56358 Federal Register / Vol. 70, No. 186 / Tuesday, September 27, 2005 / Rules and Regulations 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2005–20356; Directorate 

Identifier 2004–NM–115–AD; Amendment 

39–14294; AD 2005–20–01] 

RIN 2120–AA64 

Airworthiness Directives; Boeing 

Model 737–100, –200, –200C, –300, 

–400, and –500 Series Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Final rule. 

SUMMARY: The FAA is adopting a new 

airworthiness directive (AD) for all 

Boeing Model 737–100, –200, –200C, 

–300, –400, and –500 series airplanes. 

This AD requires repetitive inspections 

of the stiffeners at left buttock line (LBL) 

and right buttock line (RBL) 6.15 for 

cracks; and replacement of both 

stiffeners with new, improved stiffeners 

if any stiffener is found cracked. This 

AD also allows replacement of both 

stiffeners at LBL and RBL 6.15 with 

new, improved stiffeners, which 

terminates the repetitive inspections. 

This AD is prompted by reports of 

cracks in the stiffeners at LBL and RBL 

6.15 on the rear spar of the wing center 

section. We are issuing this AD to detect 

and correct cracks in the stiffeners at 

LBL and RBL 6.15, which could result 

in damage to the keel beam structure 

and consequently reduce the capability 

of the airplane to sustain flight loads. 

DATES: This AD becomes effective 

November 1, 2005. 

The incorporation by reference of a 

certain publication listed in the AD is 

approved by the Director of the Federal 

Register as of November 1, 2005. 

ADDRESSES: You may examine the AD 

docket on the Internet at http:// 

dms.dot.gov or in person at the Docket 

Management Facility, U.S. Department 

of Transportation, 400 Seventh Street, 

SW., Nassif Building, room PL–401, 

Washington, DC. 

Contact Boeing Commercial 

Airplanes, PO Box 3707, Seattle, 

Washington 98124–2207, for service 

information identified in this AD. 

FOR FURTHER INFORMATION CONTACT: 

Nancy Marsh, Aerospace Engineer, 

Airframe Branch, ANM–120S, FAA, 

Seattle Aircraft Certification Office, 

1601 Lind Avenue, SW., Renton, 

Washington 98055–4056; telephone 

(425) 917–6440; fax (425) 917–6590. 

Examining the Docket 

You may examine the AD docket on 

the Internet at http://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 street 

address stated in the ADDRESSES section. 

Discussion 

The FAA issued a notice of proposed 

rulemaking (NPRM) to amend 14 CFR 

part 39 to include an AD that would 

apply to all Boeing Model 737–100, 

–200, –200C, –300, –400, and –500 

series airplanes. That NPRM was 

published in the Federal Register on 

February 15, 2005 (70 FR 7693). (A 

correction of the NPRM was published 

in the Federal Register on May 19, 2005 

(70 FR 28988).) That NPRM proposed to 

require repetitive inspections of the 

stiffeners at left buttock line (LBL) and 

right buttock line (RBL) 6.15 for cracks; 

and replacement of both stiffeners with 

new, improved stiffeners if any stiffener 

is found cracked. That NPRM also 

proposed to allow replacement of both 

stiffeners at LBL and RBL 6.15 with 

new, improved stiffeners, which would 

terminate the repetitive inspections. 

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. 

Support for the Proposed AD 

Two commenters support the 

proposed AD. 

Request To Use Operator Equivalent 

Procedures 

One commenter requests that we 

revise paragraph (h) of the proposed AD 

to allow the use of FAA-approved, 

operator equivalent procedures for 

draining and gaining access to the 

center fuel tanks. The commenter states 

that Parts II and III of Boeing Alert 

Service Bulletin 737–57A1269, Revision 

1, dated September 16, 2004, contain 

work steps for de-fueling and purging 

the center tanks. The commenter further 

states that mandating how the fuel tanks 

are purged does not directly affect the 

means of correcting the unsafe 

condition addressed in the proposed 

AD. 

We agree that the procedures 

specified in Parts II and III are intended 

for gaining access to the center tanks. 

We also agree that using an equivalent 

procedure to gain access would not 

adversely affect the means of correcting 

the unsafe condition, which is to detect 

and correct cracks in the stiffeners at 

LBL and RBL 6.15. Therefore, we have 

revised the first sentence of paragraph 

(h) of this AD to require accomplishing 

the applicable actions in Part IV through 

Part IX of the service bulletin. 

Request for Credit for Previous 

Inspections 

One commenter requests that 

inspections performed in accordance 

with Boeing All Operator Telex (AOT) 

M–7200–01–00426, dated February 19, 

2001, be considered acceptable for 

compliance with the inspections 

specified in paragraph (g) of the 

proposed AD. The commenter states 

that both Boeing AOT M–7200–01–

00426 and Boeing Alert Service Bulletin 

737–57A1269, Revision 1, dated 

September 16, 2004, provide 

instructions for doing a detailed 

inspection of the stiffeners at LBL and 

RBL 6.15 on the rear spar of the wing 

center section within the same 

compliance time. 

We agree that the detailed inspections 

specified in Boeing AOT M–7200–01–

00426 are acceptable for compliance 

with the corresponding requirements of 

this AD. We have added a new 

paragraph (k) to this AD to give credit 

and re-lettered the subsequent 

paragraphs accordingly. 

Request To Use New Stiffeners of the 

Existing Type Design 

Two commenters request that we 

revise paragraph (h) of the proposed AD 

to add the option of replacing a cracked 

stiffener with a new stiffener of the 

existing type design (made from 7075–

T6511 aluminum extrusion). One 

commenter states that since we have 

determined a repetitive inspection 

interval of 4,500 flight cycles provides 

an adequate level of safety for detecting 

cracks in the existing stiffeners, then 

replacement with new stiffeners of the 

existing type design should also provide 

an adequate level of safety if the 

repetitive inspections are continued. 

Although there is an ample supply of 

new stiffeners of the existing type 

design available, both commenters are 

concerned that there is an insufficient 

supply of new, improved stiffeners 

(made from 2024–T351 aluminum alloy 

plate) to comply with the proposed 

replacements. 

We do not agree. The manufacturer 

has confirmed that there is a sufficient 

supply of new, improved stiffeners 

available to comply with this AD. 

Therefore, no change to this AD is 

necessary in this regard. 

Federal Register / Vol. 70, No. 186 / Tuesday, September 27, 2005 / Rules and Regulations 56359 

Request To Replace a Stiffener, Only if 

Cracked 

Two commenters request that we 

revise paragraph (h) of the proposed AD 

to state that, if only one of the two 

stiffeners is found cracked, operators 

would be required to replace only the 

cracked stiffener instead of both 

stiffeners. As justification, the first 

commenter states that it frequently finds 

only one cracked stiffener during 

inspections of the stiffeners at LBL and 

RBL 6.15. Both commenters believe that 

the proposed AD should allow the 

option of replacing only the cracked 

stiffener provided that the repetitive 

inspections for cracking are continued 

until both stiffeners are eventually 

replaced. The second commenter 

supports this change because replacing 

both stiffeners requires additional labor 

and material. The commenter also states 

that the aggressive initial inspection 

threshold will force operators to inspect 

affected airplanes outside of a heavy 

maintenance visit. The commenter 

asserts that the additional impact of 

replacing both stiffeners will strain 

available resources. 

We do not agree because the new, 

improved stiffeners are much more rigid 

than the stiffeners of the existing type 

design. Replacing only one of the two 

stiffeners will lead to changes in the 

loading of the structure and premature 

fatigue of the new, improved stiffener. 

However, we acknowledge that 

replacing a cracked stiffener with a new 

stiffener of the existing type design will 

not adversely affect the relative stiffness 

of the two keel beam stiffeners, since 

they would be the same type design. If 

service information containing repair 

instructions and subsequent inspection 

requirements for replacing a cracked 

stiffener with a new stiffener of the 

existing type design is developed, under 

the provisions of paragraph (l) of this 

AD, we may consider requests for 

approval of an AMOC. Sufficient data 

must be submitted to substantiate that 

such a design change would provide an 

acceptable level of safety. Therefore, no 

change to this AD is necessary in this 

regard. 

Request To Allow Temporary Repairs 

Three commenters request that we 

revise the proposed AD to allow 

operators to make temporary repairs 

until cracked stiffeners can be replaced. 

One commenter suggests adding an 

interim repair plan to the proposed AD 

to give operators time to schedule the 

terminating action (replacement of 

cracked stiffeners with new, improved 

stiffeners). The commenter proposes 

that an interim repair plan could consist 

of stop-drilling small cracks where 

possible and reducing the repetitive 

inspection intervals to monitor crack 

growth, until the terminating action 

could be accomplished. The commenter 

is concerned it will not be able to 

comply with the requirements of the 

proposed AD because of the short initial 

inspection threshold and number of 

affected airplanes in its fleet. 

The second commenter states that 

repairs done in accordance with Boeing 

AOT M–7200–01–00426, dated 

February 19, 2001, and Repair Sketch 

LOR–760 will take less time than 

replacement of the stiffeners, especially 

since most of its affected airplanes will 

be inspected outside of a heavy 

maintenance visit. The third commenter 

asks if we would consider the two 

temporary repairs, which do not require 

access into the center tank, as an AMOC 

to the proposed AD. 

We partially agree. The FAA is 

working with the manufacturer to 

establish appropriate inspection and 

replacement requirements for this 

interim repair. Once this evaluation is 

concluded we may, under the 

provisions of paragraph (l) of this AD, 

we approve the subject interim repairs 

as an AMOC. We do not consider that 

delaying this final rule is warranted. 

Request To Revise Compliance Time 

One commenter requests that we 

extend the compliance time of the 

initial inspection, from 180 days to 15 

months for airplanes that have 

accumulated less than 30,000 total flight 

cycles, to allow affected operators to 

perform the inspection during a 

regularly scheduled maintenance 

interval. The proposed AD reported that 

cracked stiffeners were found on two 

airplanes with over 40,000 total flight 

cycles and on a third airplane with just 

over 20,000 total flight cycles. The 

commenter believes that the data are not 

consistent enough to warrant a short 

compliance time for airplanes that have 

accumulated fewer than 40,000 total 

flight cycles. To comply with the 

proposed AD, the operator states that it 

would have to inspect more than 1 

airplane per week, since the proposed 

AD affects the majority of its fleet. The 

operator also states that its operations 

would be negatively impacted if several 

of its airplanes required the terminating 

action, estimated at 250 work hours. 

We do not agree with the commenter’s 

request. The commenter provides no 

technical justification for revising this 

inspection interval. Furthermore, since 

issuing the proposed AD, we have 

received numerous additional reports of 

cracked stiffeners. Eight of those reports 

included airplanes that have 

accumulated fewer than 30,000 total 

flight cycles. We have determined that 

the compliance time, as proposed, 

represents the maximum interval of 

time allowable for the affected airplanes 

to continue to operate safely before the 

inspection is accomplished. 

Request To Revise ‘‘Cost of 

Compliance’’

One commenter estimates that the 

proposed inspection would take about 4 

work hours, not 1 work hour as we 

specified in the proposed AD. We infer 

that the commenter would like us to 

revise the ‘‘Cost of Compliance’’ section. 

We do not agree, since the commenter 

has not provided justification for the 

increase in work hours. Our cost 

estimate is based on information that 

the manufacturer has provided to us, 

and we point out that the cost impact 

figures discussed in AD rulemaking 

actions represent only the time 

necessary to perform the specific actions 

actually required by the AD. These 

figures typically do not include 

incidental costs, such as the time 

required to gain access and close up, 

planning time, or time necessitated by 

other administrative actions. Therefore 

no change to this AD is necessary in this 

regard. 

Explanation of Changes Made to This 

AD 

We have simplified paragraph (h) of 

this AD by referring to the ‘‘Alternative 

Methods of Compliance (AMOCs)’’

paragraph of this AD for repair methods. 

Also, we have revised the ‘‘Alternative 

Methods of Compliance (AMOCs)’’

paragraph in this AD to clarify the 

delegation authority for Authorized 

Representatives for the Boeing 

Commercial Airplanes Delegation 

Option Authorization. 

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 3,132 airplanes 

worldwide. The following table 

provides the estimated costs, at an 

average labor rate of $65 per hour, for 

U.S. operators to comply with this AD. 

56360 Federal Register / Vol. 70, No. 186 / Tuesday, September 27, 2005 / Rules and Regulations 

ESTIMATED COSTS

Action Work hours Parts Cost per airplane 

Number of 

U.S.- 

registered 

airplanes 

Fleet cost 

Inspection, per inspection cycle 1 None $65, per inspection cycle .......... 1,384 $89,960, 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. 

List of Subjects in 14 CFR Part 39 

Air transportation, Aircraft, Aviation 

safety, Incorporation by reference, 

Safety. 

Adoption of the Amendment 

■ Accordingly, under the authority 

delegated to me by the Administrator, 

the FAA amends 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. 

§ 39.13 [Amended] 

■ 2. The FAA amends § 39.13 by adding 

the following new airworthiness 

directive (AD): 

2005–20–01 Boeing: Amendment 39–14294. 

Docket No. FAA–2005–20356; 

Directorate Identifier 2004–NM–115–AD. 

Effective Date 

(a) This AD becomes effective November 1, 

2005. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to all Boeing Model 

737–100, –200, –200C, –300, –400, and –500 

series airplanes, certificated in any category. 

Unsafe Condition 

(d) This AD was prompted by cracks in the 

stiffeners at left buttock line (LBL) and right 

buttock line (RBL) 6.15 on the rear spar of the 

wing center section. We are issuing this AD 

to detect and correct cracks in the stiffeners 

at LBL and RBL 6.15, which could result in 

damage to the keel beam structure and 

consequently reduce the capability of the 

airplane to sustain flight loads. 

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. 

Service Bulletin Reference 

(f) The term ‘‘service bulletin,’’ as used in 

this AD, means the Accomplishment 

Instructions of Boeing Alert Service Bulletin 

737–57A1269, Revision 1, dated September 

16, 2004. 

Initial and Repetitive Inspections 

(g) Before accumulating 15,000 total flight 

cycles, or within 180 days after the effective 

date of this AD, whichever occurs later: Do 

a detailed inspection of the stiffeners at LBL 

and RBL 6.15 for cracks, in accordance with 

Part I of the service bulletin. Thereafter at 

intervals not to exceed 4,500 flight cycles, 

repeat the detailed inspection until the 

stiffeners at LBL and RBL 6.15 have been 

replaced with new, improved stiffeners, in 

accordance with paragraph (h) or (i) of this 

AD. 

Note 1: For the purposes of this AD, a 

detailed inspection is: ‘‘An intensive 

examination of a specific item, installation, 

or assembly to detect damage, failure, or 

irregularity. Available lighting is normally 

supplemented with a direct source of good 

lighting at an intensity deemed appropriate. 

Inspection aids such as mirror, magnifying 

lenses, etc., may be necessary. Surface 

cleaning and elaborate procedures may be 

required.’’

Replacement of Cracked Stiffeners 

(h) If any crack is found during any 

inspection required by this AD, before further 

flight, replace both stiffeners with new, 

improved stiffeners by doing all of the 

applicable actions in Part IV through Part IX, 

as applicable, of the service bulletin; except 

where the service bulletin specifies to contact 

Boeing for appropriate action: Before further 

flight, repair using a method approved in 

accordance with the procedures specified in 

paragraph (l) of this AD. Accomplishing the 

replacement terminates the repetitive 

inspections required by paragraph (g) of this 

AD. 

Optional Terminating Action 

(i) Replacement of both stiffeners at LBL 

and RBL 6.15 with new, improved stiffeners 

in accordance with paragraph (h) of this AD 

terminates the repetitive inspections required 

by this AD. 

Credit for Previous Service Bulletin 

(j) The actions done before the effective 

date of this AD in accordance with Boeing 

Alert Service Bulletin 737–57A1269, dated 

December 4, 2003, are acceptable for 

compliance with the corresponding actions 

required by this AD. 

Credit for Previous Inspections 

(k) Inspections done before the effective 

date of this AD in accordance with Boeing 

All Operator Telex M–7200–01–00426, dated 

February 19, 2001, are acceptable for 

compliance with the requirements of 

paragraph (g) of this AD. 

Alternative Methods of Compliance 

(AMOCs) 

(l)(1) The Manager, Seattle Aircraft 

Certification Office (ACO), FAA, has the 

authority to approve AMOCs for this AD, if 

requested in accordance with the procedures 

found in 14 CFR 39.19. 

(2) An AMOC that provides an acceptable 

level of safety may be used for any repair 

Federal Register / Vol. 70, No. 186 / Tuesday, September 27, 2005 / Rules and Regulations 56361 

required by this AD, if it is approved by an 

Authorized Representative for the Boeing 

Commercial Airplanes Delegation Option 

Authorization Organization who has been 

authorized by the Manager, Seattle ACO, to 

make those findings. For a repair method to 

be approved, the repair must meet the 

certification basis of the airplane, and the 

approval must specifically refer to this AD. 

Material Incorporated by Reference 

(m) You must use Boeing Alert Service 

Bulletin 737–57A1269, Revision 1, dated 

September 16, 2004, to perform the actions 

that are required by this AD, unless the AD 

specifies otherwise. The Director of the 

Federal Register approved the incorporation 

by reference of this document in accordance 

with 5 U.S.C. 552(a) and 1 CFR part 51. 

Contact Boeing Commercial Airplanes, P.O. 

Box 3707, Seattle, Washington 98124–2207, 

for a copy of this service information. You 

may review copies at the Docket Management 

Facility, U.S. Department of Transportation, 

400 Seventh Street, SW., room PL–401, 

Nassif Building, Washington, DC; on the 

Internet at http://dms.dot.gov; or at 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 http:// 

www.archives.gov/federal-register/cfr/ibrlocations.html. 

Issued in Renton, Washington, on 

September 16, 2005. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. 05–19144 Filed 9–26–05; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2005–18788; Directorate 

Identifier 2003–NM–203–AD; Amendment 

39–14296; AD 2005–20–03] 

RIN 2120–AA64 

Airworthiness Directives; Boeing 

Model 737–100, –200, –200C, –300, 

–400, and –500 Series Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Final rule. 

SUMMARY: The FAA is adopting a new 

airworthiness directive (AD) for certain 

Boeing Model 737–100, –200, –200C, 

–300, –400, and –500 series airplanes. 

This AD requires repetitive inspections 

of the intercostal webs, attachment 

clips, and stringer splice channels for 

cracks; and corrective action if 

necessary. This AD is prompted by 

reports of fatigue cracks on several 

Boeing Model 737–200 series airplanes. 

We are issuing this AD to detect and 

correct fatigue cracking of the 

intercostals on the forward and aft sides 

of the forward entry door, which could 

result in loss of the forward entry door 

and rapid decompression of the 

airplane. 

DATES: This AD becomes effective 

November 1, 2005. 

The incorporation by reference of a 

certain publication listed in the AD is 

approved by the Director of the Federal 

Register as of November 1, 2005. 

ADDRESSES: For service information 

identified in this AD, contact 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 http:// 

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–2005–18788; the directorate 

identifier for this docket is 2003–NM–

203–AD. 

FOR FURTHER INFORMATION CONTACT: 

Howard Hall, Aerospace Engineer, 

Airframe Branch, ANM–120S, FAA, 

Seattle Aircraft Certification Office, 

1601 Lind Avenue, SW., Renton, 

Washington 98055–4056; telephone 

(425) 917–6430; fax (425) 917–6590. 

SUPPLEMENTARY INFORMATION: The FAA 

proposed to amend 14 CFR part 39 with 

an AD for certain Model 737–100, –200, 

–200C, –300, –400, and –500 series 

airplanes. That action, published in the 

Federal Register on August 6, 2004 (69 

FR 47808), proposed to require 

repetitive inspections of the intercostal 

webs, attachment clips, and stringer 

splice channels for cracks; and 

corrective action if necessary. 

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. 

Qualified Support for the Proposed AD 

One commenter, an operator, stated 

that the proposed AD is acceptable 

provided that the service bulletin 

referenced in the proposed AD is 

corrected to reflect the proper work 

instructions and to reference accurate 

figures for accomplishment. 

The FAA cannot respond to the 

generality of the commenter’s statement. 

However, other commenters have 

requested clarification on certain 

aspects of the work instructions and 

requested certain revision of the ‘‘Costs 

of Compliance’’ section of this AD. 

Those comments are specified and 

responded to in the appropriate 

paragraphs below. 

Request for Clarification in Paragraph 

(k) of the Proposed AD 

Two commenters request that 

paragraph (k) be revised to clarify that 

the reference to using Figure 201 instead 

of Figure 202 of the service bulletin only 

applies to Model 737–400 series 

airplanes. 

We agree that paragraph (k) of the AD 

should be clarified and have revised the 

AD accordingly. 

Request To Withdraw the Proposed AD 

One commenter, an operator, states 

that the Maintenance Planning 

Document (MPD) is the logical 

document to accomplish the main 

objectives of the inspections specified in 

the proposed AD. The commenter 

suggests that it makes more sense to 

revise MPD Task S53–22-A–2, rather 

than to issue an AD. We infer that the 

commenter is requesting that the 

proposed AD be withdrawn. 

We do not agree. We are obligated by 

part 39 of the Federal Aviation 

Regulations (FAR) to appropriately 

address any identified unsafe condition 

that is likely to exist on other airplanes. 

The MPD is appropriate for addressing 

routine maintenance of critical 

structural components. However, 

operators may submit their specific and 

particular MPD task cards for 

consideration as an alternative method 

of compliance (AMOC) if they wish, in 

accordance with paragraph (n) of the 

AD. No change is necessary to the AD 

in this regard. 

Request for More Information 

Regarding Paragraph (k) of the 

Proposed AD 

One commenter, an operator, requests 

that inspection specifics be added to 

paragraph (k) of the proposed AD for the 

stringer–16L (S–16L) area in the postrepair configuration. The commenter 

does not believe that Boeing Special 

Attention Service Bulletin 737–53–

1204, dated June 19, 2003, referenced in 

the proposed AD as the appropriate 

source of service information, provides 

sufficient inspection specifics in Figure 

1. 

The FAA does not agree that further 

inspection specifics are necessary to 

clarify paragraph (k) of the AD. Figure