[Federal Register Volume 66, Number 171 (Tuesday, September 4, 2001)]
[Proposed Rules]
[Pages 46241-46243]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 01-22089]



[[Page 46241]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-124-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, 747-200, 747-300, 
and 747SR Series Airplanes Powered by General Electric CF6-45/50 or 
Pratt & Whitney JT9D-70 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, and 747SR series airplanes powered by General 
Electric CF6-45/50 or Pratt & Whitney JT9D-70 series engines, that 
currently requires a detailed visual inspection of the outboard 
diagonal brace for heat damage and cracking; and follow-on repetitive 
inspections and corrective actions, if necessary. This action proposes 
to require accomplishment of the previously optional replacement of any 
existing sealant with heat-resistant sealant as terminating action for 
the repetitive inspections required by this AD. This proposal is 
prompted by reports of heat damage to the forward end of the diagonal 
brace after accomplishment of a previous strut and wing modification. 
The actions specified by the proposed AD are intended to prevent heat 
damage to the diagonal brace, which could cause cracking, fracture, and 
possible loss of the diagonal brace load path and consequent separation 
of the strut and engine from the airplane.

DATES: Comments must be received by October 19, 2001.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-124-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. 2001-NM-124-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.
    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 2001-NM-124-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. 2001-NM-124-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On June 4, 2001, the FAA issued AD 2001-12-05, amendment 39-12260 
(66 FR 31527, June 12, 2001), applicable to certain Boeing Model 747-
100, 747-200, 747-300, and 747SR series airplanes powered by General 
Electric CF6-45/50 or Pratt & Whitney JT9D-70 series engines, to 
require a detailed visual inspection of the outboard diagonal brace for 
heat damage and cracking; and follow-on repetitive inspections and 
corrective actions, if necessary. That action was prompted by reports 
of heat damage to the forward end of the diagonal brace after 
accomplishment of the modification of the nacelle strut and wing 
structure per AD 95-13-07, amendment 39-9287 (60 FR 33336, June 28, 
1995).

Actions Since Issuance of Previous Rule

    In the preamble to AD 2001-12-05, the FAA specified that the 
actions required by that AD were considered ``interim action'' and that 
the FAA was considering further rulemaking action to supersede that AD 
to require removal of the existing sealant and replacement with heat-
resistant sealant, which would constitute terminating action for the 
repetitive inspections required by that AD action. The FAA now has 
determined that further rulemaking action is indeed necessary, and this 
proposed AD follows from that determination.
    The FAA has determined that long-term continued operational safety 
will be better ensured by modifications or 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 repetitive 
inspections, has led the FAA to consider placing less emphasis on 
special procedures and more emphasis on design improvements. The 
proposed corrective actions are consistent with these considerations.

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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 2001-12-05 to continue to require a 
detailed visual inspection of the outboard diagonal brace for heat 
damage and cracking; and follow-on repetitive inspections and 
corrective actions, if necessary. This proposal would also require 
replacing any existing sealant with heat-resistant sealant, and either 
replacing or repairing the diagonal brace, if necessary, which 
constitutes terminating action for the repetitive inspections required 
by this proposed AD.

Difference Between the Proposed Rule and Service Bulletin

    Operators should note that the service bulletin specifies that the 
diagonal brace may either be replaced per the service bulletin, or the 
manufacturer may be contacted for possible alternative rework (repair) 
instructions. However, paragraph (c)(2)(ii) of this proposed AD 
specifies that the repair be accomplished per a method approved by the 
Manager, Seattle Aircraft Certification Office, FAA; or per 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.

Cost Impact

    There are approximately 145 Model 747 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 39 
airplanes of U.S. registry would be affected by this proposed AD.
    The repetitive inspections that are currently required by AD 2001-
12-05 take approximately 1 work hour 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 is estimated to be $2,340 
per airplane, per inspection cycle.
    The terminating action that is proposed in this AD action would 
take approximately 2 work hours per airplane to accomplish, at an 
average labor rate of $60 per work hour. Required parts would cost 
approximately $100 per airplane. Based on these figures, the cost 
impact of the proposed requirements of this AD is estimated to be 
$8,580, or $220 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 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 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 39-12260 (66 FR 
31527, June 12, 2001), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 2001-NM-124-AD. Supersedes AD 2001-12-05, Amendment 
39-12260.

    Applicability: Model 747-100, 747-200, 747-300, and 747SR series 
airplanes; certificated in any category; powered by General Electric 
CF6-45/50 series engines, or Pratt & Whitney JT9D-70 series engines.

    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 heat damage to the diagonal brace, which could cause 
cracking or fracture of the diagonal brace, and possible loss of the 
diagonal brace load path and consequent separation of the strut and 
engine from the airplane, accomplish the following:

Restatement of Certain Requirements of AD 2000-12-05

Verification

    (a) Within 90 days after June 27, 2001 (the effective date of AD 
2001-12-05), do the actions required by paragraph (a)(1) or (a)(2) 
of this AD, as applicable.
    (1) If an operator's maintenance records verify that, during the 
accomplishment of AD 95-13-07, amendment 39-9287, the seal backup 
plates were restored and BMS 5-63 high-temperature sealant was used 
in that restoration, no further action is required by this AD.
    (2) If an operator's maintenance records do not verify that the 
actions specified in paragraph (a)(1) of this AD were accomplished, 
do the actions required by paragraph (b) of this AD.

Inspections and Corrective Actions

    (b) Within 90 days after June 27, 2001, do the inspections and 
applicable corrective actions specified by paragraphs (b)(1) and 
(b)(2) of this AD per the Accomplishment Instructions of Boeing 
Alert Service Bulletin 747-54A2208, dated March 29, 2001. 
Thereafter, repeat the inspections at intervals not to exceed 6 
months, until accomplishment of paragraph (c) of this AD.

Outboard Strut Diagonal Brace

    (1) Do a detailed visual inspection of the forward 20 inches of 
the outboard strut diagonal brace, including all areas of the 
forward clevis lugs and brace body, for signs of heat damage or 
cracks, per Part 1 of the Accomplishment Instructions of the service 
bulletin.
    (i) If no sign of heat damage or cracking is found, repeat the 
detailed visual inspection

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at intervals not to exceed 6 months per the service bulletin, until 
accomplishment of paragraph (c) of this AD.
    (ii) If any primer discoloration is found, before further 
flight, do a non-destructive test (NDT) inspection of the area to 
determine if the diagonal brace has heat damage per Part 1 of the 
Accomplishment Instructions of the service bulletin.
    (A) If no heat damage is found during the NDT inspection, and no 
cracking is found during the detailed visual inspection, repeat the 
detailed visual inspection specified by paragraph (b)(1) of this AD 
at intervals not to exceed 6 months.
    (B) If any heat damage is found during the NDT inspection, or 
any cracking is found during the detailed visual inspection, before 
further flight, do the actions specified in paragraph (c)(2) of this 
AD. Thereafter, repeat the detailed visual inspection specified by 
paragraph (b)(1) of this AD at intervals not to exceed 6 months.

Firewall Openings of the Strut Aft Bulkhead

    (2) Do a detailed visual inspection of the firewall openings of 
the strut aft bulkhead to verify installation of seal backup plates 
and condition of the sealant application per Part 1 of the 
Accomplishment Instructions of the service bulletin.
    (i) If no discrepancy (including damaged or missing seal backup 
plates, or damaged or missing sealant) is found, repeat the detailed 
visual inspection specified by paragraph (b)(1) of this AD at 
intervals not to exceed 6 months.
    (ii) If the seal backup plates are not installed, before further 
flight, install the seal backup plates and apply heat-resistant 
sealant, BMS 5-63, per Part 2 of the Accomplishment Instructions of 
the service bulletin. Accomplishment of this action terminates the 
repetitive inspections required by this AD.
    (iii) If the seal backup plates are installed, but the sealant 
application is damaged or missing, before further flight, remove any 
existing sealant and apply heat-resistant sealant, BMS 5-63, per 
Part 3 of the Accomplishment Instructions of the service bulletin. 
Accomplishment of this action terminates the repetitive inspections 
required by this AD.

    Note 2: Because it is difficult to distinguish between BMS 5-95 
and BMS 5-63 sealants, removal and replacement of the existing 
sealant is required to ensure that the correct heat-resistant 
sealant, BMS 5-63, is used.

New Requirements of This AD

Terminating Action and Corrective Action

    (c) Within 18 months after the effective date of this AD: Do the 
action specified by paragraph (c)(1), (c)(2), or (c)(3) of this AD, 
as applicable. Accomplishment of the applicable action constitutes 
terminating action for the repetitive inspections required by this 
AD.
    (1) Following the inspections required by paragraphs (b)(1) and 
(b)(2) of this AD, if no cracking or heat damage is found during 
those inspections, and the seal backup plates are installed, before 
further flight, remove any existing sealant and apply heat-resistant 
sealant BMS 5-63, per Part 3 of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 747-54A2208, dated March 29, 2001.
    (2) If any sign of heat damage or cracking is found during the 
inspections required by paragraph (b) of this AD, before further 
flight, do the actions specified by either paragraph (c)(2)(i) or 
(c)(2)(ii) of this AD.
    (i) Replace the diagonal brace per Part 4 of the Accomplishment 
Instructions of Boeing Alert Service Bulletin 747-54A2208, dated 
March 29, 2001;
    (ii) Repair per a method approved by the Manager, Seattle 
Aircraft Certification Office (ACO), FAA; or per 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 Manager's approval letter must 
specifically reference this AD.
    (3) If the seal back-up plates are not installed, before further 
flight, install the seal backup plates and apply heat-resistant 
sealant BMS 5-63, per Part 2 of the Accomplishment Instructions of 
the service bulletin.

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 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

    (e) Special flight permits may be issued in accordance with 
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 August 27, 2001.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 01-22089 Filed 8-31-01; 8:45 am]
BILLING CODE 4910-13-U