Federal Register / Vol. 77, No. 181 / Tuesday, September 18, 2012 / Proposed Rules 57539 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2012–0935; Directorate 

Identifier 2011–NM–256–AD] 

RIN 2120–AA64 

Airworthiness Directives; The Boeing 

Company Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: We propose to adopt a new 

airworthiness directive (AD) for certain 

The Boeing Company Model 737–900 

and –900ER series airplanes. This 

proposed AD was prompted by reports 

of early fatigue cracks at chem-mill 

areas on the crown skin panels. This 

proposed AD would require repetitive 

inspections for cracking of the fuselage 

skin along chem-mill steps at certain 

crown skin and shear wrinkle areas, and 

repair if necessary. We are proposing 

this AD to detect and correct fatigue 

cracking of the skin panel at the 

specified chem-mill step locations, 

which could result in rapid 

decompression of the airplane. 

DATES: We must receive comments on 

this proposed AD by November 2, 2012. 

ADDRESSES: You may send comments, 

using the procedures found in 14 CFR 

11.43 and 11.45, 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: Deliver to Mail 

address above between 9 a.m. and 5 

p.m., Monday through Friday, except 

Federal holidays. 

For service information identified in 

this proposed AD, contact Boeing 

Commercial Airplanes, Attention: Data 

& Services Management, P.O. Box 3707, 

MC 2H–65, Seattle, WA 98124–2207; 

telephone 206–544–5000, extension 1; 

fax 206–766–5680; Internet https:// 

www.myboeingfleet.com. You may 

review copies of the referenced service 

information at the FAA, Transport 

Airplane Directorate; 1601 Lind Avenue 

SW., Renton, Washington. For 

information on the availability of this 

material at the FAA, call 425–227–1221. 

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 

(phone: 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; phone: (425) 

917–6447; fax: (425) 917–6590; email: 

Wayne.Lockett@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

We invite you to send any written 

relevant data, views, or arguments about 

this proposal. Send your comments to 

an address listed under the ADDRESSES

section. Include ‘‘Docket No. FAA– 

2012–0935; Directorate Identifier 2011– 

NM–256–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 received reports of early fatigue 

cracks near chem-mill areas on the 

crown skin panels of Model 737–300, 

–400, and –500 series airplanes. The 

cracks resulted from high stresses in the 

areas where chem-mill pockets are 

adjacent to non-chem-mill areas. 

Although we have not received any 

reports of this type of fuselage fatigue 

cracks on Model 737–600, –700, –700C, 

–800, –900, or –900ER series airplanes, 

a full-scale fatigue test article was 

inspected for skin cracks at similar 

structural details and two chem-mill 

cracks were found that occurred late in 

the testing program. This condition, if 

not detected and corrected, could result 

in rapid decompression of the airplane. 

Relevant Service Information 

We reviewed Boeing Service Bulletin 

737–53–1312, dated October 21, 2011, 

as revised by Boeing Service Bulletin 

737–53–1312, Revision 1, dated March 

14, 2012, for Model 737–900 and 

–900ER series airplanes. That service 

bulletin describes, among other things, 

procedures for doing repetitive external 

detailed inspections and external nondestructive inspections (medium 

frequency eddy current (MFEC), 

magneto optic imager (MOI), C-scan, or 

ultrasonic phased array (UTPA) 

inspections) of the fuselage skin at 

specified locations where chem-mill 

areas are adjacent to non-chem-mill 

areas at antenna and door bearstrap 

installations, and shear wrinkle areas at 

stringers 9 and 10 between stations 

500H and 500K; and repairs if 

necessary. 

Boeing Service Bulletin 737–53–1312, 

dated October 21, 2011, as revised by 

Boeing Service Bulletin 737–53–1312, 

Revision 1, dated March 14, 2012, also 

describes procedures for installing 

modification doublers in certain 

locations, which involves an external 

detailed inspection and an external nondestructive (MFEC, MOI, C-Scan, or 

UTPA) inspection for any cracking of 

the area to be modified prior to the 

doubler being placed on that area, a 

high frequency eddy current inspection 

of all existing holes for cracking, and 

contacting Boeing if necessary. The 

service bulletin also specifies that when 

a modification is accomplished, the 

repetitive inspection for the area under 

the modification is no longer necessary. 

Boeing Service Bulletin 737–53–1312, 

dated October 21, 2011, as revised by 

Boeing Service Bulletin 737–53–1312, 

Revision 1, dated March 14, 2012, 

specifies an initial compliance time of 

before 43,000 total flight cycles, or 

within 1,500 to 2,100 flight cycles 

(depending on inspection area) after the 

original issue date of that service 

bulletin, whichever occurs later. That 

service bulletin specifies a repetitive 

interval not to exceed 1,500 flight 

cycles, 2,100 flight cycles, or 2,700 

flight cycles depending on inspection 

method and inspection area. 

For airplanes that have incorporated 

Boeing Business Jet (BBJ) lower cabin 

altitude supplemental type certificate 

(STC) ST010697SE, all initial 

compliance times specified in flight 

cycles must be reduced to half of those 

specified in Boeing Service Bulletin 

737–53–1312, dated October 21, 2011, 

as revised by Boeing Service Bulletin 

737–53–1312, Revision 1, dated March 

14, 2012, and all repeat interval 

compliance times specified in flight 

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57540 Federal Register / Vol. 77, No. 181 / Tuesday, September 18, 2012 / Proposed Rules 

cycles must be reduced to one-quarter of 

those specified in that service bulletin. 

FAA’s Determination 

We are proposing this AD because we 

evaluated all the relevant information 

and determined the unsafe condition 

described previously is likely to exist or 

develop in other products of the same 

type design. 

Proposed AD Requirements 

This proposed AD would require 

accomplishing the actions specified in 

the service information described 

previously, except as discussed under 

‘‘Differences Between the Proposed AD 

and the Service Information.’’ 

Similar Rulemaking 

The crown skin panels on Model 737– 

900 and –900ER series airplanes are of 

a similar design to those on Model 737– 

300, –400, –500, –600, –700, –700C, and 

–800 series airplanes. Therefore, all 

these models may be subject to the 

identified unsafe condition. We are 

considering similar rulemaking for these 

additional models. 

Differences Between the Proposed AD 

and the Service Information 

Boeing Service Bulletin 737–53–1312, 

dated October 21, 2011, as revised by 

Boeing Service Bulletin 737–53–1312, 

Revision 1, dated March 14, 2012, 

specifies to contact the manufacturer for 

disposition of certain repair conditions, 

but this proposed AD would require 

repairing those conditions in one of the 

following ways: 

• In accordance with a method that 

we approve; or 

• Using data that meet the 

certification basis of the airplane, and 

that have been approved by the Boeing 

Commercial Airplanes Organization 

Designation Authorization (ODA) whom 

we have authorized to make those 

findings. 

Tables 3 and 4 in paragraph 1.E., 

‘‘Compliance,’’ of Boeing Service 

Bulletin 737–53–1312, dated October 

21, 2011, as revised by Boeing Service 

Bulletin 737–53–1312, Revision 1, dated 

March 14, 2012, specify postmodification inspections at certain 

chem-mill step locations, which may be 

used in support of compliance with 

section 121.1109(c)(2) or 129.109(c)(2) 

of the Federal Aviation Regulations (14 

CFR 121.1109(c)(2) or 129.109(c)(2)). 

However, this NPRM does not propose 

to require those post-modification 

inspections. This difference has been 

coordinated with Boeing. 

Costs of Compliance 

We estimate that this proposed AD 

affects 58 airplanes of U.S. registry. 

We estimate the following costs to 

comply with this proposed AD: 

ESTIMATED COSTS

Action Labor cost Parts cost Cost per product Cost on U.S. operators 

Inspection of chem-mill 

step locations.

31 work-hours × $85 per hour = $2,635 per inspection cycle.None ............ $2,635 per inspection 

cycle.

$152,830 per inspection 

cycle. 

We have received no definitive data 

that would enable us to provide cost 

estimates for the on-condition actions 

specified in this proposed AD. 

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. 

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), 

(3) Will not affect intrastate aviation 

in Alaska, and 

(4) 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. 

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. 

§ 39.13 [Amended] 

2. The FAA amends § 39.13 by adding 

the following new airworthiness 

directive (AD): 

The Boeing Company: Docket No. FAA– 

2012–0935; Directorate Identifier 2011– 

NM–256–AD. 

(a) Comments Due Date 

We must receive comments by November 

2, 2012. 

(b) Affected ADs 

None. 

(c) Applicability 

This AD applies to The Boeing Company 

Model 737–900 and -900ER series airplanes, 

certificated in any category, as identified in 

Boeing Service Bulletin 737–53–1312, dated 

October 21, 2011, as revised by Boeing 

Service Bulletin 737–53–1312, Revision 1, 

dated March 14, 2012. 

(d) Subject 

Joint Aircraft System Component (JASC)/ 

Air Transport Association (ATA) of America 

Code 53; Fuselage. 

(e) Unsafe Condition 

This AD was prompted by reports of early 

fatigue cracks at chem-mill areas on the 

crown skin panels. We are issuing this AD to 

detect and correct fatigue cracking of the skin 

panel at the specified chem-mill step 

locations, which could result in rapid 

decompression of the airplane. 

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Federal Register / Vol. 77, No. 181 / Tuesday, September 18, 2012 / Proposed Rules 57541 

(f) Compliance 

Comply with this AD within the 

compliance times specified, unless already 

done. 

(g) Inspections of Crown Skin Areas 

At the applicable time specified in 

paragraph 1.E., ‘‘Compliance,’’ of Boeing 

Service Bulletin 737–53–1312, dated October 

21, 2011, as revised by Boeing Service 

Bulletin 737–53–1312, Revision 1, dated 

March 14, 2012, except as required by 

paragraph (k) of this AD: Do an external 

detailed inspection and an external nondestructive inspection (a medium frequency 

eddy current (MFEC), magneto optic imager 

(MOI), C-scan, or ultrasonic phased array 

(UTPA) inspection) for cracking in the 

fuselage skin along the chem-mill steps at 

certain locations specified in, and in 

accordance with, Boeing Service Bulletin 

737–53–1312, dated October 21, 2011, as 

revised by Boeing Service Bulletin 737–53– 

1312, Revision 1, dated March 14, 2012. 

Repeat the inspections thereafter at the 

applicable times specified in paragraph 1.E., 

‘‘Compliance,’’ of Boeing Service Bulletin 

737–53–1312, dated October 21, 2011, as 

revised by Boeing Service Bulletin 737–53– 

1312, Revision 1, dated March 14, 2012. 

(h) Inspections of Shear Wrinkle Areas 

For Group 1 airplanes as identified in 

Boeing Service Bulletin 737–53–1312, dated 

October 21, 2011, as revised by Boeing 

Service Bulletin 737–53–1312, Revision 1, 

dated March 14, 2012: At the applicable time 

specified in paragraph 1.E., ‘‘Compliance,’’ of 

Boeing Service Bulletin 737–53–1312, dated 

October 21, 2011, as revised by Boeing 

Service Bulletin 737–53–1312, Revision 1, 

dated March 14, 2012, except as required by 

paragraph (k) of this AD, do an external 

detailed inspection and an external nondestructive inspection (MFEC, MOI, C-scan, 

or UTPA) for cracking in the fuselage skin 

along the chem-mill steps at certain shear 

wrinkle locations specified in, and in 

accordance with, Boeing Service Bulletin 

737–53–1312, dated October 21, 2011, as 

revised by Boeing Service Bulletin 737–53– 

1312, Revision 1, dated March 14, 2012. 

Repeat the inspections required by paragraph 

(h) of this AD thereafter at the applicable 

times specified in paragraph 1.E., 

‘‘Compliance,’’ of Boeing Service Bulletin 

737–53–1312, dated October 21, 2011, as 

revised by Boeing Service Bulletin 737–53– 

1312, Revision 1, dated March 14, 2012. 

(i) Repair 

If any cracking is found during any 

inspection required by paragraphs (g) and (h) 

of this AD, before further flight, repair the 

cracking using a method approved in 

accordance with the procedures specified in 

paragraph (m) of this AD. Accomplishing the 

repair approved in accordance with the 

procedures specified in paragraph (m) of this 

AD terminates the repetitive inspection 

requirement for that area under the repair 

only. 

(j) Optional Terminating Modification 

Modification of an inspection area 

specified in paragraph (g) of this AD, 

including doing an external detailed 

inspection and an external non-destructive 

inspection (MFEC, MOI, C-scan, or UTPA) for 

cracking of the area to be modified, and a 

high frequency eddy current inspection of all 

existing holes for cracking, in accordance 

with the Accomplishment Instructions of 

Boeing Service Bulletin 737–53–1312, dated 

October 21, 2011, as revised by Boeing 

Service Bulletin 737–53–1312, Revision 1, 

dated March 14, 2012, terminates the 

repetitive inspections required by paragraph 

(g) of this AD for that area only. If any 

cracking is found during any inspection 

described by this paragraph, before further 

flight, repair the cracking using a method 

approved in accordance with the procedures 

specified in paragraph (m) of this AD. 

(k) Service Bulletin Exception 

Boeing Service Bulletin 737–53–1312, 

dated October 21, 2011, as revised by Boeing 

Service Bulletin 737–53–1312, Revision 1, 

dated March 14, 2012, specifies compliance 

times ‘‘after the original issue date of this 

service bulletin.’’ However, this AD requires 

compliance within the specified compliance 

times ‘‘after the effective date of this AD.’’ 

(l) Post-Modification Inspections 

The post-modification inspections 

specified in Tables 3 and 4 of paragraph 1.E., 

‘‘Compliance,’’ of Boeing Service Bulletin 

737–53–1312, dated October 21, 2011, as 

revised by Boeing Service Bulletin 737–53– 

1312, Revision 1, dated March 14, 2012, are 

not required by this AD. 

Note 1 to paragraph (l) of this AD: The 

damage tolerance inspections specified in 

Tables 3 and 4 of paragraph 1.E., 

‘‘Compliance,’’ of Boeing Service Bulletin 

737–53–1312, dated October 21, 2011, as 

revised by Boeing Service Bulletin 737–53– 

1312, Revision 1, dated March 14, 2012, may 

be used in support of compliance with 

section 121.1109(c)(2) or 129.109(c)(2) of the 

Federal Aviation Regulations (14 CFR 

121.1109(c)(2) or 14 CFR 129.109(c)(2)). The 

actions specified in Part 5 of the 

Accomplishment Instructions and 

corresponding figures of Boeing Service 

Bulletin 737–53–1312, dated October 21, 

2011, as revised by Boeing Service Bulletin 

737–53–1312, Revision 1, dated March 14, 

2012, are not required by this AD. 

(m) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, Seattle Aircraft 

Certification Office (ACO), FAA, has the 

authority to approve AMOCs for this AD, if 

requested using the procedures found in 14 

CFR 39.19. In accordance with 14 CFR 39.19, 

send your request to your principal inspector 

or local Flight Standards District Office, as 

appropriate. If sending information directly 

to the manager of the ACO, send it to the 

attention of the person identified in the 

Related Information section of this AD. 

Information may be emailed to: 9-ANMSeattle-ACO-AMOC-Requests@faa.gov. 

(2) Before using any approved AMOC, 

notify your appropriate principal inspector, 

or lacking a principal inspector, the manager 

of the local flight standards district office/ 

certificate holding district office. 

(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 the 

Boeing Commercial Airplanes Organization 

Designation Authorization (ODA) that 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. 

(n) Related Information 

(1) For more information about this AD, 

contact Wayne Lockett, Aerospace Engineer, 

Airframe Branch, ANM–120S, FAA, Seattle 

Aircraft Certification Office, 1601 Lind 

Avenue SW., Renton, Washington 98057– 

3356; phone: (425) 917–6447; fax: (425) 917– 

6590; email: Wayne.Lockett@faa.gov. 

(2) For service information identified in 

this AD, contact Boeing Commercial 

Airplanes, Attention: Data & Services 

Management, P. O. Box 3707, MC 2H–65, 

Seattle, WA 98124–2207; telephone 206– 

544–5000, extension 1; fax 206–766–5680; 

Internet https://www.myboeingfleet.com. You 

may review copies of the referenced service 

information at the FAA, Transport Airplane 

Directorate, 1601 Lind Avenue SW., Renton, 

Washington. For information on the 

availability of this material at the FAA, call 

425–227–1221. 

Issued in Renton, Washington, on 

September 4, 2012. 

Ali Bahrami, 

Manager, Transport Airplane Directorate, 

Aircraft Certification Service. 

[FR Doc. 2012–22887 Filed 9–17–12; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2012–0938; Directorate 

Identifier 2011–NM–271–AD] 

RIN 2120–AA64 

Airworthiness Directives; The Boeing 

Company Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Notice of proposed rulemaking 

(NPRM). 

SUMMARY: We propose to adopt a new 

airworthiness directive (AD) for certain 

The Boeing Company Model 737–600 

series airplanes. This proposed AD was 

prompted by reports of early fatigue 

cracks at chem-mill areas on the crown 

skin panels. This proposed AD would 

require repetitive inspections for 

cracking of the fuselage skin at certain 

locations at chem-mill areas, and repair 

if necessary. We are proposing this AD 

to detect and correct fatigue cracking of 

the skin panel at the specified chemmstockstill on DSK4VPTVN1PROD with PROPOSALS