Airworthiness Directives; Boeing Model 737-600, -700, -700C, -800, and -900 Series Airplanes, 54253-54258 [05-17984]

Agencies

• Federal Aviation Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 70, Number 177 (Wednesday, September 14, 2005)]
[Rules and Regulations]
[Pages 54253-54258]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 05-17984]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2004-19750; Directorate Identifier 2003-NM-192-AD; 
Amendment 39-14264; AD 2005-18-23]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 737-600, -700, -700C, -
800, and -900 Series Airplanes

AGENCY: Federal Aviation Administration (FAA), Department of 
Transportation (DOT).

ACTION: Final rule.

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SUMMARY: The FAA is superseding an existing airworthiness directive 
(AD), which applies to all Boeing Model 737-600, -700, -700C, -800, and 
-900 series airplanes. That AD currently requires either determining 
exposure to runway deicing fluids containing potassium formate, or 
performing repetitive inspections of certain electrical connectors in 
the wheel well of the main landing gear (MLG) for corrosion, and 
follow-on actions. This new AD adds a new inspection requirement and 
related corrective actions. This AD is prompted by additional reports 
indicating that significant corrosion of the electrical connectors in 
the wheel well of the MLG has also been found on airplanes that land on 
runways treated with deicing fluids containing potassium acetate. We 
are issuing this AD to prevent corrosion and subsequent moisture 
ingress into the electrical connectors, which could result in an 
electrical short and consequent incorrect functioning of critical 
airplane systems essential to safe flight and landing of the airplane, 
including fire warning systems.

DATES: This AD becomes effective October 19, 2005.
    The incorporation by reference of Boeing Alert Service Bulletin 
737-24A1148, Revision 1, dated July 10, 2003; as listed in the AD; is 
approved by the Director of the Federal Register as of October 19, 
2005.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplanes, P.O. Box 3707, Seattle, 
Washington 98124-2207.
    Docket: The AD docket contains the proposed AD, comments, and any 
final disposition. You can examine the AD docket on the Internet at 
https://dms.dot.gov, or 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 U.S. 
Department of Transportation, 400 Seventh Street, SW., room PL-401, 
Washington, DC. This docket number is FAA-2004-19750; the directorate 
identifier for this docket is 2003-NM-192-AD.

FOR FURTHER INFORMATION CONTACT: Binh Tran, Aerospace Engineer, Systems 
and Equipment Branch, ANM-130S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone 
(425) 917-6485; fax (425) 917-6590.

SUPPLEMENTARY INFORMATION: The FAA proposed to amend part 39 of the 
Federal Aviation Regulations (14 CFR part 39) with an AD to supersede 
AD 2002-16-03, amendment 39-12842 (67 FR 52396, August 12, 2002). The 
existing AD applies to all Boeing Model 737-600, -700, -700C, -800, and 
-900 series airplanes. The proposed AD was published in the Federal 
Register on December 1, 2004 (69 FR 69832), to require either 
determining exposure to runway deicing fluids containing potassium 
formate or performing repetitive inspections of certain electrical 
connectors in the wheel well of the main landing gear (MLG) for 
corrosion, and follow-on actions.

Comments

    We provided the public the opportunity to participate in the 
development of this AD. We have considered the comments that have been 
submitted on the proposed AD.

[[Page 54254]]

Requests for Credit/Extension of Compliance Time for Previous 
Inspections

    Three commenters ask that the proposed AD be changed to allow 
credit for the repetitive inspections being accomplished per the 
existing AD. The first commenter states that it has been in compliance 
with the existing AD by performing the repetitive inspections of the 
electrical connectors, as specified in paragraph (f)(1)(ii) of the 
proposed AD, every 12 calendar months. The commenter notes that it 
chose to perform this inspection instead of determining exposure to 
runway deicing fluids containing potassium formate because it cannot 
establish whether airplanes that fly into unfamiliar airports have been 
exposed. The commenter adds that, based on the current language in the 
proposed AD, all of its airplanes would have to be re-inspected before 
further flight if exposed to potassium formate. The commenter states 
that there is no safety-of-flight issue if the airplane is already 
being repetitively inspected per the existing AD; therefore, operations 
should be continued as long as the requirements in paragraph (f)(2) of 
the proposed AD (i.e., repetitive detailed inspections and follow-on 
actions) are met. The commenter concludes that airplanes on which the 
inspections have been performed in the last 12 months before issuance 
of the proposed AD should be exempt from performing another inspection 
before further flight.
    The second commenter states that the proposed AD does not clearly 
give credit for previous compliance with the existing AD.
    The third commenter asks that, if the FAA proceeds with issuance of 
the proposed AD, all aircraft that have previously complied with the 
existing AD via detailed inspection of the electrical connectors, or 
per an approved alternative method of compliance (AMOC), not be 
required to perform the inspection for at least 12 months after 
performing the last inspection required by the existing AD.
    We agree that the commenters should get credit for the detailed 
inspections accomplished per the original issue of the service bulletin 
(which was referenced in the existing AD as the appropriate source of 
service information for accomplishing the detailed inspections of the 
electrical connectors). We have added a new paragraph (g) to this final 
rule to give such credit. Additionally, we have changed the final rule 
to specify that operators are allowed to do the actions specified in 
either paragraph (f)(1) or (f)(2) of the final rule at intervals not to 
exceed 12 months, regardless of airplane exposure. However, we have 
changed the compliance time for accomplishing the detailed inspection 
for airplanes that have been exposed to potassium formate or potassium 
acetate to 90 days after that determination is made (and thereafter at 
intervals not to exceed 12 months). The proposed AD specified 
accomplishing the detailed inspection before further flight for 
airplanes that have been exposed to potassium formate or potassium 
acetate, but we have added a 90-day grace period before the detailed 
inspection on those airplanes must be accomplished. We have determined 
that accomplishing the detailed inspection within 90 days represents an 
acceptable interval of time wherein affected airplanes may be allowed 
to operate without jeopardizing safety.
    One commenter notes that paragraph (f)(1)(ii) of the proposed AD 
requires performing the inspection required by paragraph (f)(2) of the 
proposed AD before further flight, and that this compliance time is 
troublesome. The commenter states that it would ground some airplanes 
upon the effective date of the AD until the detailed inspection is 
accomplished. The commenter adds that operators have not previously 
been required to determine airplane exposure to potassium acetate, and 
no time is given to make such a determination in the proposed AD. The 
commenter states that this is further complicated by the fact that 
credit should be given for compliance with the existing AD.
    A second commenter states that, in order to comply with paragraph 
(f)(1) of the proposed AD, it would be necessary to have written 
evidence of the runway cleaning assessment from airport management when 
deicing fluids are used due to meteorological events. The commenter 
adds that to perform the inspection required by paragraph (f)(2) before 
further flight is very restrictive if the flight is made with 
intermediate legs, which could cause delays. The commenter notes that 
it would be better to have more time to accomplish this inspection.
    A third commenter states that its partner airline must obtain a 
change or an AMOC to paragraph (f)(1)(ii), described previously. The 
commenter states that, if its partner airline cannot get the compliance 
time extended to 6 months or so, it will be required to do the 8-hour 
inspection on the same day they determine exposure, which will ground 
those airplanes until the inspection is done.
    We partially agree with the commenters. We have already extended 
the compliance time for accomplishing the initial detailed inspection 
of airplanes that have been exposed to potassium formate or potassium 
acetate to 90 days, as specified above. Additionally, operators may 
incorporate a repetitive inspection program in lieu of determining 
exposure to runway deicing fluids; therefore, it is not necessary for 
us to obtain written evidence of the runway cleaning assessment from 
airport management. We have made no change to the final rule in this 
regard.
    One commenter states that paragraph (f)(2) of the proposed AD 
requires operators to perform an airplane exposure review every 12 
months, per paragraph (f)(1) of the proposed AD. The commenter adds 
that this yearly review should not be required for operators that 
choose to inspect their airplanes every 12 months, regardless of 
airplane exposure. The commenter asks that the last sentence of 
paragraph (f)(2) be changed to read ``Repeat the actions required by 
paragraph (f)(1) or (f)(2) of this AD thereafter at intervals not to 
exceed 12 months.''
    We agree with the commenter. However, we have removed the 
repetitive interval specified in paragraph (f)(2) of the proposed AD 
and added the repetitive interval to paragraph (f) of this final rule. 
By adding the repetitive interval to the main paragraph, the actions 
for both paragraphs (f)(1) and (f)(2) of the final rule are covered. 
Paragraphs (f)(1)(i) and (f)(1)(ii) of the proposed AD identify 
airplanes that have not, and have, respectively, been exposed to 
potassium formate or potassium acetate.

Request To Extend Repetitive Inspection Interval

    Two commenters ask that the repetitive inspection interval 
specified in the proposed AD be extended.
    One commenter states that it has completed three series of 
inspections per the existing AD, and at the time of its last 
inspection, its fleet had accumulated over 691,000 flight hours and 
369,000 flight cycles with no findings. The commenter states that the 
manufacturer provided no technical objection to its request to extend 
the repetitive inspection interval in the existing AD from 12 to 24 
months. The commenter asks that the repetitive inspection interval 
specified in the proposed AD be extended to 24 months.
    The second commenter states that the manufacturer has determined 
that the amount of corrosion to be expected is dependent on the number 
of landings on runways where potassium-based deicing fluids are used. 
The commenter notes that not all operators have the

[[Page 54255]]

same quantity of flights to affected runways, yet, as proposed, 
operators with little exposure are subject to the same restrictive 
interval as operators in highly exposed regions. The commenter operates 
the majority of the affected 737NG (next generation) airplanes with 
flights mostly on eastern, western, and southern routes, and there is 
little exposure to deicing fluids on these routes; although the 
possibility of some exposure exists. The commenter asks that the 
repetitive interval be 12 months for airplanes with high exposure, and 
extended to 24 months for airplanes with medium exposure, and 36 months 
for airplanes with limited exposure.
    We do not agree with the commenters' requests. We have not received 
any verification showing that the amount of corrosion on the connectors 
can last through two winters (24 months) without affecting safety of 
flight, or that airplanes with limited exposure can resist corrosion 
for longer periods of time when exposed to deicing fluids containing 
potassium formate and potassium acetate. In addition, no technical 
justification was provided that verifies extending the repetitive 
inspection interval will still maintain an appropriate level of safety. 
In developing an appropriate compliance time for this proposed AD, we 
considered safety issues as well as the recommendations of the 
manufacturer and the practical aspects of accomplishing the required 
inspections within an interval of time that corresponds to the normal 
maintenance schedules of most affected operators. We do not find it 
necessary to change this final rule in this regard.

Request for Information/Clarification for Determining Airplane Exposure

    Two commenters ask that the phrase ``determine airplane exposure,'' 
as specified in the proposed AD, be further clarified.
    One commenter notes that the proposed AD would require either 
determining exposure to runway deicing fluids containing potassium 
formate or potassium acetate, or performing repetitive inspections of 
certain electrical connectors. The commenter states that affected 
operators have no authority or control over airports, but the FAA has 
the authority to require airports to provide the information that would 
be necessary for determination of airplane exposure. The commenter 
cites Title 14, Aeronautical and Space, Part 139--Certification of 
Airports--Subpart D--Operations, Federal Aviation Regulation (FAR) 
139.310(c), Records, and FAR 139.313(a), Snow and Ice Control, and adds 
that snow and ice control plans for most U.S. airports are authorized 
by the FAA. The commenter asks that the data necessary to make this 
determination be provided to all affected operators by the FAA.
    Another commenter states that it would be very helpful if the FAA 
would provide a written definition of what constitutes airplane 
exposure. The commenter states that information it received from the 
FAA in late 2002 defined exposure as ``Landing at or taking off from an 
airport where subject runway deicing fluid or pelletized solid had been 
applied anytime during the previous 365 days.'' The commenter believes, 
``as most of the airline industry does,'' that this is far too broad an 
exposure window since the applied fluid will wash away, or will dry up 
and blow away, within a week or so after application. The commenter 
adds that testing of the pelletized forms of the subject deicers has 
shown to be less corrosive to airplanes.
    We partially agree with the commenters. The Airport Safety and 
Operations Division (AAS-300) of the FAA issued CertAlerts No. 01-04 
and No. 02-02 to instruct airport operators to inform and coordinate 
the use of such chemicals with air carriers. The CertAlerts state that 
the airplane operators may contact airport operators to obtain 
information about deicing materials used on runways. We have made no 
change to the final rule in this regard.

Request To Include Related Service Information

    One commenter states that, since Boeing Service Bulletin 737-24-
1149, Revision 2, dated August 14, 2003, also addresses corrosion 
protection of the electrical connectors in the main wheel well, and 
those connectors are specified in the service information referenced in 
the proposed AD, that service bulletin should be required in the final 
rule. The commenter adds that granular potassium nitrate is a commonly 
used deicing product on airport ramp and gate areas; when this product 
dissolves into a solution by the melted ice and snow, it could splatter 
into the wheel well areas during taxi and takeoff.
    We do not agree with the commenter's request. The commenter did not 
provide supporting data regarding the effects of granular potassium 
nitrate. We have determined that further delay of this final rule is 
not appropriate; however, we are planning to review Boeing Service 
Bulletin 737-24-1149 and may then consider further rulemaking action on 
the issue of deicing. We have made no change to the final rule in this 
regard.

Request To Change Costs of Compliance Section

    Several commenters ask that the work hours and cost specified in 
the ``Costs of Compliance'' section be changed.
    The first commenter states that it estimates the time to accomplish 
the actions at 5 work hours; this adds aircraft out-of-service costs to 
the labor and materials estimated in the proposed AD. The commenter 
adds that, for a limited-exposure operator, the added out-of-service 
costs are not warranted, and additional operational costs to the 
airlines in this economic environment, based on the most exposed 
operator condition, adds an undue burden on the industry.
    The second commenter states that the estimated cost for the 
determination of airplane exposure is a poor labor cost estimate. The 
commenter adds that the estimate in the proposed AD is based on the 
number of airplanes operated and not on the number of airports being 
used by affected operators; the location and number of airports 
utilized by affected operators also need to be considered to more 
accurately determine the costs. The commenter notes that no estimated 
costs are specified for the required repetitive detailed inspections 
and any necessary corrective actions that will be required on a 
percentage of affected airplanes. The commenter gives an example, based 
on its experience, of labor costs for the inspection, corrective 
actions, parts cost for new connectors, cost for corrosion-inhibiting 
compound, and parts cost for consumables utilized during maintenance.
    The third commenter estimates that it takes at least 8 elapsed work 
hours and 24 work hours per airplane to comply with the actions in both 
the proposed and existing AD. The commenter adds that the proposed AD 
is presently costing over $230,000 annually for its 139 affected 
airplanes, and not the $9,035 annual total specified in the proposed 
AD.
    We partially agree with the commenters.
    We agree that the cost for the detailed inspection should be added 
to the final rule because we have changed the actions in the final rule 
to give operators the option of performing either the determination of 
exposure or the detailed inspection of the electrical connectors. The 
``Costs of Compliance'' section has been changed accordingly.
    We do not agree to add to the final rule the cost for estimated 
time or for corrective actions if any discrepancy is found. The actions 
in this final rule reflect only the direct costs of the

[[Page 54256]]

specific required actions based on the best data available from the 
manufacturer. We recognize that operators may incur incidental costs 
(such as the time for planning, access and close, and associated 
administrative actions) in addition to the direct costs. The cost 
analysis in ADs, however, typically does not include incidental costs 
or the cost for on-condition corrective actions. The compliance times 
in this AD should allow ample time for operators to do the required 
actions at the same time as scheduled major airplane inspection and 
maintenance activities, which would reduce the additional time and 
costs associated with special scheduling.
    Additionally, we do not agree that the location and number of 
airports utilized should be considered to more accurately determine the 
costs. The operational cost of airports utilized may vary significantly 
from operator to operator; therefore, individual costs for the location 
and number of airports utilized is almost impossible to calculate.

Request for Credit for AMOCs Approved for Existing AD

    Two commenters ask that previously issued AMOCs for the existing AD 
continue to be approved for the proposed AD.
    The first commenter asks that two specific approved AMOCs be 
acceptable for compliance with the proposed AD. One AMOC extended the 
compliance time to 90 days for accomplishing the procedures described 
in paragraphs (a)(1)(i) and (b) of the existing AD (which are not 
restated in the proposed AD). The other AMOC defined an acceptable 
corrosion area as 10% of the total area of the backshell of the 
connectors. The commenter adds that the second AMOC also allows 
connector replacement when the total amount of corrosion is between 10% 
and 30%. The commenter recommends that these AMOCs remain valid.
    The second commenter notes that it is already in compliance with 
the proposed AD and requires no change in its current method of 
compliance. The commenter adds that it was granted six AMOC approvals 
by the Seattle Aircraft Certification Office for accomplishing the 
existing AD's annual repetitive inspections (which currently are 
required on 139 airplanes). The commenter states that there should be 
no technical or operational reason that existing AMOCs cannot be 
applied to the proposed AD, because Revision 1 of the service bulletin, 
which was referenced in the proposed AD as the appropriate source of 
service information for accomplishing the actions, contains the same 
actions as the original issue. The commenter concludes that, if 
necessary, it will re-submit the original and approved AMOC request 
letters to the FAA requesting the same or parallel AMOCs for the 
proposed AD.
    We do not agree with the commenters' requests. As specified in the 
proposed AD, AMOCs approved previously in accordance with AD 2002-16-
03, amendment 39-12842, are not approved as AMOCs with this AD because 
of the addition of a new requirement to determine airplane exposure to 
potassium acetate. Additionally, although certain AMOCs extended the 
compliance time for corrective actions, the corrective actions are 
normally performed before further flight, so that the extension was an 
exception to normal procedures. The actions in this final rule have 
been changed, as stated previously, to allow 12 months for repeating 
either the determination of airplane exposure or the detailed 
inspection of the electrical connectors, as well as to allow 90 days to 
perform the detailed inspection for airplanes that have been exposed to 
potassium formate and/or potassium acetate. However, any additional 
corrective actions must be performed before further flight. The 
approval for replacement of the connectors if the area of corrosion is 
greater than ten percent of the total backshell surface area has been 
incorporated into the revised service information referenced in this 
final rule. We have made no change to the final rule in this regard.

Request To Change Certain Requirements

    One commenter reiterates the requirements in paragraph (f)(2) of 
the proposed AD and states that this paragraph would require all 
affected airplanes that were not inspected per Part 1, but were 
inspected per Part 2, of the original issue of Boeing Service Bulletin 
737-24A1148 (referenced in the existing AD for accomplishing certain 
actions), to be re-inspected per Part 1 of Revision 1 of the service 
bulletin, because of the wording ``by doing all the actions.'' The 
commenter adds that, since airplanes that were inspected per Part 2 of 
the original issue meet the full intent of the existing AD, the 
requirement to accomplish Part 1 of Revision 1 should not be mandated.
    We agree with the commenter. The intent of this final rule is 
essentially the same as that of the existing AD, but the proposed AD 
adds an inspection for potassium acetate. The requirements in this AD 
are based on the latest information provided by the manufacturer; 
therefore, the Accomplishment Instructions of Revision 1 of the service 
bulletin should be followed. As stated previously, we have added a 
credit paragraph for inspections already done per the existing AD using 
the original issue of the service bulletin, and that when the 
inspections are repeated, Revision 1 of the service bulletin must be 
used.

Request To Provide Terminating Action

    Several commenters ask that a terminating action for the repetitive 
inspections specified in the proposed AD be developed.
    One commenter states that operators need the manufacturer and the 
FAA to aggressively address the development of a terminating action for 
the repetitive inspections. The commenter adds that, because there have 
been no electrical connector problems, as well as limited and declining 
corrosion findings fleet-wide during two annual inspections, it 
formally requested from the manufacturer that it extend the repetitive 
inspection interval from 12 to 18 or 24 months, during the time they 
are developing a terminating action for the proposed AD. The commenter 
is awaiting new information from the manufacturer regarding newly 
designed thrust reverser (TR) cascades and electrical connectors made 
of improved stainless steel and anodized aluminum, which would be 
installed in all ten positions. The commenter suggests that the 
combination of installing improved TR cascades, replacing the existing 
connectors with new connectors, and applying corrosion inhibiting 
compound, by following the new service information to be issued by the 
manufacturer (depending on FAA analysis and acceptance) be designated 
as a terminating action for the repetitive inspections. The commenter 
adds that the cost for the terminating action could be considerable, 
but if this action terminates the repetitive inspections, it would save 
the commenter over $230,000 annually, as the present cost for the 
inspection is about $3.3 million.
    The second commenter states that the manufacturer is collecting 
data from operators to propose a more convenient maintenance interval 
for the mandated inspections. The commenter asks that the FAA consider 
both a maintenance interval based on operations on affected runways, 
and possible terminating action, prior to publishing the final rule.
    We agree that a terminating action for the repetitive inspections 
would benefit operators. The airplane manufacturer is currently 
developing a terminating action. Once the proposed terminating action 
has been submitted to us for

[[Page 54257]]

review, and we have approved the proposed action as terminating action 
for the requirements of the AD, anyone may apply for approval to use 
that terminating action as an AMOC under the provisions of paragraph 
(h)(1) of this final rule.
    The third commenter states that terminating action is possible and 
requests that the FAA implement all of the following solutions. The 
FAA's response follows each comment.
     Withdraw the proposed AD.
    We do not agree that we should withdraw the proposed AD until a 
terminating action is developed. We do not consider it appropriate to 
delay the issuance of this final rule in light of the identified unsafe 
condition. Additionally, we do not have any technical justification to 
withdraw the proposed AD, and the repetitive inspections are required 
for continued safe flight of the airplane. Therefore, we have made no 
change to the final rule in this regard.
     Determine changes that need to be made to the 
specifications for deicing materials used at airports under FAA 
authority and control to eliminate the subject corrosion. Ensure 
adequate improvements are made to the deicing material specifications, 
and then mandate to airports under FAA authority and control that only 
these improved deicing materials be used as part of FAA-authorized snow 
and ice removal plans under FAA regulations.
    The specifications for deicing fluids are determined by the Society 
of Automotive Engineers (SAE) G-12 Aircraft Ground Deicing Fluids 
Subcommittee, and the FAA enforces those deicing specifications under 
FAA regulations. We are working with the SAE subcommittee (we 
participate in this committee) to ensure that adequate improvements are 
made to the deicing material specifications.
     Direct Boeing to determine which design changes need to be 
made to the 737NG airplanes in order to eliminate unique susceptibility 
to the corrosive effects of runway deicing materials. Promulgate an AD 
requiring incorporation of the design changes determined to be 
necessary for the 737NG airplanes, in order to eliminate the subject 
corrosion problem within its MLG wheel wells.
    We have determined that the repetitive inspections required by this 
final rule will maintain an adequate level of safety for all affected 
airplanes until a terminating action is developed. As specified 
previously, the manufacturer is currently developing a terminating 
action for the repetitive inspections. After terminating action is 
developed, approved, and available, we may consider further rulemaking 
action. The terminating action should provide a solution to both the 
corrosive effects of runway deicing materials and corrosion in the MLG 
wheel wells.

Request To Address Technical Objection

    One commenter states that it has previously objected to the 
manufacturer and the FAA * * * * and still stands by this objection in 
principle * * * regarding the unwarranted detailed inspection of the 
electrical connectors. The commenter notes that the subject inspection 
is an imprudent practice, since routinely opening cannon-plug 
connectors on so many airplanes without any indication of problems 
could create a risk of pushing back or bending connector pins. This 
would leave a less secure seal that could allow the ingress of moisture 
in the future.
    We infer that the commenter wants the requirement for repetitive 
detailed inspections removed from the final rule. As explained in the 
preamble of the proposed AD, we have received reports of significant 
corrosion of the electrical connectors located in the wheel well of the 
MLG on Model 737 series airplanes that land on runways treated with 
deicing fluids containing potassium acetate. We have determined that 
the detailed inspections required by the existing AD do not account for 
exposure to deicing fluids containing potassium acetate. Therefore, we 
find that repetitive detailed inspections are necessary to prevent 
corrosion and subsequent moisture ingress into the electrical 
connectors, which could result in an electrical short and consequent 
incorrect functioning of critical airplane systems essential to safe 
flight and landing of the airplane, including fire warning systems. We 
have made no change to the final rule in this regard.

Conclusion

    We have carefully reviewed the available data, including the 
comments that have been submitted, and determined that air safety and 
the public interest require adopting the AD with the changes described 
previously. We have determined that these changes will neither increase 
the economic burden on any operator nor increase the scope of the AD.

Costs of Compliance

    This AD affects about 587 airplanes of U.S. registry.
    The new determination of airplane exposure takes about 1work hour 
per airplane, at an average labor rate of $65 per work hour. Based on 
these figures, the estimated cost of the determination of airplane 
exposure specified in this AD for U.S. operators is $38,155, or $65 per 
airplane, per cycle.
    The detailed inspection takes about 1work hour per airplane, at an 
average labor rate of $65 per work hour. Based on these figures, the 
estimated cost of the detailed inspection specified in this AD for U.S. 
operators is $65 per airplane, per inspection cycle.

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 have determined that 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.
    We prepared a regulatory evaluation of the estimated costs to 
comply with this AD. See the ADDRESSES section for a location to 
examine the regulatory evaluation.

[[Page 54258]]

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 removing amendment 39-12842 (67 FR 
52396, August 12, 2002), and by adding the following new airworthiness 
directive (AD):

2005-18-23 Boeing: Amendment 39-14264. Docket No. FAA-2004-19750; 
Directorate Identifier 2003-NM-192-AD.

Effective Date

    (a) This AD becomes effective October 19, 2005.

Affected ADs

    (b) This AD supersedes AD 2002-16-03, amendment 39-12842.
    Applicability: (c) This AD applies to all Boeing Model 737-600, 
-700, -700C, -800, and -900 series airplanes; certificated in any 
category.

Unsafe Condition

    (d) This AD was prompted by additional reports indicating that 
significant corrosion of the electrical connectors in the wheel well 
of the MLG has also been found on airplanes that land on runways 
treated with deicing fluids containing potassium acetate. We are 
issuing this AD to prevent corrosion and subsequent moisture ingress 
into the electrical connectors, which could result in an electrical 
short and consequent incorrect functioning of critical airplane 
systems essential to safe flight and landing of the airplane, 
including fire warning systems.
    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.

Determine Airplane Exposure/Significant & Corrective Actions

    (f) Within 12 months after the effective date of this AD: 
Perform the actions required by either paragraph (f)(1) or (f)(2) of 
this AD.
    (1) Determine airplane exposure to runway deicing fluids 
containing potassium formate or potassium acetate by reviewing 
airport data on the type of components in the deicing fluid used at 
airports that support airplane operations.
    (i) If the airplane has not been exposed, repeat the 
requirements specified in paragraph (f)(1) of this AD thereafter at 
intervals not to exceed 12 months.
    (ii) If the airplane has been exposed, within 90 days after that 
determination is made, do the inspection required by paragraph 
(f)(2) of this AD; and repeat the inspection thereafter at intervals 
not to exceed 12 months.
    (2) Do a detailed inspection of the electrical connectors, 
including the contacts and backshells, of the line replaceable unit 
(LRU) in the wheel well of the MLG for corrosion by doing all the 
actions in accordance with the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-24A1148, Revision 1, dated July 10, 2003. 
Do any significant/corrective actions before further flight in 
accordance with the service bulletin.

    Note 1: 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 Accomplished Previously

    (g) Inspections accomplished before the effective date of this 
AD in accordance with the Accomplishment Instructions of Boeing 
Alert Service Bulletin 737-24A1148, dated December 6, 2001, are 
acceptable for compliance with the inspections required by paragraph 
(f)(2) of this AD.

Alternative Methods of Compliance (AMOCs)

    (h)(1) The Manager, Seattle Aircraft Certification Office, FAA, 
has the authority to approve AMOCs for this AD, if requested in 
accordance with the procedures found in 14 CFR 39.19.
    (2) AMOCs approved previously in accordance with AD 2002-16-03, 
amendment 39-12842, are not approved as AMOCs with this AD.

Material Incorporated by Reference

    (i) You must use Boeing Alert Service Bulletin 737-24A1148, 
Revision 1, dated July 10, 2003, to perform the actions that are 
required by this AD, unless the AD specifies otherwise. The Director 
of the Federal Register approves the incorporation by reference of 
this document in accordance with 5 U.S.C. 552(a) and 1 CFR part 51. 
To get copies of the service information, contact Boeing Commercial 
Airplanes, P.O. Box 3707, Seattle, Washington 98124-2207. To view 
the AD docket, go to the Docket Management Facility, U.S. Department 
of Transportation, 400 Seventh Street SW, room PL-401, Nassif 
Building, Washington, DC. To review copies of the service 
information, go to the National Archives and Records Administration 
(NARA). For information on the availability of this material at the 
NARA, call (202) 741-6030, or go to https://www.archives.gov/
federal_register/code_of_federal_regulations/ibr_
locations.html.

    Issued in Renton, Washington, on September 2, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-17984 Filed 9-13-05; 8:45 am]
BILLING CODE 4910-13-P