[Federal Register Volume 71, Number 69 (Tuesday, April 11, 2006)]
[Proposed Rules]
[Pages 18242-18244]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 06-3433]


-----------------------------------------------------------------------

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2006-24410; Directorate Identifier 2005-NM-261-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).

-----------------------------------------------------------------------

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for all Boeing Model 747 airplanes. This proposed AD would require 
repetitive inspections for cracking of the web of the station (STA) 
2360 aft pressure bulkhead around the fastener heads in the critical 
fastener rows in the web lap joints, from the Y-chord to the inner 
ring; and repair if necessary. This proposed AD also would require a 
modification, which would terminate the repetitive inspections. This 
proposed AD results from analysis by the manufacturer that the radial 
lap splices of the STA 2360 aft pressure bulkhead are subject to 
widespread fatigue damage. We are proposing this AD to detect and 
correct cracking of the bulkhead web at multiple sites along the radial 
lap splice, which could join together to form cracks of critical 
length, and result in rapid decompression and loss of control of the 
airplane.

DATES: We must receive comments on this proposed AD by May 26, 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 the service information identified in this 
proposed AD.

FOR FURTHER INFORMATION CONTACT: Nicholas Kusz, Aerospace Engineer, 
Airframe Branch, ANM-120S, Seattle Aircraft Certification Office, FAA, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6432; 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 ``FAA-2006-
24410; Directorate Identifier 2005-NM-261-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 DOT's complete Privacy Act Statement in the 
Federal Register published on April 11, 2000 (65 FR 19477-78), or you 
may 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

    We have received a report indicating that the radial lap splices of 
the station (STA) 2360 aft pressure bulkhead are subject to widespread 
fatigue damage (WFD), on all Boeing Model 747 airplanes that have 
exceeded the original Design Service Object of 20,000 total flight 
cycles. This WFD, if not detected and corrected, could result in 
cracking of the bulkhead web at multiple sites along the radial lap 
splice, which could join together to form cracks of critical length, 
and result in rapid decompression and loss of control of the airplane.

Other Relevant Rulemaking

    On July 26, 2000, we issued AD 2000-15-08, amendment 39-11840 (65 
FR 74255, August 2, 2000), for certain Boeing Model 747 airplanes. That 
AD requires repetitive inspections for damage or cracking of the aft 
pressure bulkhead, and cracking of the web-to-Y-ring lap joint area and 
the upper segment of the bulkhead web; certain follow-on actions if 
necessary; and repetitive inspections to detect cracking of the upper 
and lower segments of the aft bulkhead web, including radial lap 
joints. That AD was prompted by a report of a crack in the upper 
portion of the web of the pressure bulkhead at STA 2360 on a Boeing 
Model 747 airplane. We issued that AD to detect and correct

[[Page 18243]]

fatigue cracking of the bulkhead web, which could result in rapid 
depressurization of the airplane, and consequent reduced 
controllability of the airplane. Among other actions, AD 2000-15-08 
requires inspecting the radial lap joints, which are the subject of 
this proposed AD; however, this proposed AD would require repetitive 
inspections at reduced intervals.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 747-53A2561, dated 
September 22, 2005. The service bulletin describes procedures for doing 
repetitive high-frequency eddy current inspections for cracking of the 
web of the STA 2360 aft pressure bulkhead around the fastener heads in 
the critical fastener rows in the web lap joints, from the Y-chord to 
the inner ring. The service bulletin specifies that it is not necessary 
to inspect areas where production doublers cover the lap joint. If any 
cracking is found, the service bulletin specifies repairing in 
accordance with the Structural Repair Manual (SRM), or asking Boeing 
for repair data. The service bulletin also specifies that if the length 
of the crack is more than certain specified limits defined in the SRM 
to contact Boeing for repair instructions. The service bulletin also 
recommends that a modification be installed when the airplane has flown 
35,000 total flight cycles, but does not give procedures for doing that 
modification. The modification is intended to terminate the repetitive 
inspections. 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 exist or develop on other airplanes 
of this same type design. For this reason, we are proposing this AD, 
which would require accomplishing the actions specified in the service 
information described previously, except as discussed under 
``Differences Between the Proposed AD and the Service Bulletin.''

Differences Between the Proposed AD and the Service Bulletin

    Although the service bulletin does not specify a compliance grace 
period for modifying the airplanes that have accumulated more than 
35,000 total flight cycles, this proposed AD would include an 18-month 
grace period for modifying those airplanes.
    Although the service bulletin specifies to contact Boeing for 
repair data if a damaged area is more than certain specified limits, or 
if the damage includes corrosion; and although the service bulletin 
does not specify procedures for installing the modification when the 
airplane has accumulated 35,000 total flight cycles; this proposed AD 
would require operators to do the repairs and modification using a 
method approved by the FAA.

Costs of Compliance

    There are about 949 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 153 airplanes of 
U.S. registry. The proposed inspections would take about 11 work hours 
per airplane, at an average labor rate of $680 per work hour. Based on 
these figures, the estimated cost of the proposed AD for U.S. operators 
is $134,640, or $880 per airplane, per inspection cycle.
    Because the manufacturer has not yet developed a modification that 
matches the actions specified by this proposed AD, we cannot provide 
specific information regarding the required number of work hours or the 
cost of parts to do the proposed modification. In addition, 
modification costs will likely vary depending on the operator and the 
airplane configuration.

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 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2006-24410; Directorate Identifier 2005-NM-
261-AD.

Comments Due Date

    (a) The FAA must receive comments on this AD action by May 26, 
2006.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all 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.

Unsafe Condition

    (d) This AD results from analysis by the manufacturer that the 
radial lap splices of the station (STA) 2360 aft pressure bulkhead 
are subject to widespread fatigue damage. We are issuing this AD to 
detect and correct cracking of the bulkhead web at multiple sites 
along the radial lap splice, which could join together to form 
cracks of critical length, and result in rapid decompression and 
loss of control of the airplane.

[[Page 18244]]

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.

Repetitive Inspections

    (f) Before the airplane accumulates 28,000 total flight cycles, 
or within 18 months after the effective date of this AD, whichever 
occurs later: Do a high-frequency eddy current inspection for 
cracking of the web of the STA 2360 aft pressure bulkhead around the 
fastener heads in the critical fastener rows in the web lap joints, 
from the Y-chord to the inner ring; in accordance with Part 2, 
``Access and Inspection,'' of the Accomplishment Instructions of 
Boeing Alert Service Bulletin 747-53A2561, dated September 22, 2005. 
Repeat the inspection thereafter at intervals not to exceed 2,000 
flight cycles until the modification in paragraph (h) of this AD is 
done.

Repair

    (g) If any cracking is found during any inspection required by 
paragraph (f) of this AD: Before further flight, do the applicable 
action in paragraph (g)(1) or (g)(2) of this AD.
    (1) If the cracking is within certain limits specified in Boeing 
Alert Service Bulletin 747-53A2561, dated September 22, 2005, 
(referencing the structural repair manual) do the repair in 
accordance with the Accomplishment Instructions of the alert service 
bulletin.
    (2) If the cracking is more than certain limits specified in 
Boeing Alert Service Bulletin 747-53A2561, dated September 22, 2005, 
or if the alert service bulletin specifies to ask Boeing for repair 
data: Repair the cracking using a method approved by the Manager, 
Seattle Aircraft Certification Office (ACO), FAA. For a repair 
method to be approved by the Manager, Seattle ACO, as required by 
this paragraph, the Manager's approval letter must specifically 
refer to this AD.

Modification

    (h) Before the airplane accumulates 35,000 total flight cycles 
or within 18 months after the effective date of this AD, whichever 
occurs later: Modify the aft pressure bulkhead using a method 
approved by the Manager, Seattle ACO. For a repair method to be 
approved by the Manager, Seattle ACO, as required by this paragraph, 
the Manager's approval letter must specifically refer to this AD. 
Doing this modification terminates the repetitive inspection 
requirements of paragraph (f) of this AD.

Alternative Methods of Compliance (AMOCs)

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

    Issued in Renton, Washington, on March 31, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 06-3433 Filed 4-10-06; 8:45 am]
BILLING CODE 4910-13-P