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### ---- ACTION: Notice ofproposed rulemaking (NPRM). Series Airplanes AilWorthincss Directives; The Boeing Company Model 37-200, -300, -400, and -500 RlN 2120-AA64

AGENCY: Federal Aviation Administration (FAA), DOT.



# D431 [Docket No. FAA-2010-1 IIII; Directorate Identifier 2009-NM-130-AD]

SUMMARY: We propose toadopt anew airworthiness directive (AD) forcertain Mode 737-200, -300, -400, and -500 series airplanes. This propjsed AD would require repetitive inspections forcracking ofcertain fuselage 

### fTJes and stub beams, and corrective actions ifnecessary. This proposed AD also prtvides for an optional repair, ~:,~".,,~, which would terminate the repetitive inspections. For airpianes on which acertain repair is done, this proposed AD would also require repetitive 

### ilpections forcracking of certain fuselage 

### framesand stub beams, and corrective 

### actons ifnecessary. This proposed AD results from reports oftile detection 

### offatigle cracks atcertain frame RlM"NG5\'MrlOl. sections, inaddition to stub beam cracking, caused byhi~ flight cycle stresses from bot 'NIlIAI.SiSICi pressurization and maneuver loads. We are proposing thi, AD to detect and correct 

# =:'~"'MOO' fatigue cracking ofcertain fuselage frames and stub beams and possible severed frames, which could result inreduced structural integrity ofthe frLes. This reduced structural "m,,'SSIG integrity can increase loading inthe fuselage skin, which

# r"accelerate skin crack growth and could result inrapid decompression ofthe fuSrlage. DATES: We must receive comments onthis proposed AIDby [INSERT DATE 45 DAYS AFTER DATE OF PUBLICATION INTHE FEDbRAL REGISTER]. 14CFR Part 39 Federal Aviation Administration DEPARTMENT OF TRANSPORTATION

ADDRESSES: You may send comments by any ofthe fo lowing methods:(4910-13-P]

DEPARTMENT OF TRANSPORTATION Federal Aviation Administration a"(UR~ENCES ROUnNG SYMBOl14CFR Part 39 (Docket No. FAA-2009-+++++; Directorate Identifier 009-NM-130-AD] RIN 2120-AA64 Airworthiness Directivesj Boeing Model 737-~OO~ -300, -400, and -500 Series Airplanes AGENCY: Federal Aviation Administration (FAA), DO I\';A{A 

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I isdone, this proposed would also require repetitive inspe tions forcracking ofcertain

result inreduced structural integrity ofthe frames. This re uced structural inteb'Titycan ACTION: Notice ofproposed rulemaking (NPRM). Mff-ili;Jj INrT1AtS!:>'G 

# A Pol,I 

## t¥"" Boeing Model 737-200, -300, -400, and -500 series airpl es. This proposed AD would DATE 

## I Pee.]~ ~9 require repetitive inspections forcracking ofcertain fusel~ge frames and ShIbbeams, an oulmQ $yml>ol I 

### fI\.J\"-IClf.> cor~ectiveactions~fneceSSary. ~~iSp.ropose~

AD also ~r~vides fora~optional ~epair,. 

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. ... whIch would termmate the repetItlVe mspectlOns. For alrp~anes on which acertam repaIr DAT~ 

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### >< OLm," ~MB L fuselage frames and stub beams, and corrective actions if ecessary. This proposed AD SUMMARY: We propose t~ adopt anew airworthiness irective (AD) for certain

results from reports ofthe detection offatigue cracks at c,rtain frame sections, in addition to stub beam cracking, caused byhigh flight cYcibstresses from both pressurization and maneuver load. We areproposing this "[~ to prevent fatigue cracking 

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## ! ofcertain fuselage frames and stub beams and possible seweredframes, which could ,/. ~~ n

OUTING SYMBOL increase loading inthe fuselage skin, which will accelerat skin crack groVv1h and result inrapid decompression afthe fuselage. DATES: We must receive comments on;this proposed A by [insert date 45 days after dale ofpublication inthe FEDERAL REGISTER]. OUTlNG SYMBOL ADDRESSES: You may send comments byany ofthe fa lowing methods: NmALS/SIG14910-13-P] DEPARTMENT OF TRANSPORT AnON Federal Aviation Administration 

### 14CFR Part 39 fhJm~l<\ 1'I1T1AI.SISIG rDocket No. FAA-2009-1 I I I I; Directorate Identifier 2i009-NM-130-AD] RIN 2120-AA64
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# f1/ ,,~ Pee.], '09 Ainvorthiness Directives; Boeing Model 737-2.00, -300'J1400' and -SOD Series Airplanes AGENCY: Federal Aviation Administration (FAA), DO" ACTION: Notice of proposed rulemaking (NPRM). SUMMARY: We propose t? adopt a new airworthiness di ective (AD) for certain Boeing Model 737-200, -300, -400, and -500 series airpla es. This proposed AD would require repetitive inspections for cracking of certain fusda c frames and stub beams, an corrective actions ifnecessary. This proposed AD also prorides for an optional repair, 

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which would terminate the repetitive inspections. For airplanes on which acertain repair """ ~ l;'- 

# I is done, this proposed would also require repetitive inspectrons for cracking of certain 

## ,sf-AfO fuselage frames and stub beams, and corrective actions if~ecessary. This proposed AD NlT\ALSlSIG I 

# J {>DI-[S results from reports of the detection of fatigue cracks at

# CCfin frame sections, in 

# t{/II (67 addition to stub beam cracking, 'caused 

### by high flight cycle stresses 

### from both oonNG S'/i'I5OL pressuri7..ation and maneuver load. We are proposing this f\!D to prevent fatigue cracking 

### .-t{():> 

# I NmlUS/S1G of certain fuselage frames and stub beams and possible severed frames, which could result in reduced structural integrity of the frames. This redlced structural integrity can increase loading in the fuselage skin, which will accelerate skin crack growth and result in rapid decompression ofthe fuselage. DATES: We must receive comments on',this proposed AD by [insert date 45 days after date of publication in the FEDERAL REGISTER]. ADDRESSES: You may send comments by any of the following methods: