[Federal Register Volume 78, Number 42 (Monday, March 4, 2013)]
[Rules and Regulations]
[Pages 14007-14009]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-04854]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2012-1292; Special Conditions No. 25-485-SC]


Special Conditions: Embraer S.A., Model EMB-550 Airplanes; 
Electrical/Electronic Equipment Bay Fire Detection and Smoke 
Penetration

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions.

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SUMMARY: These special conditions are issued for the Embraer S.A. Model 
EMB-550 airplane. This airplane will have novel or unusual design 
features, specifically distributed electrical and electronic equipment 
bays in pressurized areas of the airplane. Older transport category 
airplane electrical/electronic equipment bay installations are located 
in the lower lobe where the flight crew could determine the origin of 
smoke or fire by a straightforward airplane flight manual procedure. In 
distributed electrical/electronic bay installations it is not as 
straightforward. The FAA has no requirement for smoke and/or fire 
detection in the electrical/electronic equipment bays. To ensure 
effective mitigation of fires, the FAA proposes these special 
conditions. 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.

DATES: Effective April 3, 2013.

FOR FURTHER INFORMATION CONTACT: Robert C. Jones, FAA, Propulsion and 
Mechanical Systems Branch, ANM-112, Transport Airplane Directorate, 
Aircraft Certification Service, 1601 Lind Avenue SW., Renton, 
Washington 98057-3356; telephone 425-227-1234; facsimile 425-227-1149.

SUPPLEMENTARY INFORMATION: 

Background

    On May 14, 2009, Embraer S.A. applied for a type certificate for 
their new Model EMB-550 airplane. The Model EMB-550 airplane is the 
first of a new family of jet airplanes designed for corporate flight, 
fractional, charter, and private owner operations. The airplane has a 
conventional configuration with a low wing and T-tail empennage. The 
primary structure is metal with composite empennage and control 
surfaces. The Model EMB-550 airplane is designed for 8 passengers, with 
a maximum of 12 passengers. It is equipped with two Honeywell HTF7500-E 
medium bypass ratio turbofan engines mounted on aft fuselage pylons. 
Each engine produces approximately 6,540 pounds of thrust for normal 
takeoff. The primary flight controls consist of hydraulically powered 
fly-by-wire elevators, aileron and rudder, controlled by the pilot or 
copilot sidestick.
    The Model EMB-550 airplane has electrical/electronic equipment bays 
distributed throughout the airplane; three of them are in the 
pressurized area. The current airworthiness requirements do not contain 
adequate or appropriate safety standards regarding smoke/fire detection 
and protection against penetration of hazardous quantities of smoke 
from equipment bays into occupied areas of the airplane for this type 
of airplane configuration.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.17, Embraer S.A. must show that the Model EMB-550 airplane 
meets the applicable provisions of part 25, as amended by Amendments 
25-1 through 25-127 thereto.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 25) do not contain adequate or 
appropriate safety standards for the Model EMB-550 airplane because of 
a novel or unusual design feature, special conditions are prescribed 
under the provisions of Sec.  21.16.
    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 or similar 
novel or unusual design feature, the special conditions would also 
apply to the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model EMB-550 airplane 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 under section 611 of Public Law 92-574, 
the ``Noise Control Act of 1972.''
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of the type-
certification basis under Sec.  21.17(a)(2).

Novel or Unusual Design Features

    The Model EMB-550 airplane will incorporate the following novel or 
unusual design features: Distributed electrical and electronic 
equipment bays that were not envisioned at the time this rule was made.

Discussion

    In general, smoke and fire detection systems are designed to:
     Automatically shut off power to the affected equipment,
     If necessary, reconfigure the environmental control 
systems to control any smoke resulting from a fire or overheat 
condition, and
     Alert the flight crew to the existence of the fire.
    Most airplanes certified under part 25 have one or two electrical 
equipment bays located in the lower lobe, adjacent to pressure 
regulator/outflow valves or vents. If a fire occurs in an electrical 
equipment bay, any smoke is drawn toward the outflow valves or vents 
and is discharged from the airplane without entering occupied areas. In 
the event of a smoke or fire in one of the electrical equipment bays, 
the procedures to isolate the bay on some airplanes requires the flight 
crew to use trial and error to determine whether or not the source is 
in a particular electrical equipment bay. However, with this approach, 
the flight crew does not know where the fire or smoke is because it is 
difficult to identify the source, especially during changes of phases 
of flight (e.g., climbing or descending) or system transients (e.g., 
changes in the airflow from the environmental control system).
    This trial-and-error approach may be acceptable for aircraft with 
no more

[[Page 14008]]

than two electrical equipment bays, both located in the lower lobe. In 
this case, a fire in an electrical equipment bay is in either one bay 
or the other. However, for an aircraft with three or more electrical 
equipment bays, in the time it takes to determine the source of smoke, 
the fire could spread, generating even more smoke and damage.
    In the Model EMB-550 airplane, electrical equipment bays are 
distributed throughout the airplane in the pressurized compartment. 
Section 25.857 requires that cargo compartments have means to prevent 
hazardous quantities of smoke or fire extinguishing agent from 
penetrating into occupied areas of the airplane. However, the 
applicable airworthiness regulations do not address the following:
     Preventing hazardous quantities of smoke or extinguishing 
agent originating from the electrical equipment bays from penetrating 
into occupied areas of the airplane; or
     Installing smoke or fire detectors in electrical equipment 
bays.
    The FAA determined that the Model EMB-550 needs a means to detect 
smoke or fire in each electrical equipment bay that is located in the 
pressurized cabin. This means must indicate in which bay the smoke or 
fire occurs, and ensure that the flight crew can depower it. For 
situations in which it may be impossible for the flight crew to shut 
down all the equipment in the bay due to the use of critical or 
essential equipment located in it, Embraer S.A. shall conduct an 
analysis to:
     Specify the criteria for shutting down specific electrical 
equipment in the electrical equipment bay that can be shut down,
     Demonstrate that remaining electrical equipment is 
protected against fire propagation, such as thermal protection, fire 
containment, and other systems as addressed in Advisory Circular 25-16, 
Electrical Fault and Fire Prevention and Protection, dated April 5, 
1991.
    The criteria developed for aircraft designs that incorporate 
distributed electrical/electronic equipment bays are based upon 
existing smoke/fire detection and smoke penetration guidance and 
acceptable past practices. Sections 25.831(b), 25.831(c), 25.831(d), 
and 25.869(a) provide the general requirements that apply to 
electrical/electronic equipment smoke penetration and evacuation. 
Flight tests are conducted to demonstrate compliance; however, the 
amount of smoke generated and flight test conditions have been highly 
variable.
    The special conditions below require that there must be a means to 
detect smoke or fire in each electrical/electronic equipment bay 
located in the pressurized compartment. They also include requirements 
to prevent propagation of hazardous quantities of smoke or fire 
extinguishing agent throughout the passenger cabin.

Discussion of Comments

    Notice of proposed special conditions No. 25-12-17-SC for the 
Embraer S.A. Model EMB-550 airplanes was published in the Federal 
Register on December 19, 2012 (77 FR 75071). No comments were received, 
and the special conditions are adopted as proposed.

Applicability

    As discussed above, these special conditions are applicable to the 
Model EMB-550 airplane. Should Embraer S.A. apply at a later date 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.

Conclusion

    This action affects only certain novel or unusual design features 
on one model of airplanes. It is not a rule of general applicability.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

    The authority citation for these special conditions is as follows:

    Authority:  49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for Embraer S.A. Model EMB-550 airplanes.
    1. Requirements to prevent propagation of smoke that originates in 
electrical equipment bays from entering the passenger cabin and flight 
deck:
    a. To prevent such propagation, means to prevent hazardous 
quantities of smoke originating from the electrical equipment bays from 
incapacitating passengers and crew must be demonstrated. The 
demonstrations must include flight tests, and shall be conducted for 
all dispatchable system configurations.
    b. A small quantity of smoke may enter an occupied area only under 
the following conditions:
    i. The smoke enters occupied areas during system transients from 
below the deck or main deck sources. No sustained smoke penetration 
beyond that from environmental control system transients is permitted,
    ii. Penetration of the small quantity of smoke is a dynamic event, 
involving either dissipation or mobility. Dissipation is rapid dilution 
of the smoke by ventilation air. Mobility is rapid movement of the 
smoke into and out of the occupied area. In no case should a light haze 
indicative of stagnant airflow form, as this indicates that the 
ventilation system is failing to meet the requirements of 14 CFR 
25.831,
    iii. The smoke from a source below the main deck must not rise 
above armrest height on the main deck, and
    iv. The smoke from a source in the main deck must dissipate rapidly 
via dilution with fresh air and be evacuated from the airplane. The 
Airplane Flight Manual (AFM) must include procedures to evacuate smoke 
from the occupied areas. To demonstrate that the quantity of smoke is 
small, a flight test must be conducted which simulates the emergency 
procedures used in the event of a fire during flight, including the use 
of VMO/MMO descent profiles and a simulated 
landing, if such conditions are specified in the emergency procedure.
    2. Requirement for smoke or fire detection in electrical/electronic 
equipment bays: A smoke or fire detection system compliant with 
Sec. Sec.  25.855(a), (b), (c), and (d); and Sec.  25.858 must be 
provided for each electrical/electronic equipment bay in the 
pressurized cabin. Each system must provide a visual indication to the 
flight deck within one minute after the start of a fire. Airplane 
flight tests must be conducted to show compliance with these 
requirements, and the performance of the detectors must be shown in 
accordance with Advisory Circular 25-9A, Smoke Detection, Penetration, 
and Evacuation Tests and Related Flight Manual Emergency Procedures, or 
other means acceptable to the FAA.
    3. Requirement for AFM procedures safety analysis: It shall be 
demonstrated that the AFM procedures to shut down electrical/electronic 
equipment bays, or part of them, in case of smoke/fire detection, do 
not compromise the safe operation of the aircraft. If a procedure 
requests to shut down only part of the equipment, the remaining 
equipment shall be incorporated with safety precautions against fire 
propagation.


[[Page 14009]]


    Issued in Renton, Washington, on February 26, 2013.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2013-04854 Filed 3-1-13; 8:45 am]
BILLING CODE 4910-13-P