Exemption No. 7933A

UNITED STATES OF AMERICA DEPARTMENT OF TRAN~PORTATION FEDERAL AVIATION ADMIMSTRATION RENTON, WASHINGTdN 98057-3356

Inthe matter ofthepetition of Embraer Empresa Brasileira de Aeronautica Regulatory Docket No.FAA-2002-13021 S.A. (Embraer) for anexemption from § 25.901(c) ofTitle 14, Code ofFederal RegulationsGRANT OF AMENDED EXEMPTION I Byletter dated September 22,2010, Mr. Ricardo Lavall Hollerbach, Embraer Empresa Brasileira , de Aerol1Clutica

S.A. (Embraer), Av. Bligadeiro Faria Lima, 2170,12227-901

- S. Jose dos Campos

- SP, Brazil, petitioned for anamendment to e~emption no. 7933, to provide exemption , fromthe "no single failure" criteria of § 25.901(c) ofTitle 14, Code ofFederal Regulations (14 CFR) as itrelates to uncontrollable high-thrust failure dOllditions. Recent studies and service experience indicate that some existing transport category airplanes do not strictly comply with § 25.901(c) forcertain uncontrollable high thrust failure conditions. The proposed exemption, if granted, would pemlit type certification ofSImIlarlynoh-compliant Embracr Model EMB-135BJ series airplanes to allow installation ofRolls-Royce (RR) AE3007A2 series engines, and subsequent RR AE 3007A series engines. I The petitioner requires relief from the following regulations: Section 25.901(c) as amended by AmendmeJs 25-1 through 25-84: I (c)For each powerplant and auxiliary power unit installation, itmust be established that no single failure ormalfunction orprobable cOlilbination offailures willjeopardize the 

# , safe operation ofthe airplane except that the fai,ure ofstructural elements need notbe considered ifthe prohability of such failure is etemelY remote. Additional requirements as per Issue Paper 0Tl originated from the significant major modification presented in the DCA 0145-000-00020-2008 "EMB-135BJ Performance Enhancements." IThe petitioner supports its request with the followin!g information:

This section quotes the relevant infonnation from the P~titioner'S reques!. The complete petition is available at the Department of Transportation's Federal Docket Management System, on the lntcrnet at http://regulations.gov, in Docket No. FAA~2b02~ 13021. Embraer respectfully submits the enclosed Petition for an exemption for the EMB-135BJ model with the modifications presented in the qCA 0145~OOO-00020-2008IFAA, herein called EMB-135BJ Enhanced, fTomthe no single failure requirements of l4CFR §25.901 (c) as itrelates to uncontrollable h1gh thrust failhre conditions. Embraer proposes to amend the FAA Exemptiol no. 7933 granted to EMB-135BJ equipped with engine AE3007 AlE from requirJment l4CFR §25.90l (c) for the EMB135BJ Enhanced equipped with the AE3007A2 engine. Grounds Supporting Exemption The EMB-145XR and EMB-135BJ, previous medels of the Legacy Enhanced, have received partial exemption of comphance with tp.erequirement since there were three scenarios, all ofthem on ground, not successfully demonstrated to be entirely in , accordance with the requirement. FAA have granted exemption to these models through Exemptions No. 7908 (October 21,2001, for EMB-145XR) and No. 7933 (December 12, 2001 for EMB-135BJ). The EMB~] 35BJ Enhanced is equipped with Rolls-Royce AE3007 A2 engines, a modification over the previous engine model, the AE3007AIE. This engine modification consists ofa new fan module with fewer fan bl~des (22 instead of24 on AlE) and new spinner among other components of fan modul~f [Refer to Docket No. FAA-2002-l302l in the Federal Docket Management System to view a graphic Embraer provided, which illustrates the main differences between AIE an~ A2 engines.] All the rest of the engine is maintained the samd as the AlE engine, including compressor, combustion chamber, turbines, exh1aust, FPMU (Fuel Pump and Metering Unit) & FADEC hardware. FADEC software is bcmg updated to receive A2 thrust tables among other modifications/improvements. The AE3007 A2 engine Max TO (Take Off) thrust (9022 Tbf)has increased about ]4%, , comparing to the AE3007 AlE (7974 Ibf) engine currently used on EMB-135BJ, but the maximum peak thrust during a MMV (Main MJtering Valve) position failure (fully open) in the AE3007A2 is 10,501 Ibf, against the 10,150 Ibf. Aircraft handling qualities analysis for the Uncontrollable High Thrust (lJHT) scenarios , (MMV fully open), for the EMB-135BJ with AE3007 A2 engines showed that with the additional thrust increase (3.5%), the results are similar to the ones obtained with

2AE3007 AlEengines. Small differences were found between the required flight control

surfaces deflections forthe EMB-135BJ (Legacy 600) and EMB-13SBJ Enhanced (Legacy 650) (less than 1degree) and the defleotions are far from any detent. Therefore, all UHT analysis results fyomtheEMB-135BJ ~ith AE3007 AlE engines are applIcable tothe EMB-135BJ with AE3007A2 engines. I I The UHT protection logic and corrections implemented inthe EMB-145 family FADEC since first certification have shown positive results with almost 13 million flight hours accumulated with no safety issues since the 1astlUHTevent in 2003. AE3007A2 FADEC isinheriting all EMB-145 family FADEC improvements and corrections implemented during itshistory. During ameeting held during May 2010 atFAA facilities in Seattle with FAA, Embraer and Rolls Royce itwas discussed that the existibg exemption should be amended and stay valid for aperiod offour years after FAA validdtion. During this period, Embraer and Rolls-Royce will develop andmake available improved UHT logic which will shutdown engines on the ground only upon detecting highlNl and with aTLA command ator less than idlc. This improved OOT logic is the only known practical action (cost beneficial and teclmologica11yfeasible) to address the scenarios exempted by the memo, inorder to minimize the adverse effects on safety associatdd with granting exemption from 14CFR §25.901 (e) forthe EMB-135BJ Equipped withrE 3007A2 engines. No laterthan four years from the granting ofAmendment A tothis Exemption (i.e. Exemption 

### #7933A), forall airplanes EMB-135BJ to which this exemption applies, Embraer must: (a) obtain FAA approval ofamended type desigps illcorporating thrust Inalfunction detection and accommodation logic that protectk against all noncompliant uncontrollable high thrust failures on ground, except forthose due to failures within the aIrplane throttle system; I (b) assure all newEMB-135BJ model producti9n airplanes are equipped with the amended type designs ofitem (a) or subsequently approved thrust malfunction accommodation logic; and (c) obtain FAA approval ofservice instruction to facilitate retTOfitofall existing EMB-135BJ model airplanes with tbe amended1type designs ofitem (a) and/or any subsequently approved thrust malfunction accommodation logic. Based on the above considerations Embraer res~eetfullY proposes to amend the exemption granted bydocument (FAA Exemptibn no. 7933), from the requirement of 14CFR §25.901 (e), forthe EMB-135 BJ (Lcgaty Enhanced) equipped with the AE3007 A2 cngines. 

# I

3Federal Register publication

A summary ofthis petition was published intheFederJ[ Register onNovember 8,2010. The FAA received no comments. The FAA's analysis Inthe process ofevaluating the Ernbracr Model EMB-l35BJ Design Change Application (DCA) 0145-000-0020 the FAA has determined allpractical adtions had notbeen taken within the scope ofthat change to eliminate orfurther reduce the risks adrequired by Condition 1ofthe original exemption 7933, as granted onDecember 12,2002. Sp~ci:fically,while amajor engine-control software change was undertaken, thrust-malfunction-actommodation logic (i.e. logic thai identifiesand safely accOllli110datesany sustained, substantial discrepancy between the actual and commanded thrust, as sensed and validated bythe engine control) was not incorporated. Such Ihrust-malfunction-accommodation logic has been fourldto be practical and effective at eliminating all noncompliant, uncontrollable, high-thru~t failures except forthose associated with failures within the airplane throttle system (e.g. stuck tHrott1e,disagreement between actual throttle position and that input to the engine control, etc.). Embraer requests anamendment tothe original exemption no. 7933 to allow them upto 4 years from the date ofgranting to develop, certificate, put int? production, and facilitate retrofit of acceptable thrust-malfunctioD-accommodation logic, eliminating all noncompliant, uncontrollable, hJgb-thrust failures, except forthose du~ to failures within the airplane throttle system. To that end, inamending exemption 7933 to 7933A, limitation number 4 (see below) is added to the conditions and limitations ofthis exemptidn amendment. Conclusion fJlconsideration ofthe foregoing, Ifind that agrant ofexemption is inthe public interest and will not adversely affect safety. Therefore, pursuant to the a~lhority contained in49 U.S.c. 40113 and , 44701, delegated to me by theAdministrator, Embraer Empresa Brasileira de Aeromiutica S.A. (Embraer) is granted anexemption from § 25.901 (c) toItheextent necessary to allow type certification oftheModel EMB-135BJ series airplanes rith RR AE3007Al E and subsequent RR AE3007A series engines, and AE3007A2 series engines, without an exact showing of compliance with the requirements of §25.901(c) as they relate to single failures resulting in uncontrollable high-thrust conditions. For the Model E1.1B-135BJ series airplanes, tillS exemption is subject tothe following conditions and Iiri1itations: 1.Embraer must demonstrate, inaccordance wiih anFAA-approved "A.i.rworthiness 

## , Assessment and Risk Management Plan," that ap practicable actions have been taken to minimize the adverse effects on safety associatdd with granting this petition. These must includc, but arc not limited to, practical actions ~oeliminate orfurther reduce therisks by Improving designs, procedures, training and instructions forcontinued airworthi.ness.

4a. The airplane complies with § 25.901(1) forany foreseeahle uncontrollahle high· thrust failure conditions inflight and onItheground, except possibly during takeoff and landing touchdown; and 2. Embraer must demonstrate, III accordance with anFAA~approved "Airworthiness Assessment and Risk Management Plan," that the risks associated with exempting the "uncontrollable high-thrust failure condition" from the single failure provisions of § 25.901(c) are no greater fortheproposed Model EMB-135BJ series airplanes with RR AE 3007Al Eseries engines than those generally known to exist forcomparable airplanes within the current transport fleet. Acceptable risk forthis provision can be characterized as:

b. The expected frequency ofoccurrence ofthe uncontrollable high-thrust failure condition is less than once per ten-millidn airplane operating hours. 3. The following "Note" will be added tothe aiJplane Type Certification Data Sheet for any airplane certificated under this exemption: I

, The FAA has concluded that the occurrence ofany uncontrollable high-thrust 

# ~~;:~:::t:~~:~~::ea;~~; ~hr: ::s::;:~~~ec:j~:~ f;~I~;~~ ~~S;~~):V~~~.~~~:):::d 135.415(c). I Insupport ofthis "Note," Embraer must develot and obtain, prior to customer delivery, FAA approval ofthe Embraer document referenced inthe "Note." This document lists those failures that can contribute to orcause an hncontrollable high-thrust failure condition covered by this exemption. This document will then be made available as part ofthe instructions forcontinued airworthiness. Further, the failures listed within this document will beadded tothe listofrep0l1abies under § 21.3 for any airplane certificated under this exemption.

I b. Show that all new Model EMB-I35BJ production airplanes arc equipped with the amended type designs approved to s~tisfy condition 4a orany subsequently approved thrust-malfunction-accommodiation logic; and 4. No later than fouryears from this granting ofiamendment A toexemption no. 7933, for all airplanes to which this exemption applies, Embraer must:

a. Obtain FAA approval ofamended typl designs incorporating thrust· malfunction-accommodation logic that ~1iminates all noncompliant, uncontrollable, high-thrust fai.lures,excJpt forthose due to failures within the airplane throttle system;

5I I c. Obtain FAA approval of service inst~ctions to facilitate retrofit ofall existing Model EMB-135BJ airplanes with the amended type designs approved to satisfy condition 4a or any subsequently approv,edthrust-malfunction-accommodation logic. 5,The granting ofthis exemption does not relieye anyregulatory obligation to identify and coneet unsafe conditions related to uncontrollable high-thrust failure conditions. Note: Additional background and guidance reglding these provisions areprovided in FAA Letter 02-112-02, dated October 19, 2001.

issued inRenton, Washington, on

## FES 7 2011 

# ?J#r£~

Jeffrey Duven Acting Manager, Transport Airplane Directorate Aircraft Certification Service

6