[Federal Register Volume 65, Number 246 (Thursday, December 21, 2000)]
[Proposed Rules]
[Pages 80388-80390]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 00-32576]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2000-NM-354-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, 747-200, 747-300, 
747SP, and 747SR Series Airplanes Powered by Pratt & Whitney JT9D-3 and 
JT9D-7 Series 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-
100, 747-200, 747-300, 747SP, and 747SR series airplanes powered by 
Pratt & Whitney JT9D-3 or JT9D-7 series engines. That AD currently 
requires inspections of the vertical chords of the aft torque bulkhead 
of the outboard nacelle struts, and corrective action, if necessary. 
That AD also gives an optional modification of the vertical chords, 
which ends the inspections. This action would require the previously 
optional modification. The actions specified by the proposed AD are 
intended to prevent cracking of the vertical chords adjacent to the 
lower spar fitting, which could result in separation of the diagonal 
brace load path. Continued operation with a separated diagonal brace 
load path increases loads on the upper link, midspar fitting, and dual 
side links, which could result in separation of the strut and engine 
from the airplane. This action is intended to address the identified 
unsafe condition.

DATES: Comments must be received by February 5, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2000-NM-354-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. Comments may 
be submitted via fax to (425) 227-1232. Comments may also be sent via 
the Internet using the following address: [email protected]. 
Comments sent via fax or the Internet must contain ``Docket No. 2000-M-
354-AD'' in the subject line and need not be submitted in triplicate. 
Comments sent via the Internet as attached electronic files must be 
formatted in Microsoft Word 97 for Windows or ASCII text.
    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 Anderson, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, 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 action may be changed in 
light of the comments received.

[[Page 80389]]

    Submit comments using the following format:
     Organize comments issue-by-issue. For example, discuss a 
request to change the compliance time and a request to change the 
service bulletin reference as two separate issues.
     For each issue, state what specific change to the proposed 
AD is being requested.
     Include justification (e.g., reasons or data) for each 
request.
    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 action must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 2000-NM-354-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. 2000-NM-354-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On November 14, 2000, the FAA issued AD 2000-23-25, amendment 39-
11998 (65 FR 70781, November 28, 2000), applicable to certain Boeing 
Model 747-100, 747-200, 747-300, 747SP, and 747SR series airplanes 
powered by Pratt & Whitney JT9D-3 or JT9D-7 series engines; to require 
inspections of the vertical chords of the aft torque bulkhead of the 
outboard nacelle struts, and corrective action, if necessary. That AD 
also gives optional terminating action for the inspections. That action 
was prompted by reports of fatigue cracking of the vertical chords of 
the aft torque bulkhead of the outboard nacelle struts. The 
requirements of that AD are intended to detect and correct cracking of 
the vertical chords adjacent to the lower spar fitting, which could 
result in separation of the diagonal brace load path. Continued 
operation with a separated diagonal brace load path increases loads on 
the upper link, midspar fitting, and dual side links, which could 
result in separation of the strut and engine from the airplane.

Actions Since Issuance of Previous Rule

    In the preamble to AD 2000-23-25, the FAA indicated that the 
actions required by that AD were considered ``interim action'' and that 
further rulemaking action was being considered to require the 
modification of the vertical chords of the aft torque bulkhead of the 
outboard nacelle struts in Boeing Alert Service Bulletin 747-54A2201, 
dated September 28, 2000, which AD 2000-23-25 references as optional 
terminating action. The FAA has determined that further rulemaking is 
needed, and this proposed AD follows from that determination.

Explanation of Change Made to Requirements of Existing AD

    The FAA has added a note to this proposed rule to clarify the 
definition of a detailed visual inspection, as specified in paragraph 
(a)(1) of this AD.

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 2000-23-25 to continue to require 
inspections of the vertical chords of the aft torque bulkhead of the 
outboard nacelle struts, and corrective action, if necessary. The 
proposed AD would also require modification of the vertical chords, 
which would end the inspections. The actions would be required to be 
accomplished in accordance with Boeing Alert Service Bulletin 747-
54A2201, which was described in AD 2000-23-25, except as discussed 
below.

Difference Between Service Bulletin and This Proposed AD

    Operators should note that, although the service bulletin says to 
contact the manufacturer for certain repairs, this proposed AD would 
require those repairs to be accomplished by a method approved by the 
FAA, or according to data meeting the type certification basis of the 
airplane approved by a Boeing Company Designated Engineering 
Representative authorized by the FAA to make such findings.

Cost Impact

    There are approximately 366 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 115 airplanes of U.S. registry 
would be affected by this proposed AD.
    The detailed visual inspections that are currently required by AD 
2000-23-25 take approximately 18 work hours per airplane, at an average 
labor rate of $60 per work hour. Based on these figures, the FAA 
estimates that the cost impact of these inspections on U.S. operators 
is $124,200, or $1,080 per airplane, per inspection cycle.
    The ultrasonic and eddy current inspections that are currently 
required by AD 2000-23-25 take approximately 18 work hours per 
airplane, at an average labor rate of $60 per work hour. Based on these 
figures, the FAA estimates that the cost impact of these inspections on 
U.S. operators is $124,200, or $1,080 per airplane, per inspection 
cycle.
    The new modification that is proposed in this AD action would take 
approximately 48 work hours per airplane, at an average labor rate of 
$60 per work hour. Required parts would cost approximately $10,000 per 
airplane. Based on these figures, the FAA estimates that the cost 
impact of the proposed modification on U.S. operators is $1,481,200, or 
$12,880 per airplane.
    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 proposed 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.

Regulatory Impact

    The regulations proposed herein would not have a substantial direct 
effect 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, it 
is determined that this proposal would not have federalism implications 
under Executive Order 13132.
    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

[[Page 80390]]

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 39-11998 (65 FR 
70781, November 28, 2000), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 2000-NM-354-AD. Supersedes AD 2000-23-25, Amendment 
39-11998.

    Applicability: Model 747-100, 747-200, 747-300, 747SP, and 747SR 
series airplanes powered by Pratt & Whitney JT9D-3 or JT9D-7 series 
engines; as listed in Boeing Alert Service Bulletin 747-54A2201, 
dated September 28, 2000; 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 (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 cracking of the vertical chords adjacent to the lower 
spar fitting, which could result in separation of the diagonal brace 
load path and lead to separation of the strut and engine from the 
airplane, accomplish the following:

Restatement of Requirements of AD 2000-23-25:

Inspections

    (a) Except as provided by paragraph (b) of this AD, prior to the 
accumulation of 14,000 total flight cycles, or within 90 days after 
December 13, 2000 (the effective date of AD 2000-23-25), whichever 
occurs later: Accomplish paragraphs (a)(1) and (a)(2) of this AD.
    (1) Perform a detailed visual inspection to detect cracking of 
the vertical chords of the aft torque bulkhead of the outboard 
nacelle struts, in accordance with Part 2 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-54A2201, dated 
September 28, 2000. Thereafter, repeat this inspection at intervals 
not to exceed 600 flight cycles until paragraph (d) of this AD is 
accomplished.
    (2) Perform surface eddy current and ultrasonic inspections to 
detect cracking of the vertical chords of the aft torque bulkhead of 
the outboard nacelle struts, in accordance with Part 3 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 747-
54A2201, dated September 28, 2000. Thereafter, repeat these 
inspections at intervals not to exceed 1,200 flight cycles until 
paragraph (d) of this AD is accomplished.

    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.''

Optional Compliance Time

    (b) If Boeing Service Letter 747-54-055, dated April 24, 1998, 
was accomplished on the airplane during the modification of the 
nacelle strut in accordance with AD 95-10-16, amendment 39-9233: 
Accomplishment of the initial inspection in paragraph (a) of this AD 
may be deferred until 3,000 flight cycles after accomplishment of 
the service letter.

Repair

    (c) If any cracking is detected during any inspection or 
modification required by this AD: 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 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.

New Requirements of This Ad

Modification (Terminating Action)

    (d) Within 4 years after the effective date of this AD, do the 
modification of the vertical chords of the aft torque bulkhead of 
the outboard nacelle struts according to Part 4 of Boeing Alert 
Service Bulletin 747-54A2201, dated September 28, 2000. After this 
modification, stop the repetitive inspections required by paragraph 
(a) of this AD.

Alternative Methods of Compliance

    (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, Seattle ACO. 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.

Special Flight Permits

    (f) Special flight permits may be issued in accordance with 
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 December 15, 2000.
Dorenda D. Baker,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 00-32576 Filed 12-20-00; 8:45 am]
BILLING CODE 4910-13-U