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 Department of Transportation Federal Aviation Administration 14 CFR Part 25
[Docket No. NM293, Special Conditions No. 25-276-SC]
 AGENCY: Federal Aviation Administration (FAA), DOT.
 ACTION: Final special conditions; request for comments.
 SUMMARY: These special conditions are issued for the Gulfstream Aerospace Corporation Model G-1159, G-1159A, and G-1159B series airplanes modified by Business Jet Technologies. 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 applicable airworthiness regulations do not contain 
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                        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 October 18, 2004. Comments must be received on or before November 26, 2004.
 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. NM293, 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. NM293.
 FOR FURTHER INFORMATION CONTACT: Connie Beane, FAA, Standardization Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; telephone (425) 227-2796; facsimile (425) 227-1232.


SUPPLEMENTARY INFORMATION: Comments Invited The FAA has determined that notice and opportunity for prior public comment is impracticable because these procedures would significantly delay certification of and delivery of the affected airplanes. 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 based on the comments we receive. If you want the FAA to acknowledge receipt of your comments on these special conditions, 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 December 19, 2003, Business Jet Technologies, Tulsa, Oklahoma, applied to the FAA, Fort Worth Special Certification Office, for a supplemental type certificate (STC) to modify certain Gulfstream Aerospace Corporation Model G-1159, G-1159A, and G-1159B series airplanes to include the installation of two Shadin ADC-7000 RVSM capable air data computers. The avionics/electronics and electrical systems installed in these airplanes have the potential to be vulnerable to high-intensity radiated fields (HIRF) external to the airplane. The subject Gulfstream Aerospace Corporation airplanes are T-tail, low swept-wing, small transport category airplanes. This series of airplanes operates with a 2-pilot crew and can hold up to 19 passengers. Type Certification Basis Under the provisions of 14 CFR 21.101, Business Jet Technologies must show that the Gulfstream Aerospace Corporation Model G-1159, G-1159A, and G-1159B series airplanes, as changed, continue to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. A12EA, 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 Gulfstream Aerospace Corporation Model G-1159 airplanes include: Civil Air Regulations (CAR) 4b, dated December 31, 1953, including Amendments 4b-1 thru 4b-14. Special Regulation SR450A. Special Conditions in “Attachment A” of FAA letter to Grumman dated September 27, 1965. 14 CFR (Code of Federal Regulations) 25.1325 (effective February 1, 1965). Section 25.175 (effective March 1, 1965), in lieu of CAR 4b.155(b). Section 36.7(d)(3)(ii). CAR 4b.450, cooling systems. Part 25, dated February 1, 1965, as amended by Amendments No. 25-2 through 25-8, 25-10, 25-12, 25-16 thru 25-22, 25-24, and 25-26. If the Administrator finds that the applicable airworthiness regulations (part 25, as amended) do not contain adequate or appropriate safety standards for the Gulfstream Aerospace Corporation Model G-1159, G-1159A, and G-1159B series airplanes, modified by Business Jet Technologies, because of a novel or unusual design feature, special conditions are prescribed under the provisions of 21.16. In addition to the applicable airworthiness regulations and special conditions, these Gulfstream Aerospace Corporation Model G-1159, G-1159A, and G-1159B series airplanes must comply with the fuel vent and exhaust emission requirements of part 34 and the noise certification requirements of part 36. Special conditions, as defined in 14 CFR 11.19, are issued in accordance with § 11.38, and become part of the airplane's type certification basis in accordance with § 21.101. Special conditions are initially applicable to the model for which they are issued. Should Business Jet Technologies apply at a later date for a supplemental type certificate to modify any other model included on the same type certificate to incorporate the same or similar novel or unusual design feature, these special conditions would also apply to the other model under the provisions of § 21.101. Novel or Unusual Design Features The modified Gulfstream Aerospace Corporation Model G-1159, G-1159A, and G-1159B series airplanes will incorporate brand new avionics/electronics and electrical systems that will perform critical functions. These systems may be vulnerable to HIRF external to the airplane. The current airworthiness standards of part 25 do not contain adequate or appropriate safety standards for the protection of this equipment from the adverse effects of HIRF. Accordingly, this system is 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/
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                    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 Gulfstream Aerospace Corporation Model G-1159, G-1159A, and G-1159B series airplanes. 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, and 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 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 identified in the table below 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
2002GHz-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. *Applicability:*
                     As discussed above, these special conditions are applicable to the Gulfstream Aerospace Corporation Model G-1159, G-1159A, and G-1159B series airplanes. Should Business Jet Technologies apply at a later date for a supplemental type certificate to modify any other model included on Type Certificate No. A12EA to incorporate the same or similar novel or unusual design feature, these special conditions would apply to that model as well as under the provisions of § 21.101. Conclusion This action affects only certain novel or unusual design features on the Gulfstream Aerospace Corporation Model G-1159, G-1159A, and G-1159B series 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. The substance of the special conditions for these airplanes has been subjected to the 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 immediately. 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 the Gulfstream Aerospace Corporation Model G-1159, G-1159A, and G-1159B series airplanes modified by Business Jet Technologies: 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. Issued in Renton, Washington, on October 18, 2004. Kalene C. Yanamura, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.


[FR Doc. 04-23861 Filed 10-25-04; 8:45 am] BILLING CODE 4910-13-P