[Federal Register Volume 69, Number 182 (Tuesday, September 21, 2004)]
[Proposed Rules]
[Pages 56375-56377]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 04-21176]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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 

  Federal Register / Vol. 69, No. 182 / Tuesday, September 21, 2004 / 
Proposed Rules  

[[Page 56375]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19140; Directorate Identifier 2004-NM-84-AD]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 757 Series Airplanes 
Powered by Pratt & Whitney Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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

SUMMARY: The FAA proposes to adopt a new airworthiness directive (AD) 
for certain Boeing Model 757 series airplanes. This proposed AD would 
require repetitive inspections for corrosion and cracking of the 
midspar fittings in the nacelle struts, and corrective actions if 
necessary. This action also provides an optional terminating action for 
the repetitive inspections. This proposed AD is prompted by reports of 
corrosion and cracking on midspar fittings on the nacelle struts of 
several Boeing Model 757 series airplanes. We are proposing this AD to 
detect and correct cracking in the midspar fittings of the nacelle 
struts, consequent reduced structural integrity of the struts, and 
possible separation of an engine and strut from the airplane.

DATES: We must receive comments on this proposed AD by November 5, 
2004.

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.
     By 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.
    You can get the service information identified in this proposed AD 
from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 
98124-2207.
    You may examine the contents of this AD docket on the Internet at 
http://dms.dot.gov, or at the Docket Management Facility, U.S. 
Department of Transportation, 400 Seventh Street, SW., Room PL-401, on 
the plaza level of the Nassif Building, Washington, DC.

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) 914-6590.

SUPPLEMENTARY INFORMATION: 

Docket Management System (DMS)

    The FAA has implemented new procedures for maintaining AD dockets 
electronically. As of May 17, 2004, new AD actions are posted on DMS 
and assigned a docket number. We track each action and assign a 
corresponding directorate identifier. The DMS AD docket number is in 
the form ``Docket No. FAA-2004-99999.'' The Transport Airplane 
Directorate identifier is in the form ``Directorate Identifier 2004-NM-
999-AD.'' Each DMS AD docket also lists the directorate identifier 
(``Old Docket Number'') as a cross-reference for searching purposes.

Comments Invited

    We invite you to submit any written relevant data, views, or 
arguments regarding this proposed AD. Send your comments to an address 
listed under ADDRESSES. Include ``Docket No. FAA-2004-19140; 
Directorate Identifier 2004-NM-84-AD'' in the subject line 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 submitted 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.
    We are reviewing the writing style we currently use in regulatory 
documents. We are interested in your comments on whether the style of 
this document is clear, and your suggestions to improve the clarity of 
our communications that affect you. You can get more information about 
plain language at http://www.faa.gov/language and http://www.plainlanguage.gov.

Examining the Docket

    You may examine the AD docket 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 DMS 
receives them.

Discussion

    We have received reports of corrosion and cracking on midspar 
fittings on the nacelle struts of several Boeing Model 757 series 
airplanes. Investigation revealed that the fittings were made from 
4330M material. Corrosion may cause pits that result in cracking of the 
midspar fittings. This condition, if not corrected, could result in 
reduced structural integrity of the struts, and possible separation of 
an engine and strut from the airplane.

Other Related Rulemaking

    On August 29, 2003, we issued AD 2003-18-05, amendment 39-13296 (68 
FR 53496, September 11, 2003), applicable to certain Boeing Model 757 
series airplanes powered by Pratt & Whitney engines. That AD requires

[[Page 56376]]

modifying the nacelle strut and wing structure at a threshold of 37,500 
total flight cycles or 20 years, whichever is first. That AD is part of 
the manufacturer's nacelle strut improvement program. The newly 
reported cracking of the midspar fittings that prompted this proposed 
AD occurred at approximately 29,700 total flight cycles and 18 years--
below the compliance time threshold for the modifications required by 
AD 2003-18-05. If the modifications required by AD 2003-18-05 have been 
accomplished, operators do not need to do the inspections required by 
this proposed AD. The nacelle strut modification required by AD 2003-
18-05 includes replacing the midspar fittings. This proposed AD does 
not affect the requirements of AD 2003-18-05.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 757-54-
0042, dated May 13, 1999, which describes various procedures for 
repetitive visual and detail visual inspections of the midspar fittings 
located in the nacelle struts for evidence of corrosion and cracking, 
and corrective actions. Evidence of corrosion includes rust stains 
around the cap seals; along the edge of the fittings; and on the skins, 
spars, and bulkheads.
    The service bulletin effectivity is divided into two groups of 
airplanes, depending on the material used to make the midspar fittings. 
Group 1 airplanes have midspar fittings made exclusively of 4330M 
material, while Group 2 airplanes have fittings made of both 4330M 
material and 15-5PH CRES material. For both Group 1 and Group 2 
airplanes, the procedures and corrective actions include:
     Doing visual and detail visual inspections of the midspar 
fittings.
     If no corrosion is found, applying corrosion inhibitor and 
repeating the inspections at the times specified in the service 
bulletin.
     If corrosion is found and the fitting is not replaced 
before further flight, removing the clip from the affected strut and 
repeating the inspections at the times specified.
     If corrosion is found and the fitting is replaced before 
further flight, either modifying only the strut, or the wing and strut 
together, in accordance with the Accomplishment Instructions in Boeing 
Service Bulletin 757-54-0034, Revision 1, dated October 11, 2001.
     If no cracking is found, doing repetitive visual 
inspections of the upper and lower tangs of the midspar fittings at the 
intervals specified.
     If any cracking is found, replacing the fitting before 
further flight by either modifying only the strut, or the wing and 
strut together, in accordance with the Accomplishment Instructions in 
Boeing Service Bulletin 757-54-0034.
    For Group 2 airplanes, there is an additional procedure for 
identifying the material used to make each fitting.
    Accomplishment of the actions specified in Boeing Special Attention 
Service Bulletin 757-54-0042 is intended to adequately address the 
identified 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. Therefore, we are proposing this AD, which 
would require repetitive inspections for corrosion and cracking of the 
midspar fittings in the nacelle struts, and corrective actions if 
necessary. The proposed AD would require you to use the service 
information described previously to perform these actions, except as 
discussed under ``Differences Between the Proposed AD and Service 
Information.'' The proposed AD also provides an optional terminating 
action for the repetitive inspections.

Differences Between the Proposed AD and Service Information

    The service bulletin states that airplanes with any corroded 
midspar fitting may continue to fly for up to 18 months before 
replacing an affected fitting, if repetitive inspections are done at 
intervals of 300 flight cycles. Neither the referenced service 
bulletin, Boeing Special Attention Service Bulletin 757-54-0042, nor 
the Boeing 757 Structural Repair Manual, provide instructions for 
removing corrosion from these midspar fittings. Operators are allowed 
to make specific proposals for an alternative method of compliance 
through the provisions of paragraph (l) of this proposed AD. In the 
absence of established or acceptable methods of removing corrosion on 
midspar fittings, this proposed AD would require replacing any corroded 
midspar fitting before further flight. Continued operation with 
untreated corrosion can lead to cracking that emanates from a corrosion 
pit. This is especially true for a high strength steel like 4330M.
    For Group 2 airplanes, the service bulletin states that, if there 
is a mixture of midspar fittings made of 15-5PH CRES material and 4330M 
material, regular zonal inspections may be done for airplanes less than 
ten years old. This proposed AD would require repetitive detailed 
inspections for all fittings made of 4330M material at 18-month 
intervals since all affected airplanes are at least ten years old.
    The manufacturer is aware of these differences and concurs.

Clarification of Inspection Terminology

    Boeing Special Attention Service Bulletin 757-54-0042 specifies 
visual and detail visual inspections of the midspar fittings. This 
proposed AD requires general visual and detailed inspections of the 
midspar fittings. Notes 1 and 2 have been included in this proposed 
rule to define these types of inspections.

Costs of Compliance

    This proposed AD would affect about 410 airplanes worldwide. 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, per inspection               3               $65   None.............  $195, per inspection                   338   $65,910, per inspection
 cycle.                                                                            cycle.                                       cycle
--------------------------------------------------------------------------------------------------------------------------------------------------------

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.

[[Page 56377]]

    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. 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 FAA amends Sec.  39.13 by adding the following new 
airworthiness directive (AD):

Boeing: Docket No. FAA-2004-19140; Directorate Identifier 2004-NM-
84-AD.

Comments Due Date

    (a) The Federal Aviation Administration (FAA) must receive 
comments on this AD action by November 5, 2004.

Affected ADs

    (b) This AD is related to AD 2003-18-05, amendment 39-13296.

Applicability

    (c) This AD applies to Boeing Model 757 series airplanes, line 
numbers 1 through 639 inclusive, powered by Pratt & Whitney engines; 
certificated in any category.

Unsafe Condition

    (d) This AD was prompted by reports of corrosion and cracking on 
midspar fittings on the nacelle struts of several Boeing Model 757 
series airplanes. We are issuing this AD to detect and correct 
cracking in the midspar fittings of the nacelle struts, consequent 
reduced structural integrity of the struts, and possible separation 
of an engine and strut from 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.

Inspections for Group 1 Airplanes

    (f) For airplanes identified as Group 1 in Boeing Special 
Attention Service Bulletin 757-54-0042, dated May 13, 1999: Within 
18 months after the effective date of this AD, do general visual and 
detailed inspections for evidence of corrosion and/or cracking of 
the midspar fittings located in the nacelle struts, in accordance 
with the Accomplishment Instructions of Boeing Special Attention 
Service Bulletin 757-54-0042, dated May 13, 1999. Repeat the 
inspections thereafter at intervals not to exceed 18 months until 
the requirements of paragraph (j) are accomplished.

    Note 1: For the purposes of this AD, a general visual inspection 
is defined as: ``A visual examination of an interior or exterior 
area, installation, or assembly to detect obvious damage, failure, 
or irregularity. This level of inspection is made from within 
touching distance unless otherwise specified. A mirror may be 
necessary to enhance visual access to all exposed surfaces in the 
inspection area. This level of inspection is made under normally 
available lighting conditions such as daylight, hangar lighting, 
flashlight, or droplight and may require removal or opening of 
access panels or doors. Stands, ladders, or platforms may be 
required to gain proximity to the area being checked.''


    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.''

Inspections for Group 2 Airplanes

    (g) For airplanes identified as Group 2 in Boeing Special 
Attention Service Bulletin 757-54-0042, dated May 13, 1999: Within 
18 months after the effective date of this AD, do a general visual 
inspection to identify the type of material the midspar fittings are 
made from, in accordance with the Accomplishment Instructions of 
Boeing Special Attention Service Bulletin 757-54-0042, dated May 13, 
1999.
    (1) If all four midspar fittings are made of 15-5PH CRES 
material, no further action is required by this AD.
    (2) If any midspar fitting is made of 4330M material, do the 
inspections required by paragraph (h) of this AD.
    (h) For Group 2 airplanes with fittings made of 4330M material: 
After the inspection required by paragraph (g) of this AD, but 
before further flight: Do a general visual and a detailed inspection 
of the 4330M midspar fittings for evidence of corrosion and/or 
cracking, in accordance with the Accomplishment Instructions of 
Boeing Special Attention Service Bulletin 757-54-0042, dated May 13, 
1999. Repeat the inspections for corrosion and/or cracking 
thereafter at intervals not to exceed 18 months until the 
requirements of paragraph (j) of this AD are accomplished.

Corrective Actions

    (i) For Group 1 and Group 2 airplanes: If any corrosion or 
cracking is found during any inspection required by paragraph (f) or 
(h) of this AD, before further flight, replace the affected midspar 
fitting with a new midspar fitting by accomplishing all of the 
applicable actions in accordance with the Accomplishment 
Instructions of Boeing Special Attention Service Bulletin 757-54-
0042, dated May 13, 1999. Replacement of an affected midspar fitting 
terminates the repetitive inspections required by paragraphs (f) and 
(h) of this AD for that fitting only.

Optional Terminating Action

    (j) Replacement of all of the midspar fittings with new midspar 
fittings in accordance with the Accomplishment Instructions of 
Boeing Special Attention Service Bulletin 757-54-0042, dated May 13, 
1999, terminates the repetitive inspections required by paragraphs 
(f) and (h) of this AD.

Actions Accomplished Previously

    (k) Accomplishment of the nacelle strut and wing modification 
required by AD 2003-18-05, amendment 39-13296, is considered 
acceptable for compliance with the requirements of this AD.

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.
    (2) An AMOC that provides an acceptable level of safety may be 
used for any replacement required by this AD, if it is approved by a 
Boeing Company Designated Engineering Representative who has been 
authorized by the Manager, Seattle ACO, to make those findings.

    Issued in Renton, Washington, on September 13, 2004.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 04-21176 Filed 9-20-04; 8:45 am]
BILLING CODE 4910-13-P