Airworthiness standards: Special conditions— Raytheon Aircraft Co. Model 4000 airplane,

[Federal Register: March 14, 2000 (Volume 65, Number 50)]

[Proposed Rules]

[Page 13703-13704]

From the Federal Register Online via GPO Access [wais.access.gpo.gov]

[DOCID:fr14mr00-18]

[[Page 13703]]

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. NM170; Notice No. 25-00-01-SC]

Special Conditions: Raytheon Aircraft Company Model 4000; High Intensity Radiated Fields (HIRF)

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

SUMMARY: This notice proposes special conditions for the Raytheon Aircraft Company Model 4000 airplane. This airplane will utilize new avionics/electronics and electrical systems that will perform critical functions. 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 (HIRF). These proposed 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: Comments must be received on or before April 13, 2000.

ADDRESSES: Comments on these proposed special conditions may be mailed in duplicate to: Federal Aviation Administration, Transport Airplane Directorate, Attn: Rules Docket (ANM-114), Docket No. NM170, 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. NM170. Comments may be inspected in the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. and 4:00p.m.

FOR FURTHER INFORMATION CONTACT: Mark Quam, FAA, Standardization Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; telephone (425) 227-2145; facsimile (425) 227-1149.

SUPPLEMENTARY INFORMATION:

Comments Invited

Interested persons are invited to participate in the making of these 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. The proposals contained in this notice may be changed in light of the comments received. All comments received 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 filedin 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. NM170.'' The postcard will be date stamped and returned to the commenter.

Background

On May 3, 1996, Raytheon Aircraft Company, PO Box 85, Wichita, Kansas 67201-0085, submitted an application for a new type certificate for the Raytheon Model 4000. The significant aircraft design features include an 84 inch diameter graphite composite fuselage, new metal wing and a graphite composite skin on aluminum sub-structure empennage. The Model 4000 is 69 feet, 2 inches in length and 61 feet, 9 inches in width. It has a Primus Epic flightdeck, and two aft mounted PW308A engines. There are 12 forward-facing seats and a forward observer seat. The significant systems features include a new state of the art integrated avionics/electronics and electrical systems suite. The avionics/electronics and electrical systems installed in this airplane have the potential to be vulnerable to high-intensity radiated fields (HIRF) external to the airplane.

Type Certification Basis

Under the provisions of 14 CFR 21.17, Raytheon Aircraft Company must show that the Model 4000 meets the applicable provisions of part 25, as amended by Amendment 25-1 through Amendment 25-87 thereto.

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 Raytheon Aircraft Company Model 4000 airplane because of novel or unusual design features, special conditions are prescribed under the provisions of 14 CFR 21.16.

In addition to the applicable airworthiness regulations and special conditions, the Model 4000 must comply with the part 25 fuel vent and exhaust emission requirements of 14 CFR part 34 and the part 25 noise certification requirements of 14 CFR part 36, and the FAA must issue a finding of regulatory adequacy pursuant to Sec. 611 of Public Law 92- 574, the ``Noise Control Act of 1972.''

Special conditions, as appropriate, are issued in accordance with Sec. 11.49 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. 21.17(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, 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 Raytheon Aircraft Company Model 4000 airplanes will utilize new avionics/electronics and electrical systems that will perform critical functions. These systems may be vulnerable to HIRF external to the airplane. The significant systems features include a new state of the art integrated avionics/electronics and electrical systems suite. The avionics/electronics and electrical systems installed in this aircraft have the potential to 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 avionics/electronics and electrical 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 Raytheon Aircraft Company Model 4000, which require that new avionics/electronics and electrical systems 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

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the airplane, and the use of composite material in the airplane structure, the immunity of critical avionics/electronics and electrical 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 paragraph 1, OR 2 below:

1. A minimum threat of 100 volts rms per meter electric field strength from 10 KHz to 18 GHz.

   1. The threat must be applied to the system elements and their associated wiring harnesses without the benefit of airframe shielding.

   2. Demonstration of this level of protection is established through system tests and analysis.

2. A threat external to the airframe for both of the following field strengths for the frequency ranges indicated.

   Field strength (volts per meter) Frequency

   ------------------ Peak Average

   10 kHz-100 kHz....................................... 50

   50 100 kHz-500 kHz...................................... 50

   50 500 kHz-2 MHz........................................ 50

   50 2 MHz-30 MHz......................................... 100

   100 30 MHz-70 MHz........................................ 50

   50 70 MHz-100 MHz....................................... 50

   50 100 MHz-200 MHz...................................... 100

   100 200 MHz-400 MHz...................................... 100

   100 400 MHz-700 MHz...................................... 700

   50 700 MHz-1 GHz........................................ 700

   100 1 GHz-2 GHz.......................................... 2000

   200 2 GHz-4 GHz.......................................... 3000

   200 4 GHz-6 GHz.......................................... 3000

   200 6 GHz-8 GHz.......................................... 1000

   200 8 GHz-12 GHz......................................... 3000

   300 12 GHz-18 GHz........................................ 2000

   200 18 GHz-40 GHz........................................ 600 200

   The field strengths are expressed in terms of peak of the root-mean- square (rms) over the computer modulation period.

   The threat levels identified above are the result of an FAA review of existing studies on the subject of HIRF, in light of the ongoing work of the Electromagnetic Effects Harmonization Working Group of the Aviation Rulemaking Advisory Committee.

   Applicability

   As discussed above, these special conditions are applicable to the Model 4000 airplane. Should Raytheon Aircraft Company apply at a later date for a change to the type certificate to include another model incorporating 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 certain design features on the Raytheon Aircraft Company Model 4000 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.

   List of Subjects in 14 CFR Part 25

   Aircraft, Aviation safety, Reporting and recordkeeping requirements.

   PART 25--[AMENDED]

   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 Raytheon Aircraft Company Model 4000 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 capability 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 March 6, 2000. Vi L. Lipski Acting Manager, Transport Airplane Directorate, Aircraft Certification Service, ANM-100.

   [FR Doc. 00-6127Filed3-10-00; 8:45 am]

   BILLING CODE 4910-13-P