[Federal Register Volume 80, Number 65 (Monday, April 6, 2015)]
[Rules and Regulations]
[Pages 18305-18307]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2015-07713]



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Rules and Regulations
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Federal Register / Vol. 80, No. 65 / Monday, April 6, 2015 / Rules 
and Regulations

[[Page 18305]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2015-0177; Special Conditions No. 25-579-SC]


Special Conditions: Cessna Aircraft Company Model 680A Airplane, 
Pilot-Compartment View Through Hydrophobic Windshield Coatings in Lieu 
of Windshield Wipers

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions, request for comment.

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SUMMARY: These special conditions are issued for the Cessna Model 680A 
airplane. This airplane will have a novel or unusual design feature 
when compared to the state of technology envisioned in the 
airworthiness standards for transport-category airplanes. This design 
feature is hydrophobic windshield coatings in lieu of windshield 
wipers. 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: This action is effective on Cessna Aircraft 
Company on April 6, 2015. We must receive your comments by May 21, 
2015.

ADDRESSES: Send comments identified by docket number FAA-2015-0177 
using any of the following methods:
    <bullet> Federal eRegulations Portal: Go to http://www.regulations.gov/ and follow the online instructions for sending 
your comments electronically.
    <bullet> Mail: Send comments to Docket Operations, M-30, U.S. 
Department of Transportation (DOT), 1200 New Jersey Avenue SE., Room 
W12-140, West Building Ground Floor, Washington, DC 20590-0001.
    <bullet> Hand Delivery or Courier: Take comments to Docket 
Operations in Room W12-140 of the West Building Ground Floor at 1200 
New Jersey Avenue SE., Washington, DC, between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays.
    <bullet> Fax: Fax comments to Docket Operations at 202-493-2251.
    Privacy: The FAA will post all comments it receives, without 
change, to http://www.regulations.gov/, including any personal 
information the commenter provides. Using the search function of the 
docket Web site, anyone can find and read the electronic form of all 
comments received into any FAA docket, including the name of the 
individual sending the comment (or signing the comment for an 
association, business, labor union, etc.). DOT's complete Privacy Act 
Statement can be found in the Federal Register published on April 11, 
2000 (65 FR 19477-19478), as well as at http://DocketsInfo.dot.gov/ gov/.
    Docket: Background documents or comments received may be read at 
http://www.regulations.gov/ at any time. Follow the online instructions 
for accessing the docket or go to Docket Operations in Room W12-140 of 
the West Building Ground Floor at 1200 New Jersey Avenue SE., 
Washington, DC, between 9 a.m. and 5 p.m., Monday through Friday, 
except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Bob Hettman, ANM-112, Transport 
Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue 
SW., Renton, Washington 98057-3356; telephone (425) 227-2683; facsimile 
(425) 227-1149.

SUPPLEMENTARY INFORMATION:

Background

    On January 25, 2012, Cessna Aircraft Company applied for an amended 
type certificate for a new Model 680A airplane.
    The Model 680A, a derivative of the Cessna Model 680 airplane 
currently approved under type-certificate number T00012WI, is intended 
to be a nine-passenger executive airplane with a maximum takeoff weight 
of 30,300 pounds and a maximum operating altitude of 45,000 feet. The 
Model 680A airplane uses a hydrophobic windshield coating, in lieu of 
windshield wipers, for an unobstructed outside view from the pilot 
compartment.

Type Certification Basis

    Under the provisions of Title 14, Code of Federal Regulations (14 
CFR) 21.101, Cessna Aircraft Company must show that the Model 680A 
airplane meets the applicable provisions of the regulations listed in 
type-certificate no. T00012WI, or the applicable regulations in effect 
on the date of application for the change except for earlier amendments 
as agreed upon by the FAA. The regulations listed in the type 
certificate are commonly referred to as the ``original type-
certification basis.''
    The certification basis includes certain special conditions, 
exemptions, or later amended sections of the applicable part that are 
not relevant to these special conditions.
    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 680A 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 novel or 
unusual design feature, or should any other model already included on 
the same type certificate be modified to incorporate the same or 
similar novel or unusual design feature, these 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 680A airplane must comply with the fuel-vent and 
exhaust-emission requirements of part 34, and the noise-certification 
requirements of part 36.
    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.  21.101.

Novel or Unusual Design Features

    The Cessna Model 680A airplane will incorporate the following novel 
or unusual design features:

[[Page 18306]]

    The airplane flight-deck design incorporates a hydrophobic 
windshield coating that, during precipitation, provides an adequate 
outside view from the pilot compartment. Sole 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, 
special conditions are required to provide a level of safety equivalent 
to that established by the regulations.

Discussion

    Section 25.773(b)(1) requires a means to maintain a clear portion 
of the windshield for both pilots of a transport-category airplane to 
have a sufficiently extensive view along the flight path during 
precipitation conditions. The regulations require this means to 
maintain such an area clear vision during heavy-rain precipitation at 
airplane speeds up to 1.5 V<INF>SR1</INF>.
    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 V<INF>S1</INF> to 1.5 V<INF>SR1</INF> to accommodate the 
redefinition of the reference stall speed from the minimum speed in the 
stall, V<INF>S1</INF>, to greater than or equal to the 1g stall speed, 
V<INF>SR1</INF>. As noted in the preamble to the final rule for that 
amendment, the reduced factor of 1.5 on V<INF>SR1</INF> is to maintain 
approximately the same speed as the 1.6 factor on V<INF>S1</INF>.
    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 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 to maintain a clear-vision area. The heavy rain and high speed 
conditions specified in the current rule do not necessarily represent 
the limiting condition 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-vision 
area of the windshield in low-speed flight or during surface 
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 
coating's properties to result in maintaining a clear area of vision.
    The current regulations identify speed and precipitation rate 
requirements that represent limiting conditions for windshield wipers 
and blowers, but not for hydrophobic coatings. Likewise, 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 the coating to be effective at low speeds 
and low precipitation rates, as well as at 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.
    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.

Applicability

    As discussed above, these special conditions are applicable to the 
Cessna Model 680A airplane. Should Cessna 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 the Cessna Model 680A airplane. It is not a rule of general 
applicability.
    The substance of these special conditions has been subjected to the 
notice and comment period in several prior instances and has been 
derived without substantive change from those previously issued. It is 
unlikely that prior public comment would result in a significant change 
from the substance contained herein. Therefore, because a delay would 
significantly affect the certification of the airplane, which is 
imminent, the FAA has determined that prior public notice and comment 
are unnecessary and impracticable, and good cause exists for adopting 
these special conditions upon publication in the Federal Register. The 
FAA is requesting comments to allow interested persons to submit views 
that may not have been submitted in response to the prior opportunities 
for comment described above.

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, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type-certification basis for Cessna Model 680A airplanes.
    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

[[Page 18307]]

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 flightcrew, in conditions from light 
misting precipitation to heavy rain, at speeds from fully stopped in 
still air, to 1.5 V<INF>SR1</INF> with lift and drag devices retracted.

    Issued in Renton, Washington, on March 27, 2015.
Michael Kazycki,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 2015-07713 Filed 4-3-15; 8:45 am]
 BILLING CODE 4910-13-P