[Federal Register Volume 64, Number 97 (Thursday, May 20, 1999)]
[Rules and Regulations]
[Pages 27445-27447]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 99-12744]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM154, Special Conditions No. 25-99-273-SC]


Special Conditions: Dornier Model 328-300 Airplane; High 
Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final special conditions; request for comments.

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SUMMARY: These special conditions are issued for the Dornier Model 328-
300 airplane. This airplane will have novel and unusual design features 
when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. These special 
conditions contain the additional safety standards that the 
Administrator considers necessary to establish a level of safety 
equivalent to that provided by the existing airworthiness standards.

DATES: The effective date of these special conditions is April 15, 
1999.
    Comments must be received on or before July 6, 1999.

ADDRESSES: Comments on these special conditions may be mailed in 
duplicate to: Federal Aviation Administration, Office of the Regional 
Counsel, Attn: Rules Docket (ANM-7), Docket No. NM154, 1601 Lind Avenue 
SW., Renton, Washington, 98055-4056; or delivered in duplicate to the 
Office of the Regional Counsel at the above address. Comments must be 
marked: Docket No. NM154. 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: Tom Groves, FAA, International Branch, 
ANM-116, Transport Airplane Directorate, Aircraft Certification 
Service, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; 
telephone (425) 227-1503; facsimile (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA has determined that good cause exists for making these 
special conditions effective upon issuance; however, interested persons 
are invited to submit such written data, views, or arguments as they 
may desire. Communications should identify the docket and special 
conditions 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. These 
special conditions may be changed in light of the comments received. 
All comments submitted will be available in the Rules Docket for 
examination by interested persons, both before and after the closing 
date for comments. A report summarizing each substantive public contact 
with FAA personnel concerning this rulemaking will be filed in the 
docket. Persons wishing the FAA to acknowledge receipt of their 
comments submitted in response to this request must submit with those 
comments a self-addressed, stamped postcard on which the following 
statement is made: ``Comments to Docket No. NM154.'' The postcard will 
be date stamped and returned to the commenter.

Background

    On November 14, 1996, the Luftfahrt-Bundesamt (LBA) applied on 
behalf of Dornier Luftfahrt GmbH for an amendment to U.S. Type 
Certificate No. A45NM to include the new Dornier Model 328-300. The 
Model 328-300, which is a modification of the Dornier Model 328-100 
approved under Type Certificate No. A45NM, will be a 32-34 passenger 
airplane with a pressurized cabin and a maximum takeoff weight of 
33,510 pounds (15200 kg). The Model 328-300 is of a high-wing 
configuration, with twin turbofan engines mounted underneath the wings, 
and a horizontal tail mounted at the top of the vertical fin. The FAA 
subsequently determined that this airplane would require a new type 
certificate because the type of propulsion on this airplane is being 
changed from turboprop to turbofan.
    The Dornier Model 328-300 incorporates an electronic flight 
instrument system (EFIS) for display of critical flight parameters 
(altitude, airspeed, and attitude) to the crew. These displays can be 
susceptible to disruption to both command/response signals as a result 
of electrical and magnetic interference. This disruption of signals 
could result in loss of all critical flight displays and

[[Page 27446]]

annunciations or present misleading information to the pilot.

Type Certification Basis

    Under the provisions of 14 CFR 21.17, Dornier Luftfahrt GmbH must 
show that the Model 328-300 airplane meets the applicable provisions of 
part 25 as amended by Amendments 1 through 87 thereto.
    If the Administrator finds that the applicable airworthiness 
regulations (i.e., 14 CFR part 25, as amended) do not contain adequate 
or appropriate safety standards for the Dornier Model 328-300 airplane 
because of novel or unusual design features, special conditions are 
prescribed under the provisions of Sec. 21.16.
    Special conditions, as appropriate, are issued in accordance with 
14 CFR 11.49, as required by Secs. 11.28 and 11.29, and become part of 
the type certification basis in accordance with Sec. 21.17(a)(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, these special conditions would also apply to 
the other model under the provisions of Sec. 21.101(a)(1).

Novel or Unusual Design Features

    The Dornier 328-300 will incorporate an electronic flight 
instrument system (EFIS) that performs critical functions. This system 
may be vulnerable to 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 applicable regulations, special conditions are needed 
for the Dornier 328-300, which require that new electrical and 
electronic systems, such as the EFIS, that perform critical functions 
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 (HIRF)

    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.

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                                                                                         Field strength (volts per meter)
                                                         -----------------------------------------------------------------------------------------------
                        Frequency                                       US                          UK/European                    Consolidated
                                                         -----------------------------------------------------------------------------------------------
                                                               Peak           Average          Peak           Average          Peak           Average
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10 kHz-100 kHz..........................................              30              30              50              50              50              50
100 kHz-500 kHz.........................................              40              30              60              60              60              60
500 kHz-2 MHz...........................................              30              30              70              70              70              70
2 MHz-30 MHz............................................             190             190             200             200             200             200
30 MHz-70 MHz...........................................              20              20              30              30              30              30
70 MHz-100 MHz..........................................              20              20              30              30              30              30
100 MHz-200 MHz.........................................              30              30             150              30             150              30
200 MHz-400 MHz.........................................              30              30              70              70              70              70
400 MHz-700 MHz.........................................              80              80             700              40             700              80
700 MHz-1 GHz...........................................             690             240            1700              80            1700             240
1 GHz-2 GHz.............................................             970              70            5000             360            5000             360
2 GHz-4 GHz.............................................            1570             350            4500             360            4500             360
4 GHz-6 GHz.............................................            7200             300            5200             300            7200             300
6 GHz-8 GHz.............................................             130              80            2000             330            2000             330
8 GHz-12 GHz............................................            2100              80            3500             270            3500             270
12 GHz-18 GHz...........................................             500             330            3500             180            3500             330
18 GHz-40 GHz...........................................             780              20              NA              NA             780             20
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The field strengths are expressed in terms of peak root-mean-square (rms) values.

Applicability

    As discussed above, these special conditions are applicable to 
Dornier 328-300 Model airplane. Should Dornier Luftfahrt GmbH apply any 
other model included on the same type certificate to incorporate the 
same novel or unusual design feature, these special conditions would 
apply to that model as well under the provisions of Sec. 21.101(a)(1).

Conclusion

    This action affects only Dornier Model 328-300 airplanes. It is not 
a rule of general applicability and affects only the applicant who 
applied to the FAA for approval of these features on the airplane.
    The substance of the special conditions for this airplane has been 
subjected to the notice and comment procedure in several prior 
instances and has been derived without substantive change from those 
previously issued. It is unlikely that prior public comment would 
result in a significant change from the substance contained herein. For 
this reason, and because a delay

[[Page 27447]]

would significantly affect the certification of the airplane, which is 
imminent, the FAA has determined that prior public notice and comment 
are unnecessary and impracticable, and good cause exists for adopting 
these special conditions immediately. Therefore, these special 
conditions are being made effective upon issuance. The FAA is 
requesting comments to allow interested persons to submit views that 
may not have been submitted in response to the prior opportunities for 
comment described above.

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 Special Conditions

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the following special conditions are issued as part of 
the type certification basis for Dornier Model 328-300 airplane.
    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 capability of these systems to perform 
critical functions are not adversely affected when the airplane is 
exposed to high intensity radiated fields external to the airplane.
    For the purpose of these special conditions, 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 April 15, 1999.
John J. Hickey,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service, ANM-100.
[FR Doc. 99-12744 Filed 5-19-99; 8:45 am]
BILLING CODE 4910-13-P