**February 11 th**  **, 2011.**

**GCF-0177/2011 – 1/7**

**CPA**
Embraer S.A.

**Av. Brigadeiro Faria Lima, 2.170 12227-901 - S.J. dos Campos - SP**  **Brasil**

**Fone: (12) 3927-0716 Fax: (12) 3927-1184**  **PC: 179 GCF** 

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**Summary**

**Petitioner: EMBRAER Empresa Brasileira de Aeronáuti ca S/A** 

**Section of the Regulation Affected: 14CFR §25.981(a )(3) amendment 102.** 

**Description of Relief Sought: Embraer petition for a time-limited exemption from 14 CFR**  **§25.981(a)(3) for the fuel pump and wiring installa tion of**  **EMB-135BJ (Legacy 650)**

**aircraft. GCF** 

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**Embraer respectfully submits the enclosed petition for a time-limited exemption from the**  **provisions of 14 CFR §25.981(a)(3) as they apply to the fuel pump and wiring**  **installation of EMB-135BJ (Legacy 650) aircraft.**

Text of the Requirement for which exemption is soug ht

**14 CFR §25.981(a)(3) Fuel tank ignition prevention**
**Demonstrating that, an ignition source could not re sult from each single failure, from each**  **single failure in combination with each latent fail ure condition not shown to be extremely**  **remote, and from all combinations of failures not s hown to be extremely improbable. The**  **effects of manufacturing variability, aging, wear, corrosion, and likely damage must be** 

**considered.**

Background

**It has proven impractical to demonstrate compliance with §25.981(a)(3) at amendment**  **102 in a timely manner due to certain EMB-135/145 f amily fuel system design concepts**  **and practices initially proposed to be retained for the EMB-135BJ (Legacy 650).**  **Embraer requests that this time limited exemption b e granted until practicable design**  **solutions are identified, validated, and safely int egrated into the fuel system of the EMB**  **135BJ (Legacy 650).**

**Some of design aspects that must be addressed by su bsequent modifications include,**  **but may not be limited to:**

• **Each fuel pump wiring harness within a fuel tank n eeds an additional**  **independent and robust layer of protection against ignition source producing**  **faults. Consideration is being given to placing the harness completely within a**  **robust conduit which protects the harness from fore seeable damage while**  **protecting the tank vapor space from any foreseeabl e harness faults (i.e. conduit**  **provides vapor/explosion proof barrier that won’t b e lost due to damage from any**  **foreseeable harness fault);**

• **Fuel pump explosion proof features need to be made adequately fail-safe.**  **Failures that are not extremely improbable have bee n identified which can cause**  **loss of the pumps explosion containment capability. Fixes have been identified**  **and are currently being validated;**

• **The wiring installations outside the fuel tanks mu st be made adequately fail-safe.**  **Foreseeable wiring support failures have been ident ified that could cause non**  **intrinsically safe wiring to come into contact with the external skins of fuel tanks.**  **Shorting of the conductors within these wires and t he conductive skin of the tank**  **could result in prohibited hot spots or burn throug h of the tank. To date sufficient** 

**information is not available to rule out such a sho rt. Some specific fixes have**  **been identified and are currently being validated, and the analysis to assure** 

**other foreseeable failures do not exist is still in process.** **GCF**

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**Embraer offers the following justification in suppo rt of this exemption, as well as,**  **substantiation as to why the current type design pr ovides an adequate level of safety for**  **the interim period of this exemption and why granti ng the time limited exemption is in**  **the public interest, as required by 14 CFR §11.81.**

Grounds Supporting Exemption

**Embraer will certify and incorporate into the produ ction line of the EMB-135BJ (Legacy**  **650) the modifications required to demonstrate comp liance with the requirements of**  **§25.981(a)(3) at amendment 102 by September 30, 201 1.** 

**Embraer will also retrofit the EMB-135BJ (Legacy 65 0) series airplanes delivered under**  **the terms of this exemption by September 30, 2012.**

**These proposed dates are adequate considering that:**

• **The number of the airplanes that will be delivered within this period represents a**  **negligible addition to the overall fleet risk.**

• **Some of the identified failure modes of concern re quire significant aircraft**  **utilization and/or aging to develop into noncomplia nt failure conditions, and the**  **timeframe proposed for this exemption is not suffic ient for the affected airplanes**  **to accumulate the flight hours or cycles required f or the components to exhibit**  **these aging effects.**

• **The fuel pump and wiring installations of the EMB- 135BJ (Legacy 650) have the** 

**same characteristics as the rest of the EMB-145 fam ily from which it is derived.**  **That EMB-145 family has accumulated more than 17 mi llion flight hours without**  **notable adverse experience relevant to the objectiv es of the 25.981(a)(3)**  **requirement.**

• **There are five EMB-135BJ (Legacy 650) aircraft sch eduled to be delivered to**  **U.S. customers through the end of 2011. The additio nal number of flight hours**  **that will be accumulated by these EMB-135BJ (Legacy 650) airplanes during the**  **period of this exemption will be minimal due to tha t limited fleet size and the**  **lower annual utilization typical of such business j ets.** 

• **The failure conditions of concern will be mitigate d with the actions that are** 

**described below. GCF** 

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**The proposed mitigation actions for pump manufactur ing and assembly within this time**  **limited exemption application are the following:**

**1. Additional dielectric strength test on the pump harness before final assembly to**  **guarantee the proper wiring insulation. 2. Torque verification of pump locking nuts at fina**  **l inspection to guarantee the proper installation of the nut.**  **3. Addition of polysulfide sealant all over the pum p locking nuts to guarantee the**  **closure of the gap between stud and cover and, cons equently, the explosion**  **proof cavity. 4. Additional cleaning task to guarantee the adhesi**  **on of potting to connector**

**counter bore. 5. In addition to the already existing inspections,**  **a detailed visual inspection performed by qualified quality inspector to guarant**  **ee that a. The wiring adjacent to all fuel tanks is install**  **ed according to the drawings; b. The pump harness is installed according to the d**  **rawing to include: i. Clamp type (with yellow cushion)**  **ii. Clamp size iii. Clamp alignment with the harness**  **iv. Correct number and location of clamps v. Harness slack properly distributed along the len**  **gth**

**vi. Harness clearance**

**The proposed limitation for pump maintenance within this time-limited exemption**  **application is the following:**

• **Any maintenance action accessing the wing tanks co llector box or any auxiliary**  **fuel tanks to perform any maintenance either on the fuel pump itself or other**  **adjacent component or installation requires a detai led visual inspection and a**  **functional check in accordance with the fuel system limitation task number** 

**SMRD-1533 tasks 28-17-01-720-001-A01 and 28-50-01-2 20-001-A01 by a**  **qualified inspector in order to guarantee that the installation of the pumps are in** 

**accordance with the Maintenance Manual instructions and illustrations.** 

• **The fuel system limitation task number SMRD tasks 28-17-01-720-001-A01 and**  **28-50-01-220-001-A01 detailed inspections will incl ude a GVI (General Visual**  **Inspection) task number 28-41-00-200-801-A as part of the tank closure**  **procedure after a maintenance activity is performed . These fuel limitation tasks**  **will be added to the Embraer maintenance planning g uide (MPG) temporary**  **revision (TR) 7.2, before certificate of airworthin ess or first delivery whichever** 

**occurs later. GCF** 

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• **Fuel System Limitation Task Numbers as follows:**

**The DET 20-00-00-220-001-A10 periodic maintenance t ask requires, at each 18**  **months, the wire bundles at areas of concern adjace nt to the fuel tank skins to be**  **inspected, thus assuring no wiring support failure would persist.** 

Issue of Public Interest

**Denial of this petition for exemption would result in the delay in certification and delivery**  **of the EMB-135BJ (Legacy 650) to the United States (U.S.). While these airplanes are**  **not manufactured in the U. S., a significant portio n of the airplane, including the**  **engines, avionics, and interiors are manufactured b y U.S. suppliers. Denial of this**  **exemption request would result in the loss of reven ue for the U.S. suppliers and have**  **an adverse impact on the U.S. balance of trade, bot h of which are counter to the public** 

**interest.**

**In addition, our U.S. customers have made fleet sch edule plans based on the agreed**  **upon delivery schedule of these airplanes. To requi re Embraer to modify these**  **airplanes prior to service entry will unavoidably d elay delivery and have an adverse**  **financial effect on these operators. This action wo uld be counter to the public interest.** 

Request to Forego Publication in the Federal Regist er

**Because this exemption petition is similar in both the technical and regulatory aspects**  **addressed and the temporary relief sought to an exe mption that has been issued in the**  **past (Exemption 8761C) and has received no public c omments, granting of this**  **proposed exemption would not raise new issues or se t any legal precedent. In** **GCF**

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**comparison to this previous exemption, this petitio n requests only 21 months (measured**  **from February, 2011) to complete the identified mod ifications and retrofitting the**  **delivered airplanes. In addition, the previous exem ption was applicable to the entire fuel**  **system, where in the case of the EMB-135BJ (Legacy 650), the majority of the affected**  **system has already been shown compliant with 14 CFR §25.981(a)(3) and the**  **necessary modifications identified. Accordingly Emb raer requests that the FAA not**  **delay granting of this exemption for publication of the petition summary in the Federal**  **Register as allowed by 14 CFR §11.87.**

**Embraer has a contract with an U.S. operator to del iver the first EMB-135BJ (Legacy**  **650) by February 25, 2011. As described above in th e Public Interest section, a delay in**  **delivery will adversely affect this operator, forci ng him to seek alternatives to his**  **planned use of the airplane, e.g., cancel scheduled flights, charter alternative lift.** 

**Embraer also notes that this petition was filed imm ediately after the identification of the**  **non-compliance.**

**In summary, there exists the necessary justificatio n for forgoing publication of a petition**  **summary in the Federal Register, and Embraer respec tfully requests that grant this**  **petition without delay.**

Effect of the Exemption on Safety

**The entire EMB-145 family of aircraft have similar design features that could not be**  **shown to comply with §25.981(a)(3) amendment 102. T here are 689 such aircraft**  **currently operating safely within the U.S. fleet. S uch aircraft have been operating safely**  **in the U.S. for over 14 years and are expected to c ontinue to do so for many years to**  **come. Adding 5 additional aircraft expected to be d elivered until September, 30**  **th 2011,** 

**with a similar level of risk to that fleet for less than two years will clearly have a**  **negligible impact on safety.**

Operations Outside the United States

**As a manufacturer and not an operator, Embraer does not intend to operate outside the**  **United States under the terms of the exemption whic h we are requesting, but our**  **operators will certainly fly the EMB-135BJ (Legacy 650) internationally. The granting of**  **this petition will not conflict with any of the ter ms of ICAO Annex 8, so the FAA will not**  **need to file a difference with ICAO, as described i n 51 1.83.**