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CFR Citation: 14 CFR Part 25

Docket ID: [Docket No. NM170; Special Conditions No. 25-162-SC]

NOTICE: RULES

ACTION: Airworthiness standards:

DOCUMENT ACTION: Final special conditions.

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

EFFECTIVE DATES: July 6, 2000.

DOCUMENT SUMMARY: These special conditions are issued 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 highintensity radiated fields (HIRF). 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.

SUMMARY: Special conditions—; Raytheon Aircraft Co. Model 4000 airplane,

SUPPLEMENTAL INFORMATION

On May 3, 1996, Raytheon Aircraft Company, PO Box 85, Wichita, Kansas 672010085, 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 substructure 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 forwardfacing 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 highintensity radiated fields (HIRF) external to the airplane.

Type Certification Basis

Under the provisions of 14 CFR Sec. 21.17, Raytheon Aircraft Company must show that the Model 4000 meets the applicable provisions of part 25, as amended by Amendment 251 through Amendment 2587 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 Sec. 21.16.

In addition to the applicable airworthiness regulations and special conditions, the Model 4000 must comply with the fuel vent and exhaust emission requirements of part 34 and the noise certification requirements of part 36, and the FAA must issue a finding of regulatory adequacy pursuant to Sec. 611 of Public Law 92574, 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 highintensity 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 groundbased 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. These special conditions 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.

HighIntensity Radiated Fields (HIRF)

With the trend toward increased power levels from groundbased transmitters, plus the advent of space and satellite communications coupled with electronic command and control of 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 cockpitinstalled 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:

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1. A minimum threat of 100 volts rms per meter 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 for both of the following field strengths for the frequency ranges indicated. Both peak and average field strength components from the Table are to be demonstrated.
Field strength (volts per meter) Frequency
Peak Average 10 kHz100 kHz....................................... 50 50 100 kHz500 kHz...................................... 50 50 500 kHz2 MHz........................................ 50 50 2 MHz30 MHz......................................... 100 100 30 MHz70 MHz........................................ 50 50 70 MHz100 MHz....................................... 50 50 100 MHz200 MHz...................................... 100 100 200 MHz400 MHz...................................... 100 100 400 MHz700 MHz...................................... 700 50 700 MHz1 GHz........................................ 700 100 1 GHz2 GHz.......................................... 2000 200 2 GHz4 GHz.......................................... 3000 200 4 GHz6 GHz.......................................... 3000 200 6 GHz8 GHz.......................................... 1000 200 8 GHz12 GHz......................................... 3000 300 12 GHz18 GHz........................................ 2000 200 18 GHz40 GHz........................................ 600 200 The field strengths are expressed in terms of peak of the rootmean square (rms) over the complete 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.

Discussion of Comments

Notice of proposed special conditions No. 250001SC for the Raytheon Aircraft Model 4000 airplanes was published in the Federal Register on March 14, 2000 (65 FR 13703). No comments were received, and the special conditions are adopted as proposed.

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 features, 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.

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 Raytheon Aircraft Company Model 4000 airplanes.

1. Protection from Unwanted Effects of HighIntensity 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 May 22, 2000.
Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 0014156 Filed 6500; 8:45 am] BILLING CODE 491013U

FOR FURTHER INFORMATION CONTACT Mark Quam, FAA, Standardization Branch, ANM113, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington, 980554056; telephone (425) 2272145; facsimile (425) 2271149.