Federal Register/Vol. 64, No. 107/Friday, June 4, 1999/Proposed Rules

1997 (62 FR 59310). The NPRM proposed to 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 surface covers. Accomplishment of the proposed actions as specified in the NPRM would be required 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. Interested persons have been afforded an opportunity to participate in the making of this amendment. Due consideration has been given to the comments received. Comment Issue No. 1: Combine the Actions of the Proposed AD With Those of AD 98–05–04 Two commenters recommend that the FAA combine the actions of the proposed AD with those currently required by AD 98–05–04, which applies to the Model 8GCBC airplanes. These commenters feel that this would 29970 Federal Register / Vol. 64, No. 107 / Friday, June 4, 1999 / Proposed Rules provide a successful and consistent inspection program for all airplanes in the production line. The FAA concurs that combining the actions of the proposed AD and AD 98– 05–04 would provide a consistent inspection program for all ACAC airplanes in the production line. As discussed in this document, the FAA is withdrawing the NPRM (Docket No. 97– CE–79–AD) and will propose to supersede AD 98–05–04 with a new AD (will be initiated as an NPRM) that would affect all 7, 8, and 11 series airplanes and incorporate recommended alternative methods for complying with the actions. Comment Issue No. 2: Allow an Alternative Spar Inspection Method Three commenters state that inspecting the spar through the utilization of inspection holes on the bottom of the spar using mirrors and a small high intensity light source is an effective method of inspection. The commenters believe that allowing this inspection method will save the owners thousands of dollars in inspection costs. Also, because the additional inspection covers would not be needed, the aesthetics of the aircraft would be preserved. The FAA concurs that inspecting the spar through the utilization of inspection holes in the bottom of the spar using mirrors and a small high intensity light is a valid inspection method provided an inspector with wood spar compression failure experience accomplishes the inspection. For example, the inspection method was useful in detecting spar failure on one of the commenter’s airplanes, and a member of the FAA’s Chicago Aircraft Certification Office staff detected a compression failure in the rear spar of a Model 7AC airplane using this method. ACAC has incorporated procedures to accomplish this inspection method into Service Letter 406, Revision A, dated May 6, 1998, and the FAA has approved this inspection method as an alternative method of compliance to AD 98–05–04, which applies to the Model 8GCBC airplanes. The owners of the Model 8GCBC have been informed of this inspection alternative through a special airworthiness information bulletin (SAIB). As discussed in this document, the FAA is withdrawing the NPRM (Docket No. 97–CE–79–AD) and will propose to supersede AD 98–05–04 with a new AD (will be initiated as an NPRM) that would affect all 7, 8, and 11 series airplanes and incorporate recommended alternative methods for complying with the actions. The FAA will incorporate the inspection method discussed above into the combined proposed AD. Comment Issue No. 3: Exclude Certain Airplanes From the Proposed AD Numerous commenters request that the FAA exclude certain airplanes, such as the Model 7AC. The commenters state that the light-weight and low- horsepower airplanes manufactured by Aeronca and Champion Aircraft are not certificated for aerobatic flight and induce lower stresses in the spars. The commenters feel there is no justification for including them in this AD action. The FAA does not concur that these light-weight and low-horsepower airplanes should be removed from the proposed AD. Section 39.1 of the Federal Aviation Regulations (14 CFR 39.1) specifies that the FAA should issue an airworthiness directive against aircraft of the same type design where the unsafe condition exists or is likely to develop. Since there have been compression failures and spar damage reports on the light-weight and low- horsepower airplane models (i.e., Model 7AC), the AD should address these models. No changes have been made to the AD as a result of these comments. However, as discussed in this document, the proposal is being withdrawn and the actions revised and combined with the actions of the current AD required for the ACAC Model 8GCBC airplanes. Comment Issue No. 4: The Proposed AD Should Only Apply to Airplanes With Previous Wing Damage or Evidence of Compression Failures Several commenters request that the proposed AD only apply to those airplanes that have a history of wing damage. The commenters state that spar compression failures and spar damage are a direct result of the airplane flipping, ground looping, or other similar type of activity that causes wing damage. The FAA does not concur that the proposed AD should only apply to those airplanes that have a history of wing damage. The FAA agrees that incidents involving wing damage are a major cause of compression failures and other spar damage; however, the FAA has received reports of compression failures in airplanes without previous wing damage. However, to better understand all causes of spar damage of the affected airplanes, the FAA has determined that all findings of aircraft wing damage should be submitted on a Malfunction or Defect Report (M or D), FAA Form 8010–4, describing the damage and a copy of the report sent to the Chicago Aircraft Certification Office. The FAA could then initiate further rulemaking action that increases or reduces the burden upon the owners/operators of the ACAC 7, 8, and 11 series airplanes, as justified. As discussed in this document, the FAA is withdrawing the NPRM (Docket No. 97–CE–79–AD) and will propose to supersede AD 98–05–04 with a new AD (will be initiated as an NPRM) that would affect all 7, 8, and 11 series airplanes and incorporate recommended alternative methods for complying with the actions. The FAA will incorporate this reporting requirement into the combined proposed AD. Comment Issue No. 5: The Proposed AD Should Not Apply to the 7 and 11 Series Airplanes One commenter objects to an AD against the ACAC 7 and 11 series airplanes because the market value of these airplanes will decrease by several thousand dollars. The commenter believes that simply mailing the manufacturer’s service instructions to the owners of the 7 and 11 series airplanes will result in the desired effect. The FAA does not concur. The FAA’s duty to public safety must outweigh considerations of an aircraft’s market value. The FAA has worked with associations and type clubs that are interested in the safety and market value of these airplanes in order to decrease the economic impact of the proposed AD’s inspection requirements. Service history of all models of the ACAC 7, 8, and 11 series airplanes reveals susceptibility to wing spar cracking and compression failures. The FAA has no reason to believe that compliance will be guaranteed on a voluntary basis alone. No changes have been made to the proposed AD as a result of these comments. Comment Issue No. 6: The Proposed AD Should Not Address Loose and Missing Nails Four commenters feel that the proposed AD should not include procedures for inspecting for and replacing loose or missing nails in the wing spars of the ACAC 7, 8, and 11 series airplanes. The commenters state that the nails are only used during manufacture of the wing to hold the ribs in place. The FAA does not concur. Rib nails are required to transfer the load from the ribs to the spar. If the rib nails are loose or missing, damage to the wing spar could result from the ribs chafing 29971 Federal Register / Vol. 64, No. 107 / Friday, June 4, 1999 / Proposed Rules against the spar. For this reason, the FAA has determined the procedures for inspecting for and replacing loose or missing nails are justified. No changes have been made to the proposed AD as a result of these comments. Comment Issue No. 7: Properly Performed Annual Inspections Eliminate the Need for the Proposed AD Several commenters object to the proposed AD because they feel that a properly performed annual inspection is adequate to detect spar damage. These commenters state that the maintenance manual specifies regular inspections of the wing spars for cracks. The FAA concurs that the maintenance manual for the ACAC 7, 8, and 11 series airplanes specifies inspecting the wing spars for cracks during annual and 100-hour inspections, particularly at the butt and strut attach points. However, sufficient guidance is not given on accessing the spar or identifying compression failures. These compression failures appear as hardly visible, minute, and jagged series of lines that run across the grain on the top or bottom of the spar. If not viewed with detailed instruction and the right equipment, they may be overlooked. For these reasons, the FAA does not concur that the inspections specified in the maintenance manual are adequate to detect all wing spar cracks and compression failures. No changes have been made to the proposed AD as a result of these comments. Comment Issue No. 8: Compliance Extension for Airplanes With Wings That Have Been Rebuilt Several commenters request an extension to the compliance time for those airplanes where the wing has been rebuilt. The commenters state that the wing spar was inspected during the rebuild. The FAA does not concur. In order to adequately inspect the wing spars for cracks and compression failures, the detailed inspection procedures detailed in ACAC Service Letter 406, Revision A, dated May 6, 1998 (or procedures approved to be acceptable by the FAA), must be utilized to adequately perform the inspection. The FAA has determined that cracks and compression failures have been overlooked because these procedures were not followed. No changes have been made to the proposed AD as a result of these comments. Comment Issue No. 9: Reopen and Extend the Comment Period for the NPRM Two commenters request that the FAA reopen the comment period and allow more time for the public to comment on the NPRM. These commenters cite the large public interest as the reason for this request. The FAA will establish a new comment period. As discussed in this document, the FAA is withdrawing the NPRM (Docket No. 97-CE–79-AD) and will propose to supersede AD 98–05–04 with a new AD (will be initiated as an NPRM) that would affect all ACAC 7, 8, and 11 series airplanes and incorporate recommended alternative methods for complying with the actions. The FAA will utilize an NPRM with a 45-day comment period to propose this new AD to combine the actions. Comment Issue No. 10: Eliminate, Minimize, or Provide Alternatives to Installing Inspection Covers Numerous commenters express some opposition to the proposed requirement of installing inspection covers on the wings of the ACAC 7, 8, and 11 series airplanes. These comments include the following: —Top wing inspection covers could leak, causing water damage to the spar and resulting in a reduction of wing structural integrity; —Top wing inspection covers could come off during flight due to the negative pressure on the top surface, which could result in wing damage; —Top wing inspection covers will cause aerodynamic and performance concerns; and —The FAA should allow fabric patches in place of top wing inspection covers. The FAA does not concur that water damage to the wing spar, resulting in wing structural integrity reduction, or aerodynamic and performance concerns, will occur when inspection covers are installed on the wings of the affected airplanes. To address the concern of water damage, ACAC added a water- tight seal to the wing inspection cover installation, which the FAA approved. As for aerodynamic and performance concerns, the top inspection covers were designed as low-profile covers and FAA flight test pilots have evaluated and approved them. Also, out of the over 200 sets of top inspection covers delivered to the field, the FAA has not received any reports of decreased performance. The FAA does not concur that the top inspection covers would cause wing damage if they came off the airplane while in flight. The covers are designed not to damage the reinforced cutout if the eight screws that attach the covers were inadvertently left off or not tightened and the cover came off the airplane. The FAA concurs with the request of allowing fabric patches in place of the top wing inspection covers, as an acceptable standard practice. ACAC Service Letter 417, Revision C, dated May 6, 1998, includes procedures for installing fabric patches. As discussed in this document, the FAA is withdrawing the NPRM (Docket No. 97–CE–79–AD) and will propose to supersede AD 98–05–04 with a new AD (will be initiated as an NPRM) that would affect all 7, 8, and 11 series airplanes and incorporate recommended alternative methods for complying with the actions. One of these alternative methods will include the installation of these fabric patches. Comment Issue No. 11: FAA Underestimated the Cost Impact of the Proposed AD Numerous commenters believe that the cost of installing the inspection covers will be significantly greater than the FAA estimated in the NPRM. The FAA does not concur and believes that the cost impact specified in the NPRM was indicative of the initial inspection and inspection cover installation costs associated with the proposed action. The cost reflected an 11-inspection hole installation on each wing (a total of 22). Utilizing the alternative inspection method referenced in ACAC Service Letter 406, Revision A, dated May 6, 1998, would reduce the number of inspection holes required and consequently would reduce the cost impact upon the public. The FAA is incorporating this service information into a new AD (will be initiated as an NPRM) that would combine both the actions in the NPRM (Docket No. 97–CE–79–AD) and AD 98– 05–04. Comment Issue No. 12: Require Additional Training for Inspectors Three commenters state that compression failures are extremely difficult to detect and are easily overlooked. For these reasons, the commenters believe that the inspectors should obtain additional training in the detection of compression failures on ACAC 7, 8, and 11 series airplanes. The FAA concurs that the compression failures are difficult to detect and could be easily overlooked by inspectors who are untrained in this area. ACAC Service Letter 406, Revision A, dated May 6, 1998, contains a more 29972 Federal Register / Vol. 64, No. 107 / Friday, June 4, 1999 / Proposed Rules detailed description of compression failures than the original issue of this service letter, and also includes a recommendation that inspectors should have previous compression failure detection experience. The FAA has determined that this more detailed description, combined with the inspection procedures included in the service letter, should give the inspectors adequate information to detect compression failures in the wing spars of ACAC 7, 8, and 11 series airplanes. The FAA is incorporating this service information into a new AD (will be initiated as an NPRM) that would combine both the actions in the NPRM (Docket No. 97–CE–79–AD) and AD 98– 05–04. Comment Issue No. 13: Delete the Proposed Requirement To Install Additional Bottom Inspection Covers Several commenters state additional inspection covers over that which already exist may not be required for some aircraft. These commenters suggest that the FAA delete the specific proposed requirement in the NPRM of installing additional bottom inspection covers. The FAA concurs. The inspection- authorized mechanic who is performing the inspection is in the best position to determine the number of bottom inspection covers needed to accomplish the intent of the AD. The selected inspection method and the location of previously installed inspection covers will determine the number and location of the additional inspection covers required to perform a thorough inspection. The service information referenced in the NPRM has been revised and clarifies that additional inspection covers need only be installed in order to accomplish a thorough spar inspection. The FAA is incorporating this service information into a new AD (will be initiated as an NPRM) that would combine both the actions in the NPRM (Docket No. 97–CE–79–AD) and AD 98– 05–04. Comment Issue No. 14: The FAA Proposed This AD Only for the Manufacturer’s Benefit Numerous commenters object to the proposal and believe that the only reason the FAA issued an NPRM is because ACAC requested an AD to dodge a liability issue or make a profit. The FAA does not concur. The FAA has an obligation to implement AD action when an unsafe condition is found in a product and that unsafe condition could develop in other products of the same type design. The service history of all the affected airplane models indicates that cracks and compression failures in the wing spars are unsafe conditions that need to be addressed through AD action. No changes to the proposal have been made as a result of these comments. Comment Issue No. 15: Prohibit Aerobatic Flight Instead of Requiring Repetitive Inspections Five commenters state that spar damage is a direct result of aerobatic flight. Because of this, the commenters suggest that the FAA change the proposal to include a placard that specifies prohibiting aerobatic flight instead of the repetitive inspection requirement currently proposed. The FAA does not concur. Not all of the affected airplanes are certificated for aerobatic flight. However, spar damage has been found on many of the affected airplane model designs, regardless of whether they have been certificated for aerobatic flight. No changes to the proposal have been made as a result of these comments. Comment Issue No. 16: Install a ‘‘G’’ Meter Instead of Requiring Repetitive Inspections Three commenters state that installing a ‘‘G’’ meter in the airplane will help limit the peak accelerations. The commenters request that the FAA propose the ‘‘G’’ meter installation instead of repetitive inspections. The FAA does not concur. While the FAA believes that installing a ‘‘G’’ meter may aid in limiting peak accelerations, this will not account for all wing loading conditions or detect existing spar damage before structural failure of the wing. No changes to the proposal have been made as a result of these comments. Comment Issue No. 17: Allow the Use of a Borescope as an Alternative Method of Compliance to the Proposed Inspections Several commenters request that the FAA allow the use of a borescope as an alternative method of compliance to the inspections proposed in the NPRM. The FAA concurs that a borescope, when available, is an acceptable alternative inspection method. Therefore, this inspection method is being incorporated into a new AD (will be initiated as an NPRM) that would combine both the actions in the NPRM (Docket No. 97–CE–79–AD) and AD 98– 05–04. This inspection method is referenced in ACAC Service Letter 406, Revision A, dated May 6, 1998. The FAA’s Determination After careful review of all available information related to the subject presented above, including the comments submitted to the NPRM (Docket No. 97-CE–79–AD), the FAA has determined that: —The proposed rule should be withdrawn; and —A new NPRM should be issued in a different action that would supersede AD 98–05–04 with a new AD (will be initiated as an NPRM) that would affect all 7, 8, and 11 series airplanes and incorporate recommended alternative methods for complying with the actions. Withdrawal of this NPRM constitutes only such action, and does not preclude the agency from issuing future rulemaking on this issue, nor does it commit the agency to any course of action in the future. Combining the proposed actions of this NPRM and AD 98–05–04 will be initiated in a different AD action. Since this action only withdraws an NPRM, it is neither a proposed nor a final rule and therefore, is not covered under Executive Order 12866, the Regulatory Flexibility Act, or DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). List of Subjects in 14 CFR Part 39 Air transportation, Aircraft, Aviation safety, Safety. The Withdrawal Accordingly, the notice of proposed rulemaking, Docket No. 97–CE–79–AD, published in the Federal Register on November 3, 1997 (62 FR 59310), is withdrawn. Issued in Kansas City, Missouri, on May 26, 1999. Michael Gallagher, Manager, Small Airplane Directorate, Aircraft Certification Service. [FR Doc. 99–14130 Filed 6–3–99; 8:45 am] BILLING CODE 4910–13–P DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 39 [Docket No. 98–CE–121–AD] RIN 2120–AA64 Airworthiness Directives; American Champion Aircraft Corporation 7, 8, and 11 Series Airplanes AGENCY : Federal Aviation Administration, DOT.