[Federal Register Volume 71, Number 45 (Wednesday, March 8, 2006)]
[Proposed Rules]
[Pages 11551-11555]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-3263]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24102; Directorate Identifier 2005-NM-244-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747-100, 747-100B, 747-
100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, and 747SR 
Series 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 747-100 and -200 
series airplanes. The existing AD currently requires repetitive 
inspections for cracking of the station 800 frame assembly, and repair 
if necessary. This proposed AD would retain the repetitive inspection 
requirements of the existing AD, but would expand the area to be 
inspected. This proposed AD also would reduce the initial inspection 
threshold, remove the adjustment of the compliance threshold and 
repetitive interval based on cabin differential pressure, and add 
airplanes to the applicability. This proposed AD results from several 
reports of cracks of the station 800 frame assembly on airplanes that 
had accumulated fewer total flight cycles than the initial inspection 
threshold in the existing AD. We are proposing this AD to detect and 
correct fatigue cracks that could extend and fully sever the frame, 
which could result in development of skin cracks that could lead to 
rapid depressurization of the airplane.

DATES: We must receive comments on this proposed AD by April 24, 2006.

ADDRESSES: Use one of the following addresses to submit comments on 
this proposed AD.
     DOT Docket Web site: Go to http://dms.dot.gov and follow 
the instructions for sending your comments electronically.
     Government-wide rulemaking Web site: Go to http://www.regulations.gov and follow the instructions for sending your 
comments electronically.
     Mail: Docket Management Facility; U.S. Department of 
Transportation, 400 Seventh Street, SW., Nassif Building, room PL-401, 
Washington, DC 20590.
     Fax: (202) 493-2251.
     Hand Delivery: Room PL-401 on the plaza level of the 
Nassif Building, 400 Seventh Street, SW., Washington, DC, between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays.
    Contact Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207, for service information identified in this 
proposed AD.

[[Page 11552]]


FOR FURTHER INFORMATION CONTACT: Ivan Li, Aerospace Engineer, Airframe 
Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 1601 Lind 
Avenue, SW., Renton, Washington 98055-4056; telephone (425) 917-6437; 
fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: 

Comments Invited

    We invite you to submit any relevant written data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed in the ADDRESSES section. Include the docket number ``Docket No. 
FAA-2006-24102; Directorate Identifier 2005-NM-244-AD'' at the 
beginning of your comments. We specifically invite comments on the 
overall regulatory, economic, environmental, and energy aspects of the 
proposed AD. We will consider all comments received by the closing date 
and may amend the proposed AD in light of those comments.
    We will post all comments we receive, without change, to http://dms.dot.gov, including any personal information you provide. We will 
also post a report summarizing each substantive verbal contact with FAA 
personnel concerning this proposed AD. Using the search function of 
that Web site, anyone can find and read the comments in any of our 
dockets, including the name of the individual who sent the comment (or 
signed the comment on behalf of an association, business, labor union, 
etc.). You may review the DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or may 
can visit http://dms.dot.gov.

Examining the Docket

    You may examine the AD docket on the Internet at http://dms.dot.gov, or in person at the Docket Management Facility office 
between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays. The Docket Management Facility office (telephone (800) 647-
5227) is located on the plaza level of the Nassif Building at the DOT 
street address stated in the ADDRESSES section. Comments will be 
available in the AD docket shortly after the Docket Management System 
receives them.

Discussion

    On July 12, 2001, we issued AD 2001-14-22, amendment 39-12333 (66 
FR 38891, July 26, 2001), for certain Boeing Model 747-100 and -200 
series airplanes. That AD requires repetitive detailed, surface high-
frequency eddy current (HFEC), and open hole HFEC inspections for 
cracking of the station 800 frame assembly, and repair if necessary. 
That AD resulted from reports that operators had found fatigue cracks 
in the strap and inner chord angle at the station 800 frame, between 
stringers 14 and 18, on certain Boeing Model 747-100 and -200 series 
airplanes. We issued that AD to find and fix fatigue cracks that could 
extend and fully sever the frame, which could result in development of 
skin cracks that could lead to rapid depressurization of the airplane.

Actions Since Existing AD Was Issued

    Since we issued AD 2001-14-22, we have received several reports of 
cracks of the station 800 frame assembly on airplanes that had 
accumulated fewer than 19,000 total flight cycles, which is the initial 
inspection threshold for AD 2001-14-22. Cracks between 0.4 and 0.8 inch 
in length were found at the inner chord angles on three airplanes that 
had accumulated between 15,735 and 16,428 total flight cycles. A crack 
indication was also found at the inner chord angle on an airplane that 
had accumulated 9,675 total flight cycles. In addition, Boeing found a 
crack at the aft inner chord angle on a Model 747-300 stretched upper 
deck airplane that had accumulated 23,475 total flight cycles. As a 
result of this finding, Boeing examined the Model 747-400 fatigue-test 
airplane and found significant damage in the affected area, including 
severed inner chord angles on both the left and right sides. The 
fatigue-test airplane had accumulated 54,000 test cycles.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-53A2451, 
Revision 1, dated November 10, 2005. The procedures in this alert 
service bulletin are essentially the same as those in Boeing Alert 
Service Bulletin 747-53A2451, including Appendix A, dated October 5, 
2000, which was referenced as the appropriate source of service 
information for accomplishing the required actions in AD 2001-14-22. 
However, Revision 1 of the alert service bulletin adds airplanes to the 
effectivity, and expands the inspection area for the detailed and 
surface HFEC inspections.
    Accomplishing the actions specified in the service information is 
intended to adequately address the unsafe condition.

Explanation of Change to Adjustment Based on Cabin Differential 
Pressure

    Paragraph (b) of AD 2001-14-22 allows for adjustment to the 
compliance threshold by not counting the flight cycles in which cabin 
differential pressure is at 2.0 pounds per square inch (psi) or less. 
This proposed AD would not allow that adjustment. However, this 
proposed AD states that operators may continue to adjust the repetitive 
inspection interval based on a lower cabin differential pressure until 
the next scheduled inspection. Thereafter, this proposed AD would not 
allow such adjustment. We have determined that an adjustment of flight 
cycles due to a lower cabin differential pressure is not substantiated 
and will not be allowed for use in determining the flight-cycle 
threshold for this proposed AD. There have been several instances on 
other in-service issues where analytical rationales have indicated that 
pressurization cycles of less than 2.0 psi should not be counted. 
However, when fleet records have been examined, the airplanes engaging 
in such operations have the same or greater occurrences of crack 
findings compared with those on which all pressurized flights are 
counted. As a result, we carefully consider such matters based on all 
available factors, including individual operators' specific maintenance 
programs, technical rationale, and fleet experience. We have found that 
such provisions are applicable only to a small number of operators that 
may not pressurize their airplanes above 2.0 psi in all their flights. 
We have determined that the best way to handle such circumstances is 
for operators to request an alternative method of compliance (AMOC) in 
accordance with the procedures in paragraph (l) of this proposed AD, 
rather than by increasing the complexity of the AD by addressing each 
operator's unique situation.

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 2001-14-22 and retain the requirements of the 
existing AD. This proposed AD would reduce the initial inspection 
threshold, remove the adjustment of the compliance threshold and 
repetitive interval based on cabin differential pressure, and add 
airplanes to the applicability. This proposed AD would require 
accomplishing the actions specified in the service bulletin described 
previously, except as discussed under ``Differences Between the 
Proposed AD and the Service Bulletin.''

[[Page 11553]]

Differences Between the Proposed AD and the Service Bulletin

    The service bulletin specifies to contact the manufacturer for 
instructions on how to repair certain conditions, but this proposed AD 
would require repairing those conditions in one of the following ways:
     Using a method that we approve; or
     Using data that meet the certification basis of the 
airplane, and that have been approved by an Authorized Representative 
for the Boeing Commercial Airplanes Delegation Option Authorization 
Organization whom we have authorized to make those findings.
    Although the service bulletin specifies to send Boeing a report of 
any structural damage found while doing the inspections, this proposed 
AD would not include that requirement.

Explanation of Additional Changes to Existing AD

    Boeing has received a Delegation Option Authorization (DOA). We 
have revised this proposed AD to delegate the authority to approve an 
alternative method of compliance for any repair that would be required 
by this proposed AD to the Authorized Representative for the Boeing DOA 
Organization rather than the Designated Engineering Representative 
(DER).
    We have revised this action to clarify the appropriate procedure 
for notifying the principal inspector before using any approved AMOC on 
any airplane to which the AMOC applies.
    We have revised the applicability to reflect the model designations 
as published in the most recent type certificate data sheets.
    This proposed AD would retain the repetitive inspection 
requirements of AD 2001-14-22. Since AD 2001-14-22 was issued, the AD 
format has been revised, and certain paragraphs have been rearranged. 
As a result of this change, the corresponding paragraph identifiers 
have changed in this proposed AD, as listed in the following table:

                      Revised Paragraph Identifiers
------------------------------------------------------------------------
                                           Corresponding requirement in
      Requirement in  AD 2001-14-22              this proposed AD
------------------------------------------------------------------------
Paragraph (a)...........................  Paragraph (f).
Paragraph (b)...........................  Paragraph (g).
Paragraph (c)...........................  Paragraph (h).
------------------------------------------------------------------------

Clarification of Inspections

    We have changed all references to a ``detailed visual inspection'' 
in the existing AD to ``detailed inspection'' in this proposed AD. A 
definition of a detailed inspection is included in the service 
bulletin.

Costs of Compliance

    There are about 900 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 156 airplanes of 
U.S. registry.
    The inspections that are specified in AD 2001-14-22, and retained 
in this proposed AD, take between 12 and 14 work hours per airplane, 
depending on the airplane configuration. The average labor rate is $65 
per work hour. Based on these figures, the estimated cost of the 
currently required actions is between $121,680 and $141,960, or between 
$780 and $910 per airplane, per inspection cycle.
    The new proposed actions would take between 18 and 20 work hours 
per airplane, at an average labor rate of $65 per work hour. Based on 
these figures, the estimated cost of the new actions specified in this 
proposed AD for U.S. operators is between $182,520 and $202,800, or 
between $1,170 and $1,300 per airplane, per inspection cycle.

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 39-12333 (66 FR 38891, July 26, 2001) and adding the 
following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-24102; Directorate Identifier 2005-NM-
244-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by April 24, 
2006.

Affected ADs

    (b) This AD supersedes AD 2001-14-22.

Applicability

    (c) This AD applies to all Boeing Model 747-100, 747-100B, 747-
100B SUD, 747-200B, 747-200C, 747-300, 747-400, 747-400D, and 747SR 
series airplanes, certificated in any category.

Unsafe Condition

    (d) This AD results from several reports of cracks of the 
station 800 frame assembly on airplanes that had accumulated fewer 
total flight cycles than the initial inspection threshold in the 
existing AD. We are issuing this AD to detect and correct fatigue 
cracks that could extend and fully sever the frame, which could 
result in development of skin cracks that could lead to rapid 
depressurization of the airplane.

Compliance

    (e) You are responsible for having the actions required by this 
AD performed within

[[Page 11554]]

the compliance times specified, unless the actions have already been 
done.

Restatement of the Requirements of AD 2001-14-22

Repetitive Inspections

    (f) For Boeing Model 747-100, 747-100B, 747-100B SUD, -200B, 
747-200C, and 747-200F series airplanes, as identified in Boeing 
Alert Service Bulletin 747-53A2451, including Appendix A, dated 
October 5, 2000: Do detailed, surface high-frequency eddy current 
(HFEC), and open-hole HFEC inspections, as applicable, for cracking 
of the station 800 frame assembly (including the inner chord strap, 
angles, and exposed web) between stringers 14 and 18, in accordance 
with the Accomplishment Instructions of Boeing Alert Service 
Bulletin 747-53A2451, including Appendix A, dated October 5, 2000; 
or Boeing Alert Service Bulletin 747-53A2451, Revision 1, dated 
November 10, 2005; after the effective date of this AD, only 
Revision 1 of the service bulletin may be used. Except as provided 
by paragraph (g) of this AD, do the inspection at the applicable 
time specified in Table 1 of this AD, and repeat the inspections 
thereafter at intervals not to exceed 3,000 flight cycles until the 
initial inspections required by paragraph (h) of this AD are 
accomplished.

                       Table 1.--Compliance Times
------------------------------------------------------------------------
  Total flight cycles as of August 30,
2001 (the effective date of AD 2001-14-   Do the inspection in paragraph
                  22)                      (f) of this AD at this time
------------------------------------------------------------------------
(1) Fewer than 19,000..................  Before the accumulation of
                                          19,000 total flight cycles, or
                                          within 1,500 flight cycles
                                          after August 30, 2001,
                                          whichever comes later.
(2) 19,000 or more, but 21,250 or fewer  Within 1,500 flight cycles or
                                          12 months after August 30,
                                          2001, whichever comes first.
(3) 21,251 or more.....................  Within 750 flight cycles or 12
                                          months after August 30, 2001,
                                          whichever comes first.
------------------------------------------------------------------------

Adjustments to Compliance Time: Cabin Differential Pressure

    (g) For Boeing Model 747-100, 747-100B, 747-100B SUD, -200B, 
747-200C, and 747-200F series airplanes, as identified in Boeing 
Alert Service Bulletin 747-53A2451, including Appendix A, dated 
October 5, 2000, that are inspected before the effective date of 
this AD: Except as provided by paragraph (i) of this AD, for the 
purposes of calculating the compliance threshold and repetitive 
interval for the actions required by paragraph (f) of this AD, the 
number of flight cycles in which cabin differential pressure is at 
2.0 pounds per square inch (psi) or less need not be counted when 
determining the number of flight cycles that have occurred on the 
airplane, provided that the flight cycles with momentary spikes in 
cabin differential pressure above 2.0 psi are included as full 
pressure cycles. For this provision to apply, all cabin pressure 
records must be maintained for each airplane: NO fleet-averaging of 
cabin pressure is allowed.

New Requirements of This Ad

Repetitive Inspections of Expanded Area at a New Reduced Threshold

    (h) For all airplanes, at the applicable time specified in Table 
2 of this AD, except as provided by paragraph (i) of this AD, do the 
following inspections of the station 800 frame assembly in 
accordance with the Accomplishment Instructions of Boeing Alert 
Service Bulletin 747-53A2451, Revision 1, dated November 10, 2005: A 
detailed inspection for cracking of the inner chord strap, angles, 
and exposed web adjacent to the inner chords on the station 800 
frame between stringer 14 and stringer 18; and surface HFEC and 
open-hole HFEC inspections for cracking of the inner chord strap and 
angles. Do the initial inspections at the applicable time specified 
in Table 2 of this AD, and repeat the inspections thereafter at 
intervals not to exceed 3,000 flight cycles. Accomplishing the 
initial inspections required by this paragraph terminates the 
inspection requirements of paragraph (f) of this AD.

                   Table 2.--Revised Compliance Times
------------------------------------------------------------------------
Total flight cycles as of the effective  Do the inspections in paragraph
            date of this AD                (h) of this AD at this time
------------------------------------------------------------------------
(1) Fewer than 16,000..................  Before the accumulation of
                                          16,000 total flight cycles, or
                                          within 1,500 flight cycles
                                          after the effective date of
                                          this AD, whichever comes
                                          later.
(2) 16,000 or more, but 24,250 or fewer  Within 1,500 flight cycles or
                                          12 months after the effective
                                          date of this AD, whichever
                                          comes first.
(3) 24,251 or more.....................  Within 750 flight cycles or 12
                                          months after the effective
                                          date of this AD, whichever
                                          comes first.
------------------------------------------------------------------------

Adjustments to Compliance Time: Cabin Differential Pressure

    (i) For the purposes of calculating the compliance threshold and 
repetitive interval for actions required by paragraphs (f) and (h) 
of this AD, on or after the effective date of this AD: All flight 
cycles, including the number of flight cycles in which cabin 
differential pressure is at 2.0 psi or less, must be counted when 
determining the number of flight cycles that have occurred on the 
airplane. However, for airplanes on which the repetitive interval 
for the actions required by paragraph (f) of this AD have been 
calculated in accordance with paragraph (g) of this AD by excluding 
the number of flight cycles in which cabin differential pressure is 
at 2.0 pounds psi or less: Continue to adjust the repetitive 
inspection interval in accordance with paragraph (g) of this AD 
until the initial inspections required by paragraph (h) of this AD 
are accomplished. Thereafter, no adjustment to compliance times 
based on paragraph (g) of this AD is allowed.

Repair

    (j) If any cracking is detected during any inspection required 
by paragraph (f) or (h) of this AD, and the service bulletin 
specifies to contact Boeing for appropriate action: Before further 
flight, repair using a method approved in accordance with the 
procedures specified in paragraph (l) of this AD.

No Report Required

    (k) Although the Accomplishment Instructions of Boeing Alert 
Service Bulletin 747-53A2451, including Appendix A, dated October 5, 
2000; and Boeing Alert Service Bulletin 747-53A2451, Revision 1, 
dated November 10, 2005; describe procedures for reporting certain 
information to the manufacturer, this AD does not require that 
report.

Alternative Methods of Compliance (AMOCs)

    (l)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.

[[Page 11555]]

    (2) Before using any AMOC approved in accordance with Sec.  
39.19 on any airplane to which the AMOC applies, notify the 
appropriate principal inspector in the FAA Flight Standards 
Certificate Holding District Office.
    (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.
    (4) AMOCs approved previously in accordance with AD 2001-14-22, 
are approved as AMOCs for the corresponding provisions of paragraphs 
(f) and (j) of this AD.

    Issued in Renton, Washington, on February 28, 2006.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E6-3263 Filed 3-7-06; 8:45 am]
BILLING CODE 4910-13-P