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Summary

Petitioner: Embraer S/A

Section of the Regulation Affected: 14CFR 25.954 an d 25.901(c), amendment 124.

Description of Relief Sought: Embraer’s petition fo r a time-limited exemption from 14CFR 25.954 and 25.901(c) for the auxiliary fuel t anks vent system of the EMB-135BJ modified in accordance with the Design Change Appro val (DCA) 0145-000-00020-2008 Rev E (Legacy 650).GCF

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Embraer respectfully submits the enclosed petition for a time-limited exemption from the provisions of 14CFR 25.954 and 25.901(c) as they ap ply for the auxiliary fuel tanks vent system of the Legacy 650 airplane, including those that incorporate flame arrestors.

Text of the Requirements for which exemption is sou ght

14CFR 25.954 “Fuel system lightning protection”

“The fuel system must be designed and arranged to p revent the ignition of fuel vapor within the system by— (a) Direct lightning strikes to areas having a high probability of stroke attachment; (b) Swept lightning strokes to areas where swept st rokes are highly probable; and (c) Corona and streamering at fuel vent outlets.”

14CFR 25.901 ”Installation”

(c) For each powerplant and auxiliary power unit in stallation, it must be established that no single failure or malfunction o r probable combination of failures will jeopardize the safe operation of the airplane except that the failure of structural elements need not be considered if the p robability of such failure is extremely remote.

Background

The Legacy 650 design retains auxiliary fuel tank v ent system design concepts previously approved on other EMB 135/145 model airp lanes. However, the previously accepted means of demonstrating compliance was just recently found to be deficient in some respects. As a result, it is impractical to de monstrate compliance with 14 CFR 25.954 and 25.901(c) in a timely manner for the Leg acy 650. Embraer requests that this time-limited exemption be granted until unequivocal demonstration of the safety and compliance with the afore mentioned requirements is achieved through more detailed evaluation of the system and results of testing who se procedures shall be guided and approved by the FAA.

Some aspects of the proposed design and means of co mpliance that have been brought into question include:

• Adequacy of the means used to demonstrate the effe cts of lightning attachments

to vent outlets

• Potential for bypass valves to allow flames to byp ass a flame arrestor, either

under nominal or foreseeable failure conditions.

• Potential for hazardous ignition of fuel vapors wi thin the tank vents used for refueling on ground, either under nominal or forese eable failure conditions.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 design provide s an adequate level of safety for the interim period of this exemption and why granting i t is in the public interest, as required by 14 CFR 11.81.

Grounds Supporting Exemption

There are two models of flame arrestors installed i n the auxiliary tanks of the Legacy

650: - The forward and aft tanks use a circular shaped m odel, with no bypass valves; - The ventral tank that is being included uses a re ctangular shaped model that has two bypass valves;

Both models have the same honeycomb as the arrestin g element, being 2 inches long for the rectangular one and 1 inch long for the cir cular. The rectangular one has been certified at lightning strike zone 2A (more than 10 0 EMB-145XR airplanes flying with identical installation setup for accumulated 1.93 m illion hours) and the circular model has been certified for the baseline airplane EMB-13 5BJ – Legacy 600 in an identical installation at a lightning strike zone 2A (more th an 150 airplanes flying for accumulated 373 thousand hours). There is no record of damage d ue to lightning strikes on fuel system of these more than 250 airplanes that have f lown more than 2.4 million hours.

These flame arrestors models have passed a flame ho lding tests for at least 2.5 minutes (as required in the Special Condition IP P- 9 – Fuel Vent System Fire Protection document, Project #TC0714AT-T – EMB-145).

Similar models have been subjected to lightning str ike testing using Zone 2A threat

levels as defined in the AC 20-53.

While Embraer has successfully used this method in the past, we were recently informed by the certification authorities that to f ind compliance with the 25.954 requirement additional testing and/or analysis woul d be required.

However, currently there is no formal standard, pol icy or guidance from the authorities as to how this additional testing and/or analysis s hould be performed. Therefore time is required to reach agreement on mean of compliance a nd perform the additional testing and/or analysis.

Embraer intends to perform the tests by the end of October 2011 on the auxiliary tanks vent, but the actual timeframe depends upon the tes t guideline be provided. Regarding the test articles, Embraer intends to test the curr ent design of vent outlets with the current flame arrestors and in what regards the byp ass valves, with them open, simulating their fault.GCF

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Embraer requests a provision for up to 3 years from the date of granting this exemption should design changes be necessary. Such design cha nges would be incorporated into production and service instructions provided within these three years.

It is important to note that the probability of a l ightning strike to attach to a vent outlet is very low, given the vents areas by total zone 2 are a ratio is 2.16 x 10 -5 (this can be assessed as the distribution of the lightning strik es is randomly spread, being the vent outlets not a ‘preferred’ attachment point as they are not protruding from the fuselage skin) and that the probability of a lightning to st rike the EMB-145 aircraft (from service data) is 5.67 x 10 -4 per flight which gives an overall probability of 1 .22 x 10 -8 . This leads to, given the auxiliary tanks of the Legacy 650 hav e been demonstrated to have low flammability levels (around 3%), to a probability o f ignition of the effluent from the vents

is in the order of 10 -9

.

This way, the design aspects that have been found i mpractical to demonstrate compliance with those requirements, considering the very low probability of incidence of lightning strikes and flammability levels, provide adequate safety levels for the auxiliary tanks vent against ignition from lightning strikes, within the time period of this exemption.

Issue of Public Interest

Denial of this petition for exemption would result in the delay in certification and delivery of the Legacy 650 to the United States (U.S.). Alth ough these airplanes are not manufactured in the U. S., a significant portion of the airplane, including the engines, avionics, interiors and the fuel system parts are s upplied by U.S. manufacturers. Denial of this exemption request would result in the loss of revenue for these U.S. manufacturers and have an adverse impact on the U.S . balance of trade, both of which are counter to the public interest.

In addition, our U.S. customers have made fleet sch edule plans based on the agreedupon 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 the flame arrestor installation in the Lega cy 650 is identical to those found in other airplanes in service, the granting of this ex emption to 14 CFR § 25.954 and § 25.901(c) would create no precedent compared to pre vious models, both from Embraer and other manufacturers, that have been certified w ithout exemptions. In addition, this petition requests only 12 months to complete the te sts and assessments for theGCF

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identified aspects. Accordingly, Embraer requests t hat the FAA does not delay granting of this exemption for publication of the petition s ummary 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 Legacy 650 by the end of December 2010 that has already been delayed to m iddle February due to the certification process. As above mentioned, more del ays in the delivery will adversely affect this operator forcing him to seek alternativ es to his planned use of the airplane, such as canceling scheduled flights, chartering alt ernative lift, etc. or even canceling the

contract.

Embraer also notes that this petition was filed imm ediately after identified the impracticability of FAA in finding the 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-145XR and Legacy 600 fleet (more tha n 250 airplanes worldwide) have the same auxiliary tank fuel vents as the Legacy 65 0. There are more than 140 of such airplanes currently operating safely within the U.S . territory for over 8 (eight) years and are expected to continue to do so for many years to come. Eight airplanes are expected to be delivered within the first 12 months. If comp liance is found there would have been no effect on safety. If modifications are required at most a total of 25 aircraft would have been added to the current fleet within the three ye ars of this exemption. Therefore, granting this exemption will not significantly affe ct the overall safety of the U.S. fleet, as

the contributions of the accumulated hours of the 2 5 more airplanes (that have low utilization typical of such business jets) with a s imilar level of risk to that fleet, clearly represent a negligible impact on the total fleet sa fety.

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 some of our operators will certainly fly the Legacy 650 int ernationally. The granting of this petition will not conflict with any of the terms of ICAO Annex 8, so the FAA will not need to file a difference with ICAO, as described in 51 1.83.