Special Conditions: Raytheon Aircraft Company Model HS.125 Series 700A Airplanes; High Intensity Radiated Fields (HIRF)

AGENCY:

Federal Aviation Administration (FAA), DOT.

ACTION:

Final special conditions; request for comments.

SUMMARY:

These special conditions are issued for Raytheon Aircraft Company Model HS.125 Series 700A airplanes modified by Duncan Aviation. These airplanes will have novel and unusual design features when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. The modifications, under three separate supplemental type certificate (STC) projects, incorporate the installation of a Collins FDS2000 Electronic Flight Instrument System (EFIS), a dual Collins AHS-3000A Attitude Heading Reference System (AHARS), and a dual IS&S Air Data System. The applicable airworthiness 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.

DATES:

The effective date of these special conditions is September 17, 2002. Comments must be received on or before October 24, 2002.

ADDRESSES:

Comments on these special conditions may be mailed in duplicate to: Federal Aviation Administration, Transport Airplane Directorate, Attn: Rules Docket (ANM-113), Docket No. NM228, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; or delivered in duplicate to the Transport Airplane Directorate at the above address. All comments must be marked: Docket No. NM228. Comments may be inspected in the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. and 4:00 p.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:

The FAA has determined that notice and opportunity for prior public comment hereon are impracticable because these procedures would significantly delay certification of the airplane and thus delivery of the affected aircraft. In addition, the substance of these special conditions has been subject to the public comment process in several prior instances with no substantive comments received. The FAA therefore finds that good cause exists for making these special conditions effective upon issuance; however, the FAA invites interested persons to participate in this rulemaking by submitting written comments, data, or views. The most helpful comments reference a specific portion of the special conditions, explain the reason for any recommended change, and include supporting data. We ask that you send us two copies of written comments.

We will file in the docket all comments we receive, as well as a report summarizing each substantive public contact with FAA personnel concerning these special conditions. The docket is available for public inspection before and after the comment closing date. If you wish to review the docket in person, go to the address in the ADDRESSES section of this preamble between 7:30 a.m. and 4 p.m., Monday through Friday, except Federal holidays.

We will consider all comments we receive on or before the closing date for comments. We will consider comments filed late if it is possible to do so without incurring expense or delay. We may change these special conditions in light of the comments we receive.

If you want the FAA to acknowledge receipt of your comments on this proposal, include with your comments a pre-addressed, stamped postcard on which the docket number appears. We will stamp the date on the postcard and mail it back to you.

Background

On May 14, 2002, Duncan Aviation, Inc., P.O. Box 81887, Lincoln, Nebraska 68501, applied for three supplemental type certificates (STCs) to modify Raytheon Aircraft Company Model HS.125 Series 700A airplanes approved under Type Certificate No. A3EU. The HS.125 Series 700A airplanes are executive type transports that have two aft mounted turbine engines, a maximum passenger load of 15 passengers, and a maximum operating speed of 280 to 320 KTS depending on the fuel loading configuration. The modifications, under three separate supplemental type certificate (STC) projects, incorporate the installation of a Collins FDS2000 Electronic Flight Instrument System (EFIS), a dual Collins AHS-3000A Attitude Heading Reference System (AHARS), and a dual Innovative Solutions & Support, Inc. (IS&S) Air Data System.

The Collins FDS2000 (EFIS) Flight Display System provides the aircraft interface, data processing, display processing and display control to replace four existing electro-mechanical Attitude Direction/Horizontal Situation indicators (ADI/HSI). In doing this, this equipment provides critical functions, display of aircraft pitch and roll, and essential functions (display of heading and navigation). The dual Collins AHS-3000A Attitude Heading Reference System (AHARS) is a solid state strap-down attitude/heading reference system which provides measurements of the aircraft pitch, roll, and heading Euler angles for use by cockpit displays, flight control and management systems, and other avionics equipment. The dual IS&S Air Data System replaces the existing pilot and copilot pneumatic altimeters with IS&S Air Data/Altimeter units. These advanced systems use electronics to a far greater extent than the original flight and navigation systems and may be more susceptible to electrical and magnetic interference caused by high-intensity radiated fields (HIRF). This disruption of signals could result in loss of either attitude, altimeter, heading, or present misleading information to the pilot.

Type Certification Basis

Under the provisions of 14 CFR 21.101, Duncan Aviation, Inc. must show that the Raytheon Aircraft Company Model HS.125 Series 700A airplanes, as changed, continue to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. A3EU, or the applicable regulations in effect on the date of application for the change. The regulations incorporated by reference in the type certificate are commonly referred to as the “original type certification basis.” The certification basis for the modified Raytheon Aircraft Company Model HS.125 Series 700A airplanes includes CAR. 10, British Civil Airworthiness Requirements (1st November 1963), and Special Conditions notified by the United States Government to Government of the United Kingdom including Validation Arrangements (V.A.) Note 1, Issue 1 dated April 19, 1961. This certification is equivalent to CAR.4b dated December 1953, Amendment 4b-1 through 4b-11, exclusive of CAR 4b.350 (e) and includes Special Regulation SR.422B. Other applicable amendments, Federal Aviation Regulations, and special conditions are noted in Type Certificate Data Sheet (TCDS) A3EU.

If the Administrator finds that the applicable airworthiness regulations (that is, CAR 4b or 14 CFR part 25, as amended) do not contain adequate or appropriate safety standards for the Raytheon Aircraft Company Model HS.125 Series 700A airplanes 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 Raytheon Aircraft Company Model HS.125 Series 700A airplanes must comply with the fuel vent and exhaust emission requirement of 14 CFR part 34 and the noise certification requirement of part 36.

Special conditions, as defined in 14 CFR 11.19, are issued in accordance with § 11.38, and become part of the type certification basis in accordance with § 21.101(b)(2).

Special conditions are initially applicable to the model for which they are issued. Should Duncan Aviation, Inc. apply at a later date for a supplemental type certificate to modify any other model already included on the same type certificate to incorporate the same novel or unusual design features, these special conditions would also apply to the other model under the provisions of 14 CFR 21.101(a)(1).

Novel or Unusual Design Features

The Raytheon Aircraft Company Model HS.125 Series 700A airplanes will incorporate, under three separate supplemental type certificate (STC) projects, the installation of a Collins FDS-2000 Electronic Flight Instrument System (EFIS), a dual Collins AHS-3000A Attitude Heading Reference System (AHARS), and a dual IS&S Air Data System. Because these advanced systems use electronics to a far greater extent than the original flight and navigation systems, they may be more susceptible to electrical and magnetic interference caused by high-intensity radiated fields (HIRF) external to the airplane. The current airworthiness standards (14 CFR part 25) do not contain adequate or appropriate safety standards that address protecting this equipment from the adverse effects of HIRF. Accordingly, these instruments are considered to be a novel or unusual design feature.

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 HS.125 Series 700A airplanes modified to include the new flight and navigation systems. These special conditions will require that the new Collins FDS-2000 Flight Display System, the Dual Collins AHS-3000A Attitude/Heading Reference System and the Dual IS&S Air Data Systems, which 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/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 in accordance with either paragraph 1 OR 2 below:

1. A minimum threat of 100 volts rms (root-mean-square) 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 of the field strengths indicated in the table below for the frequency ranges indicated. Both peak and average field strength components from the table below are to be demonstrated.

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 Raytheon Aircraft Company Model HS.125 Series 700A airplanes modified by Duncan Aviation, Inc. to include the Collins FDS-2000 Flight Display System, the Dual Collins AHS-3000A Attitude/Heading Reference System and the Dual IS&S Air Data System. Should Duncan Aviation, Inc. apply at a later date for a supplemental type certificate to modify any other model already included on Type Certificate A3EU to incorporate the same novel or unusual design features, these special conditions would apply to that model as well under the provisions of 14 CFR 21.101(a)(1).

Conclusion

This action affects only certain design features on Raytheon Aircraft Company Model HS.125 Series 700A airplanes modified by Duncan Aviation, Inc. 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 notice and comment procedure in several prior instances and has been derived without substantive change from those previously issued. Because a delay 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 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 supplemental type certification basis for Raytheon Aircraft Company Model HS.125 Series 700A airplanes modified by Duncan Aviation, Inc.

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 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.