Document ID: FAA-2007-0289-0007
Agency: faa
Document Type: Rule
Title: Airworthiness Directives; Boeing Model 757 Airplanes
Posted Date: 2008-11-25T05:00Z

[Federal Register: November 25, 2008 (Volume 73, Number 228)]
[Rules and Regulations]               
[Page 71534-71537]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr25no08-7]                         

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

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2007-0289; Directorate Identifier 2007-NM-208-AD; 
Amendment 39-15740; AD 2008-23-19]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 757 Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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

SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
Boeing Model 757 airplanes. This AD requires sealing the fasteners on 
the front and rear spars inside the left and right main fuel tanks and 
on the rear spar and lower panel of the center fuel tank. This AD also 
requires inspections of the wire bundle support installations to verify 
if certain clamps are installed and if Teflon sleeving covers the wire 
bundles inside the left and right equipment cooling system bays, on the 
left and right rear spars, and on the left and right front spars; and 
corrective actions if necessary. This AD results from a fuel system 
review conducted by the manufacturer. We are issuing this AD to detect 
and correct improper wire bundle support installation and sleeving and 
to prevent improperly sealed fasteners in the main and center fuel 
tanks from becoming an ignition source, in the event of a fault 
current, which could result in a fuel tank explosion and consequent 
loss of the airplane.

DATES: This AD is effective December 30, 2008.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in this AD as of December 30, 
2008.

ADDRESSES: 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 AD, the regulatory evaluation, 
any comments received, and other information. The address for the 
Docket Office (telephone 800-647-5527) is the Document Management 
Facility, U.S. Department of Transportation, Docket Operations, M-30, 
West Building Ground Floor, Room W12-140, 1200 New Jersey Avenue, SE., 
Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Judy Coyle, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6497; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION:

Discussion

    We issued a notice of proposed rulemaking (NPRM) to amend 14 CFR 
part 39 to include an airworthiness directive (AD) that would apply to 
certain Boeing Model 757 series airplanes. That NPRM was published in 
the Federal Register on December 6, 2007 (72 FR 68764). That NPRM 
proposed to require sealing the fasteners on the front and rear spars 
inside the left and right main fuel tanks and on the lower panel of the 
center fuel tank. That NPRM also proposed to require inspections of the 
wire bundle support installations to verify if certain clamps are 
installed and if Teflon sleeving covers the wire bundles inside the 
left and right equipment cooling system bays, on the left and right 
rear spars, and on the left and right front spars; and corrective 
actions if necessary.

Comments

    We gave the public the opportunity to participate in developing 
this AD. We considered the comments received from the four commenters.

Request for Justification of the NPRM

    Northwest Airlines (NWA) has no objection to the intent of the 
NPRM, but it states it is not clear that we have shown that the 
probability of a fuel tank explosion due to unsealed fuel tank 
fasteners reaches the threshold for justifying the proposed 
modification. NWA requests that we provide more detail regarding the 
risk and benefit of the NPRM.
    We agree to provide clarification. The unsafe condition encompassed 
the scenario of single failures (for example, a wire bundle clamp 
failure that could result in wire bundle contact with the fuel tank 
causing an ignition source internal to the tank) that place an airplane 
at risk of a fuel tank explosion.

[[Page 71535]]

The in-tank sealant is designed to provide a second level of protection 
against fuel tank ignition by encapsulating and containing the 
potential source of ignition. Further, the risk level associated with 
this single failure scenario was determined to warrant the actions 
required by this AD. No change to the AD is necessary in this regard.

Request To Clarify the Unsafe Condition

    Boeing requests that we revise paragraph (d) of the NPRM to cover 
the requirement to do the general visual inspection for wire bundle 
support installation and sleeving. Boeing states that failures of the 
wire bundles and shorting to clamps are the prime candidates for the 
fault current source, and that they should be identified as the unsafe 
condition.
    We agree because accomplishing the general visual inspections for 
wire bundle supports and sleeving is one of the requirements of this 
AD. We have revised the Summary and paragraph (d) of this AD 
accordingly.

Request To Clarify Requirements

    Boeing requests that we revise the Summary of the NPRM to include 
the requirement to seal the fasteners on the rear spar of the center 
fuel tank. Boeing states that this action is called out on page 149 in 
view B of Figure 7 of Boeing Alert Service Bulletin 757-57A0064, dated 
July 16, 2007.
    We agree and have revised the Summary of this AD accordingly. 
Although the specific location of the ``rear spar of the center tank'' 
was inadvertently omitted from the Summary of the NPRM, it was covered 
by paragraph (f) of the NPRM, which specified accomplishing all of the 
applicable actions specified in the Accomplishment Instructions of 
Boeing Alert Service Bulletin 757-57A0064, dated July 16, 2007.

Request To Delay Issuance To Provide Instructions for Maintaining the 
Design Change

    Continental Airlines (CAL) is concerned that not enough attention 
has been given to ensure that the changes detailed in Boeing Alert 
Service Bulletin 757-57A0064, dated July 16, 2007, are preserved for 
the long-term operation of its Model 757 fleet. CAL states that, other 
than this service bulletin and some generic information found in the 
Boeing 757 Maintenance Planning Data (MPD) document, there are no other 
published ``maintenance'' documents currently available to show each 
specific requirement as detailed in the service bulletin. CAL further 
states that information detailed by the service bulletin must be 
available in manuals that are routinely used by maintenance personnel. 
CAL asserts that making this information available will prevent the 
inadvertent reversal of the implemented changes, which could lead to 
violation of the NPRM, in addition to compromising the higher level of 
safety intended for the Model 757 fleet.
    CAL believes the current program, as provided by the service 
bulletin and proposed by the NPRM, is not ready to be implemented. CAL 
states that, if the NPRM is mandated as proposed, CAL would not be able 
to incorporate the modification on its Model 757-200 series airplanes, 
and a high risk of future de-modification would exist for those 
airplanes that could be modified. CAL recommends that we coordinate 
with Boeing regarding its requested changes.
    We infer that CAL requests that we delay issuance of the AD until 
Boeing has revised the applicable maintenance documents to provide 
detailed information for maintenance personnel to maintain the required 
design change. We agree with CAL's concern about ensuring that the 
requirements of this AD are maintained throughout the life of the 
airplane. We are considering additional rulemaking in this regard. 
However, we disagree with delaying issuance of the final rule until 
Boeing has worked through its process to revise the applicable 
maintenance documents. To delay this action would be inappropriate, 
since we have determined that an unsafe condition exists and that the 
actions required by this AD must be mandated to ensure continued 
safety. However, as a result of this comment, we have initiated 
discussions with Boeing about including more detail in the Instructions 
for Continued Airworthiness (ICA) to ensure that the integrity of this 
AD is maintained throughout the life of an airplane. Those discussions 
are ongoing at this time. We have not changed the AD in this regard.

Request To Delay Issuance of the AD To Provide Instructions for 
Modified Airplanes

    CAL states that all of its 41 Model 757-200 series airplanes were 
modified in the past with a Aviation Partners Boeing (APB) winglet 
design that incorporated significant changes to the forward and rear 
spars. CAL states that Boeing has acknowledged that Boeing Alert 
Service Bulletin 757-57A0064, dated July 16, 2007, does not include 
instructions for the configuration of CAL's modified airplanes. CAL 
also states that Boeing is currently assessing the configuration of 
CAL's airplanes and that Boeing will respond with an action plan.
    We infer that CAL requests that we delay issuance of the AD until 
Boeing has revised the service bulletin to provide instructions for 
accomplishing the modification on airplanes equipped with APB winglets 
installed in accordance with Supplemental Type Certificate (STC) 
ST01518SE. We disagree with delaying issuance of the final rule because 
we have determined that an unsafe condition exists and that the actions 
required by this AD must be mandated to ensure continued safety. 
Further, we have discussed CAL's concern about the service bulletin 
instructions with both the airplane and winglet manufacturers. They 
both indicated that the procedures in the service bulletin, as 
published, can be accomplished on airplanes equipped with APB winglets 
installed in accordance with STC ST01518SE. We have not changed the AD 
in this regard.

Request To Extend Compliance Time

    European Air Transport, on behalf of DHL Air, and NWA request that 
we extend the compliance time from 60 months to 72 months. European Air 
Transport states that, due to the high number of work hours needed to 
accomplish the proposed actions, it plans to do the work during a 4C-
check (corresponding to 72 months, 24,000 flight hours, or 12,000 
flight cycles, whichever occurs first). European Air Transport also 
states that a 60-month compliance time would require it to do the 
proposed actions on some of its airplanes outside the 4C-check, but 
that a 72-month compliance time will allow it to do the proposed 
actions on the entire fleet during base maintenance.
    NWA states that, due to access requirements, it considers the 
proposed modification to be consistent with a D-check level of work. 
NWA also states that it does not understand the substantiation for the 
60-month compliance time and believes that doing the work during 
scheduled fuel tank access will ensure more consistent quality of the 
modification, as well as reduced costs to industry. NWA also states 
that it is unaware of any accident or incident that has been attributed 
to unsealed fuel tank fasteners, or that the risk is such that 
compliance should be required within 60 months instead of 72 months. 
NWA believes that a 1-year extension of the compliance time would not 
have an appreciable impact on safety. NWA further states its request is 
consistent with the FAA harmonization policy of the aging airplane 
programs in

[[Page 71536]]

accordance with ``Fuel Tank Safety Compliance Extension (Final Rule) 
and Aging Airplane Program Update (Request for Comments)'' (69 FR 
45936, July 30, 2004).
    We do not agree with the request to extend the compliance time. In 
developing an appropriate compliance time for this action, we 
considered the urgency associated with the subject unsafe condition and 
the practical aspect of accomplishing the required modification within 
a period of time that corresponds to the normal scheduled maintenance 
for most affected operators. We recognize that operators have different 
maintenance schedules for accomplishing heavy maintenance on Model 757 
airplanes, but at the same time we understand that a 60-month 
compliance time will accommodate most operators' schedules for that 
type of work. However, according to the provisions of paragraph (g) of 
this AD, we may approve requests to adjust the compliance time if the 
request includes data that prove that the new compliance time would 
provide an acceptable level of safety. We have not changed the AD in 
this regard.

Conclusion

    We reviewed the relevant data, considered the comments received, 
and determined that air safety and the public interest require adopting 
the AD with the changes described previously. We also determined that 
these changes will not increase the economic burden on any operator or 
increase the scope of the AD.

Costs of Compliance

    There are about 1,049 airplanes of the affected design in the 
worldwide fleet. This AD affects about 539 airplanes of U.S. registry. 
The required actions take up to 545 work hours per airplane depending 
on the airplane configuration, at an average labor rate of $80 per work 
hour. Required parts cost about $325 per airplane. Based on these 
figures, the estimated cost of the AD for U.S. operators is up to 
$23,675,575, or up to $43,925 per airplane.

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

    This AD will not have federalism implications under Executive Order 
13132. This AD will 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 this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Is not a ``significant rule'' under 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, Incorporation by 
reference, Safety.

Adoption of the Amendment

0
Accordingly, under the authority delegated to me by the Administrator, 
the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
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]

0
2. The FAA amends Sec.  39.13 by adding the following new AD:

2008-23-19 Boeing: Amendment 39-15740. Docket No. FAA-2007-0289; 
Directorate Identifier 2007-NM-208-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective December 30, 
2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 757-200, -200CB, -200PF, and 
-300 series airplanes, certificated in any category; as identified 
in Boeing Alert Service Bulletin 757-57A0064, dated July 16, 2007.

Unsafe Condition

    (d) This AD results from a fuel system review conducted by the 
manufacturer. We are issuing this AD to detect and correct improper 
wire bundle support installation and sleeving and to prevent 
improperly sealed fasteners in the main and center fuel tanks from 
becoming an ignition source, in the event of a fault current, which 
could result in a fuel tank explosion and consequent loss 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.

Fastener Sealing and Inspections

    (f) Within 60 months after the effective date of this AD, seal 
the applicable fasteners and do the general visual inspections of 
the wire bundle support installations, and do all the applicable 
corrective actions before further flight, by accomplishing all of 
the applicable actions specified in the Accomplishment Instructions 
of Boeing Alert Service Bulletin 757-57A0064, dated July 16, 2007.

Alternative Methods of Compliance (AMOCs)

    (g)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, ATTN: Judy Coyle, Aerospace Engineer, Propulsion Branch, ANM-
140S, FAA, Seattle ACO, 1601 Lind Avenue SW., Renton, Washington 
98057-3356; telephone (425) 917-6497; 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.

Material Incorporated by Reference

    (h) You must use Boeing Alert Service Bulletin 757-57A0064, 
dated July 16, 2007, to do the actions required by this AD, unless 
the AD specifies otherwise.
    (1) The Director of the Federal Register approved the 
incorporation by reference of this service information under 5 
U.S.C. 552(a) and 1 CFR part 51.
    (2) For service information identified in this AD, contact 
Boeing Commercial Airplanes, P.O. Box 3707, Seattle, Washington 
98124-2207; telephone 206-544-9990; fax 206-766-5682; e-mail 
DDCS@boeing.com; Internet https://www.myboeingfleet.com.
    (3) You may review copies of the service information 
incorporated by reference at the

[[Page 71537]]

FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington; or at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, call 202-741-6030, or go to: http://www.archives.gov/federal_
register/code_of_federal_regulations/ibr_locations.html.

    Issued in Renton, Washington, on October 24, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E8-27168 Filed 11-24-08; 8:45 am]

BILLING CODE 4910-13-P