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

[Federal Register Volume 74, Number 111 (Thursday, June 11, 2009)]
[Rules and Regulations]
[Pages 27691-27693]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E9-13304]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-1364; Directorate Identifier 2008-NM-103-AD; 
Amendment 39-15928; AD 2009-12-05]
RIN 2120-AA64


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

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: We are adopting a new airworthiness directive (AD) for certain 
Boeing Model 737-300, -400, and -500 series airplanes. This AD requires 
modifying the control power wiring of the normal supply fan and the low 
flow sensor for the equipment cooling system of the electronic flight 
instrument system (EFIS). This AD results from a report of loss of both 
the normal EFIS cooling supply and the indication of EFIS cooling loss 
due to a single failure of the battery bus, causing eventual power-down 
of the EFIS displays; the standby attitude indication is also powered 
by this battery bus. We are issuing this AD to prevent loss of all 
attitude indications from both the standby indicator and EFIS displays, 
which could decrease the ability of the flightcrew to maintain the safe 
flight and landing of the airplane.

DATES: This AD is effective July 16, 2009.
    The Director of the Federal Register approved the incorporation by 
reference of a certain publication listed in the AD as of July 16, 
2009.

ADDRESSES: For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 206-
544-5000, extension 1, fax 206-766-5680; e-mail [email protected]; 
Internet https://www.myboeingfleet.com.

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: Suk Jang, Aerospace Engineer, Systems 
and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98057-3356; telephone 
(425) 917-6511; 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 737-300, -400, and -500 series airplanes. That 
NPRM was published in the Federal Register on January 12, 2009 (74 FR 
1153). That NPRM proposed to require modifying the control power wiring 
of the normal supply fan and the low flow sensor for the equipment 
cooling system of the electronic flight instrument system (EFIS).

Comments

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

Supportive Comments

    Boeing and Continental Airlines support the actions in the NPRM.

Request To Add an Alternate Method of Compliance

    Lufthansa German Airlines asks that we add a method acceptable for 
compliance with the corresponding requirements of the NPRM. Lufthansa 
notes that, as specified in paragraphs (f), (g)(1), and (g)(2) of the 
NPRM, actions done in accordance with Boeing Alert Service Bulletin 
737-21A1156, Revision 1, dated October 23, 2007; or Boeing Alert 
Service Bulletin 737-21A1156, dated June 20, 2006; are acceptable for 
compliance. Lufthansa adds that these actions prevent loss of all 
attitude indications from both the standby indicator and EFIS displays 
in case of battery bus failure. (The following is a clarification of 
the commenter's description of acceptable sources of service 
information specified in this AD: Boeing Alert Service Bulletin 737-
21A1156, Revision 2, dated December 11, 2008, is the source of service 
information referred to in the NPRM for accomplishing the specified 
actions. Actions done previously in accordance with Boeing Alert 
Service Bulletin 737-21A1156, Revision 1, dated October 23, 2007; or 
Boeing Alert Service Bulletin

[[Page 27692]]

737-21A1156, dated June 20, 2006 (for Groups 1 and 2 airplanes 
identified in Boeing Alert Service Bulletin 737-21A1156, Revision 1), 
are acceptable for compliance with the corresponding requirements of 
this AD.)
    Lufthansa asks that we consider another method to address this 
unsafe condition, which is to append an abnormal procedure task to the 
flight crew operations manual in case of battery bus failure to specify 
setting the equipment cooling switch to alternate if the battery bus 
fails. This would allow the alternate supply fan to still cool the EFIS 
displays and prevent them from failing.
    We disagree with the commenter's request to add this additional 
method of compliance to the AD requirements. The identified unsafe 
condition is loss of all attitude indications from both the standby 
indicator and EFIS displays, which could decrease the ability of the 
flightcrew to maintain the safe flight and landing of the airplane. 
Although we recognize the commenter's suggestion provides some safety 
mitigation for the unsafe condition, the inherently unsafe design of 
the EFIS cooling system must be corrected to ensure that flightcrews 
are equipped with attitude indications. Therefore, after the 
modification of the control power wiring of the EFIS cooling system is 
done, revising the flightcrew operations manual is not necessary and is 
not acceptable as an alternate method of compliance to this AD. We have 
made no change to 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 as proposed.

Costs of Compliance

    We estimate that this AD will affect 263 airplanes of U.S. 
registry. The following table provides the estimated costs for U.S. 
operators to comply with this AD.

                                                                     Estimated Costs
--------------------------------------------------------------------------------------------------------------------------------------------------------
                                                                                 Average
                                                                        Work      labor                Cost per  Number of U.S.-
                       Action/airplane group                           hours     rate per    Parts     product     registered           Fleet cost
                                                                                   hour                             airplanes
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Groups 1 & 2 modification..........................................          3        $80         $0       $240             153                  $36,720
Group 4 modification...............................................          2        $80         $0       $160             113                  $18,080
--------------------------------------------------------------------------------------------------------------------------------------------------------

     Currently, there are no Group 3 airplanes on the U.S. Register. 
However, if an affected airplane is imported and placed on the U.S. 
Register in the future, the required actions would take about 5 work 
hours, at an average labor rate of $80 per work hour. Based on these 
figures, we estimate the cost of this AD for Group 3 airplanes to be 
$400 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:

2009-12-05 Boeing: Amendment 39-15928. Docket No. FAA-2008-1364; 
Directorate Identifier 2008-NM-103-AD.

Effective Date

    (a) This airworthiness directive (AD) is effective July 16, 
2009.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-300, -400, and -500 
series airplanes, certificated in any category; as identified in 
Boeing Alert Service Bulletin 737-21A1156, Revision 2, dated 
December 11, 2008.

Unsafe Condition

    (d) This AD results from a report of loss of both the normal 
electronic flight instrument system (EFIS) cooling supply and the 
indication of EFIS cooling loss due to a single failure of the 
battery bus, causing eventual power-down of the EFIS displays; the 
standby attitude indication is also powered by this battery bus. We 
are issuing this AD to prevent loss of all attitude indications from 
both the standby indicator and EFIS displays, which could decrease 
the ability of the flightcrew to maintain the safe flight and 
landing of the airplane.

Compliance

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

Modification

    (f) Within 24 months after the effective date of this AD: Modify 
the control power

[[Page 27693]]

wiring of the normal supply fan and the low flow sensor for the 
equipment cooling system of the EFIS, by doing all the applicable 
actions specified in the Accomplishment Instructions of Boeing Alert 
Service Bulletin 737-21A1156, Revision 2, dated December 11, 2008.

Credit for Actions Done Using Previous Service Information

    (g)(1) Actions done before the effective date of this AD in 
accordance with Boeing Alert Service Bulletin 737-21A1156, Revision 
1, dated October 23, 2007, are acceptable for compliance with the 
corresponding requirements of this AD.
    (2) For Groups 1 and 2 airplanes identified in Boeing Alert 
Service Bulletin 737-21A1156, Revision 1, dated October 23, 2007: 
Actions done before the effective date of this AD in accordance with 
Boeing Alert Service Bulletin 737-21A1156, dated June 20, 2006, are 
acceptable for compliance with the corresponding requirements of 
this AD.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, ATTN: Suk Jang, Aerospace Engineer, Systems and Equipment 
Branch, ANM-130S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356; telephone (425) 917-6511; 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 principal maintenance inspector (PMI) or 
principal avionics inspector (PAI), as appropriate, or lacking a 
principal inspector, your local Flight Standards District Office. 
The AMOC approval letter must specifically reference this AD.

Material Incorporated by Reference

    (i) You must use Boeing Alert Service Bulletin 737-21A1156, 
Revision 2, dated December 11, 2008; 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, Attention: Data & Services Management, 
P.O. Box 3707, MC 2H-65, Seattle, Washington 98124-2207; telephone 
206-544-5000, extension 1, fax 206-766-5680; e-mail 
[email protected]; Internet https://www.myboeingfleet.com.
    (3) You may review copies of the service information at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington. For information on the availability of this material at 
the FAA, call 425-227-1221 or 425-227-1152.
    (4) You may also review copies of the service information that 
is incorporated by reference 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 June 1, 2009.
Stephen P. Boyd,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E9-13304 Filed 6-10-09; 8:45 am]
BILLING CODE 4910-13-P

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