[Federal Register Volume 72, Number 6 (Wednesday, January 10, 2007)]
[Rules and Regulations]
[Pages 1135-1137]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E7-200]


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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 [email protected].

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