[Federal Register Volume 62, Number 26 (Friday, February 7, 1997)] [Proposed Rules] [Pages 5785-5787] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 97-3028] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 96-NM-137-AD] RIN 2120-AA64 Airworthiness Directives; Construcciones Aeronauticas, S.A. (CASA) Model CN-235 Series Airplanes AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed rulemaking (NPRM). ----------------------------------------------------------------------- SUMMARY: This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain CASA Model CN-235 series airplanes. This proposal would require repetitive inspections of the torsion tubes and fittings of the elevator and rudder assemblies to detect stress corrosion cracking, and replacement of cracked parts. This proposed action also would require the accomplishment of a modification that would constitute terminating action for the repetitive inspections. This proposal is prompted by reports indicating that stress corrosion cracking in these parts has been found on some airplanes. The actions specified by the proposed AD are intended to prevent loss of control of the elevator and/or rudder, due to failure of the elevator and/or rudder assemblies as a result of stress corrosion cracking. DATES: Comments must be received by March 20, 1997. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 96-NM-137-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9:00 a.m. and 3:00 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule may be obtained from Construcciones Aeronauticas, S.A., Getafe, Madrid, Spain. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. FOR FURTHER INFORMATION CONTACT: Greg Dunn, Aerospace Engineer, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2799; fax (206) 227-1149. SUPPLEMENTARY INFORMATION: Comments Invited Interested persons are invited to participate in the making of the proposed rule by submitting such written data, views, or arguments as they may desire. Communications shall 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 summarizing 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 Number 96-NM-137-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, Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 96-NM-137-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion The Direccion General de Aviacion (DGAC), which is the airworthiness authority for Spain, has notified the FAA that an unsafe condition may exist on certain CASA Model CN-235 series airplanes. The DGAC advises that it has received reports indicating that stress corrosion cracks were detected in the torsion tubes and fittings of the elevator and rudder assemblies on some of these airplanes. This condition, if not corrected, could result in failure of these assemblies and subsequent loss of control of the elevator and/or rudder. Explanation of Relevant Service Information CASA has issued Service Bulletin SB-235-27-05, Revision 1, dated September 29, 1993 (for non-military airplanes), and Service Bulletin SB-235-27-05M, Revision 2, dated January 25, 1996 (for military airplanes). These service bulletins describe procedures for conducting repetitive visual inspections of the torsion tubes for the rudder and elevator to detect stress corrosion cracking, and replacement of discrepant tubes with tubes of a new design. Installation of the newly- designed torsion tubes is intended to preclude stress corrosion cracking and eliminates the need for repetitive visual inspections. The DGAC classified Service Bulletin SB-235-27-05 (for non-military airplanes) as mandatory and issued Spanish airworthiness directive 06/ 94, dated August 1994, in order to assure the continued airworthiness of these airplanes in Spain. The DGAC classified Service Bulletin SB- 235-27-05M (for military airplanes) as ``recommended.'' FAA's Conclusions This airplane model is manufactured in Spain and is type certificated for operation in the United States under the provisions of section 21.29 of the Federal Aviation Regulations (14 CFR 21.29) and the applicable bilateral airworthiness agreement. Pursuant to this bilateral airworthiness agreement, the DGAC has kept the FAA informed of the situation described above. The FAA has examined the findings of the DGAC, reviewed all available information, and determined that AD action is necessary for products of this type design that are certificated for operation in the United States. [[Page 5786]] Explanation of Requirements of Proposed Rule Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, the proposed AD would require repetitive visual inspections of the torsion tubes and fittings of the rudder and elevator assemblies to detect stress corrosion cracking, and replacement of discrepant parts. This proposed AD also would require the eventual installation of newly- designed torsion tubes assemblies on all airplanes, which, when accomplished, would constitute terminating action for the required inspections. The actions would be required to be accomplished in accordance with the applicable service bulletin described previously. Differences Between Proposed AD and Parallel Spanish Action Operators should note that the Spanish DGAC has not mandated the accomplishment of the terminating modification; however, this AD proposes to require it. The FAA has determined that long term continued operational safety will be better assured by design changes to remove the source of the problem, rather than by repetitive inspections. Long term inspections may not be providing the degree of safety assurance necessary for the transport airplane fleet. This, coupled with a better understanding of the human factors associated with numerous continual inspections, has led the FAA to consider placing less emphasis on inspections and more emphasis on design improvements. The proposed modification requirement is in consonance with these considerations. Cost Impact The FAA estimates that 1 CASA Model CN-235 series airplane of U.S. registry would be affected by this proposed AD. It would take approximately 6 work hours per airplane to accomplish each proposed visual inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the proposed inspections on the single affected U.S. operator is estimated to be $360 per inspection. It would take approximately 40 work hours to accomplish the proposed terminating modification, at an average labor rate of $60 per work hour. (The work hour figure does not include the time needed for preparation of the airplane or equipment: familiarization with the service bulletin; curing times for adhesive, sealant, paint, etc.; tool collection; or down time.) Required parts would cost approximately $8,900 per airplane. Based on these figures, the cost impact of the proposed modification on the single affected U.S. operators is estimated to be $9,140. The cost impact figure discussed above is based on assumptions that no operator has yet accomplished any of the proposed requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. 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 proposed regulation (1) is not a ``significant regulatory action'' under Executive Order 12866; (2) is not a ``significant rule'' under the 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 is contained 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 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 adding the following new airworthiness directive: CASA: Docket 96-NM-137-AD. Applicability: Model CN-235 airplanes as listed in CASA Service Bulletin SB-235-27-05, Revision 1, dated September 29, 1993 (non- military airplanes), and CASA Service Bulletin SB-235-27-05M, Revision 2, dated January 25, 1996 (military airplanes); certificated in any category. Note 1: This AD applies to each airplane identified in the preceding applicability provision, regardless of whether it has been otherwise 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 (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, unless accomplished previously. To prevent loss of control of the elevator and/or rudder, due to failure of the elevator and/or rudder assemblies as a result of stress corrosion cracking in the torsion tubes and fittings, accomplish the following: Note 2: Actions required by this AD that were accomplished previous to the effective date of this AD, and in accordance with earlier versions of the specified CASA service bulletins, are considered acceptable for compliance with the applicable requirements of this AD. (a) At the applicable time specified in either paragraph (a)(1) or (a)(2) of this AD, conduct a visual inspection of the torsion (torsion) tubes on the elevator and rudder assemblies to detect stress corrosion cracking, in accordance with CASA Service Bulletin SB-235-27-05, Revision 1, dated September 29, 1993 (for non-military airplanes) or CASA Service Bulletin SB-235-27-05M, Revision 2, dated January 25, 1996 (for military airplanes), as applicable. (1) For airplanes that have accumulated more than 600 total hours time-in-service, or more than 1,000 total landings, as of the effective date of this AD: Conduct the inspection required by paragraph (a) of this AD prior to the accumulation of 50 hours time- in-service, or 100 landings, or within 3 months, after the effective date of this AD, whichever occurs first. (2) For all other airplanes: Conduct the inspection required by paragraph (a) of this AD prior to the accumulation of 600 total hours time-in-service, or 1,000 total landings, or within 6 months, after the effective date of this AD, whichever occurs first. (b) If no cracking is detected during the inspection required by paragraph (a) of this AD, repeat that inspection at intervals not to exceed 600 hours time-in-service, or 1,000 landings, or 6 months, whichever occurs first. (c) If any cracking is detected during the inspection required by paragraph (a) of this AD, prior to further flight, accomplish either paragraph (c)(1) or (c)(2) of this AD. (1) Replace cracked parts with a new parts of the original design, in accordance with the [[Page 5787]] service bulletin. After replacement, repeat the visual inspection required by paragraph (a) of this AD at intervals not to exceed 600 hours time-in-service, or 1,000 landings, or 6 months, whichever occurs first. OR (2) Replace cracked parts with a newly-designed parts, in accordance with CASA Service Bulletin SB-235-27-05, Revision 1, dated September 29, 1993 (for non-military airplanes); or CASA Service Bulletin SB-235-27-05M, Revision 2, dated January 25,1996 (for military airplanes); as applicable. This replacement constitutes terminating action for the repetitive visual inspections of that part required by paragraph (b) of this AD. (d) Within 2 years after the effective date of this AD, replace all original design parts comprising the torsion tube assemblies on the elevator and rudder assemblies with newly-designed parts, in accordance with CASA Service Bulletin SB-235-27-05, Revision 1, dated September 29, 1993 (for non-military airplanes); or CASA Service Bulletin SB-235-27-05M, Revision 2, dated January 25, 1996 (for military airplanes); as applicable. This action constitutes terminating action for the inspection requirements of this AD. (e) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. Operators shall submit their requests through an appropriate FAA Principal Maintenance Inspector, who may add comments and then send it to the Manager, Standardization Branch, ANM-113. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Standardization Branch, ANM-113. (f) 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. Issued in Renton, Washington, on January 31, 1997. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 97-3028 Filed 2-6-97; 8:45 am] BILLING CODE 4910-13-U