inspection to the FAA. The FAA will then analyze these reports to determine whether additional rulemaking (repetitive inspections, modifications, etc.) is necessary for these airplanes. Accomplishment of the inspection is in accordance with American Champion Service Letter 408. This service letter also depicts the crosshatched areas of the wing front strut fittings to be inspected. The replacement (if necessary) is accomplished in accordance with the applicable maintenance manual.

Since a situation exists (possible structural failure of the wing assembly caused by cracked or scratched wing front strut fittings) that requires the immediate adoption of this regulation, it is found that notice and opportunity for public prior 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-08-AD." The postcard will be date stamped and returned to the commenter.

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 USC 106(g), 40113, 44701.

Section 39.13 - [AMENDED]
2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: