[Federal Register Volume 70, Number 125 (Thursday, June 30, 2005)]
[Proposed Rules]
[Pages 37715-37717]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 05-12883]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM310; Notice No. 25-05-07-SC]


Special Conditions: Gulfstream Aerospace Limited Partnership 
(GALP) Model G150 Airplane; Windshield Coating in Lieu of Wipers

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This notice proposes special conditions for the Gulfstream 
Aerospace Limited Partnership (GALP) Model G150 airplane. This airplane 
will have a novel or unusual design feature associated with use of a 
hydrophobic 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. These proposed 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: Comments must be received on or before August 15, 2005.

ADDRESSES: Comments on this proposal may be mailed in duplicate to: 
Federal Aviation Administration, Transport Airplane Directorate, Attn: 
Rules Docket (ANM-113), Docket No. NM310, 1601 Lind Avenue SW., Renton, 
Washington 98055-4056; or delivered in duplicate to the Transport 
Airplane Directorate at the above address. Comments must be marked: 
Docket No. NM310. Comments may be inspected 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 98055-4056; telephone (425) 227-1365; facsimile (425) 227-
1320, e-mail [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites interested persons to participate in this 
rulemaking by submitting written comments, data, or views. The most 
helpful comments reference a specific portion of the special 
conditions, 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 these special conditions. The docket is available for public 
inspection 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 9 a.m. and 5 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 
these special conditions in light of 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 September 22, 2002, GALP applied for an amendment to Type 
Certificate Number A16NM to include the new GALP Model G150 airplane. 
The GALP Model G150, which is a derivative of the GALP Model G100 
currently approved under Type Certificate Number A16NM, is intended to 
be a nine passenger executive airplane with a maximum takeoff weight of 
26,000 pounds and a maximum operating altitude of 45,000 feet.
    The GALP Model G150 flightdeck design incorporates a hydrophobic 
coating to provide adequate pilot

[[Page 37716]]

compartment view in the presence of precipitation. 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 that provides the level of 
safety equivalent to that established by the regulations.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, GALP must show that the 
Model G150 meets the applicable provisions of the regulations 
incorporated by reference in Type Certificate Number A16NM or the 
applicable regulations in effect on the date of application for the 
change to the type certificate. 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 Number A16NM are 14 CFR part 25, 
effective February 1, 1965, including Amendments 25-1 through 25-107.
    In addition, if the regulations incorporated by reference do not 
provide adequate standards with respect to the change, the applicant 
must comply with certain regulations in effect on the date of 
application for the change. GALP has elected to voluntarily comply with 
Amendment 25-108 for the G150 type certification program.
    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 G150 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 G150 must comply with (1) either the ``No 
Acoustical Change'' provisions of Sec.  21.93(b) or 14 CFR part 36, as 
amended by Amendments 36-1 thru 36-24, and (2) either the ``No Emission 
Change'' provisions of Sec.  21.93(c) or 14 CFR part 34, as amended by 
Amendments 34-1 through 34-3.
    Special conditions, as defined in 14 CFR 11.19, are issued in 
accordance with Sec.  11.38 and become part of the type certification 
basis in accordance with 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 novel or unusual design feature, the special conditions would also 
apply to the other model under the provisions of Sec.  21.101.

Novel or Unusual Design Features

    The GALP Mode G150 will incorporate the following novel or unusual 
design feature: Hydrophobic windshield coating as the sole means to 
maintain a clear portion of the windshield, during precipitation 
conditions, sufficient for both pilots to have a sufficiently extensive 
view along the flight path.

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 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 
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. 
Alternately, 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

[[Page 37717]]

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, these special conditions are applicable to the 
Model G150. Should GALP apply at a later date for a change to the type 
certificate to include other type designs 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 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 Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for Gulfstream Aerospace Limited Partnership (GALP) Model G150 
airplane.
    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 flight path in normal 
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 June 21, 2005.
Ali Bahrami,
Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 05-12883 Filed 6-29-05; 8:45 am]
BILLING CODE 4910-13-M