Airworthiness directives: Boeing,
[Federal Register: October 19, 1999 (Volume 64, Number 201)]
[Proposed Rules]
[Page 56276-56279]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr19oc99-15]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 39
[Docket No. 99-NM-208-AD]
RIN 2120-AA64
Airworthiness Directives; Boeing Model 747-400 and 767-200 and - 300 Series Airplanes Powered by Pratt & Whitney Model PW4000 Series Engines
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 747-400 and 767-200 and -300 series airplanes. This proposal would require repetitive inspections to detect damage and wear of the auxiliary track assembly of the thrust reverser, and corrective actions, if necessary. This proposal would also
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require eventual replacement of the liner and slider, or the entire assembly, with new, improved parts, which, when accomplished, would terminate the repetitive inspections. This proposal is prompted by reports of damage and wear to the auxiliary track assembly. The actions specified by the proposed AD are intended to prevent a slider disengaging from the auxiliary track assembly, which could lead to separation of a portion of the thrust reverser from the airplane during flight, possible impact of separated portions on airplane structure, and consequent possible rapid decompression of the airplane, reduced controllability of the airplane, or reduced structural integrity of the fuselage.
DATES: Comments must be received by December 3, 1999.
ADDRESSES: Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-114, Attention: Rules Docket No. 99-NM-208-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: Sulmo Mariano, Aerospace Engineer, Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 227-2686; fax (425) 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 filedin 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 99-NM-208-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-114, Attention: Rules Docket No. 99-NM-208-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.
Discussion
The FAA has received reports indicating that damage and wear was found on the upper and lower auxiliary track assemblies of the thrust reverser halves on Boeing Model 747 and 767 series airplanes equipped with Pratt & Whitney Model PW4000 series engines. Further investigation revealed that the damage and wear is caused by loss of the Rulon J tape on the slider of the auxiliary track assembly. This condition, if not corrected, could result in a slider disengaging from the auxiliary track assembly, which could lead to separation of a portion of the thrust reverser from the airplane during flight, possible impact of separated portions on airplane structure, and consequent possible rapid decompression of the airplane, reduced controllability of the airplane, or reduced structural integrity of the fuselage.
Explanation of Relevant Service Information
The FAA has reviewed and approved Boeing Service Bulletin 747- 78A2164, Revision 2, dated December 3, 1998 (for Model 747-400 series airplanes), and Boeing Service Bulletin 767-78A0079, Revision 2, dated December 3, 1998 (for Model 767-200 and -300 series airplanes). These service bulletins describe procedures for repetitive inspections of the auxiliary track assembly of the thrust reverser to detect missing segments of the track lip; to detect signs that the slider has disengaged from the track; to detect cracks, gouges, and wear of the liner; and to measure the auxiliary track liner gap. The service bulletins also describe procedures for temporary repairs and repetitive inspections of those repairs, if necessary. The service bulletins describe procedures for replacement of the liner and slider with a new, improved liner and slider, installation of a retainer bar, and replacement of the auxiliary track assembly with a new, improved assembly. Such modifications eliminate the need for repetitive inspections. Accomplishment of the actions specified in the applicable service bulletin is intended to adequately address the identified unsafe condition.
Explanation of Requirements of Proposed Rule
Since an unsafe condition has been identified that is likely to exist or develop on other products of this same type design, the proposed AD would require accomplishment of the actions specified in the applicable service bulletin described previously, except as discussed below.
Differences Between Proposed Rule and Service Bulletins
Operators should note that this proposed AD would mandate, at various compliance times depending on the findings during the repetitive inspections, the replacement of the liner and slider, or the entire auxiliary track assembly, with new, improved parts. Such replacement is described in the service bulletins as optional terminating action for the repetitive inspections.
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 replacement requirement is consistent with these conditions.
The service bulletins describe, for certain damage or wear detected on the auxiliary track assembly, replacement of the liner and slider with a new, improved liner and slider, installation of a retainer bar, and a one-time inspection of the repair as a permanent repair. The service bulletins state that such actions would eliminate the need for the repetitive inspections. The proposed AD would only allow this repair as a temporary repair and would
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require eventual replacement of the repaired auxiliary track assembly with a new, improved assembly. The FAA has determined that this repair would not prevent excessive damage and wear in the future because the cause of that damage and wear is related to how the parts mate during installation, and, therefore, such repair would not prevent the subject unsafe condition.
Cost Impact
There are approximately 254 airplanes of the affected design in the worldwide fleet. The FAA estimates that 12 Model 747-400 series airplanes and 46 Model 767-200 and -300 series airplanes of U.S. registry would be affected by this proposed AD.
It would take approximately 4 work hours per engine to accomplish the proposed repetitive inspection, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the proposed AD on U.S. operators of Model 747-400 series airplanes (4 engines per airplane) is estimated to be $11,520, or $960 per airplane, per inspection cycle. The cost impact of the proposed AD on U.S. operators of Model 767 series airplanes (2 engines per airplane) is estimated to be $22,080, or $480 per airplane, per inspection cycle.
Should an operator be required to accomplish the replacement of the auxiliary track assembly, it would take approximately 220 work hours per auxiliary track assembly to accomplish the proposed replacement, at an average labor rate of $60 per work hour. Required parts would cost approximately $30,090. Based on these figures, the cost impact of this replacement is estimated to be $43,290 per assembly. There are four auxiliary track assemblies per engine.
Should an operator be required to accomplish the replacement of the liner and slider, it would take approximately 8 work hours per auxiliary track assembly to accomplish the proposed replacement, at an average labor rate of $60 per work hour. Required parts would be provided at no cost by the airplane manufacturer. Based on these figures, the cost impact of this replacement is estimated to be $480 per assembly. There are four auxiliary track assemblies per engine.
The cost impact figures discussed above are 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
-
The authority citation for part 39 continues to read as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701.
Sec. 39.13 [Amended]
-
Section 39.13 is amended by adding the following new airworthiness directive:
Boeing: Docket 99-NM-208-AD.
Applicability: Model 747-400 series airplanes powered by Pratt & Whitney PW4000 series engines, line numbers 696 through 1100 inclusive; and Model 767-200 and -300 series airplanes powered by Pratt & Whitney PW4000 series engines, line numbers 1 through 646 inclusive; certificated in any category.
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 indicated, unless accomplished previously.
To prevent a slider disengaging from the auxiliary track assembly, which could lead to separation of a portion of the thrust reverser from the airplane during flight, possible impact of separated portions on airplane structure, and consequent possible rapid decompression of the airplane, reduced controllability of the airplane, or reduced structural integrity of the fuselage, accomplish the following:
Initial Inspection
(a) Prior to the accumulation of 3,000 total flight cycles, or within 90 days after the effective date of this AD, whichever occurs later, perform a detailed visual inspection of the upper and lower auxiliary track assemblies on each thrust reverser half of each engine to detect missing segments of the track lip; to detect signs that the slider has disengaged from the track; to detect cracks, gouges, and wear of the liner; and to measure the auxiliary track liner gap; in accordance with Part A of the Accomplishment Instructions of Boeing Service Bulletin 747-78A2164, Revision 2, dated December 3, 1998 (for Model 747-400 series airplanes); or Boeing Service Bulletin 767-78A0079, Revision 2, dated December 3, 1998 (for Model 767 series airplanes); as applicable.
Note 2: For the purposes of this AD, a detailed visual inspection is defined as: ``An intensive visual examination of a specific structural area, system, installation, or assembly to detect damage, failure, or irregularity. Available lighting is normally supplemented with a direct source of good lighting at intensity deemed appropriate by the inspector. Inspection aids such as mirror, magnifying lenses, etc., may be used. Surface cleaning and elaborate access procedures may be required.''
Repetitive Inspections/Corrective Actions
(1) If no discrepancy is detected, repeat the detailed visual inspection thereafter at intervals not to exceed 3,000 flight cycles or 7,000 flight hours, whichever occurs earlier, until paragraph (b) or (c), as applicable, has been accomplished.
(2) If the auxiliary track lip has a missing segment of 3 inches or longer, or longitudinal cracks at the base of the lip, or other indications that the slider has disengaged from the track in the forward 4 inches, prior to further flight, repair in accordance with Part A of the Accomplishment Instructions of the applicable service bulletin. Repeat the detailed visual inspection thereafter at the applicable intervals specified in Part A of the Accomplishment Instructions of the applicable service bulletin, until paragraph (c) of this AD has been accomplished.
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(3) If the auxiliary track lip has a missing segment of 3 inches or longer, or longitudinal cracks at the base of the lip, or other indications that the slider has disengaged from the track AFT of the forward four inches, accomplish paragraphs (a)(3)(i) or (a)(3)(ii) of this AD.
(i) Prior to further flight, repair in accordance with Part A of the Accomplishment Instructions of the applicable service bulletin. Repeat the detailed visual inspection thereafter at the applicable intervals specified in Part A of the Accomplishment Instructions of the applicable service bulletin, until paragraph (c) of this AD has been accomplished.
(ii) Accomplish both paragraphs (a)(3)(ii)(A) and (a)(3)(ii)(B) of this AD:
(A) Prior to further flight, deactivate the associated thrust reverser in accordance with Section 78-2 of Boeing Document D6U10151, ``Boeing 747-400 Dispatch Deviations Guide,'' Revision 11, dated March 31, 1998 (for Model 747-400 series airplanes); or Section 78-2 of Boeing Document D630T002, ``Boeing 767 Dispatch Deviations Guide,'' Revision 19, dated May 14, 1999 (for Model 767 series airplanes); as applicable. No more than one thrust reverser on any airplane may be deactivated under the provisions of the paragraph.
Note 3: The airplane may be operated for up to 30 days in accordance with the provisions and limitations specified in the operator's FAA-approved Master Minimum Equipment List, provided that no more than one thrust reverser on the airplane is inoperative.
(B) Within 30 days after deactivation of any thrust reverser in accordance with paragraph (a)(3)(ii)(A) of this AD, the thrust reverser must be repaired in accordance with Part A of the Accomplishment Instructions of the applicable service bulletin; once this is accomplished, the thrust reverser may then be reactivated. Repeat the detailed visual inspection thereafter at the applicable intervals specified in Part A of the Accomplishment Instructions of the applicable service bulletin, until paragraph (c) of this AD has been accomplished.
Terminating Action
(b) For any auxiliary track assembly on which no discrepancy is detected during any detailed visual inspection required by paragraph (a) of this AD: Replace the liner and slider of the auxiliary track assembly with a new, improved liner and slider, in accordance with Part A of the Accomplishment Instructions of Boeing Service Bulletin 747-78A2164, Revision 2, dated December 3, 1998 (for Model 747-400 series airplanes); or Boeing Service Bulletin 767-78A0079, Revision 2, dated December 3, 1998 (for Model 767 series airplanes); as applicable; at the later of the times specified in paragraphs (b)(1) and (b)(2) of this AD. Such action constitutes terminating action for the requirements of this AD for that assembly.
(1) Within 6,000 flight cycles, 14,000 flight hours, or 5 years after the date of the first inspection, whichever occurs earliest; or
(2) Within 4 years after the effective date of this AD.
(c) For any auxiliary track assembly on which any discrepancy is detected during any detailed visual inspection required by paragraph (a) of this AD: Replace the auxiliary track assembly with a new, improved assembly (including a new liner and slider), in accordance with Part A of the Accomplishment Instructions of Boeing Service Bulletin 747-78A2164, Revision 2, dated December 3, 1998 (for Model 747-400 series airplanes); or Boeing Service Bulletin 767-78A0079, Revision 2, dated December 3, 1998 (for Model 767 series airplanes); as applicable; at the later of the times specified in paragraphs (c)(1) and (c)(2) of this AD. Such action constitutes terminating action for the requirements of this AD for that assembly.
(1) Within 4,500 flight cycles, 10,000 flight hours, or 3 years after the date of the first repair, whichever occurs earliest; or
(2) Within 2 years after the effective date of this AD.
Alternative Methods of Compliance
(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 4: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Seattle ACO.
Special Flight Permits
(e) 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 October 13, 1999. D.L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 99-27273Filed10-18-99; 8:45 am]
BILLING CODE 4910-13-U
