[Federal Register: November 3, 1997 (Volume 62, Number 212)] [Proposed Rules] [Page 59310-59313] From the Federal Register Online via GPO Access [wais.access.gpo.gov] [DOCID:fr03no97-15] ======================================================================= ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 97-CE-79-AD] RIN 2120-AA64 Airworthiness Directives; American Champion Aircraft Corporation 7, 8, and 11 Series Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes to adopt a new airworthiness directive (AD) that would apply to American Champion Aircraft Corporation (ACAC) 7, 8, and 11 series airplanes, excluding Model 8GCBC airplanes. The Federal Aviation Administration (FAA) previously proposed similar AD action for the ACAC Model 8GCBC airplanes. The proposed AD would require installing inspection holes on the top and bottom wing surfaces, repetitively inspecting the front and rear wood spars for damage, repairing or replacing any damaged wood spar, and installing inspection covers. Damage is defined as cracks; compression cracks; longitudinal cracks through the bolt holes or nail holes; or loose or missing rib nails. The proposed AD results from a review of the service history of the affected airplanes that incorporate wood wing spars. The review was prompted by in-flight wing structural failures on ACAC Model 8GCBC airplanes, and revealed several incidents where damage was found on the front and rear wood spars on the affected airplanes. The actions specified by the proposed AD are intended to prevent possible compression cracks and other damage in the wood spar wing, which, if not detected and corrected, could eventually result in in-flight structural failure of the wing with consequent loss of the airplane. DATES: Comments must be received on or before January 8, 1998. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 97-CE-79-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Comments may be inspected at this location between 8 a.m. and 4 p.m., Monday through Friday, holidays excepted. Service information that applies to the proposed AD may be obtained from American Champion Aircraft Corporation, P.O. Box 37, 32032 Washington Avenue, Highway D, Rochester, Wisconsin 53167. This information also may be examined at the Rules Docket at the address above. FOR FURTHER INFORMATION CONTACT: Mr. William Rohder, 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: Comments Invited Interested persons are invited to participate in the making of the proposed rule by submitting such [[Page 59311]] 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, specified above, will be considered before taking action on the proposed rule. The proposals contained in this notice may be changed in light of the comments received. Comments are specifically invited on the overall regulatory, economic, environmental, and energy aspects of the proposed 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 proposal will be filed in the Rules Docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket No. 97-CE-79-AD.'' The postcard will be date stamped and returned to the commenter. Availability of NPRMs Any person may obtain a copy of this NPRM by submitting a request to the FAA, Central Region, Office of the Regional Counsel, Attention: Rules Docket No. 97-CE-79-AD, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Discussion AD 87-18-09, Amendment 39-5725, currently requires inspecting (one- time) the sides of the front and rear wood spars for compression cracks on ACAC Model 8GCBC airplanes, repairing or replacing any wood spar with compression cracks, and re-inspecting immediately after any incident involving wing damage. AD 87-18-09 was the result of three accidents involving ACAC Model 8GCBC airplanes where structural damage to the wing caused by compression cracks in a wood spar was considered to be a primary factor of the accidents. Wood compression cracks are failures of wood fibers on a plane perpendicular to the wood fiber longitudinal axis. Repetitive high stress can initiate these compression cracks on the top surface of the wing spar that is adjacent to doubler plate glue lines and rib nail holes. These high stress conditions can occur during crop dusting, banner and glider tow operations, turbulence, and rough field or float operations. Compression cracks can also initiate if the wing contacts the ground. Compression cracks can initiate at either the top or bottom surface of the spar depending on the loads (either upward or downward) at impact. In-flight structural failure of the wing recently occurred on an ACAC Model 8GCBC airplane that was initially inspected as required by AD 87-18-09. A possible contributing factor of this incident was an undetected compression crack on the right wing front spar. Investigation of this accident and data acquired from inspections of several ACAC Model 8GCBC airplanes indicate that wood spar compression cracks can occur without previous wing damage. The data indicates that detection of compression crack initiation is unlikely on the sides of the spar, unless the crack is in an advanced state of propagation. Based on this data, the FAA believes that repetitive inspections are necessary. The FAA recently issued an NPRM on the Model 8GCBC airplanes that was published in the Federal Register on September 26, 1997 (62 FR 50527). This NPRM proposes to supersede AD 87-18-09, and, if issued as a final rule, would require similar action to that proposed in this document. Reasons for the Proposed AD The above-referenced incidents on the ACAC Model 8GCBC airplanes prompted the FAA to review the service history of the other ACAC 8 series airplanes, as well as the 7 and 11 series airplanes. The FAA has record of eight reports of accidents (five fatal) on ACAC 7 and 8 series airplanes, other than the Model 8GCBC airplanes. Four of these accidents are attributed to overstress, two to wing failure due to previous damage going undetected, one to an overload condition with evidence of wing panel failure prior to impact, and one spar with an out-of-specification wood spar grain slope. This review revealed 16 reports of spar crack damage (spar butt end and/or longitudinal cracks), 6 reports of compression cracked spars, and 13 reports of loose/missing rib nails. These reports break down as follows: --Model 7AC (2,626 U.S. registered airplanes): 12 reports of spar crack damage, plus 2 reports of loose/missing rib nails; --Model 7BCM (253 U.S. registered airplanes): 1 report of spar crack damage; --Model 7ECA (871 U.S. registered airplanes): 1 report of a compression cracked spar, plus 6 reports of loose/missing rib nails; --Model 7GCBC (829 U.S. registered airplanes): 1 report of a compression cracked spar; --Model 7KCAB (482 U.S. registered airplanes): 2 reports of spar crack damage, 2 reports of compression cracked spars, and 3 reports of loose/ missing rib nails; and --Model 8KCAB (480 U.S. registered airplanes): 1 report of spar crack damage, 2 reports of compression cracked spars, and 2 reports of loose/ missing rib nails. The FAA believes that many cracked/damaged spars are not reported because general aviation operators (operating in accordance with part 91 of the Federal Aviation Regulations (14 CFR part 91)) are not required to submit service difficulty reports. Relevant Service Information The FAA has reviewed and approved the technical contents of ACAC Service Letter 406, dated March 28, 1994, and ACAC Service Letter 417, Revision A, dated October 2, 1997. ACAC Service Letter 406, dated March 28, 1994, includes procedures for conducting a detailed visual inspection of both the front and rear wood wing spars for cracks; compression cracks; longitudinal cracks through the bolt holes or nail holes; and loose or missing rib nails (referred to as damage hereafter). ACAC Service Letter 417, Revision A, dated October 2, 1997, includes procedures for installing inspection holes and surface covers and assuring that all applicable lower surface drain holes are installed. The FAA's Determination After examining the circumstances and reviewing all available information related to the incidents and accidents described above, including the referenced service information, the FAA has determined that (1) the wing design of all 7, 8, and 11 series airplanes equipped with wood spars is similar and is conducive to spar cracks/damage; and (2) AD action should be taken to prevent possible compression cracks and other damage in the wood spar wing, which, if not detected and corrected, could eventually result in in-flight structural failure of the wing with consequent loss of the airplane. Explanation of the Provisions of the Proposed AD Since an unsafe condition has been identified that is likely to exist or develop in other ACAC 7, 8, and 11 series airplanes (excluding the Model 8GCBC airplanes) of the same type design, the FAA is proposing AD action. The proposed AD would require installing inspection holes on the top [[Page 59312]] and bottom wing surfaces, repetitively inspecting the front and rear wood spars for damage, repairing or replacing any damaged wood spar, and installing surface covers. Accomplishment of the proposed actions would be as follows: --Installations: in accordance with ACAC Service Letter 417, Revision A, dated October 2, 1997; --Inspections: in accordance with ACAC Service Letter 406, dated March 28, 1994; and --Spar Repair and Replacement, as applicable: in accordance with Advisory Circular (AC) 43-13-1A, Acceptable Methods, Techniques and Practices; or other data that the FAA has approved for spar repair and replacement. Differences Between This Proposed AD and ACAC Service Letter 406 ACAC Service Letter 406, dated March 28, 1994, specifies the same inspections as are proposed in this notice of proposed rulemaking (NPRM). The differences between the service letter and NPRM are: --the service letter specifies the proposed action within the next 30 days or 10 flight hours and at each 100 hour/annual inspection thereafter. The FAA has determined that a more realistic and enforceable compliance time would be to require: 1. The proposed initial inspection at the first annual inspection that occurs 3 calendar months or more after the effective date of the AD or within 15 calendar months after the effective date of the AD, whichever occurs first; and 2. The proposed repetitive inspections thereafter at intervals not to exceed 12 calendar months or 500 hours time-in-service (TIS), whichever occurs first; and --the service letter applies to all ACAC 7 and 8 series airplanes, whereas the NPRM applies to ACAC 7, 8, and 11 series airplanes with similar design, except for the Model 8GCBC airplanes. The FAA previously proposed similar AD action for the ACAC Model 8GCBC airplanes, Docket No. 97-CE-33-AD (62 FR 50527, September 26, 1997). Compliance Time of the Proposed AD The compliance time of the proposed AD is presented in calendar time and hours TIS. Although the unsafe condition specified in the proposed AD is a result of airplane operation, operators of the affected airplanes utilize their airplanes in different ways. For example, an operator may utilize his/her airplane 50 hours TIS in a year while utilizing the aircraft in no or very little crop dusting operations, banner and glider tow operations, or rough field or float operations. This airplane would obviously have a lower crack propagation rate than an airplane operated 300 hours TIS a year in frequent crop dusting operations, banner and glider tow operations, or rough field or float operations. However, this airplane could have pre- existing and undetected wood spar damage that occurred during previous operations. In this situation, the damage to the wood spar would propagate at a level that depends on the operational exposure of the airplane and severity of the initial wood spar damage. To assure that compression cracks do not go undetected in the wood spars of the affected airplanes, the FAA has determined that the following compliance times should be used: 1. The proposed initial inspection at the first annual inspection that occurs 3 calendar months or more after the effective date of the AD or within 15 calendar months after the effective date of the AD, whichever occurs first; and 2. The proposed repetitive inspections thereafter at intervals not to exceed 12 calendar months or 500 hours TIS, whichever occurs first. Cost Impact The FAA estimates that 6,440 airplanes in the U.S. registry would be affected by the proposed AD, that it would take approximately 6 workhours (Installations: 5 workhours; Initial Inspection: 1 workhour) per airplane to accomplish the proposed action, and that the average labor rate is approximately $60 an hour. Parts cost approximately $292 per airplane, provided that each airplane would only need 11 additional standard inspection hole covers per wing bottom surface (total of 22 new covers per airplane). If the airplane would require the installation of more inspection covers (i.e., a result of previous non- factory wing recover work), the cost could be slightly higher. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $4,198,880 or $652 per airplane. This cost figure is based on the presumption that no affected airplane owner/operator has accomplished the installations or the initial inspection. The FAA has no knowledge of any owner/operator of the affected airplanes that has already accomplished the installations and initial inspection. This cost figure also does not account for repetitive inspections. The FAA has no way of determining the number of repetitive inspections each owner/operator of the affected airplanes will incur over the life of his/her airplane. However, each proposed repetitive inspection would cost substantially less than the initial inspection because of the cost of the initial proposed inspection hole and cover installations would not be repetitive. The inspection covers allow easy access for the inspection of the wood spars, and the proposed compliance time would enable the owners/operators of the affected airplanes to accomplish the repetitive inspections at regularly scheduled annual inspections. Regulatory Impact The regulations proposed herein would 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 proposal would not have sufficient federalism implications to warrant the preparation of a Federalism Assessment. For the reasons discussed above, I certify that this action (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) if promulgated, will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A copy of the draft regulatory evaluation prepared for this action has been placed in the Rules Docket. A copy of it may be obtained by contacting the Rules Docket at the location provided under the caption ADDRESSES. List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Safety. The Proposed Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration proposes to amend 14 CFR part 39 of the Federal Aviation Regulations 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. [[Page 59313]] Sec. 39.13 [Amended] 2. Section 39.13 is amended by adding a new airworthiness directive (AD) to read as follows: American Champion Aircraft Company: Docket No. 97-CE-79-AD. Applicability: The following airplane models, all serial numbers, certificated in any category, that are equipped with wood wing spars: 7AC 7BCM (L-16A) 7DC S7EC 7GC 7GCB 7HC 7KCAB S11AC 7ACA 7CCM (L-16B) S7DC 7ECA 7GCA 7GCBA 7JC 8KCAB 11BC S7AC S7CCM 7EC 7FC 7GCAA 7GCBC 7KC 11AC S11BC Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been modified, altered, repaired, or reconfigured in the area subject to the requirements of this AD. For airplanes that have been modified, altered, repaired, or reconfigured 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 (e) 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 indicated in the body of this AD, unless already accomplished. To prevent possible compression cracks and other damage in the wood spar wing, which, if not detected and corrected, could eventually result in in-flight structural failure of the wing with consequent loss of the airplane, accomplish the following: (a) At the first annual inspection that occurs 3 calendar months or more after the effective date of this AD or within the next 15 calendar months after the effective date of this AD, whichever occurs first, accomplish the following: (1) Install inspection holes in the top and bottom surface of each wing in accordance with American Champion Aircraft Corporation (ACAC) Service Letter 417, Revision A, dated October 2, 1997. Assure that all drainage holes are installed as depicted in this service letter, and install drainage holes as necessary. (2) Inspect (detailed visual) both the front and rear wood wing spars for cracks; compression cracks; longitudinal cracks through the bolt holes or nail holes; and loose or missing rib nails (referred to as damage hereafter). Accomplish these inspections in accordance with ACAC Service Letter 406, dated March 28, 1994. (3) If any spar damage is found, prior to further flight, accomplish the following: (i) Repair or replace the wood wing spar in accordance with Advisory Circular (AC) 43-13-1A, Acceptable Methods, Techniques and Practices; or other data that is approved by the FAA for wing spar repair or replacement. (ii) If the wing is recovered, accomplish the installations required by paragraph (a)(1) of this AD, as applicable. (4) Install inspection hole covers on the top and bottom surface of the wing in accordance with ACAC Service Letter 417, Revision A, dated October 2, 1997. (b) Within 12 calendar months or 500 hours TIS (whichever occurs first) after accomplishing all actions required by paragraph (a) of this AD, and thereafter at intervals not to exceed 12 calendar months or 500 hours TIS, whichever occurs first, accomplish the inspection, repair, replacement, and installation required by paragraphs (a)(2), (a)(3), as applicable; including its subparagraphs; and (a)(4) of this AD. (c) If, after the effective date of this AD, any of the affected airplanes are involved in an incident/accident that involves wing contact damage (e.g., surface deformations such as abrasions, gouges, scratches, or dents, etc.), prior to further flight after that incident/accident, accomplish the inspection, repair, replacement, and installation required by paragraphs (a)(2), (a)(3), as applicable; including its subparagraphs; and (a)(4) of this AD. (d) 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. (e) 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. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Chicago ACO. (f) All persons affected by this directive may obtain copies of the documents referred to herein upon request to American Champion Aircraft Corporation, P.O. Box 37, 32032 Washington Avenue, Highway D, Rochester, Wisconsin 53167; or may examine these documents at the FAA, Central Region, Office of the Regional Counsel, Room 1558, 601 E. 12th Street, Kansas City, Missouri 64106. Issued in Kansas City, Missouri, on October 27, 1997. Mary Ellen A. Schutt, Acting Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. 97-28984 Filed 10-31-97; 8:45 am] BILLING CODE 4910-13-U