This section of the FEDERAL REGISTER

contains notices to the public of the proposed

issuance of rules and regulations. The

purpose of these notices is to give interested

persons an opportunity to participate in the

rule making prior to the adoption of the final

rules.

Proposed Rules Federal Register

48307 

Vol. 73, No. 161 

Tuesday, August 19, 2008 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2007–28283; Directorate 

Identifier 2006–NM–254–AD] 

RIN 2120–AA64 

Airworthiness Directives; Boeing 

Model 737–600, –700, –700C, –800 and 

–900 Series Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Supplemental notice of 

proposed rulemaking (NPRM); 

reopening of comment period. 

SUMMARY: We are revising an earlier 

proposed airworthiness directive (AD) 

for certain Boeing Model 737–600, –700, 

–700C, –800 and –900 series airplanes. 

The original NPRM would have 

required a one-time general visual 

inspection of frames between body 

station (BS) 360 and BS 907 to 

determine if certain support brackets of 

the air conditioning (A/C) outlet 

extrusions are installed; medium- and 

high-frequency eddy current inspections 

for cracking of the frames around the 

attachment holes of the subject brackets; 

and repair if necessary. The original 

NPRM would also have required 

installing new, improved fittings for all 

support brackets of the A/C outlet 

extrusions between BS 360 and BS 907. 

The original NPRM resulted from 

numerous reports of multiple cracks in 

the frames around the attachment holes 

of certain support brackets of the A/C 

outlet extrusions. This action revises the 

original NPRM by adding an airplane to 

the applicability and reducing the 

compliance time for certain airplanes. 

We are proposing this supplemental 

NPRM to prevent frame cracking, 

which, if not corrected, could lead to a 

severed frame that, combined with 

cracking of the skin lap splice above 

stringer 10, could result in rapid 

decompression of the airplane. 

DATES: We must receive comments on 

this supplemental NPRM by September 

15, 2008. 

ADDRESSES: You may send comments by 

any of the following methods: 

• 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, for the service 

information identified in this proposed 

AD. 

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: 

Wayne Lockett, Aerospace Engineer, 

Airframe Branch, ANM–120S, FAA, 

Seattle Aircraft Certification Office, 

1601 Lind Avenue, SW., Renton, 

Washington 98057–3356; telephone 

(425) 917–6447; 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–2007–28283; Directorate Identifier 

2006–NM–254–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 issued a notice of proposed 

rulemaking (NPRM) (the ‘‘original 

NPRM’’) to amend 14 CFR part 39 to 

include an airworthiness directive (AD) 

that would apply to certain Boeing 

Model 737–600, –700, –700C, –800 and 

–900 series airplanes. That original 

NPRM was published in the Federal 

Register on May 25, 2007 (72 FR 29280). 

That original NPRM proposed to require 

a one-time general visual inspection of 

frames between body station (BS) 360 

and BS 907 to determine if certain 

support brackets of the air conditioning 

(A/C) outlet extrusions are installed; 

medium- and high-frequency eddy 

current inspections for cracking of the 

frames around the attachment holes of 

the subject brackets; and repair if 

necessary. That original NPRM also 

proposed to require installing new, 

improved fittings for all support 

brackets of the A/C outlet extrusions 

between BS 360 and BS 907. 

Actions Since Original NPRM Was 

Issued 

Since we issued the original NPRM, 

Boeing has issued Special Attention 

Service Bulletin 737–25–1544, Revision 

1, dated January 16, 2008. The revised 

service bulletin adds an airplane to the 

effectivity and deletes all references to 

an unreleased service bulletin. The 

service bulletin also reduces inspection 

thresholds for airplanes on which 

Boeing Business Jet (BBJ) lower cabin 

altitude modification has been 

incorporated in accordance with 

Supplemental Type Certificate (STC) 

ST01697SE. 

Comments 

We gave the public the opportunity to 

participate in developing this AD. We 

considered the comments received from 

the commenters. 


ebenthall on PRODPC60 with PROPOSALS
48308 Federal Register / Vol. 73, No. 161 / Tuesday, August 19, 2008 / Proposed Rules 

Support for the Original NPRM 

Boeing concurs with the content of 

the original NPRM. 

Request To Clarify Inspection 

Requirements 

AirTran Airways requests that we 

clarify the inspection requirements of 

the NPRM. AirTran suggests that we 

revise paragraphs (g) and (h) of the 

NPRM to specify that, in accordance 

with Boeing Special Attention Service 

Bulletin 737–25–1544, dated October 4, 

2006, some frames between body station 

(BS) 360 and BS 907 are excluded from 

the inspection requirements of the 

service bulletin. AirTran asserts that 

this will help to ensure that the 

inspection requirements of the original 

NPRM do not deviate from the 

procedures described in the service 

bulletin. 

We partially agree with this request. 

Some frames are machined or fabricated 

from a thicker material or have a threerivet attachment fitting, rather than the 

two-rivet attachment fitting. Further, the 

notes of Step 3.B.1 of ‘‘Part 1—Access’’

of the Accomplishment Instructions of 

the service bulletin specify that these 

frames are not subject to the 

inspections. Therefore, we have revised 

paragraph (g) of the supplemental 

NPRM to clarify that certain frames are 

not subject to the inspection 

requirements of the proposed AD. 

However, paragraph (h) of the 

supplemental NPRM refers to the 

modification, which affects all frames 

between BS 360 and BS 907; therefore, 

it is not appropriate to exempt the 

frames specified by the commenter from 

the requirements of paragraph (h) of the 

supplemental NPRM. As specified in 

paragraph (h) of the supplemental 

NPRM all frames are affected. We have 

not changed the supplemental NPRM in 

this regard. 

Compliance Time for Certain Airplanes 

We have determined from Boeing 

Special Attention Service Bulletin 737–

25–1544, Revision 1, dated January 16, 

2008, that the compliance time for 

airplanes on which BBJ lower cabin 

altitude modification has been 

incorporated in accordance with STC 

ST01697SE must be reduced by one-half 

for the flight cycle compliance time. 

Therefore, we have added new 

paragraph (i) to the supplemental NPRM 

to define the compliance time for these 

airplanes as: Before the accumulation of 

18,000 total flight cycles, or within 72 

months after the effective date of this 

AD, whichever occurs later. 

Credit for Use of Original Issue of 

Service Bulletin 

We have revised this supplemental 

NPRM to refer to Boeing Special 

Attention Service Bulletin 737–25–

1544, Revision 1, dated January 16, 

2008, as the appropriate source of 

service information for doing the 

requirements of the proposed AD. 

Therefore, we have added new 

paragraph (j) to the supplemental NPRM 

to give credit for actions done prior to 

the effective date of the AD according to 

Boeing Special Attention Service 

Bulletin 737–25–1544, dated October 4, 

2006. We have also re-identified 

paragraph (i) of the original NPRM as 

paragraph (k) of the supplemental 

NPRM. 

Clarification of Paragraph (g)(1) of the 

NPRM 

Paragraph (g)(1) of the NPRM 

specifies that for any support bracket 

not attached with a two-rivet attachment 

fitting, no further action is required by 

paragraph (g) of the NPRM. 

We have revised paragraph (g)(1) of 

the supplemental NPRM to specify that 

for any support bracket attached with 

three or more rivets, no further action is 

required by paragraph (g) of the 

supplemental NPRM. 

Clarification of Compliance Time in 

Paragraph (g)(2) of the NPRM 

Paragraph (g)(2) of the NPRM does not 

specify a compliance time for doing the 

inspections specified in that paragraph. 

We intended that the inspections be 

done within the same compliance time 

specified in paragraph (g) of the NPRM. 

We have added the compliance time 

specified in paragraph (g) of the 

supplemental NPRM to paragraph (g)(2) 

of the supplemental NPRM. 

Clarification of Unsafe Condition 

Statement 

We have replaced the phrase ‘‘to 

detect and correct’’ in the unsafe 

condition statement in the Summary 

and in paragraph (d) of the 

supplemental NPRM with the phrase 

‘‘to prevent’’ to clarify that the actions 

in this supplemental NPRM are 

intended to prevent the identified 

unsafe condition. 

FAA’s Determination and Proposed 

Requirements of the Supplemental 

NPRM 

We are proposing this supplemental 

NPRM because we evaluated all 

pertinent information and determined 

an unsafe condition exists and is likely 

to exist or develop on other products of 

the same type design. Certain changes 

described above expand the scope of the 

original NPRM. As a result, we have 

determined that it is necessary to reopen 

the comment period to provide 

additional opportunity for the public to 

comment on this supplemental NPRM. 

Costs of Compliance 

There are about 1,679 airplanes of the 

affected design in the worldwide fleet. 

This proposed AD would affect about 

626 airplanes of U.S. registry. The 

following table provides the estimated 

costs for U.S. operators to comply with 

this proposed AD, at an average labor 

rate of $80 per work hour. Operators 

should note that special cold working 

tools and sleeves will be needed if any 

repair is required, which may increase 

costs. 

ESTIMATED COSTS

Action Work hours Parts Cost per airplane Fleet cost 

General visual inspection .. 1 ........................................ No parts required .............. $80 .................................... $50,080. 

MFEC and HFEC inspections.Between 170 and 216 ....... No parts required .............. Between $13,600 and 

$17,280.

Up to $10,817,280. 

Replace support fittings ..... Between 258 and 346 ....... Between $56,095 and 

$81,339.

Between $76,735 and 

$109,019.

Up to $68,245,894. 

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: 


ebenthall on PRODPC60 with PROPOSALS
Federal Register / Vol. 73, No. 161 / Tuesday, August 19, 2008 / Proposed Rules 48309 

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. 

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, 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. 

§ 39.13 [Amended] 

2. The FAA amends § 39.13 by adding 

the following new AD: 

Boeing: Docket No. FAA–2007–28283; 

Directorate Identifier 2006–NM–254–AD. 

Comments Due Date 

(a) We must receive comments by 

September 15, 2008. 

Affected ADs 

(b) None. 

Applicability 

(c) This AD applies to Boeing Model 737–

600, –700, –700C, –800 and –900 series 

airplanes; certificated in any category; as 

identified in Boeing Special Attention 

Service Bulletin 737–25–1544, Revision 1, 

dated January 16, 2008. 

Unsafe Condition 

(d) This AD results from numerous reports 

of multiple cracks in the frame around the 

attachment holes of the support bracket of 

the air conditioning (A/C) outlet extrusion. 

We are issuing this AD to prevent frame 

cracking, which, if not corrected, could lead 

to a severed frame that, combined with 

cracking of the skin lap splice above stringer 

10, could result in rapid decompression of 

the airplane. 

Compliance 

(e) You are responsible for having the 

actions required by this AD performed within 

the compliance times specified, unless the 

actions have already been done. 

Service Bulletin Reference 

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

this AD, means the Accomplishment 

Instructions of Boeing Special Attention 

Service Bulletin 737–25–1544, Revision 1, 

dated January 16, 2008. 

Inspections 

(g) Before the accumulation of 36,000 total 

flight cycles, or within 72 months after the 

effective date of this AD, whichever occurs 

later, except as required by paragraph (i) of 

this AD: Do a general visual inspection to 

determine if the support brackets of the 

A/C outlet extrusions between body station 

(BS) 360 and BS 907 have two-rivet 

attachment fittings in accordance with Part 2 

of the service bulletin, except at the locations 

identified in the notes of Step 3.B.1 of Part 

1 of the service bulletin. 

(1) For any support bracket attached with 

three or more rivets: No further action is 

required by paragraph (g) of this AD. 

(2) For any subject support bracket having 

a two-rivet attachment fitting: Before the 

accumulation of 36,000 total flight cycles, or 

within 72 months after the effective date of 

this AD, whichever occurs later, except as 

required by paragraph (i) of this AD, do 

medium- and high-frequency eddy current 

inspections for cracking of the frame around 

the attachment holes of the support bracket, 

in accordance with Part 2 of the service 

bulletin. If any cracking is discovered, before 

further flight, repair the cracking in 

accordance with Part 3 of the service 

bulletin. 

Modification 

(h) Except as required by paragraph (i) of 

this AD: Before the accumulation of 36,000 

total flight cycles, or within 72 months after 

the effective date of this AD, whichever 

occurs later, replace the support fittings of all 

A/C outlet extrusions between BS 360 and BS 

907 with new, improved support fittings, in 

accordance with Part 4 of the service 

bulletin. 

Compliance Time for Certain Airplanes 

(i) For airplanes on which Boeing Business 

Jet (BBJ) lower cabin altitude modification is 

incorporated in accordance with 

Supplemental Type Certificate ST01697SE: 

Before the accumulation of 18,000 total flight 

cycles, or within 72 months after the effective 

date of this AD, whichever occurs later, do 

the actions specified in paragraphs (g) and (h) 

of this AD. 

Actions Accomplished According to 

Previous Issue of Service Bulletin 

(j) Actions accomplished before the 

effective date of this AD according to Boeing 

Special Attention Service Bulletin 737–25–

1544, dated October 4, 2006, are considered 

acceptable for compliance with the 

corresponding actions specified in this AD. 

Alternative Methods of Compliance 

(AMOCs) 

(k)(1) The Manager, Seattle Aircraft 

Certification Office (ACO), FAA, ATTN: 

Wayne Lockett, Aerospace Engineer, 

Airframe Branch, ANM–120S, FAA, Seattle 

ACO, 1601 Lind Avenue, SW., Renton, 

Washington 98057–3356, telephone (425) 

917–6447, fax (425) 917–6590, has the 

authority to approve AMOCs for this AD, if 

requested in accordance with 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. 

(3) An AMOC that provides an acceptable 

level of safety may be used for any repair 

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. 

Issued in Renton, Washington, on August 

7, 2008. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. E8–19149 Filed 8–18–08; 8:45 am] 

BILLING CODE 4910–13–P 


ebenthall on PRODPC60 with PROPOSALS