[Federal Register: August 15, 2007 (Volume 72, Number 157)]
[Rules and Regulations]
[Page 45624-45626]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr15au07-2]
=======================================================================
-----------------------------------------------------------------------
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 23
[Docket No. CE270; Special Condition No. 23-210-SC]
Special Conditions: Adam Aircraft, Model A700; Fire Extinguishing
for Aft Fuselage Mounted Engines
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
-----------------------------------------------------------------------
SUMMARY: These special conditions are issued for the Adam Aircraft,
Model A700 airplane. This airplane will have
[[Page 45625]]
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.
DATES: Effective Date: August 6, 2007
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
leslie.b.taylor@faa.gov.
SUPPLEMENTARY INFORMATION:
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.
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 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 part 21, Sec. 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 section 611 of Public Law 92-574, the ``Noise
Control Act of 1972.''
Discussion
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).
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 of Comments
A notice of proposed special conditions, Notice No. 23-07-02-SC,
for the Adam Aircraft Model A700 was published in the Federal Register
on June 25, 2007 (72 FR 34644). No comments were received, and the
special conditions are adopted as proposed.
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 Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special
[[Page 45626]]
conditions are issued 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 needs 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 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 August 6, 2007.
Kim Smith,
Manager, Small Airplane Directorate, Aircraft Certification Service.
[FR Doc. E7-15973 Filed 8-14-07; 8:45 am]
BILLING CODE 4910-13-P