Document ID: FAA-2008-0357-0001
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Boeing Model 737-300, -400, and -500 Series Airplanes
Posted Date: 2008-03-26T04:00Z

[Federal Register: March 26, 2008 (Volume 73, Number 59)]
[Proposed Rules]               
[Page 15959-15961]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr26mr08-31]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-0357; Directorate Identifier 2008-NM-005-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 737-300, -400, and -500 
Series Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: We propose to adopt a new airworthiness directive (AD) for all 
Boeing Model 737-300, -400, and -500 series airplanes. This proposed AD 
would require repetitive inspections for discrepancies of the fuse pins 
of the inboard and outboard midspar fittings of the nacelle strut, and 
corrective actions if necessary. This proposed AD results from a report 
of corrosion damage of the chrome runout on the head side found on all 
four midspar fuse pins of the nacelle strut. Additionally, a large 
portion of the chrome plate was missing from the corroded area of the 
shank. We are proposing this AD to detect and correct discrepancies of 
the fuse pins of the inboard and outboard midspar fittings of the 
nacelle strut, which could result in reduced structural integrity of 
the fuse pins and consequent loss of the strut and separation of the 
engine from the airplane.

DATES: We must receive comments on this proposed AD by May 12, 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: Allen Rauschendorfer, Aerospace 
Engineer, Airframe Branch, ANM-120S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 917-6432; 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-2008-0357; 
Directorate Identifier 2008-NM-005-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

    We have received a report of corrosion damage of the chrome runout 
on the head side found on all four midspar fuse pins of the nacelle 
strut on a Model 737-300 airplane. Additionally, a large portion of the 
chrome plate was missing from the corroded area of the shank. The 
airplane had a total of 28,621 flight cycles. This condition, if not 
corrected, could result in discrepancies of the fuse pins of the 
inboard and outboard midspar fittings of the nacelle strut, reduced 
structural integrity of the fuse pins, and consequent loss of the strut 
and separation of the engine from the airplane.

Relevant Service Information

    We have reviewed Boeing Special Attention Service Bulletin 737-54-
1044, dated December 10, 2007. The service bulletin describes 
procedures for

[[Page 15960]]

repetitive detailed inspections for discrepancies (cracking, pitting, 
corrosion, or chrome plate damage) of the fuse pins of the left- and 
right-side inboard and outboard midspar fittings of the nacelle strut, 
and corrective actions if necessary. The corrective actions include 
blending out pitting or corrosion damage, inspecting blended areas to 
make sure all damage was removed, and repairing or replacing damaged 
fuse pins with new or serviceable fuse pins.
    The compliance time specified in the service bulletin is the latest 
of the following: Within 180 months from the date of issuance of the 
original standard certificate of airworthiness or original export 
certificate of airworthiness, within 180 months from date of previous 
pin replacement, or within 24 months after the effective date of the 
service bulletin. The repetitive interval is not to exceed 60 months.

FAA's Determination and Requirements of This Proposed AD

    We are proposing this AD because we evaluated all relevant 
information and determined the unsafe condition described previously is 
likely to exist or develop in other products of the same type design. 
This proposed AD would require accomplishing the actions specified in 
the service information described previously.

Interim Action

    We consider this proposed AD interim action. The manufacturer is 
currently developing a modification that will address the unsafe 
condition identified in this AD. Once this modification is developed, 
approved, and available, we might consider additional rulemaking.

Costs of Compliance

    We estimate that this proposed AD would affect 616 airplanes of 
U.S. registry. We also estimate that it would take about 4 work-hours 
per product to comply with the inspection in this proposed AD. The 
average labor rate is $80 per work-hour. Based on these figures, we 
estimate the cost of this proposed AD to the U.S. operators to be 
$197,120, or $320 per product.

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 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 this 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.
    You can find our regulatory evaluation and the estimated costs of 
compliance in the AD Docket.

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 AD:

Boeing: Docket No. FAA-2008-0357; Directorate Identifier 2008-NM-
005-AD.

Comments Due Date

    (a) We must receive comments by May 12, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to all Boeing Model 737-300, -400, and -500 
series airplanes, certificated in any category.

Unsafe Condition

    (d) This AD results from a report of corrosion damage of the 
chrome runout on the head side found on all four midspar fuse pins 
of the nacelle strut. Additionally, a large portion of the chrome 
plate was missing from the corroded area of the shank. We are 
issuing this AD to detect and correct damage of the fuse pins of the 
inboard and outboard midspar fittings of the nacelle strut, which 
could result in reduced structural integrity of the fuse pins and 
consequent loss of the strut and separation of the engine from the 
airplane.

Compliance

    (e) Comply with this AD within the compliance times specified, 
unless already done.

Repetitive Inspections/Corrective Actions

    (f) At the applicable time specified in paragraph 1.E., 
``Compliance'' of Boeing Special Attention Service Bulletin 737-54-
1044, dated December 10, 2007; except, where the service bulletin 
specifies a compliance time after the date on the service bulletin, 
this AD requires compliance within the specified compliance time 
after the effective date of this AD: Do a detailed inspection for 
discrepancies of the fuse pins of the inboard and outboard midspar 
fittings of the nacelle strut by doing all the actions, including 
all applicable corrective actions, in accordance with the 
Accomplishment Instructions of the service bulletin. Do all 
applicable corrective actions before further flight. Repeat the 
inspection at the time specified in paragraph 1.E. of the service 
bulletin.

Alternative Methods of Compliance (AMOCs)

    (g)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, ATTN: Allen Rauschendorfer, Aerospace Engineer, Airframe 
Branch, ANM-120S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356; telephone (425) 917-6432; 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

[[Page 15961]]

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.

    Issued in Renton, Washington, on March 19, 2008.
Dionne Palermo,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-6106 Filed 3-25-08; 8:45 am]

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