[Federal Register Volume 71, Number 210 (Tuesday, October 31, 2006)]
[Proposed Rules]
[Pages 63723-63725]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E6-18288]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM358; Notice No. 25-06-12-SC]


Special Conditions: Gulfstream Aerospace Corporation, Model GV, 
GV-SP, and GIV-X Airplanes; Windshield Coating in Lieu of Wipers

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special condition.

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SUMMARY: This action proposes a special condition for the Gulfstream 
Aerospace Corporation Model GV, GV-SP, and GIV-X airplanes. These 
airplanes will have a novel or unusual design feature(s) 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 proposed 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.

DATES: We must receive your comments by November 20, 2006.

ADDRESSES: You must mail two copies of your comments to: Federal 
Aviation Administration, Transport Airplane Directorate, Attn: Rules 
Docket (ANM-113), Docket No. NM358, 1601 Lind Avenue SW., Renton, 
Washington, 98057-3356. You may deliver two copies to the Transport 
Airplane Directorate at the above address. You must mark your comments: 
Docket No. NM358. You can inspect comments in the Rules Docket 
weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

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: 

Comments Invited

    We invite interested people to take part in this rulemaking by 
sending written comments, data, or views. The most helpful comments 
reference a specific portion of the special condition, 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 this special condition. You can 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 
this special condition 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 December 19, 2005, Gulfstream Aerospace Corporation applied for 
a change to Type Certificate No. A12EA to use a hydrophobic windshield 
coating as the sole means of providing adequate pilot compartment view 
in the presence of precipitation for Gulfstream Model GV, GV-SP and 
GIV-X airplanes. The Gulfstream Model GV, GV-SP and GIV-X airplanes are 
currently approved under Type Certificate No. A12EA. The Model GV 
airplane is powered by two BMW-Rolls Royce Deutschland BR700-710A1-10 
engines, operates with a two person flightcrew, and has the capacity to 
carry 19 passengers. The Model GV-SP airplane is powered by two BMW-
Rolls Royce Deutschland BR700-710C4-11 engines, operates with a two 
person flightcrew, and has the capacity to carry 19 passengers. The 
Model GIV-X airplane is powered by two Rolls Royce Tay Mark 611-8C 
engines, operates with a two person flightcrew, and has the capacity to 
carry 19 passengers.

Type Certification Basis

    Under the provisions of Sec.  21.101, Gulfstream Aerospace 
Corporation must show that the Model GV, GV-SP and GIV-X airplanes, as 
changed, continue to meet the applicable provisions of the regulations 
incorporated by reference in Type Certificate No. A12EA, or the 
applicable regulations in effect on the date of application for the 
change. The regulations incorporated by reference in the type 
certificate are commonly referred to as the ``original type 
certification basis.''
    The regulations incorporated by reference in Type Certificate No. 
A12EA include:
     For Model GV airplanes--part 25, effective February 1, 
1965, Amendment 25-1 through Amendment 25-81, with exceptions.
     For Model GV-SP airplanes--part 25, effective February 1, 
1965, Amendment 25-1 through Amendment 25-98.
     For Model GIV-X airplanes--part 25, effective February 1, 
1965, Amendment 25-1 through Amendment 25-101, with exceptions.
    In addition, the certification basis includes other regulations, 
special conditions and exemptions that are not relevant to this 
proposed special condition.
    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 GV, GV-SP and GIV-X 
airplanes 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 GV, GV-SP and GIV-X airplanes 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 issues special conditions, as defined in Sec.  11.19, under 
Sec.  11.38, and they become part of the type certification basis under 
Sec.  21.101.
    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, 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, the special conditions 
would also apply to the other model under Sec.  21.101.

Novel or Unusual Design Features

    The Gulfstream Model G-V, GV-SP and GIV-X flightdeck designs

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incorporate a 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. Therefore, special conditions are required that provide the 
level of safety equivalent to that established by the regulations.

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, 1990, Amendment 25-108 
changed the criterion for effectiveness of the means to maintain an 
area of clear vision from 1.6 VS1 to 1.5 VSR1 to 
accommodate the redefinition of the reference stall speed as the 1-g 
stall speed. As noted in the preamble to the final rule for that 
amendment, the 7 percent decrease in the speed value offsets a 
corresponding increase in the reference stall speed associated with the 
use of VSR1 rather than 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 airflow 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 air stream blown 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 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 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.
    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 sole 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.

Applicability

    As discussed above, this special condition is applicable to 
Gulfstream Model GV, GV-SP and GIV-X airplanes. Should Gulfstream 
Aerospace Corporation 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 condition would apply to that model 
as well.
    The substance of this special condition has been subject to the 
notice and public comment procedure in several prior instances. 
Therefore, because a delay would significantly affect scheduled 
airplane deliveries, we are shortening the public comment period to 20 
days.

Conclusion

    This action affects only certain novel or unusual design features 
on Gulfstream Model GV, GV-SP, and GIV-X airplanes. 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 these special conditions is as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Proposed Special Condition

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special condition as part of the type certification basis for 
Gulfstream Aerospace Corporation Model GV, GV-SP, and GIV-X 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.


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    Issued in Renton, Washington, on October 23, 2006.
Kalene C. Yanamura,
Acting Manager,Transport Airplane Directorate, Aircraft Certification 
Service.
 [FR Doc. E6-18288 Filed 10-30-06; 8:45 am]
BILLING CODE 4910-13-P