
[Federal Register: October 22, 2008 (Volume 73, Number 205)]
[Proposed Rules]               
[Page 62937-62940]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr22oc08-23]                         

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2008-1116; Directorate Identifier 2007-NM-231-AD]
RIN 2120-AA64

 
Airworthiness Directives; Boeing Model 737-100, -200, -200C, -
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 
certain Boeing Model 737-100, -200, -200C, -300, -400, and -500 series 
airplanes. For certain airplanes, this proposed AD would require 
deactivation or modification of the wiring to the outboard landing 
lights, until the wire bundles and electrical connectors have been 
replaced. For all airplanes, this proposed AD would also require an 
inspection for any broken, damaged, or missing fairleads, grommets, and 
wires in the four electrical junction boxes of the main wheel well, and 
corrective actions if necessary. For certain airplanes, this proposed 
AD would also require replacement of certain wire bundles for the 
landing lights and fuel shutoff valves, and related investigative, 
other specified, and corrective actions if necessary. For certain 
airplanes, this proposed AD would also require replacement of certain 
electrical connectors and backshell clamps. This proposed AD results 
from reports of uncommanded engine shutdowns and burned and damaged 
wire bundles associated with the outboard landing lights and engine 
fuel shutoff valves. This proposed AD also results from reports of 
damaged and missing grommets and broken and damaged fairleads in the 
electrical junction boxes of the main wheel well. We are proposing this 
AD to prevent a hot short between the outboard landing light and fuel 
shutoff valve circuits, which could result in an uncommanded engine 
shutdown. We are also proposing this AD to prevent corrosion of the 
electrical connectors of the wing rear spars, which could result in 
short circuits and consequent incorrect functioning of airplane systems 
needed for safe flight and landing.

DATES: We must receive comments on this proposed AD by December 8, 
2008.

ADDRESSES: You may send comments by any of the following methods:

[[Page 62938]]

     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: Stephen Oshiro, Aerospace Engineer, 
Systems and Equipment Branch, ANM-130S, FAA, Seattle Aircraft 
Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98057-
3356; telephone (425) 917-6480; 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-2008-1116; 
Directorate Identifier 2007-NM-231-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 reports of uncommanded engine shutdowns and burned 
and damaged wire bundles where the wire bundle exits the main wheel 
well in the area of the wing rear spar on Boeing Model 737-300, -400, 
and -500 series airplanes. Investigation revealed that the uncommanded 
engine shutdowns were caused by uncommanded closure of the engine fuel 
shutoff valves, which resulted from short circuits between the 115 volt 
alternating current (VAC) circuits of the outboard landing lights and 
the 28 volt direct current (VDC) circuits of the engine fuel shutoff 
valves. This short circuit causes the valve to move towards the closed 
position. Failure of the valve occurs shortly after reaching the closed 
position due to exposure of the 28-VDC valve to 115-VAC power from the 
outboard landing light circuit. The loss of ability to reopen the valve 
prevents restarting the engine due to the unavailability of fuel. 
Uncommanded closure of the fuel shutoff valve due to a hot short 
between the outboard landing light and the fuel shutoff valve circuits, 
if not corrected, could result in an uncommanded engine shutdown.
    Subsequently, Boeing published Boeing Service Bulletin 737-28-1241, 
dated April 7, 2006, to provide instructions for replacing certain wire 
bundles with new, re-designed wire bundles to prevent short circuits 
between the outboard landing light and engine fuel shutoff valve 
circuits. After issuing that service bulletin, Boeing discovered that 
some of the replacement wire bundles were inadvertently assembled and 
delivered with electrical connectors and backshells having a cadmium-
plated finish instead of an anodized aluminum finish. The electrical 
connectors and backshells are located on the rear spar of the left and 
right wings. The cadmium-plated connectors and backshells corrode 
quickly when exposed to potassium-based de-icing fluids. This corrosion 
leads to moisture ingress into the electrical connectors and subsequent 
corrosion of the electrical contacts within the electrical connectors. 
This condition, if not corrected, could result in short circuits and 
consequent incorrect functioning of airplane systems needed for safe 
flight and landing.
    We have also received reports of damaged and missing grommets and 
broken and damaged fairleads in the electrical junction boxes of the 
main wheel well on Boeing Model 737-100, -200, -200C, -300, -400, and -
500 series airplanes. Although there is no evidence that these wiring 
discrepancies have contributed to uncommanded engine shutdowns, the 
wiring in this area includes the wire bundles for the engine fuel 
shutoff valves, as well as wiring for other systems needed for 
continued safe flight and landing of the airplane.

Relevant Service Information

    We have reviewed Boeing Alert Service Bulletin 737-33A1140, dated 
May 22, 2006, for Model 737-300, -400, and -500 series airplanes. The 
service bulletin specifies accomplishing the actions in either Part 1 
or Part 2 of the Accomplishment Instructions. Part 1 describes 
procedures for deactivating the outboard landing lights. The 
deactivation includes installing collars and ``do not close'' tags on 
the circuit breakers for the outboard landing lights, and capping and 
stowing the wires from the circuit breakers. Part 2 describes 
procedures for modifying the wiring to the outboard landing lights. The 
modification includes capping and stowing the existing wires to the 
outboard landing lights, and routing new wires to the outboard landing 
lights.
    We have also reviewed Boeing Service Bulletin 737-28-1241, Revision 
1, dated August 31, 2007, for Model 737-100, -200, -200C, -300, -400, 
and -500 series airplanes. Part 1 of the Accomplishment Instructions of 
the service bulletin applies to certain Model 737-300, -400, and -500 
series airplanes. Part 1 describes procedures for replacing certain 
wire bundles for the landing lights and fuel shutoff valves with new, 
re-designed wire bundles, and doing related investigative, other 
specified, and corrective actions if necessary. The related 
investigative actions include (1) doing a detailed inspection for any 
broken, damaged, or missing grommet where the wire bundles go from the 
wheel well to the wing and (2) doing a detailed inspection for any 
broken, damaged, or missing fairleads, any damaged or missing grommets, 
and any chafed or damaged wires or wire bundles in the electrical 
junction boxes of the main wheel well. The other specified actions 
include (1) removing any additional outboard landing light wires from 
the wire bundles installed in accordance with Boeing Alert Service 
Bulletin 737-33A1140 and (2) terminating the outboard landing lights at 
the circuit breakers, as necessary. The corrective actions include (1) 
replacing any broken, damaged, or missing fairlead with a new fairlead, 
(2) replacing any damaged or missing grommet with a new grommet, and 
(3) repairing or

[[Page 62939]]

replacing any chafed or damaged wires and wire bundles with new wires 
and wire bundles.
    Part 2 of the Accomplishment Instructions of Boeing Service 
Bulletin 737-28-1241 describes procedures for doing a detailed 
inspection for any broken, damaged, or missing fairleads, any damaged 
or missing grommets, and any chafed or damaged wires or wire bundles in 
the four electrical junction boxes of the main wheel well, and doing 
the corrective actions as necessary.
    Part 3 of the Accomplishment Instructions of Boeing Service 
Bulletin 737-28-1241 applies to certain Model 737-300, -400, and -500 
series airplanes on which the wire bundle replacement was done in 
accordance with the original issue of the service bulletin, dated April 
7, 2006. Part 3 describes procedures for replacing certain electrical 
connectors and backshell clamps with new, improved electrical 
connectors and backshell clamps.
    Accomplishing the applicable actions specified in Boeing Service 
Bulletin 737-28-1241 would end the need for accomplishing the 
deactivation or modification specified in Boeing Alert Service Bulletin 
737-33A1140.
    Boeing Alert Service Bulletin 737-33A1140 and Boeing Service 
Bulletin 737-28-1241 specify prior or concurrent accomplishment of 
Boeing Special Attention Service Bulletin 737-28-1196, dated December 
5, 2002; Revision 1, dated March 13, 2003; Revision 2, dated August 21, 
2003; or Revision 3, dated April 1, 2004. Boeing Special Attention 
Service Bulletin 737-28-1196 describes procedures for changing the wire 
connections for the engine fuel shutoff valves and the outboard landing 
lights.

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(se) same type 
design(s). This proposed AD would require the following actions:
     For Model 737-300, -400, and -500 series airplanes, 
deactivation or modification of the wiring to the outboard landing 
lights, until the wire bundles and electrical connectors have been 
replaced.
     For all airplanes, a detailed inspection for any broken, 
damaged, or missing fairleads, any damaged or missing grommets, and any 
chafed or damaged wires or wire bundles in the four electrical junction 
boxes of the main wheel well, and corrective actions if necessary.
     For certain airplanes, replacement of certain wire bundles 
for the landing lights and fuel shutoff valves with new, re-designed 
wire bundles, and related investigative, other specified, and 
corrective actions if necessary.
     For certain airplanes, replacement of certain electrical 
connectors and backshell clamps with new, improved electrical 
connectors and backshell clamps.

Difference Between the Proposed AD and Service Bulletins

    Although Boeing Service Bulletin 737-28-1241 and Boeing Alert 
Service Bulletin 737-33A1140 specify prior or concurrent accomplishment 
of Boeing Special Attention Service Bulletin 737-28-1196, this proposed 
AD would not require that action. The accomplishment of Boeing Special 
Attention Service Bulletin 737-28-1196 is already required by AD 2005-
10-11, amendment 39-14088 (70 FR 28419, May 18, 2005).

Costs of Compliance

    We estimate that the actions specified in Boeing Alert Service 
Bulletin 737-33A1140 would affect about 511 Model 737-300, -400, and -
500 series airplanes of U.S. registry. Operators may accomplish either 
the deactivation or modification.
    We estimate that the deactivation would take about 1 work-hour per 
product to comply with this proposed AD. The average labor rate is $80 
per work-hour. Based on these figures, we estimate the cost of the 
deactivation to the U.S. operators to be $40,880, or $80 per product.
    We estimate that the modification would take about 31 work-hours 
per product to comply with this proposed AD. The average labor rate is 
$80 per work-hour. Required parts for the modification would cost about 
$573 per product. Based on these figures, we estimate the cost of 
modification to the U.S. operators to be $1,560,083, or $3,053 per 
product.
    We estimate that the actions specified in Boeing Alert Service 
Bulletin 737-28-1241 would affect up to 891 Model 737-100, -200, -200C, 
-300, -400, and -500 series airplanes of U.S. registry. The following 
table provides the estimated costs, at an average labor rate of $80 per 
work-hour, for U.S. operators to comply with the actions specified in 
that service bulletin.

                                                                     Estimated Costs
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                                                                                                                          Number of U.S.-
                Action                             Work hours                         Parts                  Cost per       registered      Fleet cost
                                                                                                             airplane        airplanes
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Part 1--Replacement of wire bundles...  Up to 91.......................  Up to $18,439..................         $25,719             511     $13,142,409
Part 2--Inspection of junction boxes..  1..............................  0..............................              80             891          71,280
Part 3--Replacement of electrical       2..............................  298............................             458             400         183,200
 connectors.
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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.

[[Page 62940]]

    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, Incorporation by 
reference, 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-2008-1116; Directorate Identifier 2007-NM-
231-AD.

Comments Due Date

    (a) We must receive comments by December 8, 2008.

Affected ADs

    (b) None.

Applicability

    (c) This AD applies to Boeing Model 737-100, -200, -200C, -300, 
-400, and -500 series airplanes, certificated in any category; as 
identified in Boeing Service Bulletin 737-28-1241, Revision 1, dated 
August 31, 2007.

Unsafe Condition

    (d) This AD results from reports of uncommanded engine shutdowns 
and burned and damaged wire bundles associated with the outboard 
landing lights and engine fuel shutoff valves. This AD also results 
from reports of damaged and missing grommets and broken and damaged 
fairleads in the electrical junction boxes of the main wheel well. 
We are issuing this AD to prevent a hot short between the outboard 
landing light and fuel shutoff valve circuits, which could result in 
an uncommanded engine shutdown. We are also issuing this AD to 
prevent corrosion of the electrical connectors of the wing rear 
spars, which could result in short circuits and consequent incorrect 
functioning of airplane systems needed for safe flight and landing.

Compliance

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

Deactivation or Modification of the Outboard Landing Lights

    (f) For Model 737-300, -400, and -500 series airplanes 
identified in Boeing Alert Service Bulletin 737-33A1140, dated May 
22, 2006 (``the alert service bulletin''): Within 180 days after the 
effective date of this AD, accomplish the actions specified in 
either paragraph (f)(1) or (f)(2) of this AD. Accomplishing the 
applicable actions required by paragraph (g) of this AD terminates 
the requirements of this paragraph.
    (1) Deactivate the outboard landing lights, by accomplishing all 
of the actions specified in Part 1 of the Accomplishment 
Instructions of the alert service bulletin.

    Note 1: The Master Minimum Equipment List (MMEL) prohibits 
dispatching an airplane for night operations with deactivated 
outboard landing lights in the event that either of the inboard 
landing lights fail. Operators should note that, if the outboard 
landing lights are deactivated in accordance with Part 1 of the 
service bulletin, there is no MMEL relief allowing for this 
configuration for night operations should any inboard landing light 
fail.

    (2) Modify the wiring to the outboard landing lights, by 
accomplishing all of the actions specified in Part 2 of the 
Accomplishment Instructions of the alert service bulletin.

Inspection and Replacements

    (g) For all airplanes: Within 60 months after the effective date 
of this AD, do the applicable actions specified in paragraphs 
(g)(1), (g)(2), and (g)(3) of this AD, by accomplishing all of the 
applicable actions specified in the Accomplishment Instructions of 
Boeing Service Bulletin 737-28-1241, Revision 1, dated August 31, 
2007. For Model 737-300, -400, and -500 series airplanes identified 
in Boeing Alert Service Bulletin 737-33A1140, dated May 22, 2006, 
accomplishing the applicable actions required by this paragraph 
terminates the requirements of paragraph (f) of this AD.
    (1) Replace the wire bundles for the landing lights and fuel 
shutoff valves with new, re-designed wire bundles, and do the 
related investigative, other specified, and corrective actions, as 
applicable. The related investigative, other specified, and 
corrective actions must be done before further flight after the 
replacement.
    (2) Do a detailed inspection for any broken, damaged, or missing 
fairleads, any damaged or missing grommets, and any chafed or 
damaged wires or wire bundles in the four electrical junction boxes 
of the main wheel well, and do the applicable corrective actions. 
The corrective actions must be done before further flight after the 
inspection.
    (3) Replace the electrical connectors and backshell clamps with 
new, improved electrical connectors and backshell clamps, as 
applicable.

Credit for Actions Done According to Previous Issue of Service Bulletin

    (h) For airplanes identified as Groups 1 and 2 in Boeing Service 
Bulletin 737-28-1241, Revision 1, dated August 31, 2007: Actions 
done before the effective date of this AD in accordance with Boeing 
Service Bulletin 737-28-1241, dated April 7, 2006, are acceptable 
for compliance with the requirements of paragraph (g) of this AD.
    (i) For all airplanes: Actions done before the effective date of 
this AD in accordance with Part 2 of the Accomplishment Instructions 
of Boeing Service Bulletin 737-28-1241, dated April 7, 2006, are 
acceptable for compliance with the requirements of paragraph (g)(2) 
of this AD.

Alternative Methods of Compliance (AMOCs)

    (j)(1) The Manager, Seattle Aircraft Certification Office (ACO), 
FAA, ATTN: Stephen Oshiro, Aerospace Engineer, Systems and Equipment 
Branch, ANM-130S, FAA, Seattle ACO, 1601 Lind Avenue, SW., Renton, 
Washington 98057-3356; telephone (425) 917-6480; 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.

    Issued in Renton, Washington, on October 10, 2008.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. E8-25048 Filed 10-21-08; 8:45 am]

BILLING CODE 4910-13-P
