[Federal Register Volume 63, Number 129 (Tuesday, July 7, 1998)]
[Proposed Rules]
[Pages 36628-36630]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-17947]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-185-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes 
Equipped with Pratt & Whitney Model JT9D-70 Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 747 
series airplanes, that currently requires repetitive inspections to 
detect fatigue cracking of the spring beams on the outboard struts; 
replacement of cracked spring beams with new or serviceable spring 
beams; and follow-on actions. That action also provides an optional 
terminating action for the repetitive inspections. This action would 
remove that optional terminating action, and would require a new 
terminating action. This proposal is prompted by the development of an 
improved process for manufacturing titanium spring beams that will 
eliminate the embedded porosity flaws in the existing spring beams from 
which fatigue cracking can originate. The actions specified by this 
proposal are intended to prevent fatigue cracking of the spring beam, 
which could result in loss of an outboard strut.

DATES: Comments must be received by August 21, 1998.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 97-NM-185-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 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: Tamara L. Anderson, Aerospace 
Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane 
Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; telephone (425) 227-2771; 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

[[Page 36629]]

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 97-NM-185-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. 97-NM-185-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On November 30, 1994, the FAA issued AD 94-25-01, amendment 39-9085 
(59 FR 63003, December 7, 1994), applicable to certain Boeing Model 747 
series airplanes, to require repetitive detailed visual inspections to 
detect fatigue cracking of the spring beams on the outboard struts; 
replacement of cracked spring beams with new or serviceable spring 
beams; and follow-on actions. That action also provides an optional 
terminating action for the repetitive inspections.
    AD 94-25-01 was prompted by a report of failure of a spring beam 
due to cracking that was propagated by fatigue. The requirements of 
that AD are intended to prevent failure of the spring beam, which could 
result in loss of an outboard strut.

Actions Since Issuance of Previous Rule

    Since the issuance of that AD, the FAA has determined that the 
specified optional terminating action, if accomplished, would not 
adequately address the unsafe condition. Neither the fluorescent dye 
penetrant inspection nor the zero-time overhaul, which are part of the 
optional terminating action, would detect the porosity flaws that are 
embedded within the titanium material of the existing spring beams. In 
addition, an improved process for manufacturing titanium spring beams 
has been developed that will eliminate the embedded porosity flaws in 
the existing spring beams from which fatigue cracking can originate. 
Such fatigue cracking, if not corrected, could result in loss of an 
outboard strut.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Service Bulletin 747-54-
2177, dated June 27, 1996, which describes procedures for replacement 
of the spring beams on the outboard struts with new, improved spring 
beams, which would eliminate the need for the repetitive inspections of 
the spring beams.
    In addition, the FAA has reviewed and approved Boeing Service 
Bulletin 747-54A2171, Revision 1, dated June 27, 1996, which changes 
the original issue of the alert service bulletin (which was referenced 
in AD 94-25-01 as the appropriate source of service information). This 
revision changes the repetitive inspection intervals and the 
terminating action. Accomplishment of the actions specified in the 
service bulletins 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 supersede AD 94-25-01 to continue to require the 
repetitive inspections to detect fatigue cracking of the spring beams 
on the outboard struts, and to remove the follow-on actions. For 
certain airplanes, this proposed AD would reinstate the repetitive 
inspections of AD 94-25-01 to detect fatigue cracking of the spring 
beams on the outboard struts. In addition, the proposed AD would remove 
the current optional terminating action, and would require a new 
terminating action for the repetitive inspections. The actions would be 
required to be accomplished in accordance with Boeing Service Bulletin 
747-54-2177 and Boeing Alert Service Bulletin 747-54A2171.

Cost Impact

    There are approximately 7 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 5 airplanes of U.S. registry 
would be affected by this proposed AD.
    The inspections that are currently required by AD 94-25-01, and 
retained in this proposed AD, take approximately 40 work hours per 
airplane, per inspection cycle, to accomplish, at an average labor rate 
of $60 per work hour. Based on these figures, the cost impact of the 
currently required inspections on U.S. operators is estimated to 
be$12,000, or $2,400 per airplane, per inspection cycle.
    The new replacement proposed by this AD would take approximately 
376 work hours per airplane to accomplish, at an average labor rate of 
$60 per work hour. Required parts would cost approximately $105,000 per 
airplane. Based on these figures, the cost impact of the replacement 
proposed by this AD on U.S. operators is estimated to be$637,800, or 
$127,560 per airplane.
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or 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 removing amendment 39-9085 (59 FR 
63003, December 7, 1994), and by

[[Page 36630]]

adding a new airworthiness directive (AD), to read as follows:

Boeing: Docket 97-NM-185-AD. Supersedes AD 94-25-01, Amendment 39-
9085.

    Applicability: Model 747 series airplanes, line numbers 202 
through 396 inclusive, equipped with Pratt & Whitney Model JT9D-70 
engines; 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 (f) 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 fatigue cracking of the spring beam, which could 
result in loss of an outboard strut, accomplish the following:
    (a) Prior to the accumulation of 10,000 total flight cycles, or 
within 30 days after December 22, 1994 (the effective date of AD 94-
25-01), whichever occurs later, perform a detailed visual inspection 
to detect fatigue cracking of the spring beams on the outboard 
struts, in accordance with Boeing Alert Service Bulletin 747-
54A2171, dated October 31, 1994, or Revision 1, dated June 27, 1996. 
(Remove the gap covers and fairing access panels to perform this 
inspection.)
    (1) If no cracking is detected, repeat the visual inspection 
thereafter at intervals not to exceed 300 flight cycles until the 
requirements of paragraph (d) of this AD have been accomplished.
    (2) If any cracking is detected, prior to further flight, 
accomplish the replacement actions specified in paragraph (d) of 
this AD.

    Note: 2: Accomplishment of the optional terminating action 
specified in paragraph (b) of AD 94-25-01 does not constitute 
terminating action for the requirements of this AD.

    (b) For airplanes that have accomplished terminating action in 
accordance with paragraph (b) of AD 94-25-01: Within 1,000 flight 
cycles after accomplishment of the terminating action specified by 
AD 94-25-01, or within 90 days after the effective date of this AD, 
whichever occurs later, perform a detailed visual inspection to 
detect fatigue cracking of the spring beams on the outboard struts, 
in accordance with Boeing Alert Service Bulletin 747-54A2171, dated 
October 31, 1994, or Revision 1, dated June 27, 1996.
    (1) If no cracking is detected, repeat the detailed visual 
inspection thereafter at intervals not to exceed 300 flight cycles 
until the requirements of paragraph (d) of thisAD have been 
accomplished.
    (2) If any cracking is detected, prior to further flight, 
accomplish the replacement actions specified in paragraph (d) of 
this AD.
    (c) For airplanes that have accomplished installation of the 
Boeing-inspected spare titanium spring beams in accordance with 
Boeing Service Bulletin 747-54A2171,Revision 1, dated June 27, 1996: 
Within 3,000 flight cycles after accomplishment of the installation 
of the spare spring beams, or within 90 days after the effective 
date of thisAD, whichever occurs later, perform a detailed visual 
inspection to detect fatigue cracking of the spring beams on the 
outboard struts, in accordance with Boeing AlertService Bulletin 
747-54A2171, dated October 31, 1994, or Revision 1, dated June 27, 
1996.
    (1) If no cracking is detected, repeat the detailed visual 
inspection thereafter at intervals not to exceed 300 flight cycles 
until the requirements of paragraph (d) of thisAD have been 
accomplished.
    (2) If any cracking is detected, prior to further flight, 
accomplish the replacement actions specified in paragraph (d) of 
this AD.
    (d) For all airplanes: Prior to the accumulation of 10,000 total 
flight cycles, or within 18 months after the effective date of this 
AD, whichever occurs later, replace the spring beams on the outboard 
struts with new, improved spring beams, in accordance with Boeing 
Service Bulletin 747-54-2177, dated June 27, 1996. Accomplishment of 
this replacement constitutes terminating action for the repetitive 
inspection requirements of this AD.
    (e) As of the effective date of this AD, no person shall install 
a spring beam assembly, part numbers 65B89175-5, -6, -9, -10, -13, -
14, -19, and -20, on any airplane.
    (f) 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 3: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (g) Special flight permits may be issued in accordance with 
sections Secs. 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 June 30, 1998.
Vi L. Lipski,
Acting Manager, Transport Airplane Directorate,Aircraft Certification 
Service.
[FR Doc. 98-17947 Filed 7-6-98; 8:45 am]
BILLING CODE 4910-13-U