[Federal Register: January 10, 2007 (Volume 72, Number 6)]
[Rules and Regulations]
[Page 1135-1137]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr10ja07-2]
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DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM348; Special Conditions No. 25-343-SC]
Special Conditions: Dassault Aviation Model Falcon 7X Airplane,
Windshield Coating in Lieu of Wipers
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
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SUMMARY: This special condition is issued for the Dassault Aviation
Model Falcon 7X airplane. This airplane will have a novel or unusual
design feature associated with use of a hydrophobic windshield coating,
rather than windshield wipers, as the means to maintain a clear portion
of the windshield during precipitation conditions, as required by the
airworthiness standards for transport category airplanes. The
applicable airworthiness regulations do not contain adequate or
appropriate safety standards for this design feature. This special
condition contains the additional safety standards that the
Administrator considers necessary to establish a level of safety
equivalent to that established by the existing airworthiness standards.
[[Page 1136]]
DATES: Effective Date: December 29, 2006.
FOR FURTHER INFORMATION CONTACT: John McConnell, Airplane and Flight
Crew Interface Branch, ANM-111, Transport Airplane Directorate,
Aircraft Certification Service, 1601 Lind Avenue, SW., Renton,
Washington 98057-3356; telephone (425) 227-1365; facsimile (425) 227-
1320; e-mail john.mcconnell@faa.gov.
SUPPLEMENTARY INFORMATION:
Background
On June 4, 2002, Dassault Aviation, 9 rond Point des Champs
Elys[eacute]es, 75008, Paris, France, applied for a type certificate
for its new Model Falcon 7X airplane. The Model Falcon 7X is a 19
passenger transport category airplane, powered by three aft mounted
Pratt & Whitney PW307A high bypass ratio turbofan engines. Operation of
the airplane is accomplished using a fly-by-wire (FBW) primary flight
control system. This will be the first application of a FBW primary
flight control system in a private/corporate use airplane.
The Dassault Aviation Model Falcon 7X flightdeck design
incorporates a hydrophobic windshield coating to provide adequate pilot
compartment view in the presence of precipitation. Primary reliance on
such a coating, without windshield wipers, constitutes a novel or
unusual design feature for which the applicable airworthiness
regulations do not contain adequate or appropriate safety standards.
Therefore, a special condition is required that provides the level of
safety equivalent to that established by the regulations.
Type Certification Basis
Under the provisions of 14 CFR 21.17, Dassault Aviation must show
that the Model Falcon 7X airplane meets the applicable provisions of
part 25, as amended by Amendment 25-1 through Amendment 25-108.
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 Falcon 7X because of a novel
or unusual design feature, special conditions are prescribed under the
provisions of Sec. 21.16.
In addition to the applicable airworthiness regulations and special
conditions, the Model Falcon 7X 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. The FAA must also 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).
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 Falcon 7X will incorporate the following novel or unusual
design feature: Hydrophobic windshield coating to provide adequate
pilot compartment view in the presence of precipitation. Sole reliance
on such a coating, without windshield wipers or a windshield blower,
constitutes a novel or unusual design feature for which the applicable
airworthiness regulations do not contain adequate or appropriate safety
standards.
Discussion
Section 25.773(b)(1) requires that both pilots of a transport
category airplane be provided a means to maintain a sufficiently clear
portion of the windshield during precipitation conditions, and that
this clear portion of the windshield must have a sufficiently extensive
view along the flight path. The regulations require this means to
maintain such an area during precipitation in heavy rain at speeds up
to 1.5 VSR1.
This requirement has existed in principle since 1953 in Part 4b of
the Civil Air Regulations (CAR). Section 4b.351(b)(1) of CAR 4b
required that ``Means shall be provided for maintaining a sufficient
portion of the windshield clear so that both pilots are afforded a
sufficiently extensive view along the flight path in all normal flight
attitudes of the airplane. Such means shall be designed to function
under the following conditions without continuous attention on the part
of the crew: (i) In heavy rain at speeds up to 1.6 VS1,
flaps retracted.'' Effective December 26, 2002, Amendment 25-108
changed the speed for effectiveness of the means to maintain an area of
clear vision from up to 1.6 VS1 to 1.5 VSR1 to
accommodate the redefinition of the reference stall speed from the
minimum speed in the stall, VS1, to greater than or equal to
the 1-g stall speed. As noted in the preamble to the final rule for
that amendment, the reduced factor of 1.5 on VSR1 is to
maintain approximately the same speed as the 1.6 factor on
VS1.
The requirement that the means to maintain a clear area of forward
vision must function at high speeds and high precipitation rates is
based on the use of windshield wipers as the means to maintain an
adequate area of clear vision in precipitation conditions. The
requirement in 14 CFR 121.313(b), and in 14 CFR 125.213(b), to provide
``a windshield wiper or equivalent for each pilot station'' has
remained unchanged since at least 1953.
The effectiveness of windshield wipers to maintain an area of clear
vision normally degrades as airspeed and precipitation rates increase.
It is assumed that because high speeds and high precipitation rates
represent limiting conditions for windshield wipers, they will also be
effective at lower speeds and precipitation levels. Accordingly, Sec.
25.773(b)(1)(i) does not require maintenance of a clear area of forward
vision at lower speeds or lower precipitation rates.
A forced airflow blown directly over the windshield has also been
used to maintain an area of clear vision in precipitation. The limiting
conditions for this technology are comparable to those for windshield
wipers. Accordingly, introduction of this technology did not present a
need for special conditions to maintain the level of safety embodied in
the existing regulations.
Hydrophobic windshield coatings may depend to some degree on
airflow directly over the windshield to maintain a clear vision area.
The heavy rain and high-speed conditions specified in the current rule
do not necessarily represent the limiting conditions for this new
technology. For example, airflow over the windshield, which may be
necessary to remove moisture from the windshield, may not be adequate
to maintain a sufficiently clear area of the windshield in low speed
flight or during ground operations. Alternatively, airflow over the
windshield may be disturbed during such critical times as the approach
to land, where the airplane is at a higher than normal pitch attitude.
In these cases, areas of airflow disturbance or separation on the
windshield could cause failure to maintain a clear vision area on the
windshield.
In addition to potentially depending on airflow to function
effectively, hydrophobic coatings may also be dependent on water
droplet size for effective precipitation removal. For example,
precipitation in the form of a light mist may not be sufficient for the
[[Page 1137]]
coating's properties to result in maintaining a clear area of vision.
In summary, the current regulations identify speed and
precipitation rate requirements that represent limiting conditions for
windshield wipers and blowers, but not for hydrophobic coatings, so it
is necessary to issue special conditions to maintain the level of
safety represented by the current regulations.
These special conditions provide an appropriate safety standard for
the hydrophobic coating technology as the means to maintain a clear
area of vision by requiring it to be effective at low speeds and
precipitation rates as well as the higher speeds and precipitation
rates identified in the current regulation. These are the only new or
changed requirements relative to those in Sec. 25.773(b)(1) at
Amendment 25-108.
Discussion of Comments
Notice of proposed special condition No. 25-06-07 for the Dassault
Aviation Model Falcon 7X airplane was published in the Federal Register
on July 12, 2006 (71 FR 39235). No comments were received and this
special condition is adopted as proposed.
Applicability
As discussed above, this special condition is applicable to the
Model Falcon 7X. Should Dassault Aviation apply at a later date for a
change to the type certificate to include another model on the same
type certificate incorporating the same novel or unusual design
feature, the special condition would apply to that model as well.
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 Dassault
Model Falcon 7X is imminent, the FAA finds that good cause exists to
make this special condition effective upon issuance.
Conclusion
This action affects only certain novel or unusual design features
on one model of airplane. 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 this special condition is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Special Condition
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special condition is issued as part of the
type certification basis for Dassault Aviation Model Falcon 7X
airplanes.
Pilot Compartment View--Hydrophobic Coatings in Lieu of Windshield
Wipers
The airplane must have a means to maintain a clear portion of the
windshield, during precipitation conditions, enough for both pilots to
have a sufficiently extensive view along the ground or flight path in
normal taxi and flight attitudes of the airplane. This means must be
designed to function, without continuous attention on the part of the
crew, in conditions from light misting precipitation to heavy rain at
speeds from fully stopped in still air, to 1.5 VSR1 with
lift and drag devices retracted.
Issued in Renton, Washington, on December 29, 2006.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. E7-200 Filed 1-9-07; 8:45 am]
BILLING CODE 4910-13-P