[Federal Register Volume 72, Number 121 (Monday, June 25, 2007)]
[Proposed Rules]
[Pages 34644-34646]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-12121]


 ========================================================================
 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
 
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 

  Federal Register / Vol. 72, No. 121 / Monday, June 25, 2007 / 
Proposed Rules  

[[Page 34644]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 23

[Docket No. CE270; Notice No. 23-07-02-SC]


Special Conditions: Adam Aircraft, Model A700; Fire Extinguishing 
for Aft Fuselage Mounted Engines

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Adam Aircraft, 
Model A700 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 proposed 
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: We must receive your comments by July 25, 2007.

ADDRESSES: Mail two copies of your comments to: Federal Aviation 
Administration, Regional Counsel, ACE-7, 901 Locust, Room 506, Kansas 
City, Missouri 64106. You may deliver two copies to the Small Airplane 
Directorate at the above address. Mark your comments: Docket No. CE270. 
You may inspect comments in the Rules Docket weekdays, except Federal 
holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Leslie B. Taylor, Regulations & Policy 
Branch, ACE-111, Federal Aviation Administration, Small Airplane 
Directorate, Aircraft Certification Service, 901 Locust, Kansas City, 
MO 64106; telephone (816) 329-4134; facsimile (816) 329-4090, e-mail at 
[email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    We invite interested parties to take part in this rulemaking by 
sending written comments, data, or views. The most helpful comments 
reference a specific portion of the special conditions, explain the 
reason for any recommended change, and include supporting data. We ask 
that you send us two copies of written comments.
    We will file in the docket all comments we receive, as well as a 
report summarizing each substantive public contact with FAA personnel 
concerning these special conditions. You may inspect the docket before 
and after the comment closing date. If you wish to review the docket in 
person, go to the address in the ADDRESSES section of this preamble 
between 7:30 a.m. and 4 p.m., Monday through Friday, except Federal 
holidays.
    We will consider all comments we receive on or before the closing 
date for comments. We will consider comments filed late if it is 
possible to do so without incurring expense or delay. We may change 
these special conditions based on the comments we receive.
    If you want the FAA to acknowledge receipt of your comments on this 
proposal, include with your comments a pre-addressed, stamped postcard 
on which the docket number appears. We will stamp the date on the 
postcard and mail it back to you.

Background

    On April 12, 2004, Adam Aircraft applied for a type certificate for 
their new Model A700. The Model A700, is a 6 to 8 seat, pressurized, 
retractable-gear, composite structure airplane with two turbofan 
engines mounted on pylons on either side of the aft fuselage.
    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 effects relatively easy. Other design features of these simple 
aircraft, such as low stall speeds and short landing distances, ensure 
that even in the event of an off field landing, 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 A700 airplane. The Model A700 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 in the 
aft fuselage, the ability to visually detect a fire is minimal.

Type Certification Basis

    Under 14 CFR 21.17, Adam Aircraft must show that the Model A700 
meets the applicable provisions of part 23, as amended by Amendments 
23-1 through 23-55 thereto.
    If the Administrator finds that the applicable airworthiness 
regulations in 14 CFR part 23 do not contain adequate or appropriate 
safety standards for the Model A700 because of a novel or unusual 
design feature, special conditions are prescribed under Sec.  21.16.
    In addition to the applicable airworthiness regulations and special 
conditions, the Model A700 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 Sec.  611 of Public Law 92-574, the ``Noise 
Control Act of 1972.''
    The FAA issues special conditions, as defined in Sec.  11.19, under 
Sec.  11.38, and they become part of the type certification basis under 
Sec.  21.17(a)(2).

[[Page 34645]]

    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.

Novel or Unusual Design Features

    The Model A700 will incorporate the following novel or unusual 
design features:
    The Model A700 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 in 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 A700 engine 
location.
    While the certification basis for the Model A700 requires that a 
fire detection system be installed due to the engine location, fire 
extinguishing is also considered a requirement. A sustained fire could 
result in loss of control of the airplane and damage to primary 
structure before an emergency landing could be made. Because of the 
location of critical structures and flight controls, a means to 
minimize the probability of re-ignition from occurring is necessary. 
One acceptable method to minimize re-ignition is to install a two-shot 
system. The effects of a fire emanating from an enclosed engine 
installation are more varied, adverse, and more difficult to predict 
than an engine fire envisioned for typical part 23 airplanes.

Discussion

    The engines are on pylons on either side of the aft fuselage so 
there is a need to prevent flammable vapors, flammable fluids, and 
flame from accumulating. Finally, there is a need to extinguish fires.

Applicability

    As discussed above, these special conditions are applicable to the 
Model A700. Should Adam Aircraft 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.

Conclusion

    This action affects only certain novel or unusual design features 
on one model 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.

List of Subjects in 14 CFR Part 23

    Aircraft, Aviation safety, Signs and symbols.

Citation

    The authority citation for these special conditions is as follows:

    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.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for Adam Aircraft, Model A700 airplanes.
    Aft fuselage mounted engines need to protect the airplane from 
fires that were not envisioned in the development of part 23. 
Therefore, special conditions for a fire extinguishing system are 
required for airplanes with this engine configuration.
    Regulations requiring and defining engine compartment fire 
extinguishing systems already exist for part 23 commuter category 
airplanes. These regulations will provide an adequate level of safety 
for the normal category Model A700 aircraft with its aft pylon mounted 
engines.
    As the extinguishing agent is subject to change during the service 
life of the airplane, the certification basis has the need to include 
14 CFR part 23, Sec.  23.1197 in its entirety.
    Each fire zone should be ventilated to prevent the accumulation of 
flammable vapors. It must also be designed such that it will not allow 
entry of flammable fluids, vapors, or flames from other fire zones. It 
must be designed such that it does not create an additional fire hazard 
from the discharge of vapors or fluids.
    1. SC 23.1195--Add the requirements of Sec.  23.1195 while deleting 
``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 except for embedded engines where a ``two-shot'' system is 
required.
    (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 Sec.  23.1197 while deleting 
``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.
    3. SC 23.1199--Add the requirements of Sec.  23.1199 while deleting 
``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

[[Page 34646]]

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 Sec.  23.1201 while deleting 
``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.

    Issued in Kansas City, Missouri, on June 14, 2007.
Kim Smith,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. E7-12121 Filed 6-22-07; 8:45 am]
BILLING CODE 4910-13-P