Federal Register / Vol. 77, No. 117 / Monday, June 18, 2012 / Rules and Regulations 36131 

(1) Bombardier, Inc. Model CL–600–2C10 

(Regional Jet Series 700, 701, & 702) 

airplanes, serial numbers 10003 through 

10331 inclusive. 

(2) Bombardier, Inc. Model CL–600–2D15 

(Regional Jet Series 705) and CL–600–2D24 

(Regional Jet Series 900) airplanes, serial 

numbers 15001 through 15279 inclusive. 

(d) Subject 

Air Transport Association (ATA) of 

America Code 36: Pneumatic. 

(e) Reason 

This AD was prompted by reports of a 

bleed air leak from the high pressure ducts 

which was not immediately detected by the 

bleed leak detection system. We are issuing 

this AD to prevent an undetected bleed air 

leak which can cause loss of rudder control, 

can lead to degradation of structural 

integrity, and could be a potential heat 

source that can lead to fuel being ignited. 

(f) Compliance 

You are responsible for having the actions 

required by this AD performed within the 

compliance times specified, unless the 

actions have already been done. 

(g) Install Protective Shields 

For Model CL–600–2C10 airplanes having 

serial numbers 10003 through 10326 

inclusive, and Model CL–600–2D15 and CL– 

600–2D24 airplanes having serial numbers 

15001 through 15267 inclusive: Within 6,600 

flight hours or 24 months after the effective 

date of this AD, whichever occurs first, 

install protective shields on the rudder 

quadrant support-beam in the aft equipment 

compartment, in accordance with the 

Accomplishment Instructions of Bombardier 

Service Bulletin 670BA–36–014, Revision A, 

dated October 11, 2011. 

(h) Install Protective Blankets and Sensing 

Elements 

For Model CL–600–2C10 airplanes having 

serial numbers 10003 through 10331 

inclusive and Models CL–600–2D15 and CL– 

600–2D24 airplanes having serial numbers 

15001 through 15279 inclusive: Within 6,600 

flight hours or 24 months after the effective 

date of this AD, whichever occurs first, 

install protective blankets on the upper 

surface of the wing box and fuel components, 

and install new sensing elements in the 

wheel well of the main landing gear and the 

overwing area, in accordance with the 

Accomplishment Instructions of Bombardier 

Service Bulletin 670BA–36–016, Revision A, 

dated October 11, 2011. 

(i) Credit for Previous Actions 

This paragraph provides credit for 

installations, required by paragraphs (g) and 

(h) of this AD, if those actions were 

performed before the effective date of this AD 

using Bombardier Service Bulletin 670BA– 

36–014 or 670BA–36–016, both dated April 

7, 2011, as applicable. 

(j) Other FAA AD Provisions 

The following provisions also apply to this 

AD: 

(1) Alternative Methods of Compliance 

(AMOCs): The Manager, New York Aircraft 

Certification Office, ANE–170, 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 ACO, send it to ATTN: Program 

Manager, Continuing Operational Safety, 

FAA, New York ACO, 1600 Stewart Avenue, 

Suite 410, Westbury, New York 11590; 

telephone 516–228–7300; fax 516–794–5531. 

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. The AMOC 

approval letter must specifically reference 

this AD. 

(2) Airworthy Product: For any requirement 

in this AD to obtain corrective actions from 

a manufacturer or other source, use these 

actions if they are FAA-approved. Corrective 

actions are considered FAA-approved if they 

are approved by the State of Design Authority 

(or their delegated agent). You are required 

to assure the product is airworthy before it 

is returned to service. 

(k) Related Information 

Refer to MCAI Canadian Airworthiness 

Directive CF–2012–06, dated January 26, 

2012, and the service bulletins specified in 

paragraphs (k)(1) and (k)(2) of this AD, for 

related information. 

(1) Bombardier Service Bulletin 670BA– 

36–014, Revision A, dated October 11, 2011. 

(2) Bombardier Service Bulletin 670BA– 

36–016, Revision A, dated October 11, 2011. 

(l) Material Incorporated by Reference 

(1) The Director of the Federal Register 

approved the incorporation by reference 

(IBR) of the following service information 

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

(2) You must use the following service 

information to do the actions required by this 

AD, unless the AD specifies otherwise. 

(i) Bombardier Service Bulletin 670BA–36– 

014, Revision A, dated October 11, 2011. 

(ii) Bombardier Service Bulletin 670BA– 

36–016, Revision A, dated October 11, 2011. 

(3) For service information identified in 

this AD, contact Bombardier, Inc., 400 CoˆteVertu Road West, Dorval, Que ́bec H4S 1Y9, 

Canada; telephone 514–855–5000; fax 514– 

855–7401; email 

thd.crj@aero.bombardier.com; Internet http:// 

www.bombardier.com. 

(4) You may review copies of the 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. 

(5) You may also review copies of the 

service information that is incorporated by 

reference at the National Archives and 

Records Administration (NARA). For 

information on the availability of this 

material at an NARA facility, call 202–741– 

6030, or go to http://www.archives.gov/ 

federal_register/code_of_federal_regulations/ 

ibr_locations.html. 

Issued in Renton, Washington, on May 31, 

2012. 

Michael Kaszycki, 

Acting Manager, Transport Airplane 

Directorate, Aircraft Certification Service. 

[FR Doc. 2012–14042 Filed 6–15–12; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2012–0562; Directorate 

Identifier 2012–SW–038–AD; Amendment 

39–17068; AD 2012–11–05] 

RIN 2120–AA64 

Airworthiness Directives; Enstrom 

Helicopter Corporation Helicopters 

AGENCY: Federal Aviation 

Administration (FAA), Department of 

Transportation (DOT). 

ACTION: Final rule; request for 

comments. 

SUMMARY: We are superseding an 

existing airworthiness directive (AD) for 

Enstrom Helicopter Corporation 

(Enstrom) Model F–28C, F–28C–2, F– 

28F, 280C, 280F, 280FX, TH–28, 480, 

and 480B helicopters to add another 

trim relay to the applicability and to 

revise the modification instructions. 

This AD is prompted by the discovery 

that another part-numbered trim relay, 

inadvertently omitted from the current 

AD, may contain the same unsafe 

condition. These actions are intended to 

prevent failure of the cyclic trim system 

and subsequent loss of control of the 

helicopter. 

DATES: This AD becomes effective July 

3, 2012. 

The Director of the Federal Register 

approved the incorporation by reference 

of a certain publication listed in this AD 

as of July 3, 2012. 

The Director of the Federal Register 

approved the incorporation by reference 

of a certain other publication listed in 

this AD as of January 23, 2012 (77 FR 

729, January 6, 2012). 

We must receive comments on this 

AD by August 17, 2012. 

ADDRESSES: You may send comments by 

any of the following methods: 

• Federal eRulemaking Docket: Go to 

http://www.regulations.gov. Follow the 

online instructions for sending your 

comments electronically. 

• Fax: 202–493–2251. 

• Mail: Send comments to the U.S. 

Department of Transportation, Docket 

Operations, M–30, West Building 

Ground Floor, Room W12–140, 1200 


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36132 Federal Register / Vol. 77, No. 117 / Monday, June 18, 2012 / Rules and Regulations 

New Jersey Avenue SE., Washington, 

DC 20590–0001. 

• Hand Delivery: Deliver to the 

‘‘Mail’’ address between 9 a.m. and 

5 p.m., Monday through Friday, except 

Federal holidays. 

Examining the AD Docket: You may 

examine the AD docket on the Internet 

at http://www.regulations.gov or in 

person at the Docket Operations Office 

between 9 a.m. and 5 p.m., Monday 

through Friday, except Federal holidays. 

The AD docket contains this AD, the 

economic evaluation, any comments 

received, and other information. The 

street address for the Docket Operations 

Office (telephone 800–647–5527) is in 

the ADDRESSES section. Comments will 

be available in the AD docket shortly 

after receipt. 

For service information identified in 

this AD, contact Enstrom Helicopter 

Corporation, 2209 22nd St., Menominee, 

Michigan, 49858–0490; telephone: 906– 

863–1200; email: customerservice@

enstromhelicopter.com; Web site: 

http://www.enstromhelicopter.com/

enstrom_new/enstrom_support_tec.

html. You may review a copy of the 

referenced service information at the 

FAA, Office of the Regional Counsel, 

Southwest Region, 2601 Meacham 

Blvd., Room 663, Fort Worth, Texas 

76137. 

FOR FURTHER INFORMATION CONTACT: 

Gregory J. Michalik, Enstrom Program 

Manager, FAA, Chicago Aircraft 

Certification Office, 2300 East Devon 

Avenue, Room 107, Des Plaines, Illinois, 

60018; telephone (847) 294–7135; email: 

gregory.michalik@faa.gov. 

SUPPLEMENTARY INFORMATION: 

Comments Invited 

This AD is a final rule that involves 

requirements affecting flight safety, and 

we did not provide you with notice and 

an opportunity to provide your 

comments prior to it becoming effective. 

However, we invite you to participate in 

this rulemaking by submitting written 

comments, data, or views. We also 

invite comments relating to the 

economic, environmental, energy, or 

federalism impacts that resulted from 

adopting this AD. The most helpful 

comments reference a specific portion of 

the AD, explain the reason for any 

recommended change, and include 

supporting data. To ensure the docket 

does not contain duplicate comments, 

commenters should send only one copy 

of written comments, or if comments are 

filed electronically, commenters should 

submit them only one time. We will file 

in the docket all comments that we 

receive, as well as a report summarizing 

each substantive public contact with 

FAA personnel concerning this 

rulemaking during the comment period. 

We will consider all the comments we 

receive and may conduct additional 

rulemaking based on those comments. 

Discussion 

On December 14, 2011, we issued AD 

2011–26–10, amendment 39–16900 

(77 FR 729, January 6, 2012) for Enstrom 

Model F–28C, F–28C–2, F–28F, 280C, 

280F, 280FX, TH–28, 480, and 480B 

helicopters with a trim relay, partnumber (P/N) KUP14D55–472, M83536/ 

10–015M, or M83536/10–024M. That 

AD requires modifying the lateral and 

longitudinal trim actuator assemblies by 

replacing the actuator and limit switch 

bracket to provide a positive stop for the 

trim actuator. In the event of a trim 

actuator runaway, the new bracket will 

stop the actuator, causing the circuit 

breaker to trip before any significant 

loss of control occurs. After the trim 

actuator assemblies are modified, that 

AD requires performing operational 

(ground) and flight tests to determine 

that the trim relay is working correctly. 

That AD was prompted by reports of 4 

failures in the cyclic trim system in the 

field, 2 that occurred on the Enstrom 

Model 480B helicopter and 2 that 

occurred on the Enstrom Model F28 

helicopter. These failures resulted in 

reduced controllability of the helicopter. 

We issued that AD to prevent failure of 

the cyclic trim system and subsequent 

loss of control of the helicopter. 

Comments 

Since we issued immediately adopted 

AD 2011–26–10, we received one 

comment from Enstrom, the 

manufacturer, and Revision 4 to 

Enstrom Service Directive Bulletin No. 

0110, dated January 23, 2012 (SDB 

0110), for Model F–28C, F–28C–2, F– 

28F, 280C, 280F, and 280FX helicopters. 

In its comment, the manufacturer stated 

that the list of affected part numbers for 

the F–28 series and 280 series helicopter 

should include P/N KUP14D55–24 and 

that this P/N was erroneously left off of 

Enstrom’s original Service Directive 

Bulletin. It stated that the same safety 

concerns also exist with this relay and 

that adding this P/N will not affect the 

cost analysis or fleet size as these 

aircraft were included in the initial 

calculations. 

We agree with the commenter that the 

additional part numbered relay 

contained in Enstrom SDB 0110 should 

be added to the applicability section of 

the AD because it may contain the same 

unsafe condition. Also, we agree that 

the revised compliance instructions 

contained in SDB 0110 should be 

required. 

FAA’s Determination 

We are issuing this AD because we 

evaluated all the relevant information, 

including the comment received and the 

revised service information, and 

determined the unsafe condition 

described previously is likely to exist or 

develop in other helicopters of these 

same type designs. 

Related Service Information 

We reviewed Enstrom SDB No. T– 

039, Revision 3, dated July 6, 2011 (SDB 

T–039), for Model TH–28, 480, and 

480B helicopters and Enstrom SDB 

0110, for Model F–28C, F–28C–2, F– 

28F, 280C, 280F, and 280FX helicopters. 

SDB T–039 specifies, for helicopters 

with a trim relay, P/N M83536/10– 

024M, procedures for modifying the 

lateral and longitudinal trim actuator 

assembly using the cyclic trim assembly 

kit (modification kit), P/N 4230045–1, 

and specifies performing an operational 

check and flight test to determine if the 

trim is operating correctly after the 

modification. SDB 0110 specifies, for 

helicopters with a trim relay, P/N 

KUP14D55–24, KUP14D55–472, 

M83536/10–015M, or M83536/10– 

024M, procedures for modifying the 

lateral and longitudinal trim actuator 

assembly using the modification kit, 

P/N 28–01063–1, and specifies 

performing an operational check and 

flight test to determine if the trim is 

operating correctly after the 

modification. The SDBs state that the 

modification kits contain the upgraded 

bracket. 

AD Requirements 

In addition to those part-numbered 

trim relays contained in the 

applicability section of the current AD 

2011–26–10, this AD adds trim relay 

P/N KUP14D55–24. Also, this AD 

adopts the revised modification 

instructions for the Model F–28C, F– 

28C–2, F–28F, 280C, 280F, and 280FX 

helicopters contained in SDB 0110. 

Otherwise, this AD retains most of the 

requirements of AD 2011–26–10, which 

requires modifying the lateral and 

longitudinal trim actuator assembly, 

using modification kit, P/N 28–01063–1, 

for the Model F–28C, F–28C–2, F–28F, 

280C, 280F, and 280FX helicopters and 

modification kit, P/N 4230045–1, for the 

Model TH–28, 480, and 480B 

helicopters, and verifying that the 

modification has been completed 

properly by performing an operational 

and flight test after the modification is 

complete. 

The actions required by this AD are to 

be accomplished by following specified 


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Federal Register / Vol. 77, No. 117 / Monday, June 18, 2012 / Rules and Regulations 36133 

portions of the SDBs described 

previously. 

Differences Between This AD and the 

Service Information 

The SDBs specify, before further 

flight, to insert a special addendum into 

the Emergency Procedures section of the 

Flight Manual, and this AD does not 

require this action. 

Costs of Compliance 

We estimate that this AD will affect 

207 helicopters of U.S. Registry. We 

estimate that operators may incur the 

following costs in order to comply with 

this AD. For Model 480, 480B, and 

TH–28, modifying the actuator 

assemblies will require 8 work hours at 

a cost of $85 per hour and parts will 

cost $327; the cost per helicopter will be 

$1,007. For Model 280C, 280F, 280FX, 

F–28C, F–28C–2, and F–28F, modifying 

the actuator assemblies will require 8 

work hours at a cost of $85 per hour; 

parts will cost $383; and the cost per 

helicopter will be $1,063. 

FAA’s Justification and Determination 

of the Effective Date 

Providing an opportunity for public 

comments prior to adopting these AD 

requirements would delay 

implementing the safety actions needed 

to correct this known unsafe condition. 

Therefore, we find that the risk to the 

flying public justifies waiving notice 

and comment prior to the adoption of 

this rule because the required corrective 

actions must be accomplished within 5 

hours time-in-service, a very short time 

period based on the average flight-hour 

utilization rate of these helicopters. 

Since an unsafe condition exists that 

requires the immediate adoption of this 

AD, we determined that notice and 

opportunity for public comment before 

issuing this AD are impracticable and 

contrary to the public interest and that 

good cause exists for making this 

amendment effective in less than 30 

days. 

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 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, 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); 

3. Will not affect intrastate aviation in 

Alaska to the extent that it justifies 

making a regulatory distinction; 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. 

We prepared an economic evaluation 

of the estimated costs to comply with 

this AD and placed it in the AD docket. 

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 

removing Amendment 39–16900 (77 FR 

729, January 6, 2012), and adding the 

following new airworthiness directive 

(AD): 

2012–11–05 Enstrom Helicopter 

Corporation: Amendment 39–17068; 

Docket No. FAA–2012–0562; Directorate 

Identifier 2012–SW–038–AD. 

(a) Applicability 

This AD applies to the Enstrom Model 

F–28C, F–28C–2, F–28F, 280C, 280F, 280FX, 

TH–28, 480, and 480B helicopters with a trim 

relay, part-number (P/N) KUP14D55–24, 

KUP14D55–472, M83536/10–015M, or 

M83536/10–024M, certificated in any 

category. 

Note to paragraph (a) of this AD: This AD 

does not apply to the specified helicopters 

with a reversible trim motor, P/N 28–16621 

(Ford Motor Company C1AZ–14553A) or P/ 

N AD1R–10 (Signal Electric). 

(b) Unsafe Condition 

This AD defines the unsafe condition as a 

failure of a trim relay in the cyclic trim 

system. This condition could result in 

reduced controllability of the helicopter and 

subsequent loss of control of the helicopter. 

(c) Other Affected ADs 

This AD supersedes AD 2011–26–10, 

Amendment 39–16900 (77 FR 729, January 6, 

2012). 

(d) Effective Date 

This AD becomes effective July 3, 2012. 

(e) Compliance 

You are responsible for performing each 

action required by this AD within the 

specified compliance time unless it has 

already been accomplished prior to that time. 

(f) Required Actions 

Within 5 hours time-in-service (TIS) or at 

the next annual or 100 hour TIS inspection, 

whichever occurs first: 

(1) For the Enstrom Model F–28C, F–28C– 

2, F–28F, 280C, 280F, and 280FX helicopters, 

modify the lateral and longitudinal trim 

actuator assemblies using the cyclic trim 

assembly kit (modification kit), P/N 28– 

01063–1, in accordance with the instructions 

in paragraph 6.1 of the Enstrom Service 

Directive Bulletin (SDB) No. 0110, Revision 

4, dated January 23, 2012 (SDB No. 0110 R4), 

except when the instructions specify using 

‘‘Aeroshell 22 grease’’ or ‘‘VC–3 Vibra-tite 

thread locker,’’ you may use an equivalent 

product. 

(2) For the Enstrom Model TH–28, 480, and 

480B helicopters, modify the lateral and 

longitudinal trim actuator assemblies using 

the modification kit, P/N 4230045–1, in 

accordance with the instructions in 

paragraph 6.1 of the Enstrom SDB No. T–039, 

Revision 3, dated July 6, 2011 (SDB No. 

T–039 R3), except when the instructions 

specify using ‘‘Aeroshell 22 grease’’ or ‘‘VC– 

3 Vibra-tite thread locker,’’ you may use an 

equivalent product, and you are not required 

to contact Enstrom Customer Service. 

(3) After modifying the lateral and 

longitudinal trim actuator assemblies in 

accordance with paragraphs (f)(1) or (f)(2) of 

this AD, before further flight, operationally 

test the trim limits in accordance with 

paragraph 6.2. of the SDB for your model 

helicopter, and determine during a flight test 

whether there is appropriate trim authority in 

accordance with paragraph 6.3. of the SDB 

for your model helicopter. 

(g) Special Flight Permits 

A one-time special-flight permit may be 

issued in accordance with 14 CFR 21.197 and 

21.199 provided the helicopter is operated 

with the trim system circuit breaker pulled. 


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36134 Federal Register / Vol. 77, No. 117 / Monday, June 18, 2012 / Rules and Regulations 

(h) Alternative Methods of Compliance 

(AMOCs) 

(1) The Manager, Chicago Aircraft 

Certification Office, FAA, may approve 

AMOCs for this AD. Send your proposal to: 

Gregory J. Michalik, Enstrom Program 

Manager, FAA, Chicago Aircraft Certification 

Office, 2300 East Devon Avenue, Room 107, 

Des Plaines, Illinois, 60018; telephone (847) 

294–7135; fax (847) 294–7834; email: 

gregory.michalik@faa.gov. 

(2) For operations conducted under a 

14 CFR part 119 operating certificate or 

under 14 CFR part 91, subpart K, we suggest 

that you notify your principal inspector, or 

lacking a principal inspector, the manager of 

the local flight standards district office or 

certificate holding district office before 

operating any aircraft complying with this 

AD through an AMOC. 

(i) Subject 

Joint Aircraft Service Component (JASC) 

Code: 6710: Main Rotor Control. 

(j) Material Incorporated by Reference 

(1) The Director of the Federal Register 

approved the incorporation by reference 

(IBR) of the following service information 

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

(2) You must use the following service 

information to do the actions required by this 

AD, unless the AD specifies otherwise. 

(3) The following service information was 

approved for IBR on July 3, 2012. 

(i) Enstrom Service Directive Bulletin No. 

0110, Revision 4, dated January 23, 2012, for 

Model F–28C, F–28C–2, F–28F, 280C, 280F, 

and 280FX helicopters. 

(4) The following service information was 

approved for IBR on January 23, 2012 (77 FR 

729, January 6, 2012). 

(i) Enstrom Service Directive Bulletin No. 

T–039, Revision 3, dated July 6, 2011, for 

Model TH–28, 480, and 480B helicopters. 

(5) For service information identified in 

this AD, contact Enstrom Helicopter 

Corporation, 2209 22nd St., Menominee, 

Michigan, 49858–0490; telephone: 906–863– 

1200; email: customerservice@

enstromhelicopter.com; Web site: http://

www.enstromhelicopter.com/enstrom_new/ 

enstrom_support_tec.html. 

(6) You may review a copy of the 

referenced service information at the FAA, 

Office of the Regional Counsel, Southwest 

Region, 2601 Meacham Blvd., Room 663, Fort 

Worth, Texas 76137 or at the National 

Archives and Records Administration 

(NARA). For information on the availability 

of this material at NARA, call 202–741–6030, 

or go to: http://www.archives.gov/federal_

register/code_of_federal_regulations/ibr_

locations.html. 

Issued in Fort Worth, Texas, on May 17, 

2012. 

Kim Smith, 

Manager, Rotorcraft Directorate, Aircraft 

Certification Service. 

[FR Doc. 2012–14634 Filed 6–15–12; 8:45 am] 

BILLING CODE 4910–13–P 

DEPARTMENT OF TRANSPORTATION 

Federal Aviation Administration 

14 CFR Part 39 

[Docket No. FAA–2011–1254; Directorate 

Identifier 2010–NM–178–AD; Amendment 

39–17083; AD 2012–12–04] 

RIN 2120–AA64 

Airworthiness Directives; The Boeing 

Company Airplanes 

AGENCY: Federal Aviation 

Administration (FAA), DOT. 

ACTION: Final rule. 

SUMMARY: We are superseding an 

existing airworthiness directive (AD) for 

certain The Boeing Company Model 

737–300, –400, and –500 series 

airplanes. That AD currently requires 

repetitive external detailed inspections 

or non-destructive inspections to detect 

cracks in the fuselage skin along the 

chem-mill steps at stringers S–1 and S– 

2R, between station (STA) 400 and STA 

460, and repair if necessary. This new 

AD adds inspections for cracking in 

additional fuselage skin locations, and 

repair if necessary. This new AD also 

reduces the inspection thresholds and 

repetitive intervals for certain airplanes. 

This AD was prompted by reports of 

additional crack findings of the fuselage 

skin at the chem-mill steps. We are 

issuing this AD to detect and correct 

fatigue cracking of the fuselage skin 

panels at the chem-mill steps, which 

could result in sudden fracture and 

failure of the fuselage skin panels, and 

consequent rapid decompression of the 

airplane. 

DATES: This AD is effective July 23, 

2012. 

The Director of the Federal Register 

approved the incorporation by reference 

of a certain publication listed in the AD 

as of July 23, 2012. 

ADDRESSES: For service information 

identified in this AD, contact Boeing 

Commercial Airplanes, Attention: Data 

& Services Management, P.O. Box 3707, 

MC 2H–65, Seattle, Washington 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 AD, the regulatory 

evaluation, any comments received, and 

other information. The address for the 

Docket Office (phone: 800–647–5527) is 

Document Management Facility, U.S. 

Department of Transportation, Docket 

Operations, M–30, West Building 

Ground Floor, Room W12–140, 1200 

New Jersey Avenue SE., Washington, 

DC 20590. 

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: 

Discussion 

We issued a notice of proposed 

rulemaking (NPRM) to amend 14 CFR 

part 39 to supersede AD 2008–19–03, 

Amendment 39–15670 (73 FR 56958, 

October 1, 2008). That AD applies to the 

specified products. The NPRM 

published in the Federal Register on 

November 28, 2011 (76 FR 72853). That 

NPRM proposed to continue to require 

repetitive external detailed inspections 

or non-destructive inspections to detect 

cracks in the fuselage skin along the 

chem-mill steps at stringers S–1 and S– 

2R, between station (STA) 400 and STA 

460, and repair if necessary. That NPRM 

also proposed to add inspections for 

cracking in additional fuselage skin 

locations, and repair if necessary. That 

NPRM also proposed to reduce the 

inspection thresholds and repetitive 

intervals for certain airplanes. 

Comments 

We gave the public the opportunity to 

participate in developing this AD. The 

following presents the comments 

received on the proposal (76 FR 72853, 

November 28, 2011) and the FAA’s 

response to each comment. 

Support for the NPRM (76 FR 72853, 

November 28, 2011) 

The National Transportation Board 

supports the NPRM (76 FR 72853, 

November 28, 2011). 

Request To Revise Paragraph (j) of the 

NPRM (76 FR 72853, November 28, 

2011) 

Boeing asked that we include Boeing 

Alert Service Bulletin 737–53A1293, 

Revision 1, dated July 7, 2010, in the 

exception to the service bulletin 


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