[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]


 ========================================================================
 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