96-18548. Special Conditions: deHavilland DHC-8-400 Airplane; High- Intensity Radiated Fields  

  • [Federal Register Volume 61, Number 141 (Monday, July 22, 1996)]
    [Proposed Rules]
    [Pages 37844-37845]
    From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
    [FR Doc No: 96-18548]
    
    
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    Proposed Rules
                                                    Federal Register
    ________________________________________________________________________
    
    This section of the FEDERAL REGISTER contains notices to the public of 
    the proposed issuance of rules and regulations. The purpose of these 
    notices is to give interested persons an opportunity to participate in 
    the rule making prior to the adoption of the final rules.
    
    ========================================================================
    
    
    Federal Register / Vol. 61, No. 141 / Monday, July 22, 1996 / 
    Proposed Rules
    
    [[Page 37844]]
    
    
    
    DEPARTMENT OF TRANSPORTATION
    
    Federal Aviation Administration
    
    14 CFR Part 25
    
    [Docket No. NM-128; Notice No. SC-96-3-NM]
    
    
    Special Conditions: deHavilland DHC-8-400 Airplane; High-
    Intensity Radiated Fields
    
    AGENCY: Federal Aviation Administration, DOT.
    
    ACTION: Notice of proposed special conditions.
    
    -----------------------------------------------------------------------
    
    SUMMARY: This notice proposes special conditions for the deHavilland 
    DHC-8-400 airplane. This airplane will utilize new avionics/electronic 
    systems that provide critical data to the flightcrew. The applicable 
    regulations do not contain adequate or appropriate safety standards for 
    the protection of these systems from the effects of high-intensity 
    radiated fields. 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 September 5, 1996.
    
    ADDRESSES: Comments on this proposal may be mailed in duplicate to: 
    Federal Aviation Administration, Office of the Assistant Chief Counsel, 
    Attn: Rules Docket (ANM-7), Docket No. NM-128, 1601 Lind Avenue SW., 
    Renton, Washington, 98055-4056; or delivered in duplicate to the Office 
    of the Assistant Chief Counsel at the above address. Comments must be 
    marked: Docket No. NM-128. Comments may be inspected in the Rules 
    Docket weekdays, except Federal holidays, between 7:30 a.m. and 4:00 
    p.m.
    
    FOR FURTHER INFORMATION CONTACT:
    Phil Forde, FAA, Standardization Branch, ANM-113, Transport Airplane 
    Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., 
    Renton, Washington, 98055-4056, telephone (206) 227-2146 or facsimile 
    (206) 227-1149.
    
    SUPPLEMENTARY INFORMATION:
    
    Comments Invited
    
        Interested persons are invited to participate in the making of 
    these proposed special conditions by submitting such written data, 
    views, or arguments as they may desire. Communications should identify 
    the regulatory docket or notice number and be submitted in duplicate to 
    the address specified above. All communications received on or before 
    the closing date for comments will be considered by the Administrator 
    before further rulemaking action on this proposal is taken. The 
    proposals contained in this notice may be changed in light of the 
    comments received. All comments received will be available, both before 
    and after the closing date for comments, in the Rules Docket for 
    examination by interested parties. A report summarizing each 
    substantive public contact with FAA personnel concerning this 
    rulemaking will be filed in the docket. Commenters wishing the FAA to 
    acknowledge receipt of their comments submitted in response to this 
    notice must include a self-addressed, stamped postcard on which the 
    following statement is made: ``Comments to Docket No. NM-128.'' The 
    postcard will be dated stamped and returned to the commenter.
    
    Background
    
        On January 31, 1995, the de Havilland Aircraft Company of Canada, 
    Garratt Boulevard, Downsview, Ontario M3K1Y5, applied for an amendment 
    to their Type Certificate No. A13NM to include their new model Dash 8 
    Series 400 (DHC-8-400), Model 401/402 airplane, which is a derivative 
    of the DHC-8-300. The DHC-8-400 is a high wing, T-tail, twin engine, 
    turbopropeller powered regional transport. Each engine will be capable 
    of delivering 4830 shaft horsepower. The flight controls are manual, 
    except for the tandem rudder which will be hydraulically powered. The 
    airplane has a seating capacity of up to 78, and a maximum takeoff 
    weight of 62,500 pounds.
    
    Type Certification Basis
    
        Under the provisions of 14 CFR Sec. 21.101, deHavilland must show 
    that the DHC-8-400 meets the applicable provisions of the regulations 
    incorporated by reference in Type Certificate No. A13NM, or the 
    applicable regulations in effect on the date of application for the 
    change to the Model 300. 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. A13NM include part 25, as amended by Amendments 
    25-1 through 25-83. In addition to the applicable airworthiness 
    regulations and special conditions, the DHC-8-400 must comply with the 
    fuel vent and exhaust emission requirements of part 34, effective 
    September 10, 1990, plus any amendments in effect at the time of 
    certification; and the noise certification requirements of part 36, 
    effective December 1, 1969, as amended by Amendment 36-1 through the 
    amendment in effect at the time of certification. No exemptions are 
    anticipated. The special conditions that may be developed as a result 
    of this notice will form an additional part of the type certification 
    basis.
        If the Administrator finds that the applicable airworthiness 
    regulations (i.e., part 25, as amended) do not contain adequate or 
    appropriate safety standards for the DHC-8-400 because of a novel or 
    unusual design feature, special conditions are prescribed under the 
    provisions of Sec. 21.16 to establish a level of safety equivalent to 
    that established in the regulations.
        Special conditions, as appropriate, are issued in accordance with 
    Sec. 11.49 of the FAR after public notice, as required by Secs. 11.28 
    and 11.29(b), and become part of the type certification basis in 
    accordance with Sec. 21.101(b)(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 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(a)(1).
    
    Novel or Unusual Design Features
    
        The DHC-8-400 airplane avionics enhancement will utilize electronic 
    systems that perform critical functions,
    
    [[Page 37845]]
    
    including a digital Electronic Flight Instrument System (EFIS), 
    attitude and heading reference systems (AHRS), and air data systems 
    (ADS). These systems may be vulnerable to high-intensity radiated 
    fields (HIRF) external to the airplane.
    
    Discussion
    
        There is no specific regulation that addresses protection 
    requirements for electrical and electronic systems from HIRF. Increased 
    power levels from ground based radio transmitters, and the growing use 
    of sensitive electrical and electronic systems to command and control 
    airplanes, have made it necessary to provide adequate protection.
        To ensure that a level of safety is achieved equivalent to that 
    intended by the regulations incorporated by reference, special 
    conditions are needed for the DHC-8-400, which require that new 
    technology electrical and electronic systems, such as the EFIS, AHRS 
    and ADS, be designed and installed to preclude component damage and 
    interruption of function due to both the direct and indirect effects of 
    HIRF.
    
    High-Intensity Radiated Fields
    
        With the trend toward increased power levels from ground based 
    transmitters, plus the advent of space and satellite communications, 
    coupled with electronic command and control of the airplane, the 
    immunity of critical digital avionics systems to HIRF must be 
    established.
        It is not possible to precisely define the HIRF to which the 
    airplane will be exposed in service. There is also uncertainty 
    concerning the effectiveness of airframe shielding for HIRF. 
    Furthermore, coupling of electromagnetic energy to cockpit-installed 
    equipment through the cockpit window apertures is undefined. Based on 
    surveys and analysis of existing HIRF emitters, an adequate level of 
    protection exists when compliance with the HIRF protection special 
    condition is shown with either paragraphs 1 or 2 below:
        1. A minimum threat of 100 volts per meter peak electric field 
    strength from 10 KHz to 18 GHz.
        a. The threat must be applied to the system elements and their 
    associated wiring harnesses without the benefit of airframe shielding.
        b. Demonstration of this level of protection is established through 
    system tests and analysis.
        2. A threat external to the airframe of the following field 
    strengths for the frequency ranges indicated.
    
    ------------------------------------------------------------------------
                                                        Peak  (V/   Average 
                         Frequency                          M)       (V/M)  
    ------------------------------------------------------------------------
    10 KHz-100 KHz....................................         50         50
    100 KHz-500 KHz...................................         60         60
    500 KHz-2000 KHz..................................         70         70
    2 MHz-30 MHz......................................        200        200
    30 MHz-100 MHz....................................         30         30
    100 MHz-200 MHz...................................        150         33
    200 MHz-400 MHz...................................         70         70
    400 MHz-700 MHz...................................      4,020        935
    700 MHz-1000 MHz..................................      1,700        170
    1 GHz-2 GHz.......................................      5,000        990
    2 GHz-4 GHz.......................................      6,680        840
    4 GHz-6 GHz.......................................      6,850        310
    6 GHz-8 GHz.......................................      3,600        670
    8 GHz-12 GHz......................................      3,500      1,270
    12 GHz-18 GHz.....................................      3,500        360
    18 GHz-40 GHz.....................................      2,100        750
    ------------------------------------------------------------------------
    
        As discussed above, these special conditions would be applicable 
    initially to the DHC-8-400 airplane. Should de Havilland apply at a 
    later date for a change to the type certificate to include another 
    incorporating the same novel or unusual design feature, the special 
    conditions would apply to that model as well, under the provisions of 
    Sec. 21.101(a)(1).
    
    Conclusion
    
        This action affects certain design features only on the modified 
    DHC-8-400 airplane. It is not a rule of general applicability and 
    affects only the manufacturer who applied to the FAA for approval of 
    these features on the airplane.
    
    List of Subjects in 14 CFR Part 25
    
        Aircraft, Aviation safety, Reporting and record keeping 
    requirements.
    
        The authority citation for these proposed 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 the deHavilland DHC-8-400 series airplanes.
        1. Protection from Unwanted Effects of High-Intensity Radiated 
    Fields (HIRF). Each electrical and electronic system that performs 
    critical functions must be designed and installed to ensure that the 
    operation and operational capacity of these systems to perform critical 
    functions are not adversely affected when the airplane is exposed to 
    high-intensity radiated fields.
        2. For the purpose of this special condition, the following 
    definition applies:
        Critical Functions. Functions whose failure would contribute to or 
    cause a failure condition that would prevent the continued safe flight 
    and landing of the airplane.
    
        Issued in Renton, Washington, on July 9, 1996.
    Darrell M. Pederson,
    Acting Manager, Transport Airplane Directorate, Aircraft Certification 
    Service.
    [FR Doc. 96-18548 Filed 7-19-96; 8:45 am]
    BILLING CODE 4910-13-M
    
    
    

Document Information

Published:
07/22/1996
Department:
Federal Aviation Administration
Entry Type:
Proposed Rule
Action:
Notice of proposed special conditions.
Document Number:
96-18548
Dates:
Comments must be received on or before September 5, 1996.
Pages:
37844-37845 (2 pages)
Docket Numbers:
Docket No. NM-128, Notice No. SC-96-3-NM
PDF File:
96-18548.pdf
CFR: (2)
14 CFR 21.101(a)(1)
14 CFR 11.49