Document ID: FAA-2008-1071-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Boeing Model 747 Airplanes
Posted Date: 2008-10-08T04:00Z

[Federal Register: October 8, 2008 (Volume 73, Number 196)]
[Proposed Rules]               
[Page 58903-58906]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr08oc08-26]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-1071; Directorate Identifier 2008-NM-093-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 747 Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: The FAA proposes to supersede an existing airworthiness 
directive (AD) that applies to certain Boeing Model 747 airplanes. The 
existing AD currently requires repetitive inspections to detect 
evidence of wear damage in the area at the interface between the 
vertical stabilizer seal and fuselage skin, and corrective actions, if 
necessary. The existing AD also provides for an optional terminating 
action for the repetitive inspections. For all airplanes, this proposed 
AD would require doing repetitive inspections for wear damage and 
cracks of the fuselage skin in the interface area of the vertical 
stabilizer seal and fuselage skin, doing a detailed inspection for wear 
damage and cracks of the surface of any skin repair doubler in the 
area, and doing corrective actions. For airplanes on which the fuselage 
skin has been blended to remove wear damage, this proposed AD would 
require doing repetitive external detailed inspections or high 
frequency eddy current inspections for cracks of the blended area of 
the fuselage skin, and corrective actions if necessary. This proposed 
AD results from reports of wear damage on airplanes with fewer than 
8,000 total flight cycles. In addition, there have been three reports 
of skin wear damage on airplanes that applied BMS 10-86 Teflon-filled 
coating (terminating action per AD 2002-26-15). We are issuing this AD 
to detect and correct wear damage and cracks of the fuselage skin in 
the interface area of the vertical stabilizer seal and fuselage skin in 
sections 46 and 48, which could cause in-flight depressurization of the 
airplane.

DATES: We must receive comments on this proposed AD by November 24, 
2008.

ADDRESSES: You may send comments by any of the following methods:
     Federal eRulemaking Portal: Go to http://
www.regulations.gov. Follow the instructions for submitting comments.
     Fax: 202-493-2251.
     Mail: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Hand Delivery: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    For service information identified in this AD, contact Boeing 
Commercial Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207.

Examining the AD Docket

    You may examine the AD docket on the Internet at http://
www.regulations.gov; or in person at the Docket Management Facility 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The AD docket contains this proposed AD, the regulatory 
evaluation, any comments received, and other information. The street 
address for the Docket Office (telephone 800-647-5527) is in the 
ADDRESSES section. Comments will be available in the AD docket shortly 
after receipt.

FOR FURTHER INFORMATION CONTACT: Ivan Li, Aerospace Engineer, Airframe 
Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind 
Avenue, SW., Renton, Washington 98057-3356; telephone (425) 917-6437; 
fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite you to send any written relevant data, views, or 
arguments about this proposed AD. Send your comments to an address 
listed under the ADDRESSES section. Include ``Docket No. FAA-2008-1071; 
Directorate Identifier 2008-NM-093-AD'' at the beginning of your 
comments. We specifically invite comments on the overall regulatory, 
economic, environmental, and energy aspects of this proposed AD. We 
will consider all comments received by the closing date and may amend 
this proposed AD because of those comments.
    We will post all comments we receive, without change, to http://
www.regulations.gov, including any personal information you provide. We 
will also post a report summarizing each substantive verbal contact we 
receive about this proposed AD.

Discussion

    On December 24, 2002, we issued AD 2002-26-15, amendment 39-13003 
(68 FR 476, January 6, 2003), for certain Boeing Model 747 series 
airplanes. That AD requires repetitive inspections to detect evidence 
of skin wear damage in the interface area of the vertical stabilizer 
seal and fuselage skin, and corrective actions, if necessary. The 
existing AD also provides for an optional terminating action for the 
repetitive inspections. That AD resulted from reports of wear damage at 
the interface area of the vertical stabilizer seal and fuselage skin in 
sections 46 and 48. We issued that AD to detect and correct wear damage 
of the fuselage skin, which could result in thinning and cracking of 
the fuselage skin, and consequent in-flight depressurization of the 
airplane.

Actions Since Existing AD Was Issued

    Since we issued AD 2002-26-15, we have received several reports of 
skin wear damage on airplanes with less than 8,000 total flight cycles. 
As a result, Boeing has revised the initial inspection threshold of the 
repetitive inspections to 20,000 total flight hours. In addition, there 
have been three reports of skin wear damage on airplanes that have 
received the Boeing Material Specifications (BMS) 10-86 Teflon-filled 
coating application (terminating action per AD 2002-26-15). We have 
concluded that the one-time Teflon-filled coating application does not 
provide the necessary skin wear resistance; therefore, the terminating 
action no longer terminates the repetitive inspections. The 
requirements of 2002-26-15 do not adequately address the identified 
unsafe condition of that AD.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-53A2478, 
Revision 1, dated March 27, 2008. The service bulletin describes the 
following procedures:
     For all airplanes: Do repetitive external inspections for 
wear damage and cracks of the fuselage skin at the interface area of 
the vertical stabilizer

[[Page 58904]]

seal and fuselage skin, and do a detailed inspection for wear damage 
and cracks of the surface of any repair doubler installed in the area.
     For airplanes on which the fuselage skin has been blended 
to remove wear damage: Do repetitive external detailed inspections or 
high frequency eddy current inspections for cracks of the blended area 
of the fuselage skin.
     If no wear damage or crack is found: Before further 
flight, apply BMS 10-86 Teflon-filled coating.
     If any wear damage or crack is found: Before further 
flight, measure the depth of the wear and location, repair any wear 
damage and crack, and apply BMS 10-86 Teflon-filled coating.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition.

FAA's Determination and Requirements of the Proposed AD

    We have evaluated all pertinent information and identified an 
unsafe condition that is likely to develop on other airplanes of the 
same type design. For this reason, we are proposing this AD, which 
would supersede AD 2002-26-15. This proposed AD would retain the 
requirements of that AD and also require accomplishing the actions 
described previously, except as discussed under ``Differences Between 
the Proposed AD and the Service Bulletin.''

Differences Between the Proposed AD and Service Bulletin

    The service bulletin specifies to contact the manufacturer for 
actions if corrosion resistant steel rubstrips are installed in the 
interface area of the vertical stabilizer seal and fuselage skin, but 
this proposed AD would require contacting the FAA for inspections using 
a method that we approve.

Costs of Compliance

    There are about 917 airplanes of the affected design in the 
worldwide fleet. The following table provides the estimated costs for 
U.S. operators to comply with this proposed AD.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                                                   Number of U.S.-
               Action                  Work hours     Average labor          Parts            Cost per airplane      registered          Fleet cost
                                                      rate per hour                                                   airplanes
--------------------------------------------------------------------------------------------------------------------------------------------------------
Inspection (required by AD 2002-26-              12             $80  None.................  $960, per inspection              253  $242,880, per
 15).                                                                                        cycle.                                 inspection cycle.
Inspection and application of BMS                 8              80  None.................  $640, per inspection              165  $105,600, per
 10-86 Teflon-filled coating (new                                                            cycle.                                 inspection cycle.
 proposed action).
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Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, Section 106, describes the 
authority of the FAA Administrator. Subtitle VII, Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    We are issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701, ``General 
requirements.'' Under that section, Congress charges the FAA with 
promoting safe flight of civil aircraft in air commerce by prescribing 
regulations for practices, methods, and procedures the Administrator 
finds necessary for safety in air commerce. This regulation is within 
the scope of that authority because it addresses an unsafe condition 
that is likely to exist or develop on products identified in this 
rulemaking action.

Regulatory Findings

    We have determined that this proposed AD would not have federalism 
implications under Executive Order 13132. This proposed AD 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.
    For the reasons discussed above, I certify that the 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. 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this proposed AD and placed it in the AD docket. See the 
ADDRESSES section for a location to examine the regulatory evaluation.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Safety.

The Proposed Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA proposes to amend 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. The Federal Aviation Administration (FAA) amends Sec.  39.13 by 
removing amendment 39-13003 (68 FR 476, January 6, 2003) and adding the 
following new airworthiness directive (AD):

Boeing: Docket No. FAA-2008-1071; Directorate Identifier 2008-NM-
093-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by November 
24, 2008.

Affected ADs

    (b) This AD supersedes AD 2002-26-15.

Applicability

    (c) This AD applies to Boeing Model 747-100, 747-100B, 747-100B 
SUD, 747-200B, 747-200C, 747-200F, 747-300, 747-400, 747-400D, 747-
400F, 747SR, and 747SP series airplanes, certificated in any 
category, as identified in Boeing Alert Service Bulletin 747-
53A2478, Revision 1, dated March 27, 2008.

[[Page 58905]]

Unsafe Condition

    (d) This AD results from reports of skin wear damage on 
airplanes with fewer than 8,000 total flight cycles. In addition, 
there have been three reports of skin wear damage on airplanes on 
which BMS 10-86 Teflon-filled coating was applied (terminating 
action per AD 2002-26-15). We are issuing this AD to detect and 
correct wear damage and cracks of the fuselage skin in the interface 
area of the vertical stabilizer seal and fuselage skin in sections 
46 and 48, which could cause in-flight depressurization of the 
airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within the compliance times specified, unless the 
actions have already been done.

Requirements of AD 2002-26-15

Inspections for Damage/Corrective Actions

    (f) For airplanes identified in Boeing Alert Service Bulletin 
747-53A2478, dated February 7, 2002: Prior to the accumulation of 
15,000 total flight cycles, or within 1,200 flight cycles after 
February 10, 2003 (the effective date of AD 2002-26-15), whichever 
occurs later, perform a detailed inspection to detect evidence of 
wear damage of the fuselage skin at the interface area of the 
vertical stabilizer seal and fuselage skin, per the service 
bulletin.
    (1) If no wear damage of the fuselage skin is detected or any 
existing blendout is within the structural repair manual (SRM) 
allowable damage limits: Repeat the detailed inspection at intervals 
not to exceed 6,000 flight cycles.
    (2) If any wear damage of the fuselage skin is detected or any 
existing blendout exceeds the allowable damage limits specified in 
the SRM: Before further flight, repair the vertical stabilizer seal 
interface and refinish the skin with BMS 10-86 Teflon-filled 
coating, per the alert service bulletin. Accomplishment of the 
repair and refinishing is terminating action for the repetitive 
inspections required by paragraph (f)(1) of this AD.

    Note 1: 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.''

Previously Accomplished Inspections and Terminating Action

    (g) For airplanes identified in Boeing Alert Service Bulletin 
747-53A2478, dated February 7, 2002: Inspections and terminating 
action done before February 10, 2003, per Boeing Service Bulletin 
747-53-2192, dated July 21, 1981, are acceptable for compliance with 
the corresponding actions required by paragraph (f) of this AD, 
provided BMS 10-86 Teflon-filled coating was used, and the new 
allowable damage limits specified in Boeing Alert Service Bulletin 
747-53A2478, dated February 7, 2002, are met.

New Requirements of This AD

New Service Bulletin Revision

    (h) The term ``service bulletin,'' as used in paragraphs (i) 
through (l) of this AD, means Boeing Alert Service Bulletin 747-
53A2478, Revision 1, dated March 27, 2008, unless otherwise 
specified.

New Repetitive Inspections

    (i) Except as provided by paragraph (j) of this AD: At the 
applicable times specified in Table 1 of this AD, do the actions 
specified in paragraphs (i)(1) and (i)(2) of this AD, as applicable. 
Accomplishing the initial inspection specified in paragraph (i) 
terminates the requirements of paragraph (f) of this AD.
    (1) For all airplanes: Do the actions specified in paragraphs 
(i)(1)(i) and (i)(1)(ii) of this AD, as applicable.
    (i) Do repetitive external detailed inspections for wear damage 
and cracks of the fuselage skin in the interface area of the 
vertical stabilizer seal and fuselage skin, in accordance with the 
Accomplishment Instructions of the service bulletin.
    (ii) Where a skin repair doubler is present in the interface 
area of the vertical stabilizer seal and fuselage skin, do a 
detailed inspection for wear damage and cracks of the surface of the 
repair doubler.
    (2) For airplanes that have reduced skin thickness in Section 46 
due to blending without reinforcement: Do repetitive external 
detailed inspections or high frequency eddy (HFEC) current 
inspections for cracks of the blended area of the fuselage skin, in 
accordance with the Accomplishment Instructions of the service 
bulletin.

                                            Table 1--Compliance Times
----------------------------------------------------------------------------------------------------------------
                                           Compliance time (whichever occurs later)
               Action               -----------------------------------------------------  Repeat interval (not
                                              Threshold                Grace period             to exceed)
----------------------------------------------------------------------------------------------------------------
For actions required by paragraph    Prior to the accumulation    Within 6,000 flight     7,500 flight hours.
 (i)(1) of this AD.                   of 20,000 total flight       hours after the
                                      hours since the date of      effective date of
                                      issuance of the original     this AD.
                                      airworthiness certificate
                                      or the date of issuance of
                                      the original export
                                      certificate of
                                      airworthiness, or within
                                      7,500 flight hours after
                                      the last inspection of
                                      this AD, whichever occurs
                                      later.
For actions required by paragraph    Prior to the accumulation    Within 1,000 flight     1,200 flight cycles
 (i)(2) of this AD.                   of 20,000 total flight       cycles after the        for external detailed
                                      cycles since the date of     effective date of       inspection, or 6,000
                                      issuance of the original     this AD.                flight cycles for
                                      airworthiness certificate                            HFEC inspection.
                                      or the date of issuance of
                                      the original export
                                      certificate of
                                      airworthiness, or within
                                      6,000 flight cycles after
                                      the initial blend,
                                      whichever occurs later.
----------------------------------------------------------------------------------------------------------------

Exception to the Repetitive Inspections

    (j) If corrosion-resistant steel rubstrips are installed in the 
interface area of the vertical stabilizer seal and fuselage skin: 
Within the applicable compliance times specified in paragraph (i) of 
this AD, inspect the fuselage skin using a method approved in 
accordance with the procedures specified in paragraph (m) of this 
AD.

For No Wear Damage or Cracks Found: Apply Teflon

    (k) If no wear damage or crack is found in the fuselage skin 
during any inspection required by paragraph (i) of this AD: Before 
further flight, apply Boeing Material Specifications (BMS) 10-86 
Teflon-filled coating in accordance with the Accomplishment 
Instructions of the service bulletin.

For Any Wear Damage or Crack Found: Applicable Corrective Actions

    (l) If any wear damage or crack is found in the fuselage skin 
during any inspections required by paragraph (i) of this AD: Before 
further flight, after the inspection required by paragraph (i), do 
the actions specified in paragraphs (l)(1), (l)(2), and (l)(3) of 
this AD, in accordance with the Accomplishment Instructions of the 
service bulletin.
    (1) Measure the depth of the wear and record the location.
    (2) Repair any wear damage and any crack.

[[Page 58906]]

    (3) Apply BMS 10-86 Teflon-filled coating.

Alternative Methods of Compliance (AMOCs)

    (m)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, ATTN: Ivan Li, Aerospace Engineer, Airframe Branch, ANM-120S, 
FAA, Seattle ACO, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone (425) 917-6437; fax (425) 917-6590; has the 
authority to approve AMOCs for this AD, if requested using the 
procedures found in 14 CFR 39.19.
    (2) To request a different method of compliance or a different 
compliance time for this AD, follow the procedures in 14 CFR 39.19. 
Before using any approved AMOC on any airplane to which the AMOC 
applies, notify your appropriate principal inspector (PI) in the FAA 
Flight Standards District Office (FSDO), or lacking a PI, your local 
FSDO.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair required by this AD, if it is approved by an 
Authorized Representative for the Boeing Commercial Airplanes 
Delegation Option Authorization Organization who has been authorized 
by the Manager, Seattle ACO, to make those findings. For a repair 
method to be approved, the repair must meet the certification basis 
of the airplane, and the approval must specifically refer to this 
AD.

    Issued in Renton, Washington, on September 26, 2008.
Michael Kaszycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-23824 Filed 10-7-08; 8:45 am]

BILLING CODE 4910-13-P