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Special Conditions: Embraer S.A., Model EMB-500; Fire Extinguishing for Aft Fuselage Mounted Engines

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Information about this document as published in the Federal Register.

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Federal Aviation Administration (FAA), DOT.


Final special conditions; request for comments.


These special conditions are issued for the Embraer Model EMB-500 airplane. This airplane will have a novel or unusual design feature(s) associated with aft mounted engine fire protection. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for this design feature. These special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.


The effective date of these special conditions is January 7, 2008. Comments must be received on or before February 19, 2008.


Comments on these special conditions may be mailed in duplicate to: Federal Aviation Administration, Regional Counsel, ACE-7, Attention: Rules Docket CE281, 901 Locust, Room 506, Kansas City, Missouri 64106; or delivered in duplicate to the Regional Counsel at the above address. Comments may be inspected in the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

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Peter L. Rouse, Federal Aviation Administration, Aircraft Certification Service, Small Airplane Directorate, ACE-111, 901 Locust, Room 301, Kansas City, Missouri 64106; 816-329-4135, fax 816-329-4090.

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Comments Invited

Interested persons are invited to submit such written data, views, or arguments as they may desire. Identify the regulatory docket or special condition number and submit comments in duplicate to the address specified above. All communications received on or before the closing date for comments will be considered by the Administrator. The special conditions may be changed in light of the comments received. All comments received will be available in the Rules Docket for examination by interested persons, both before and after the closing date for comments. A report summarizing each substantive public contact with FAA personnel concerning this rulemaking will be filed in the docket. If you wish the FAA to acknowledge receipt of the comments submitted in response to this notice, include a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. CE281.” The postcard will be date stamped and returned to the commenter.


On October 5, 2005, Embraer S.A. applied for a type certificate for their new Model EMB-500. The Model EMB-500 is a normal category, low-winged monoplane with “T” tailed vertical and horizontal stabilizers, retractable tricycle type landing gear and twin turbofan engines mounted on the aircraft fuselage. Its design characteristics include a predominance of metallic construction. The maximum takeoff weight is 9,700 pounds, the VMO/MMO is 275 KIAS/M 0.70 and maximum altitude is 41,000 feet.

14 CFR part 23 has historically addressed fire protection through prevention, identification, and containment. Prevention has been provided through minimizing the potential for ignition of flammable fluids and vapors. Identification has been provided by locating engines within the pilots' primary field of view and/or with the incorporation of fire detection systems. This has provided both rapid detection of a fire and confirmation when it was extinguished. Containment has been provided through the isolation of designated fire zones, through flammable fluid shutoff valves, and firewalls.

This containment philosophy also ensures that components of the engine control system will function effectively to permit a safe shutdown of an engine. However, containment has only been demonstrated for 15 minutes. If a fire occurs in traditional part 23 airplanes, the appropriate corrective action is to land as soon as possible. For a small, simple airplane originally envisioned by part 23, it is possible to descend and land within 15 minutes; thus, the occupants can safely exit the airplane before the firewall is breached. These simple airplanes normally have the engine located away from critical flight control systems and primary structure. This has ensured that, throughout a fire event, a pilot can continue safe flight, and it has made the prediction of fire Start Printed Page 3386effects relatively easy. Other design features of these simple aircraft, such as low stall speeds and short landing distances, ensure that even if an off-field landing occurs, the potential for the outcome being catastrophic has been minimized.

Title 14 CFR part 23 did not envision the type of configuration of the Model EMB-500 airplane. The Model EMB-500 incorporates two turbofan engines located on pylons on either side of the aft fuselage. These engines are not in the pilots' field of view. With the location on the aft fuselage, the ability to visually detect a fire is minimal.

Type Certification Basis

Under the provisions of 14 CFR 21.17, Embraer S.A. must show that the Model EMB-500 meets the applicable provisions of 14 CFR part 23, as amended by Amendments 23-1 through 23-55, thereto.

If the Administrator finds that the applicable airworthiness regulations (i.e., 14 CFR part 23) do not contain adequate or appropriate safety standards for the Model EMB-500 because of a novel or unusual design feature, special conditions are prescribed under the provisions of § 21.16.

In addition to the applicable airworthiness regulations and special conditions, the Model EMB-500 must comply with the fuel vent and exhaust emission requirements of 14 CFR part 34 and the noise certification requirements of 14 CFR part 36, and the FAA must issue a finding of regulatory adequacy pursuant to section 611 of Public Law 92-574, the “Noise Control Act of 1972.”

Special conditions, as appropriate, as defined in 11.19, are issued under § 11.38, and become part of the type certification basis under § 21.17(a)(2).

Special conditions are initially applicable to the model for which they are issued. Should the type certificate for that model be amended later to include any other model that incorporates the same novel or unusual design feature, the special conditions would also apply to the other model under the provisions of § 21.101(a)(1).

Novel or Unusual Design Features

The Model EMB-500 incorporates two turbofan engines located on pylons on either side of the aft fuselage. These engines are not in the pilots' field of view. The effects of a fire in such a compartment are more varied and adverse than the typical engine fire in a simple part 23 airplane. With the location on the aft fuselage, the ability to visually detect a fire is minimal. However, the ability to extinguish an engine fire becomes extremely critical with the Model EMB-500 engine location.


As discussed above, these special conditions are applicable to the Model EMB-500. Should Embraer S. A. apply later for a change to the type certificate to include another model incorporating the same novel or unusual design feature, the special conditions would apply to that model as well under § 21.101(a)(1).

Good Cause

The FAA has determined that notice and opportunity for prior public comment hereon are impracticable because these procedures would significantly delay issuance of the design approval and thus delivery of the affected aircraft. In addition, the substance of these special conditions has been subject to the public comment process in several prior instances with no substantive comments received. The FAA therefore finds that good cause exists for making these special conditions effective upon issuance.


Under standard practice, the effective date of final special conditions would be 30 days after the date of publication in the Federal Register; however, as the certification date for the Embraer S. A. Model EMB-500 is imminent, the FAA finds that good cause exists to make these special conditions effective upon issuance.

This action affects only certain novel or unusual design features on one model, Model EMB-500, of airplane. It is not a rule of general applicability, and it affects only the applicant who applied to the FAA for approval of these features on the airplane.

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List of Subjects in 14 CFR Part 23

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The authority citation for these special conditions is as follows:

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Authority: 49 U.S.C. 106(g), 40113 and 44701; 14 CFR 21.16 and 21.17; and 14 CFR 11.38 and 11.19.

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The Special Conditions

Accordingly, pursuant to the authority delegated to me by the Administrator, the following special conditions are issued as part of the type certification basis for Embraer S. A. Model EMB-500 airplanes.

1. SC 23.1195—Add the requirements of § 23.1195 while deleting the phrase, “For commuter category airplanes.”

23.1195, Fire Extinguishing Systems

(a) Fire extinguishing systems must be installed and compliance shown with the following:

(1) Except for combustor, turbine, and tailpipe sections of turbine-engine installations that contain lines or components carrying flammable fluids or gases for which a fire originating in these sections is shown to be controllable, a fire extinguisher system must serve each engine compartment;

(2) The fire extinguishing system, the quantity of extinguishing agent, the rate of discharge, and the discharge distribution must be adequate to extinguish fires. An individual “one-shot” system may be used; and

(3) The fire extinguishing system for a nacelle must be able to simultaneously protect each compartment of the nacelle for which protection is provided.

(b) If an auxiliary power unit is installed in any airplane certificated to this part, that auxiliary power unit compartment must be served by a fire extinguishing system meeting the requirements of paragraph (a)(2) of this section.

2. SC 23.1197—Add the requirements of § 23.1197 while deleting the phrase, “For commuter category airplanes.”

23.1197, Fire Extinguishing Agents

The following applies:

(a) Fire extinguishing agents must—

(1) Be capable of extinguishing flames emanating from any burning fluids or other combustible materials in the area protected by the fire extinguishing system; and

(2) Have thermal stability over the temperature range likely to be experienced in the compartment in which they are stored.

(b) If any toxic extinguishing agent is used, provisions must be made to prevent harmful concentrations of fluid or fluid vapors (from leakage during normal operation of the airplane or as a result of discharging the fire extinguisher on the ground or in flight) from entering any personnel compartment, even though a defect may exist in the extinguishing system. This must be shown by test except for built-in carbon dioxide fuselage compartment fire extinguishing systems for which—

(1) Five pounds or less of carbon dioxide will be discharged under established fire control procedures into any fuselage compartment; or

(2) Protective breathing equipment is available for each flight crewmember on flight deck duty. Start Printed Page 3387

3. SC 23.1199—Add the requirements of § 23.1199 while deleting the phrase, “For commuter category airplanes.”

23.1199, Extinguishing Agent Containers

The following applies:

(a) Each extinguishing agent container must have a pressure relief to prevent bursting of the container by excessive internal pressures.

(b) The discharge end of each discharge line from a pressure relief connection must be located so that discharge of the fire-extinguishing agent would not damage the airplane. The line must also be located or protected to prevent clogging caused by ice or other foreign matter.

(c) A means must be provided for each fire extinguishing agent container to indicate that the container has discharged or that the charging pressure is below the established minimum necessary for proper functioning.

(d) The temperature of each container must be maintained, under intended operating conditions, to prevent the pressure in the container from—

(1) Falling below that necessary to provide an adequate rate of discharge; or

(2) Rising high enough to cause premature discharge.

(e) If a pyrotechnic capsule is used to discharge the fire extinguishing agent, each container must be installed so that temperature conditions will not cause hazardous deterioration of the pyrotechnic capsule.

4. SC 23.1201—Add the requirements of § 23.1201 while deleting the phrase, “For commuter category airplanes.”

23.1201, Fire Extinguishing System Materials

The following apply:

(a) No material in any fire extinguishing system may react chemically with any extinguishing agent so as to create a hazard.

(b) Each system component in an engine compartment must be fireproof.

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Issued in Kansas City, Missouri on January 7, 2008.

John Colomy,

Acting Manager, Small Airplane Directorate, Aircraft Certification Service.

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[FR Doc. E8-849 Filed 1-17-08; 8:45 am]