Source: https://www.federalregister.gov/documents/2001/07/31/01-18469/airworthiness-directives-boeing-model-747-series-airplanes-powered-by-pratt-and-whitney-jt9d-7
Timestamp: 2018-08-16 05:06:58
Document Index: 557762859

Matched Legal Cases: ['art 39', 'art 39', 'art 2', 'art 4', 'art 2', 'art 4', 'art 5', 'art 3', 'art 2', 'art 5', 'art 5', '§\u200921', 'art 51']

66 FR 39425
Docket No. 2000-NM-271-AD
Amendment 39-12349
AD 2001-15-15
01-18469
Refer to Specific Part of Referenced Service Bulletin
Give Credit for Inspections Accomplished Previously
Remove Inspections From Paragraph (f)
Reference Alternative Method of Compliance for AD 2000-18-01
Make Specific Tooling Optional
Restatement of Requirements of AD 2000-18-01
Ultrasonic Inspection—Initial and Repetitive Inspections
Repetitive Detailed Visual and Physical Measurement Inspections
On-Condition Rework
Optional Rework
Exception to Repair Requirement
https://www.federalregister.gov/d/01-18469 https://www.federalregister.gov/d/01-18469
This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 747 series airplanes powered by Pratt & Whitney JT9D-7 series engines, that currently requires detailed visual inspections of the lugs on the bulkhead fitting of the rear engine mount, and corrective action, if necessary. The existing AD also specifies optional Start Printed Page 39426ultrasonic inspections, which, if accomplished, extend the repetitive interval for the required detailed visual inspections. This amendment requires accomplishment of the previously optional ultrasonic inspections and, for certain airplanes, rework of the bulkhead fitting of the rear engine mount. The actions specified by this AD are intended to detect and correct bushing migration, corrosion, or cracking of the lugs on the bulkhead fitting of the rear engine mount, which could result in fracture of the lugs and separation of the engine from the airplane. This action is intended to address the identified unsafe condition.
The incorporation by reference of Boeing Service Bulletin 747-54A2200, Revision 1, dated February 15, 2001, as listed in the regulations, is approved by the Director of the Federal Register as of September 4, 2001.
The incorporation by reference of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000, as listed in the regulations, was approved previously by the Director of the Federal Register as of September 18, 2000 (65 FR 53161, September 1, 2000).
A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 2000-18-01, amendment 39-11886 (65 FR 53161, September 1, 2000), which is applicable to certain Boeing Model 747 series airplanes powered by Pratt & Whitney JT9D-7 series engines, was published in the Federal Register on March 21, 2001 (66 FR 15814). The action proposed to continue to require detailed visual inspections of the lugs on the bulkhead fitting of the rear engine mount, and corrective action, if necessary. The action also proposed to require ultrasonic inspections (which were provided as an option in the existing AD) and, for certain airplanes, rework of the bulkhead fitting of the rear engine mount.
One commenter requests that the FAA clarify the unsafe condition as stated in the SUMMARY and “Discussion” sections of the proposed AD. The commenter requests that the unsafe condition state that bushing migration, corrosion, or cracking of the lugs on the bulkhead fitting of the rear engine mount could result in fracture of the lugs, which could result in separation of the engine from the airplane.
The FAA concurs with the commenter's request and has made this change in the SUMMARY section of this final rule. The “Discussion” section of the proposed AD is not restated in this final rule, so no change to that section is needed.
One commenter requests that the FAA revise the cost impact information in the proposed AD to include the time needed for gaining access and closing up for the proposed ultrasonic inspection. The commenter notes that, due to the 9-month compliance time, it may be necessary for operators to do this inspection at a time other than a normal scheduled heavy maintenance visit.
The FAA concurs with the commenter's request. We note that the cost analysis in AD rulemaking actions typically does not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. Because incidental costs may vary significantly from operator to operator, they are almost impossible to calculate. However, we acknowledge that it may or may not be possible to accomplish the ultrasonic inspection required by this AD during a normal scheduled maintenance visit due to the compliance times for the initial and repetitive inspections. Therefore, we have revised the cost impact information for the ultrasonic inspections in this final rule from 4 to 36 work hours to include the work hours necessary for gaining access and closing up.
One commenter requests that the FAA revise paragraph (d) of the proposed AD to refer to Part 2 of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000; or Revision 1, dated February 15, 2001. The commenter does not state a reason for its request.
The FAA infers that the commenter's request is to make paragraph (d) consistent with other paragraphs of the AD. The FAA concurs and has revised paragraph (d) of this final rule accordingly. Also, the same change has been made to paragraph (a) of this AD.
One commenter requests that the FAA revise paragraph (c) of the proposed AD to provide a third compliance time option for airplanes inspected per the ultrasonic method provided as an option in AD 2000-18-01. The commenter states that operators who did the ultrasonic inspection per AD 2000-18-01 would be required to repeat this inspection within 9 months after the effective date of this AD. The commenter emphasizes that such a requirement would impose undue economic and scheduling burdens on affected operators.
The FAA does not concur. Credit for inspections accomplished prior to the effective date of the AD is always provided in an AD by means of the statement at the beginning of the “Compliance” section of each AD: “Required as indicated, unless accomplished previously.” No change to the final rule is necessary in this regard.
One commenter requests that the FAA revise paragraph (f) to remove the requirement to perform detailed visual and non-destructive test inspections for damage of the upper engine mount during accomplishment of the rework of the lugs on the bulkhead fitting of the rear engine mount. The commenter states that these inspections should be necessary only if there is insufficient clearance between the migrated end of the outer lug plain bushing and the adjacent lug of the aft upper engine mount.
The FAA does not concur. We infer that the commenter assumes that there will be no damage to the upper engine mount if sufficient clearance is maintained between the migrated end of the outer lug plain bushing and the adjacent lug of the aft upper engine mount. However, we have determined that the bushing may migrate in either Start Printed Page 39427direction. For example, the bushing may have migrated to a position of no positive clearance and caused damage, but then subsequently may have migrated inward to a position where there is sufficient clearance. Thus, we find it necessary to require the inspections during the rework according to the service bulletin. No change to the final rule is necessary in this regard.
One commenter requests that the FAA revise the proposed AD to reference a specific alternative method of compliance (AMOC) that was approved previously for AD 2000-18-01. The commenter states that the AMOC addresses conditions of no positive clearance, which may be found during the rework according to Part 4 of the service bulletin.
The FAA does not concur with the request. Paragraph (h)(2) of the proposed AD allows the use of previously approved AMOCs for AD 2000-18-01 for compliance with corresponding actions in the proposed AD. Listing references for specific AMOCs would unnecessarily complicate this final rule. No change to the final rule is necessary in this regard.
One commenter requests that the FAA revise the proposed AD to make the use of specific tooling identified in the service bulletin optional for compliance with the proposed AD. The commenter refers to a specific boring fixture called out in the service bulletin, and states that use of this specific tooling should be optional. The commenter states that other tooling capable of producing the desired dimensions and finishes specified in the service bulletin should be acceptable for compliance. The commenter notes that inspection requirements and dimensional checks contained in the service bulletin are sufficient to ensure that lugs are properly reworked and free of damage.
The FAA does not concur with the commenter's request. We find that the tooling used to bore the lugs may affect the unsafe condition addressed by this AD and, therefore, it is inappropriate not to specify the tooling to be used. However, operators may request approval of an AMOC under paragraph (h)(1) of this AD if they can show that tooling other than that identified in the service bulletin will provide an acceptable level of safety. No change to the final rule is necessary in this regard.
There are approximately 200 Model 747 series airplanes of the affected design in the worldwide fleet. The FAA estimates that 47 airplanes of U.S. registry will be affected by this AD.
The detailed visual inspections that are currently required by AD 2000-18-01 take approximately 8 work hours per airplane to accomplish, at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the currently required actions on U.S. operators is estimated to be $22,560, or $480 per airplane, per inspection cycle.
The new inspections required by this AD will take approximately 36 work hours per airplane to accomplish (including time for gaining access and closing up), at an average labor rate of $60 per work hour. Based on these figures, the cost impact of the new requirements of this AD on U.S. operators is estimated to be $101,520, or $2,160 per airplane, per inspection cycle.
The cost impact figures discussed above are based on assumptions that no operator has yet accomplished any of the requirements of this AD action, and that no operator would accomplish those actions in the future if this AD were not adopted. The cost impact figures discussed in AD rulemaking actions represent only the time necessary to perform the specific actions actually required by the AD. These figures typically do not include incidental costs, such as the time required to gain access and close up, planning time, or time necessitated by other administrative actions. However, for the new inspections required by this AD, the time for gaining access and closing up has been included in the figures above because it may not be possible for operators to accomplish these inspections during normal scheduled maintenance due to the compliance times associated with these inspections.
2. Section 39.13 is amended by removing amendment 39-11886 ( 65 FR 53161, September 1, 2000), and by adding a new airworthiness directive (AD), amendment 39-12349, to read as follows:
2001-15-15 Boeing: Amendment 39-12349. Docket 2000-NM-271-AD. Supersedes AD 2000-18-01, Amendment 39-11886.
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 Start Printed Page 39428accordance with paragraph (h)(1) 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.
(a) At the later of the times in paragraphs (a)(1) and (a)(2) of this AD, perform a detailed visual inspection for bushing migration, corrosion, or cracking; and a physical measurement inspection using feeler gages for bushing migration; of the lugs on the bulkhead fitting of the rear engine mount, in accordance with Part 2 of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000; or Revision 1, dated February 15, 2001. Thereafter, repeat the inspection at intervals not to exceed 90 days, until the inspections required by paragraphs (c) and (d) of this AD have been accomplished.
(2) Within 90 days after September 18, 2000 (the effective date of AD 2000-18-01, amendment 39-11886).
(b) During any inspection accomplished in accordance with paragraph (a), (c), or (d) of this AD; if bushing migration, corrosion, or cracking is detected, accomplish paragraph (b)(1) or (b)(2) of this AD, as applicable.
(1) If light corrosion or bushing migration is found: Prior to further flight, do interim rework in accordance with Part 4 of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000; or Revision 1, dated February 15, 2001; EXCEPT where the service bulletin specifies to contact Boeing, prior to further flight, repair in accordance with a method approved by the Manager, Seattle Aircraft Certification Office (ACO), FAA; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company Designated Engineering Representative (DER) who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD.
(2) If moderate to severe corrosion or any cracking is found: Prior to further flight, rework the lugs on the bulkhead fitting of the rear engine mount in accordance with Part 5 of Boeing Service Bulletin 747-54A2200, Revision 1, dated February 15, 2001, except as provided by paragraph (g) of this AD; or in accordance with a method approved by the Manager, Seattle ACO; or in accordance with data meeting the type certification basis of the airplane approved by a Boeing Company DER who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD. Such rework resets the compliance threshold for the inspections per paragraphs (c) and (d) of this AD to 15 years or 10,000 flight cycles since rework, whichever is earlier.
(c) At the later of the times in paragraphs (c)(1) and (c)(2) of this AD, except as provided by paragraph (f) of this AD, perform an ultrasonic inspection to detect corrosion or cracking of the lugs on the bulkhead fitting of the rear engine mount, per Part 3 of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000; or Revision 1, dated February 15, 2001. Thereafter, repeat the ultrasonic inspection described in this paragraph at intervals not to exceed 1,400 flight cycles or 18 months, whichever occurs first.
(2) Within 9 months after the effective date of this AD.
(d) After initial accomplishment of the inspections required by paragraph (c) of this AD, perform repetitive detailed visual inspections for bushing migration, corrosion, or cracking; and physical measurement inspections using feeler gages for bushing migration; of the lugs on the bulkhead fitting of the rear engine mount; per Part 2 of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000; or Revision 1, dated February 15, 2001. Perform the inspections at the interval stated in paragraph (d)(1) or (d)(2) of this AD, except as provided by paragraph (f) of this AD. Accomplishment of repetitive inspections per this paragraph constitutes terminating action for the inspections required by paragraph (a) of this AD.
(1) If no bushing migration is found during any inspection per this AD, the repetitive interval is not to exceed 1,400 flight cycles or 18 months, whichever occurs first.
(2) If any bushing migration is found during any inspection per this AD, the repetitive interval is not to exceed 180 days, until paragraph (e) of this AD has been done.
(e) If any bushing migration is found during any inspection per this AD, within 30 months after finding the migrated bushing, or within 18 months after the effective date of this AD, whichever occurs later, do rework of the lugs on the bulkhead fitting of the rear engine mount (including a detailed visual inspection of the aft upper engine mount for damage; a Non-Destructive Testing inspection and repair of the aft upper engine mount, as applicable; and rework of the lugs, and installation of new bushings in the lug, on the bulkhead fitting of the rear engine mount) per Part 5 of Boeing Alert Service Bulletin 747-54A2200, Revision 1, dated February 15, 2001. Such rework resets the compliance threshold for the inspections per paragraphs (c) and (d) of this AD to 15 years or 10,000 flight cycles since rework, whichever is earlier.
(f) Rework of the lugs on the bulkhead fitting of the rear engine mount (including a detailed visual inspection of the aft upper engine mount for damage; a Non-Destructive Testing inspection and repair of the aft upper engine mount, as applicable; and rework of the lugs, and installation of new bushings in the lug, on the bulkhead fitting of the rear engine mount) per Part 5 of Boeing Alert Service Bulletin 747-54A2200, Revision 1, dated February 15, 2001, resets the compliance threshold for the inspections per paragraphs (c) and (d) of this AD to 15 years or 10,000 flight cycles since rework, whichever is earlier.
(g) Where Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000; or Revision 1, dated February 15, 2001; says to contact Boeing for repair instructions: Before further flight, repair per a method approved by the Manager, Seattle ACO, or per data meeting the type certification basis of the airplane approved by a Boeing Company DER who has been authorized by the Manager, Seattle ACO, to make such findings. For a repair method to be approved by the Manager, Seattle ACO, as required by this paragraph, the approval letter must specifically reference this AD.
(2) Alternative methods of compliance, approved previously in accordance with AD 2000-18-01, amendment 39-11886, are approved as alternative methods of compliance for corresponding actions in this AD.
(i) Special flight permits may be issued in accordance with §§ 21.197 and 21.199 of the Start Printed Page 39429Federal 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.
(j) Except as provided by paragraphs (b) and (g) of this AD, the actions shall be done in accordance with Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000; or Boeing Service Bulletin 747-54A2200, Revision 1, dated February 15, 2001; as applicable.
(1) The incorporation by reference of Boeing Service Bulletin 747-54A2200, Revision 1, dated February 15, 2001, is approved by the Director of the Federal Register in accordance with 5 U.S.C. 552(a) and 1 CFR part 51.
(2) The incorporation by reference of Boeing Alert Service Bulletin 747-54A2200, dated July 7, 2000, was approved previously by the Director of the Federal Register as of September 18, 2000 (65 FR 53161, September 1, 2000).
(3) Copies of these service bulletins may be obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. Copies may be inspected at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.
(k) This amendment becomes effective on September 4, 2001.
[FR Doc. 01-18469 Filed 7-30-01; 8:45 am]