[4910-13-

DEPARTMENT OF TRANSPORT AnON Federal Aviation Administratibn 14 CFR Part 39 

# DI (Docket No. FAA-20lOJh+; birectoratc Identifier 2009-NM-263-AD] RlN 2120-AA64 Airworthiness Directives; The Cessna Aircraft Company Model 750 Airplanes AGENCY: Federal Aviation Administration (FAA), DOT. ACTiON: Notice ofproposed mlemaking (NPRM). SUMMARY: We propose to adopt a new airworthiness directive (AD) for certain M 750 airplanes. This proposed AD would require an inspection to determine the serial

- (O~ numbers ofthe auxiliary power unit (APU) generator and the left andright engine D ' 

# :t~~· generators, and related corrective actions ifnecessary. This proposed AD would also require revising the airplane flight manual. This proposed AD results from areport 0 DC generator overvoltage eventwhich caused smoke inthe cockpit and damage to
numerous avionics and electrical components. We are proposing this AD to detect an correct an overvoltage condition all the DC electrical busses caused by exciter stator winding failures, and subsequent failure ofthe generator control unit (GCU) overvolt protection circuitry, which could result in damage to critical electrical and avionics components. 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 c.omments by any ofthe following methods:

• Fed.eral eRulemaking Portal: Go to http://v.'ww.regulations.gov.Followthe instructions for submitting comments .

• Fax: 202-493-225l. 

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FAA Form 1360-14_1 (6-89) 0FFtCtAl FilE COPY 

## *u.s. GOVERNMENT PRINTING OFFICE:

# 'rs -769·211{4910-13-P DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14CFR Pa,'39 IDocket No. FAA-2010M++++; Directorate Identifier 2009-NM-263-ADj RIN 212Q..AA64 Airworthiness Directives; The Cessna Aircraft Company Model 750 Airplanes AGENCY: Federal Aviation Administration (FAA), DOT. ACfJON: Notice of proposed rulemaking (NPRM). SUMMARY; We propose to adopt anew airworthiness direclivc (AD) forcertain Mo 750 airplanes. This proposed AD would require aninspection todctcm1inc the serial numbers ofthe auxiliary power unit(APU) generator andthe leftand right engine DC generators, and related corrective actions ifnecessary. This prdposed AD would also require revising the airplane Hightmanual. This proposed AD results from areport of DC generator overvoltage event which caused smoke inthe cockpit and damage 10
numerous avionics and electrical components. We areproposing this AD to detect and correct anovervoltage condition on thc DC electrical busses caused byexciter stator winding failures. undsubsequent failure ofthc generator control unit (GCU) ovcrvolta protection circuilry, which could result indamage tocritical electrical and avionics components. DATES: We must receive comments onthisproposed AD by [INSERT DATE 45 DAYS AFrER DATE OF PUBLICAnON IN THE FEDERAL REGISTER). ADDRESSES: You may send comments byany oflhe following methods:

• Federal cRulcmaking Portal: Go to hllr:!:www.r~glllalillns.gllY.Follow the instructions for submit1ing comments .

• Fax: 202-493-2251. 

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FAA Form 1360-14.1 (6-89) OFFICIAL FILE COPY