Exemption No. 7933A

UNITED STATES OF AMERICA

DEPARTMENT OF TRAN~PORTATION

FEDERAL AVIATION ADMIMSTRATION

RENTON, WASHINGTdN 98057-3356

In the matter of the petition of

Embraer Empresa Brasileira de Aeronautica Regulatory Docket No.F AA-2002-13021

S.A. (Embraer)

for an exemption from § 25.901(c) of Title 14,

Code of Federal Regulations

GRANT OF AMENDED EXEMPTION

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By letter dated September 22,2010, Mr. Ricardo Lavall Hollerbach, Embraer Empresa Brasileira ,

de Aerol1CluticaS.A. (Embraer), Av. Bligadeiro Faria Lima, 2170,12227-901 - S. Jose dos

Campos - SP, Brazil, petitioned for an amendment to e~emption no. 7933, to provide exemption ,

from the "no single failure" criteria of § 25.901(c) of Title 14, Code of Federal Regulations (14

CFR) as it relates 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) for certain uncontrollable high thrust failure conditions. The proposed exemption, if

granted, would pemlit type certification of SImIlarly noh-compliant Embracr Model EMB-135BJ

series airplanes to allow installation of Rolls-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:

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(c) For each powerplant and auxiliary power unit installation, it must be established that

no single failure or malfunction or probable cOlilbination of failures will jeopardize the ,

safe operation of the airplane except that the fai,ure of structural elements need not be

considered if the 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." I
The 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, fTom the no single failure requirements of l4CFR §25.901

(c) as it relates 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.e requirement since there were three

scenarios, all of them 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 A IE 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

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AE3007 Al E engines. Small differences were found between the required flight control

surfaces deflections for the EMB-135BJ (Legacy 600) and EMB-13SBJ Enhanced

(Legacy 650) (less than 1 degree) and the defleotions are far from any detent. Therefore,

all UHT analysis results fyom the EMB-135BJ ~ith AE3007 AlE engines are applIcable

to the EMB-135BJ with AE3007 A2 engines. I

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The UHT protection logic and corrections implemented in the EMB-145 family FADEC

since first certification have shown positive results with almost 13 million flight hours

accumulated with no safety issues since the 1astlUHT event in 2003. AE3007 A2 FADEC

is inheriting all EMB-145 family FADEC improvements and corrections implemented

during its history.

During a meeting held during May 2010 at FAA facilities in Seattle with FAA, Embraer

and Rolls Royce it was discussed that the existibg exemption should be amended and stay

valid for a period of four years after FAA validdtion. During this period, Embraer and

Rolls-Royce will develop and make available improved UHT logic which will shutdown

engines on the ground only upon detecting highlNl and with a TLA command at or less

than idlc. This improved OOT logic is the only known practical action (cost beneficial

and teclmologica11y feasible) to address the scenarios exempted by the memo, in order to

minimize the adverse effects on safety associatdd with granting exemption from 14CFR

§25.901 (e) for the EMB-135BJ Equipped withrE 3007A2 engines.

No later than four years from the granting of Amendment A to this Exemption (i.e.

Exemption # 7933A), for all airplanes EMB-135BJ to which this exemption applies,

Embraer must:

(a) obtain FAA approval of amended type desigps illcorporating thrust Inalfunction

detection and accommodation logic that protectk against all noncompliant uncontrollable

high thrust failures on ground, except for those due to failures within the aIrplane throttle

system; I

(b) assure all new EMB-135BJ model producti9n airplanes are equipped with the

amended type designs of item (a) or subsequently approved thrust malfunction

accommodation logic; and

(c) obtain FAA approval of service instruction to facilitate retTOfitof all existing

EMB-135BJ model airplanes with tbe amended1type designs of item (a) and/or any

subsequently approved thrust malfunction accommodation logic.

Based on the above considerations Embraer res~eetfullY proposes to amend the

exemption granted by document (FAA Exemptibn no. 7933), from the requirement of

14CFR §25.901 (e), for the EMB-135 BJ (Lcgaty Enhanced) equipped with the

AE3007 A2 cngines. I

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Federal Register publication

A summary of this petition was published in the FederJ[ Register on November 8, 2010. The

FAA received no comments.

The FAA's analysis

In the process of evaluating the Ernbracr Model EMB-l35BJ Design Change Application (DCA)

0145-000-0020 the FAA has determined all practical adtions had not been taken within the scope

of that change to eliminate or further reduce the risks ad required by Condition 1 of the original

exemption 7933, as granted on December 12, 2002. Sp~ci:fically, while a major engine-control

software change was undertaken, thrust-malfunction-actommodation logic (i.e. logic thai

identi fies and safely accOllli110datesany sustained, substantial discrepancy between the actual and

commanded thrust, as sensed and validated by the engine control) was not incorporated. Such

Ihrust-malfunction-accommodation logic has been fourld to be practical and effective at

eliminating all noncompliant, uncontrollable, high-thru~t failures except for those 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 an amendment to the original exemption no. 7933 to allow them up to 4 years

from the date of granting to develop, certificate, put int? production, and facilitate retrofit of

acceptable thrust-malfunctioD-accommodation logic, eliminating all noncompliant,

uncontrollable, hJgb-thrust failures, except for those du~ to failures within the airplane throttle

system. To that end, in amending exemption 7933 to 7933A, limitation number 4 (see below) is

added to the conditions and limitations of this exemptidn amendment.

Conclusion

fJlconsideration of the foregoing, I find that a grant of exemption is in the public interest and will

not adversely affect safety. Therefore, pursuant to the a~lhority contained in 49 U.S.c. 40113 and ,

44701, delegated to me by the Administrator, Embraer Empresa Brasileira de Aeromiutica S.A.

(Embraer) is granted an exemption from § 25.901 (c) to Ithe extent necessary to allow type

certification of the Model EMB-135BJ series airplanes rith RR AE3007 Al E and subsequent RR

AE3007 A series engines, and AE3007 A2 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 to the following conditions and Iiri1itations:

1. Embraer must demonstrate, in accordance wiih an FAA-approved "A.i.rworthiness

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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 or further reduce the risks by

Improving designs, procedures, training and instructions for continued airworthi.ness.

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a. The airplane complies with § 25.901(1) for any foreseeahle uncontrollahle high·

thrust failure conditions in flight and on Ithe ground, except possibly during

takeoff and landing touchdown; and

2. Embraer must demonstrate, III accordance with an FAA~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 for the proposed Model EMB-135BJ series airplanes with RR

AE 3007Al E series engines than those generally known to exist for comparable airplanes

within the current transport fleet. Acceptable risk for this provision can be characterized

as:

b. The expected frequency of occurrence of the uncontrollable high-thrust failure

condition is less than once per ten-millidn airplane operating hours.

3. The following "Note" will be added to the aiJplane Type Certification Data Sheet for

any airplane certificated under this exemption: I

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The FAA has concluded that the occurrence of any uncontrollable high-thrust

~~;:~:::t:~~:~~::ea;~~; ~hr: ::s::;:~~~ec:j~:~ f;~I~;~~ ~~S;~~):V~~~.~~~:

135.415(c). I

In support of this "Note," Embraer must develot and obtain, prior to customer delivery,

FAA approval of the Embraer document referenced in the "Note." This document lists

those failures that can contribute to or cause an hncontrollable high-thrust failure

condition covered by this exemption. This document will then be made available as part

of the instructions for continued airworthiness. Further, the failures listed within this

document will be added to the list ofrep0l1abies under § 21.3 for any airplane certificated

under this exemption.

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b. Show that all new Model EMB-I35BJ production airplanes arc equipped with

the amended type designs approved to s~tisfy condition 4a or any subsequently

approved thrust-malfunction-accommodiation logic; and

4. No later than four years from this granting ofiamendment A to exemption no. 7933, for

all airplanes to which this exemption applies, Embraer must:

a. Obtain FAA approval of amended typl designs incorporating thrust·

malfunction-accommodation logic that ~1iminates all noncompliant,

uncontrollable, high-thrust fai.lures, excJpt for those due to failures within the

airplane throttle system;

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c. Obtain FAA approval of service inst~ctions to facilitate retrofit of all existing

Model EMB-135BJ airplanes with the amended type designs approved to satisfy

condition 4a or any subsequently approv,ed thrust-malfunction-accommodation

logic.

5, The granting of this exemption does not relieye any regulatory obligation to identify

and coneet unsafe conditions related to uncontrollable high-thrust failure conditions.

Note: Additional background and guidance reglding these provisions are provided in

FAA Letter 02-112-02, dated October 19, 2001.

issued in Renton, Washington, on FES 7 2011

?J#r£~

Jeffrey Duven

Acting Manager, Transport Airplane Directorate

Aircraft Certification Service

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