ExpressJet Airlines

Dear Sirs, Expressjet Airlines would like to comment on Docket No. 2011-0312: Directorate Identifier 2010-NM-159-AD concerning the inspection of the Auxiliary Power Unit (APU) Firewall on select EMB-145 series aircraft for signs of cracking. The initial inspection of the proposed AD is called out to be accomplished within 3,300 flight hours of the effective date and if a crack or cracks are found the repair or replacement of the APU firewall is to be accomplished prior to further flight. Based on ExpressJet’s previous experience of repairing and/or replacing APU firewalls, this can be a time consuming process which would be better addressed during a heavy maintenance check, therefore ExpressJet requests that the initial inspection be accomplished within 5000 flight hours or at the next heavy maintenance visit, whichever occurs first. In addition, the proposed rule states that the optional terminating action of replacing the APU firewall is to be done in accordance with EMB Service Bulletin 145-53-0062, Revision 6, however, ExpressJet’s EMB-135 ER/LR and EMB-145EP aircraft are missing from the effectivity of this latest version of the Service Bulletin, so an additional revision to Service Bulletin 145-53-0062 is being requested. Your assistance in this matter is greatly appreciated. Sincerely, Ben Manning Sr. Manager of Engineering Expressjet Airlines