[Federal Register Volume 59, Number 31 (Tuesday, February 15, 1994)] [Unknown Section] [Page 0] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 94-3460] [[Page Unknown]] [Federal Register: February 15, 1994] ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION 14 CFR Part 39 [Docket No. 93-NM-228-AD] Airworthiness Directives; Boeing Model 767 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 Boeing Model 767 series airplanes. This proposal would require dye penetrant inspection and proof pressure testing to detect cracks or ruptures of the crossover pneumatic duct, and repair or replacement, as necessary. This proposal would also require stress relieving of the crossover pneumatic duct assembly. This proposal is prompted by several reports of ruptured engine bleed air crossover ducts. The actions specified by the proposed AD are intended to prevent failure of the engine bleed air crossover duct, which could result in loss of pneumatics and damage to adjacent structure. DATES: Comments must be received by April 11, 1994. ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 93-NM-228-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Comments may be inspected at this location between 9 a.m. and 3 p.m., Monday through Friday, except Federal holidays. The service information referenced in the proposed rule may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington. FOR FURTHER INFORMATION CONTACT: Barbara Mudrovich, Aerospace Engineer, Systems and Equipment Branch, ANM-130S; Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2670; fax (206) 227-1181. 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 93-NM-228-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. 93-NM-228-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056. Discussion On July 14, 1993, the FAA issued AD 93-14-11, Amendment 39-8635 (58 FR 43550, August 17, 1993), applicable to Boeing Model 767 series airplanes, line position 001 through 307, inclusive. That AD requires a dye penetrant inspection and proof pressure testing to detect cracks or ruptures of the crossover pneumatic ducts, and repair or replacement, as necessary. That action was prompted by several reported incidents of ruptured engine bleed air crossover ducts on certain Boeing Model 767 series airplanes. The duct ruptures resulted in a loss of cabin pressure, loss of bleed air to the air driven hydraulic pump, loss of wing thermal anti-ice capabilities, and damage to the air conditioning panels. These duct ruptures were caused by cracking, which started and progressed around the circumferential welds. These cracks formed in the heat affected zones of the duct welds because of hydrogen oxide (hydride) concentration. The hydrides have an embrittling effect on the duct material, which may initiate the cracking. Duct ruptures, if not corrected, could result in loss of pneumatics for cabin pressurization, air conditioning, air driven hydraulic pump, wing thermal anti-ice, hydraulic reservoir pressurization, engine cross starting ability, and cargo heating, and could also damage air conditioning panels. Since the issuance of AD 93-14-11, the manufacturer has discovered that stress relieving of one of the four crossover ducts was incorporated during production on airplanes starting at line number 322 instead of line number 308. The manufacturer has informed the FAA that 14 airplanes did not receive stress relieving of the crossover duct. Therefore, these 14 airplanes would be subject to the same unsafe condition as addressed by AD 93-14-11. The FAA has reviewed and approved Boeing Service Bulletin 767- 36A0041, Revision 2, dated October 28, 1993, that describes procedures for conducting dye penetrant inspections and proof pressure tests of the crossover pneumatic duct. This service bulletin also describes procedures for repairing or replacing this duct, and stress relieving this duct. Stress relieving this duct will eliminate the residual stress and local stress concentration. A dye penetrant inspection, proof pressure test, and stress relieving will reduce the possibility of engine bleed air crossover duct rupture caused by cracking due to hydride formation. The effectivity listing of this service bulletin includes the 14 airplanes on which the stress relieving procedure was not accomplished during production. Since an unsafe condition has been identified that is likely to exist on other products of this same type design, the proposed AD would require conducting dye penetrant inspections and proof pressure tests of the crossover pneumatic duct on 14 specific airplanes. This proposed AD would also require repairing or replacing this duct, and stress relieving this duct. The actions would be required to be accomplished in accordance with the service bulletin described previously. (Note: The FAA's normal policy is that, when an AD requires a substantive change, such as a change in its applicability, the ``old'' AD is superseded by being removed from the system and a new AD added. In the case of this AD action, the FAA normally would have proposed superseding AD 93-14-11 to expand its applicability to include the 14 additional airplanes. However, in reconsideration of the entire fleet size that would be affected by such a supersedure action, and the consequent workload associated with revising maintenance record entries, the FAA has determined that a less burdensome approach is to issue a separate AD applicable only to the 14 airplanes. This AD does not supersede AD 93-14-11; airplanes listed in the applicability of AD 93-14-11 continue to be required to comply with the requirements of that AD. This proposed AD is a separate AD action, and is applicable only to airplanes having line numbers 308 through 321, inclusive.) There are 14 Model 767 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 6 airplanes of U.S. registry would be affected by this proposed AD, that it would take approximately 18 work hours per airplane to accomplish the proposed actions, and that the average labor rate is $55 per work hour. Required parts would cost approximately $2,208 per airplane. Based on these figures, the total cost impact of the proposed AD on U.S. operators is estimated to be $19,188, or $3,198 per airplane. This total cost figure assumes that no operator has yet accomplished the proposed requirements of this AD action. 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 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. App. 1354(a), 1421 and 1423; 49 U.S.C. 106(g); and 14 CFR 11.89. Sec. 39.13 [Amended] - 2. Section 39.13 is amended by adding the following new airworthiness directive: Boeing: Docket 93-NM-228-AD. -Applicability: Model 767 series airplanes, line position 308 through 321 inclusive, certificated in any category. - Compliance: Required as indicated, unless accomplished previously. -Note 1: Inspections, testing, and repair or replacement accomplished prior to the effective date of this amendment in accordance with Boeing Alert Service Bulletin 767-36A0041, dated July 2, 1992; or Revision 1, dated February 25, 1993; are considered acceptable for compliance with the applicable action specified in this amendment. - To prevent failure of the engine bleed air crossover duct, which could result in loss of pneumatics and damage to adjacent structure, accomplish the following: - (a) OPTION 1: As an alternative to the requirements of paragraph (b) of this AD, accomplish the following: - (1) Within 6 months after the effective date of this AD, or prior to the accumulation of 7,000 total flight cycles, whichever occurs later, conduct a dye penetrant inspection and proof pressure test of the crossover pneumatic duct, in accordance with Boeing Service Bulletin 767-36A0041, Revision 2, dated October 28, 1993. - (i) If cracks or ruptures are detected, prior to further flight, repair or replace the crossover pneumatic duct in accordance with the service bulletin. - (ii) Stress relieving of the duct, in accordance with the service bulletin, may be accomplished in conjunction with the initial dye penetrant inspection and proof pressure test required by this paragraph. Such action constitutes terminating action for the requirements of paragraph (a)(2) of this AD. - (2) Within 3,000 flight cycles after accomplishing the initial dye penetrant inspection and proof pressure test required by paragraph (a)(1) of this AD, conduct an additional dye penetrant inspection and proof pressure test of the crossover pneumatic duct, and stress relieve the crossover pneumatic duct assembly, in accordance with Boeing Service Bulletin 767-36A0041, Revision 2, dated October 28, 1993. If cracks or ruptures are detected, prior to further flight, repair or replace the crossover pneumatic duct in accordance with the service bulletin. - (b) OPTION 2: As an alternative to the requirements of paragraph (a) of this AD, accomplish the following: - (1) Within 18 months after the effective date of this AD, or prior to the accumulation of 7,000 total flight cycles, whichever occurs later, conduct a dye penetrant inspection and proof pressure test of the crossover pneumatic duct and stress relieve the crossover pneumatic duct assembly, in accordance with Boeing Service Bulletin 767-36A0041, Revision 2, dated October 28, 1993. - (2) If cracks or ruptures are detected, prior to further flight, repair or replace the crossover pneumatic duct in accordance with the service bulletin. - (c) Replacement of the crossover pneumatic duct with a stress relieved duct in accordance with Boeing Service Bulletin 767- 36A0041, Revision 2, dated October 28, 1993, constitutes terminating action for the requirements of paragraphs (a) and (b) of this AD. (d) 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, Seattle Aircraft Certification Office (ACO), 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, Seattle ACO. Note 2: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO. -(e) Special flight permits may be issued in accordance with FAR 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 February 9, 1994. Darrell M. Pederson, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 94-3460 Filed 2-14-94; 8:45 am] BILLING CODE 4910-13-U