### 14 CFR Part 39 ·14910-13

DEPARTMENT OF TRANSPORT AnON Federal Aviation Administration



# DlO'5 IDocket No. FAA-2010-+++++; Directorate Identifier 2009-NM-206-AD) R1N 2120-AA64 Airworthiness Directives; McDonnell Douglas Corporation Model OC-9-14, DC-9-1 and DC-9-15F Airplanes; and Model DC-9·20, DC-9-30, DC-9-40, and DC-9-50 S Airplanes AGENCY: Federal Aviation Administration (FAA), Department ofTransportation (DOT). 

### ACTION: Notice ofproposed rulemaking (NPRM). SUMMARY: The FAA proposes to supersede an existing airworthiness directive ( that applies to certain Model DC-9-14 and OC-9-15 airplanes; and Model DC-9-20, OC-9-30, DC-9-40, and DC-9-50 series airplanes. The existing AD currently requires repetitlve high frequency eddy current inspections to detect cracking inthe vertical fadi (also known as the "vertical leg") oflhe upper 1ap ofthe center wing rear spar, and rep ifnecessary. This proposed AD expands the area to be inspected by including inspectio to detect cracking orthe horizontal flange ofthi upper cap ofthe left and right center wing rear spar, and repair ifnecessary. This prJposed AD also adds c~rtain airplanes to the applicability. This proposed AD results frol reports ofcracking inthe horizontal flange on the inboard side ofthe ofthe rear spar upper cap, which resulted from stress DATf



### corrosion. We are proposing this AD to detect and correct cracking inthe vertical leg or the horizontal flange of the upper cap ofthe le~ orright center wing rear spar, which could cause apossible fuel leak, damage to the wing skin, and structural failure ofthe upper cap, and result inreduced structural integrity ofthe airplane.

FAA Form 1360-14.1 (6-89) OFFICIAL FILE C0PY *U.S,GPQ:' 990<1·766-01 2!20' 0'[4910-I3-P]

DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14CPR Part 39 fDocket No. FAA~2009~+++++; Directorate IdcntifiC12009_NM-206-ADl RIN 2120-AA64 Ain\'orfhiness Directives; McDonnell Douglas Carpar" tion Model DC-9~ 14 and DC-9-15 Airplanes; and Model DC-9-20, DC-9-30, DC-~-40, and DC-9-50 Senes Airplanes I AGENCY: Federal AVlahon Admill1stration (FAA), Department of Transportation (DOT). ACTION: Notice ofproposd rulemaking (NPRM). SUMMARY: The FAA proposes to supersede an existirg airworthiness directive (AD) that applies to certain Model DC-9-] 4 and DC-9-15 airplanes~ and Model DC-9-20, DC-9-JO, DC-9-40, and DC-9-50 se,ies ai'planes. The +sting AD currently wqui,es repetitive high frequency eddy current inspections to delfct cracking in the Vertical radius ofthe upper cap ofthe center wing rear spar, and repair ilfnecessary. This proposed AD expands the area to be inspected by including inspection ofthe horizontal nange ofthe upper cap of the left and right center wing rear spar, and repair ifnecessary_ This proposed AD re~-ullsfrom reports ofcracking inthe horizontal flange on the inboard side ofthe ofthe rear spar uppereap, which resulted from

# strtl 5S corrosion. We are proposing this AD to detect and correct cracking in the vertical leg I rthe honzontal flange ofthe upper cap orthe left or right cent..::rwmg rear spar, Wlllclrcould cause apossible fuel leak, damage to the ",ing skin, and structural failure of

# tIe upper cap, and result in reduced structural integrity of the airplane DATES: We must receive comments on this proposed 0 by

# rInsert date 45 days after date ofpublication in the FEDERAL REGISTER]. fOATa 

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FAA Form 13611-14.1 (6-89) OFFICIAL FILE COpy \,>U.$.GOVERNMLNTf'RINTINGOi'FICE: 1~'· 76~211



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