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Rule

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

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.

 

Table of Contents Back to Top

EFFECTIVE DATE: Back to Top

July 6, 2000.

FOR FURTHER INFORMATION CONTACT: Back to Top

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: Back to Top

Background Back to Top

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 Back to Top

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 92, 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 Back to Top

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 Back to Top

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) Back to Top

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:

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 Average
The field strengths are expressed in terms of peak of the root-mean-square (rms) over the complete modulation period.
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 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 Back to Top

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 Back to Top

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 Back to Top

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 Back to Top

The authority citation for these special conditions is as follows:

Authority: Back to Top

49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Special Conditions Back to Top

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

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