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DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14CFR Part 39 [Docket No. FAA-2010-0042; Directorate Identifier 2009-NM-OIO-AD) RlN 2120-AA64 Airworthiness Directives; 8aab AB, Saab Aerosystems Model SAAB 340A (SAAB/SF340A) 

### and SAAB 340B Airplanes Mbdified in Accordance with Supplemen Type Certificate (STC) SA00224WI-D, STOOI416WI-D,or SA984GL-D AGENCY: Federal Aviation Administration (FAA), DOT.



## - 0 ACTION: Supplemental notice ofproposed ruJemaking (NPRM); reopening ofcomme period. SUMMARY: We are revising anearlier proposed aiIViorthiness directive (AD) for



# . certain Saab AB, Saab Aerosystems Model SAAB 340A (SAAB/SF340A) and SAAB 340B airplanes. The original NPRM would have required inspecting the fuselage sUTfae o;w.H 

### for corrosion and cracking behind the external aoapter plate ofthe antennae installation, OOU1''''' SY~5O<- 

### and repair 

### ifnecessary. The original NPRM resJlted from areport ofa crack found tNm~LSlSIG"~rU~£ 

### behind the external adapter plate ofthe antennaJ during inspection. Similar cracking wa c~Te 

### found ontwo additional airplanes, and extensiv1 eorrosion was found on one airplane. This action revises the original NPRM by correiting an STC Dumber, which would expand the applicability ofthe original NPRM. We are proposing this supplemental NPRM to detect and correct corrosion and cracking behind the external adapter plate of the antennae ofcertain damage-tolerant structure, which could result inreduced structur integrity and consequent rapid depressurization ofthe airplane. DATES: We must receive comments on this supplemental NPRM by [INSERT DATE

• U.S,GPQ, ,1190-<I- 768-0' 2120I01 

### 25 DAYS AFTER DATE OF PUBLICATION INTHE FEDERAL REGISTER]. ADDRESSES: You may send comments by anJ ofthe following methods: I OFFICIAL FILE C0PY FAA Form 1360-14.1 (6-89)

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Federal A\'iation Administration 14CFR Part 39 [Docket No. FAA-20tO-0042; o;rCCloratc Idc1ntificr 2009·NM-OIO-ADJ IUN 2120-AA64 DEPARTMENT Of TRANSJ'ORT-AnON

Ain\'orthincss Directives; Saab AS, Saab Acrasystems Model SAAB 340A 

## \'lLJ (SAAB/SF340A) and SAAB 3408 Airplanes Modified inAccordance with Supplemc; ~~~ Type Certificate (STC) SA00224WI-D, STOOI46WI-D, or SA984GL-D o.o.n - 1 

## ?-1JV'""7e 2iJ/D AGENCY: Federal Aviation Administration (FfA), DOT. 

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ACTION: Supplemental notice ofproposed rulcmaking (NPRM); reopening of

# com~WltfuAu period. \.-.l: SUMMARY: We are revising an earlier propostd airworthiness directive (AD) for 

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__ certain Saab All, Saab Acrosys,[.clllsModel SA1B 340A (SAAB/SF340A) ,nd SAAIl! " 340B airplanes. The original NPRM would have required inspecting the fuselage surf;

# ~e2k-1£Q for corrosion and cracking behind the external 

### JaPlcr plate ofthe antennae installatio 

# :]5) and repair ifnecessary. The onginal NPRM resulted from areport ora crack found bch;nd [he ex[e""l adapter pl,[e of [he 'ntennJ during ;nspectwn. S;ntil,r crock;ng \ ;:;" found on two add;[;on,i ,;rplanes, and ex[eos;vcicorros;on was found on one a;rpi,nel<;=,,,"~ This action revises the original NPRM by correClting an STC number, which would 

### ~~::,:-, 

### -- expand the applicability of lhe original NPRt•••.. 1.We are proposing this supplemental



# . I -.."'" SYloISOI. NPRM to detect and correct corrosion and ctacking behind the external adapter plate ,.. 0" I "'m.<~"":T~ the antennae ofceriain d,'llH1gc-lolerant strllCltlr~,which could result inreduced strue! mll 

## I I-~",,:;,--- integrity and consequenL rapid depressurization ofthe airplane. DATES: We must receive commenlS on this SU~Plemel~(a(NPRM 

### by [INSERT 

### Dl~:rE. 25 DAYS AFTER DATE OF PUBLICATION fN THE FEDERAL REGfSTERj. ADDRESSES: You may send comments by any ofthe foJlowing methods:DEPAR.TMENT OF TRANsrOR11A TION Federal Aviation Administration ]4 CFR Pnrt 39 IDocket No. FAA-201 0-0042; Dirceloflllc Idcntifie:r 2009*NM~OIO-AD[ R1N ZlZO*AA64 

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.: Airworli.incss Dirceti,'cs; Saab AI3, Saab ;\erosystcllls Model SAAB 340/\ """" •••.• ,,'00<. I 

### I'<SLJ (SAAB/SF340A) and SAAB 340B Airplanes Modified in Accordance with Supplemcllm--'="'-.: I ' Type Certifi,calc (STC) 8A00224\\'I-O, STOOI16W1-D, or SA9S4GL-D "'''. AGENCY: Federal Aviation Administration 

### (FrA), DOT. AcnON: Supplemental noticc ofproposed rulcmaking (NPRlvf); reopening ofcomn;tttrt:r1 period. \,""""
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## -ID SUMMARY: We arc revising an earlier proposed ail"\'1onhiness directi\'c (AD) lor """""'~ •.• - I I ~ certain Saab AB, Saab Aerosys.\ems ModeJ SAtB 340A (SAA13/SF340A) and SAAI3-.•••••••.•.• ..,.....,,.,; 34013 airplanes. The original NPRM would have required inspecting the fuselage surt: "el( for corrosion and cracking behind the external a~aPlcr plate ofthe·antennae illstallatio 

# 115"0<>. I """""""""""""'" and repair jfnecessary. The original NPRM resulted from areport of a crack found nd behind lhe exlcrnal ndaptcr platc ofthe amellnad during illspccti~n. SimiJarcracking \

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, I -.n0>0;"~""" found 011 two additional nirplanes, and extensive corrosion W(1S found on om.:airplane'l 

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. ·~rw"",.,, •. """" This action revises the original NPRM by correcting nn STC number, which would I 

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- expand the applicability ofIhe original NPRM. \IVeme proposing this supplemelltal NPRM to dctecl and correct corrosion and cr"ad~j,ng bchind the exlernal adapler plate 

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# --""'7 I "~="""""'" the antennae of cerl,lin damage-tolcr<nll structure, which could res\lJ[ illreduced slruct tral

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# If I " I .,. 1Il1cgmyan consequent rapl cpresSUrJ7.<l.llOll 0 tIC UlfP ,me. . DATES: We must receive- eommcll!~ Oilthis sU~PICmCnla[NPRM by [INSERT DJ.l.Tl:: I " 25 DAYS AFTER DATE Or: PUBLICATION IN Ti-IEFEDEHAL REGISTER]. ADDRESSES: YOLI JI1<1Y send commenls by anJ orllle following methods: \