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 Department of Transportation Federal Aviation Administration 14 CFR Part 25
[Docket No. NM170; Special Conditions No. 25-162-SC]
 AGENCY: Federal Aviation Administration (FAA), DOT.
 ACTION: Final special conditions.
 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 high-intensity 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.
 EFFECTIVE DATE: July 6, 2000.
 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: 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 § 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 § 611 of Public Law 92-574, the “Noise Control Act of 1972.” Special conditions, as appropriate, are issued in accordance with § 11.49, after public notice, as required by §§ 11.28 and 11.29(b), and become part of the type certification basis in accordance with § 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 § 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. 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. 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, 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: 
                    ( print page 35814) 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. Frequency
Field strength (volts per meter)Peak
Average10 kHz-100 kHz
50
50100 kHz-500 kHz
50
50500 kHz-2 MHz
50
502 MHz-30 MHz
100
10030 MHz-70 MHz
50
5070 MHz-100 MHz
50
50100 MHz-200 MHz
100
100200 MHz-400 MHz
100
100400 MHz-700 MHz
700
50700 MHz-1 GHz
700
1001 GHz-2 GHz
2000
2002 GHz-4 GHz
3000
2004 GHz-6 GHz
3000
2006 GHz-8 GHz
1000
2008 GHz-12 GHz
3000
30012 GHz-18 GHz
2000
20018 GHz-40 GHz
600
200The field strengths are expressed in terms of peak of the root-mean-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. 25-00-01-SC 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 § 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 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 May 22, 2000. Donald L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.


[FR Doc. 00-14156 Filed 6-5-00; 8:45 am] BILLING CODE 4910-13-U