[Federal Register Volume 72, Number 158 (Thursday, August 16, 2007)]
[Proposed Rules]
[Pages 45961-45963]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-16103]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-28990; Directorate Identifier 2007-NM-033-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 757-200, -200CB, and -300 
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 adopt a new airworthiness directive (AD) 
for certain Boeing Model 757-200, -200CB, and -300 series airplanes. 
This proposed AD would require repetitive inspections for cracks of the 
intercostal tee clips and attachment fasteners at the number 3 and 
number 4 doorstops of the passenger door cutouts, or repetitive 
inspections for cracks of the intercostal tee clips; and related 
investigative/ corrective actions if necessary. This proposed AD also 
provides an optional terminating action for the repetitive inspections. 
This proposed AD results from reports of cracked intercostal tee clips 
at the number 3 and number 4 doorstops of the passenger door cutouts. 
We are proposing this AD to detect and correct cracking of the tee 
clips, which could result in additional stress on the adjacent tee 
clips, surrounding intercostals, edge frame, door structure and 
doorstops. This additional stress could cause further cracking or 
breaking of the tee clips, which could result in failure of the door to 
seal and consequent rapid decompression of the airplane.

DATES: We must receive comments on this proposed AD by October 1, 2007.

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: U.S. Department of Transportation, Docket 
Operations, M-30, West Building Ground Floor, Room W12-140, 1200 New 
Jersey Avenue, SE., Washington, DC 20590.
     Fax: (202) 493-2251.
     Hand Delivery: Room W12-140 on the ground floor of the 
West Building, 1200 New Jersey Avenue, SE., 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: Dennis Stremick, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (425) 
917-6450; 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-2007-
28990; Directorate Identifier 2007-NM-033-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 Operations office between 9 
a.m. and 5 p.m., Monday through Friday, except Federal holidays. The 
Docket Operations office (telephone (800) 647-5527) is located on the 
ground floor of the West 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 eight reports indicating that cracked intercostal 
tee clips were found at the number 3 and number 4 doorstops of the 
passenger door cutouts on certain Boeing Model 757-200, -200CB, and -
300 series airplanes. These cracks were found during normal maintenance 
checks on passenger doorway number 4, at the aft edge frame of body 
station 1681.8 on the left and right sides. On two airplanes, cracks 
were found on the intercostal tee clips at both the number 3 and number 
4 doorstops. The cracks occurred in the radius area of the tee clip, 
between the horizontal and vertical flange. The number of flight cycles 
for these airplanes was between 22,700 and 25,000. The cracks in the 
tee clips are attributed to a preload of the tee clip; continued flight 
with cracks in the tee clips can place additional stress on the 
adjacent tee clips, surrounding intercostals, edge frame, door 
structure and doorstops. This additional stress, if not corrected, 
could cause further cracking or breaking of the tee clips, which could 
result in failure of the door to seal and consequent rapid 
decompression of the airplane.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 757-53A0093, dated 
November 8, 2006. The service bulletin describes procedures for 
repetitive detailed inspections with a borescope for cracks of the 
intercostal tee clips; or repetitive detailed inspections for cracks of 
the intercostal tee clips and attachment fasteners at the number 3 and 
number 4 doorstops of the passenger door cutouts after the galley/
lavatory has been removed; and related investigative and corrective 
actions if necessary. The related investigative and corrective actions 
include the following:

[[Page 45962]]

     Condition 1: For airplanes on which any tee clip for only 
door stop intercostal number 3 is cracked or broken; the procedures 
specify replacing any cracked tee clip with a new tee clip and 
contacting Boeing before further flight. In addition, the procedures 
describe inspections of the door stop fittings on the forward side of 
body station 1681.8 edge frame; the inner chord, web, and outer chord; 
the number 4 door structure including the door stop fittings and stop 
beams above and below the cracked tee clips; and the number 4 aft door 
frame.
     Condition 2: For airplanes on which any tee clip for only 
door stop intercostal number 4 is cracked or broken; the procedures 
specify replacing any cracked tee clip with a new tee clip and 
contacting Boeing before further flight. In addition, the procedures 
describe inspections of the tee clip and intercostal for cracking at 
door stop intercostal number 5; and from door stop number 3 through 
number 5: Inspecting the door stop fittings on the forward side of the 
body station 1681.8 edge frame; the inner chord, web, and outer chord; 
the number 4 door structure including the door stop fittings and stop 
beams above and below the cracked tee clips; and the number 4 aft door 
frame.
     Condition 3: For airplanes on which both tee clips for 
only door stop intercostal numbers 3 and 4 are cracked or broken; the 
procedures specify replacing the cracked tee clip with a new tee clip 
and contacting Boeing before further flight. In addition, the 
procedures describe inspections of the fasteners; the door stop 
fittings on the forward side of the body station 1681.8 edge frame; the 
inner chord, web, and outer chord; the number 4 door structure 
including the door stop fittings and stop beams above and below the 
cracked tee clips; for airplanes with greater than 28,000 flight 
cycles, the fasteners and the fillet radius of the stop fittings; and 
the number 4 aft door frame.
    If cracked or broken tee clips are found during any inspection, the 
procedures describe inspecting the tee clip and intercostal for cracks 
of the door stop intercostal number 2 and doing inspections from door 
stop numbers 2 through 5. The additional inspections are for cracks of 
the door stop fittings; the inner chord, web, and outer chord; and the 
body station 1681.8 edge frame.
    Replacing both tee clips on the left and right sides with new tee 
clips would eliminate the need for 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 
``Difference Between the Proposed AD and Service Information.''

Difference Between the Proposed AD and Service Information

    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.

Costs of Compliance

    There are about 912 airplanes of the affected design in the 
worldwide fleet. This proposed AD would affect about 324 airplanes of 
U.S. registry.
    The proposed detailed inspection, if accomplished, would take about 
2 work hours per airplane, at an average labor rate of $80 per work 
hour. Based on these figures, the estimated cost of the inspections 
proposed by this AD is $51,840, or $160 per airplane, per inspection 
cycle.
    The proposed borescope inspection, if accomplished, would take 
about 3 work hours per airplane, at an average labor rate of $80 per 
work hour. Based on these figures, the estimated cost of the 
inspections proposed by this AD is $77,760, or $240 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 
adding the following new airworthiness directive (AD):

Boeing: Docket No. FAA-2007-28990; Directorate Identifier 2007-NM-
033-AD.

[[Page 45963]]

Comments Due Date

    (a) The FAA must receive comments on this AD action by October 
1, 2007.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 757-200, -200CB, and -300 
series airplanes, certificated in any category; as identified in 
Boeing Alert Service Bulletin 757-53A0093, dated November 8, 2006.

Unsafe Condition

    (d) This AD results from reports of cracked intercostal tee 
clips at the number 3 and number 4 doorstops of the passenger door 
cutouts. We are issuing this AD to detect and correct cracking of 
the tee clips, which could result in additional stress on the 
adjacent tee clips, surrounding intercostals, edge frame, door 
structure and doorstops. This additional stress could cause further 
cracking or breaking of the tee clips, which could result in failure 
of the door to seal and consequent rapid decompression 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.

Repetitive Inspections/Investigative and Corrective Actions

    (f) Before the accumulation of 20,000 total flight cycles or 
within 3,000 flight cycles after the effective date of this AD, 
whichever is later: Do the applicable inspection specified in 
paragraph (f)(1) or (f)(2) of this AD by doing all the actions 
including all applicable related investigative (additional detailed 
inspections if necessary) and corrective actions; except as provided 
by paragraph (g) of this AD; in accordance with the Accomplishment 
Instructions of Boeing Alert Service Bulletin 757-53A0093, dated 
November 8, 2006. All related investigative and corrective actions 
must be done before further flight.
    (1) Do a detailed inspection for cracks of the intercostal tee 
clips and attachment fasteners at the number 3 and number 4 
doorstops of the passenger door cutouts. Repeat the inspection 
thereafter at intervals not to exceed 3,000 flight cycles until 
accomplishment of the terminating action specified in paragraph (h) 
of this AD.
    (2) Do a detailed inspection with a borescope for cracks of the 
intercostal tee clips. Repeat the inspection thereafter at intervals 
not to exceed 3,000 flight cycles until accomplishment of the 
terminating action specified in paragraph (h) of this AD.
    (g) If any cracked structure is found during any inspection 
required by this AD, and the Accomplishment Instructions of Boeing 
Alert Service Bulletin 757-53A0093, dated November 8, 2006, specify 
to contact Boeing for appropriate action: Before further flight, 
repair any cracked structure using a method approved in accordance 
with the procedures specified in paragraph (i)(2) of this AD.

Optional Terminating Action

    (h) Replacing both intercostal tee clips on the left and right 
sides with new tee clips in accordance with Part 3 of the 
Accomplishment Instructions of Boeing Alert Service Bulletin 757-
53A0093, dated November 8, 2006, terminates the repetitive 
inspections required by this AD.

Alternative Methods of Compliance (AMOCs)

    (i)(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.
    (2) 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.
    (3) 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.

    Issued in Renton, Washington, on August 2, 2007.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E7-16103 Filed 8-15-07; 8:45 am]
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