[Federal Register Volume 67, Number 186 (Wednesday, September 25, 2002)]
[Proposed Rules]
[Pages 60189-60191]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 02-24281]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 2001-NM-394-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to certain Boeing Model 747 series 
airplanes. This proposal would require an initial inspection to 
identify all H-11 steel bolts on the outer chord of the body station 
(BS) 2360 aft pressure bulkhead between stringers 12L and 12R; follow-
on repetitive inspections to identify all remaining H-11 steel bolts on 
the entire outer chord of the BS 2360 aft pressure bulkhead; and 
follow-on and corrective actions, if necessary. This proposal also 
would require eventual replacement of all H-11 steel bolts with Inconel 
bolts. This action is necessary to prevent broken bolts, which could 
result in progressive failure of the remaining bolts and consequent 
structural damage and rapid depressurization of the airplane. This 
action is intended to address the identified unsafe condition.

DATES: Comments must be received by November 12, 2002.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-114, 
Attention: Rules Docket No. 2001-NM-394-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. 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-394-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: Technical Information: Rick Kawaguchi, 
Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-
4056; telephone (425) 227-1153; fax (425) 227-1181.
    Other Information: Sandi Carli, Airworthiness Directive Technical 
Editor/Writer; telephone (425) 687-4243, fax (425) 687-4248. Questions 
or comments may also be sent via the Internet using the following 
address: [email protected]. Questions or comments sent via the 
Internet as attached electronic files must be formatted in Microsoft 
Word 97 for Windows or ASCII text.

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:
    [sbull] 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.
    [sbull] For each issue, state what specific change to the proposed 
AD is being requested.
    [sbull] Include justification (e.g., reasons or data) for each 
request.

[[Page 60190]]

    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-394-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-394-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    The FAA has received several reports of numerous broken H-11 steel 
bolts found on the outer chord of the aft pressure bulkhead on certain 
Boeing Model 747 series airplanes. The broken bolts have been 
attributed to the steel material being susceptible to corrosion and 
subsequent stress corrosion cracking. If multiple adjacent H-11 steel 
bolts are broken, a progressive failure of the remaining bolts may 
occur. Such failure could result in structural damage and consequent 
rapid depressurization of the airplane.

Explanation of Relevant Service Information

    The FAA has reviewed and approved Boeing Alert Service Bulletin 
747-53A2474, dated October 25, 2001, which describes procedures for an 
initial inspection to identify all H-11 steel bolts on the outer chord 
of the body station (BS) 2360 aft pressure bulkhead between stringers 
12L and 12R. The inspection procedures include checking the bolt part 
number stamped on the top, the outside diameter, or the sloped surface 
of the bolt head; or verifying the bolt is steel by using a magnet.
    The service bulletin also describes procedures for follow-on 
repetitive inspections to identify all remaining H-11 steel bolts on 
the entire outer chord of the BS 2360 aft pressure bulkhead.
    The follow-on and corrective action procedures include doing either 
an ultrasonic inspection or a torque check for cracked or broken bolts 
if any H-11 steel bolt is found, or replacing the H-11 steel bolt with 
an Inconel bolt; and, if the H-11 steel bolt is replaced, visually 
inspecting the bolt hole for corrosion, oversizing the hole up to \1/
32\-inch to remove any corrosion, and, after installation of a new 
Inconel bolt, coating the bolt with corrosion inhibitor compound. The 
procedures also recommend replacing any cracked or broken bolt with an 
Inconel bolt before further flight.
    The service bulletin also specifies contacting the manufacturer if 
additional oversizing of the bolt holes is necessary. Replacing all H-
11 steel bolts with Inconel bolts would eliminate the need for the 
repetitive inspections. Accomplishment of the actions specified in the 
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 service bulletin described previously, except as discussed below.

Differences Between This Proposed Rule and the Service Information

    The service bulletin does not specify the type of initial and 
follow-on inspections to be used to find H-11 steel bolts on the outer 
chord of the body station 2360 aft pressure bulkhead. For the purposes 
of this AD, we have determined that the procedures in the service 
bulletin constitute a ``detailed inspection.'' Note 2 of this proposed 
AD defines such an inspection.
    Although the service bulletin specifies that the manufacturer may 
be contacted for disposition of certain repairs, this proposed AD would 
require such repairs to be accomplished per a method approved by us, 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 Aircraft Certification Office, to 
make such findings.

Cost Impact

    There are approximately 487 airplanes of the affected design in the 
worldwide fleet. The FAA estimates that 165 airplanes of U.S. registry 
would be affected by this proposed AD.
    It would take approximately 9 work hours per airplane to accomplish 
the proposed initial inspection, at an average labor rate of $60 per 
work hour. Based on these figures, the cost impact of the initial 
inspection on U.S. operators is estimated to be $89,100, or $540 per 
airplane.
    It would take approximately 35 work hours per airplane to 
accomplish the proposed follow-on inspection to identify all remaining 
H-11 steel bolts on the entire outer chord, at an average labor rate of 
$60 per work hour. Based on these figures, the cost impact of the 
follow-on inspection on U.S. operators is estimated to be $346,500, or 
$2,100 per airplane, per inspection cycle.
    Should an operator be required to replace the H-11 steel bolts, it 
would take approximately 108 work hours per airplane to accomplish the 
proposed replacement, at an average labor rate of $60 per work hour. 
Required parts would cost approximately $3,233 per airplane. Based on 
these figures, the cost impact is estimated to be $9,713 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 60191]]

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 adding the following new 
airworthiness directive:

Boeing: Docket 2001-NM-394-AD.

    Applicability: Model 747 series airplanes, line numbers 1 
through 644 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 (g) 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 broken H-11 steel bolts, which could result in 
progressive failure of the remaining bolts and consequent structural 
damage and rapid depressurization of the airplane, accomplish the 
following:

Initial Inspection

    (a) Within 18 months after the effective date of this AD: Do a 
detailed inspection to identify all H-11 steel bolts on the outer 
chord of the body station (BS) 2360 aft pressure bulkhead between 
stringers 12L and 12R. Do the inspection by checking the bolt part 
number stamped on the bolt head, or verifying the bolt is steel by 
using a magnet, per Boeing Alert Service Bulletin 747-53A2474, dated 
October 25, 2001. If no H-11 steel bolt is found, no further action 
is required by this paragraph. If any H-11 steel bolt is found, do 
the requirements specified in paragraph (c) of this AD.

    Note 2: For the purposes of this AD, a detailed 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.''

Follow-On Inspections/Corrective Actions

    (b) Within 18 months after doing the inspection required by 
paragraph (a) of this AD, or within 18 months after the effective 
date of this AD, whichever is later: Do a detailed inspection to 
identify all remaining H-11 steel bolts on the entire outer chord of 
the BS 2360 aft pressure bulkhead, per Boeing Alert Service Bulletin 
747-53A2474, dated October 25, 2001. If no H-11 steel bolt is found, 
no further action is required by this AD. If any H-11 steel bolt is 
found, do the requirements specified in paragraph (c) of this AD.
    (c) For any H-11 steel bolt found during any inspection required 
by paragraph (a) or (b) of this AD: Before further flight, do either 
an ultrasonic inspection or a torque check for cracked or broken 
bolts, or replace the H-11 steel bolt with an Inconel bolt per 
Boeing Alert Service Bulletin 747-53A2474, dated October 25, 2001. 
Replace any cracked or broken bolt with an Inconel bolt before 
further flight per the service bulletin. Then repeat the inspection 
at least every 18 months until the terminating action required by 
paragraph (d) of this AD is done.

Terminating Action

    (d) Within 6 years after the effective date of this AD: Replace 
all H-11 steel bolts on the entire outer chord of the BS 2360 aft 
pressure bulkhead with Inconel bolts (including visually inspecting 
the bolt hole for corrosion, oversizing the hole up to \1/32\ inch 
to remove any corrosion, and, after installing an Inconel bolt, 
coating the bolt with corrosion inhibitor compound), per Boeing 
Alert Service Bulletin 747-53A2474, dated October 25, 2001. When 
this paragraph is done, the requirements of this AD are terminated.

Exceptions to Service Information

    (e) Where Boeing Alert Service Bulletin 747-53A2474, dated 
October 25, 2001, specifies to contact Boeing for appropriate 
action: Before further flight, repair in accordance with 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, the 
approval must specifically reference this AD.

Spares

    (f) As of the effective date of this AD: No person shall install 
an H-11 steel bolt on the outer chord of the BS 2360 aft pressure 
bulkhead on any airplane.

Alternative Methods of Compliance

    (g) 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 Permit

    (h) Special flight permits may be issued in accordance with 
Sec. Sec.  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 September 16, 2002.
Vi L. Lipski,
Manager, , Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 02-24281 Filed 9-24-02; 8:45 am]
BILLING CODE 4910-13-P