[Federal Register Volume 68, Number 100 (Friday, May 23, 2003)]
[Notices]
[Pages 28315-28316]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 03-13049]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration


Proposed Revisions to Advisory Circular 25.1419-1, Certification 
of Transport Category Airplanes for Flight in Icing Conditions

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed advisory circular revision and request for 
comments.

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SUMMARY: The Federal Aviation Administration invites comments 
concerning a proposed revision to Advisory Circular 25.1419-1, 
``Certification of Transport Category Airplanes for Flight in Icing 
Conditions.'' The proposed revision provides revised guidance for 
certification of airframe ice detection and protection systems on 
transport category airplanes. This action provides interested persons 
an opportunity to comment on the proposed revision to the AC.

DATES: Send your comments on or before July 22, 2003.

ADDRESSES: You should send your comments on the proposed AC revision to 
the Federal Aviation Administration, Attention: Robert Jones, 
Propulsion/Mechanical Systems Branch, ANM-112, Transport Airplane 
Directorate, Aircraft Certification Service, 1601 Lind Ave SW., Renton, 
WA 98055-4056. You may examine comments at this address between 7:30 
a.m. and 4 p.m. weekdays, except Federal holidays.

FOR FURTHER INFORMATION CONTACT: Robert Jones at the above address, 
telephone (425) 227-1118, facsimile (425) 227-1320, or e-mail at: 
[email protected].

SUPPLEMENTARY INFORMATION: 

How Do I Submit Comments on the Advisory Circular Revision?

    You are invited to comment on the proposed revision to AC 25.1419-1 
by submitting written comments, data, or views. You should identify the 
title of the AC and submit comments in duplicate to the address 
specified above. The Transport Airplane Directorate will consider all 
comments received on or before the closing date for comments before 
issuing a revision to the AC. You may view the complete text of AC 
25.1419-1 at the following Internet address: http://www.airweb.faa.gov/rgl. At the home page, click on ``Advisory Circulars,'' then at the 
next page, enter ``AC 25.1419-1'' in the ``Search'' box and press 
``GO.''

Discussion

    AC 25.1419-1, ``Certification of Transport Category Airplanes for 
Flight in Icing Conditions,'' dated August 18, 1999, provides guidance 
for certification of airframe ice detection and protection systems on 
transport category airplanes. Paragraph 3, Analyses, describes 
information that should be included in a certification plan submitted 
by the

[[Page 28316]]

applicant. Note 2 of that paragraph states:
    An applicant may determine that protection is not required for one 
or more of these areas or components. If so, the applicant should 
include supporting data and rationale in the analyses for allowing 
those areas or components to go unprotected. The applicant should show 
that the lack of protection does not adversely affect the handling 
characteristics or performance of the airplane. If there is uncertainty 
about the effects of the lack of protection, the effects should be 
determined by flight test demonstration.
    Several questions regarding the meaning of this note have been 
raised. Several applicants have erroneously thought this note allowed 
adequate analysis and testing to preclude the requirement for flight 
test demonstrations. However, 14 CFR 25.1419(b) at amendment level 25-
72 requires flight testing in natural icing conditions as a means to 
verify the analyses required by paragraph (a) to check for icing 
anomalies, and to demonstrate that the ice protection system and its 
components are effective. Guidance material may not supersede the rule 
and, therefore, Note 2 does not preclude the need for flight testing in 
natural icing conditions.
    As part of a new type certification program, flight in natural 
icing conditions is required to show compliance with Sec.  25.1419(b). 
In addition to flight in natural icing conditions, additional wind 
tunnel, laboratory, and other flight tests may be required to verify 
the analyses required by Sec.  25.1419(a). However, under some 
circumstances, flight test data acquired on a previous certification 
program may be found to be applicable to a new or modified airplane 
(such a derivative model). To use the previous flight test data, the 
applicant is required to provide supporting data and rationale that 
show:
    a. The original flight test data is applicable (similarity)
    b. The applicant possesses the flight test data
    c. The new or modified configuration is safe for flight in icing 
conditions.
    Because of the erroneous interpretations, the following 
clarification is provided.

Proposed Revision to AC 25.1419-1

    Replace the existing Note 2, paragraph 3a, with the following:

    Note 2: An applicant may determine that protection is not 
required for one or more of these areas or components. If so, the 
applicant should include supporting data and rationale in the 
analyses for allowing those areas or components to go unprotected. 
The applicant should show that the lack of protection does not 
adversely affect the handling characteristics or performance of the 
airplane. Section 25.1419(b) of part 25 at amendment level 25-72 
requires certain flight testing. However, flight test data from 
previous certification programs may be used to show partial 
compliance with Sec.  25.1419(b) if it can be shown that the data is 
applicable to the airplane in question. This would generally require 
a similarity analysis. If a similarity analysis is used, the 
guidelines of paragraph 3(f) of this AC are applicable. If there is 
uncertainty about the effects of the lack of protection, or the 
similarity analysis, the manufacturer should conduct flight test 
demonstrations.


    Issued in Renton, Washington, on May 12, 2003.
Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 03-13049 Filed 5-22-03; 8:45 am]
BILLING CODE 4910-13-M