[Federal Register Volume 63, Number 57 (Wednesday, March 25, 1998)] [Proposed Rules] [Pages 14381-14383] From the Federal Register Online via the Government Publishing Office [www.gpo.gov] [FR Doc No: 98-7826] ======================================================================= ----------------------------------------------------------------------- DEPARTMENT OF TRANSPORTATION Federal Aviation Administration 14 CFR Part 25 [Docket No. NM147; Notice No. 25-98-02-SC] Special Conditions: Boeing Model 757-300; High-Intensity Radiated Fields AGENCY: Federal Aviation Administration, DOT. ACTION: Notice of proposed special conditions. ----------------------------------------------------------------------- SUMMARY: This notice proposes special conditions for the Boeing Model 757-300. This airplane will utilize new avionics/electronic systems that provide critical data to the flightcrew. 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. These proposed special conditions contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards. DATES: Comments must be received on or before April 24, 1998. ADDRESSES: Comments on this proposal may be mailed in duplicate to: Federal Aviation Administration, Office of the Regional Counsel, Attn: Rules Docket (ANM-7), Docket No. NM147, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; or delivered in duplicate to the Office of the Regional Counsel at the above address. Comments must be marked: Docket No. NM147. 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: John Dimtroff, FAA, Airplane and Flight Crew Interface Branch, ANM-111, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington, 98055-4056, telephone (425) 227-2117 or facsimile (425) 227-1320. SUPPLEMENTARY INFORMATION: Comments Invited Interested persons are invited to participate in the making of these proposed special conditions by submitting such written data, views, or arguments as they may desire. Communications should identify the regulatory docket or notice number and be submitted in duplicate to the address specified above. All communications received on or before the closing date for comments will be considered by the Administrator before further rulemaking action on this proposal is taken. The proposals contained in this notice may be changed in light of the comments received. All comments received will be available, both before and after the closing date for comments, in the Rules Docket for examination by interested parties. A report summarizing each substantive public contact with FAA personnel concerning this rulemaking will be filed in the docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to this notice must include a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket No. NM147.'' The [[Page 14382]] postcard will be date stamped and returned to the commenter. Background On February 21, 1996, the Boeing Commercial Airplane Group, P. O. Box 3707, Seattle, Washington 98124-2207, applied for an amendment to Type Certificate No. A2NM to include the new Model 757-300, a derivative of the 757-200. The 757-300 is a swept-wing, conventional- tail, twin-engine, turbofan-powered transport. Each engine will be capable of delivering 43,100 pounds of thrust. The flight controls are unchanged beyond those changes deemed necessary to accommodate the stretched configuration. The airplane has a seating capacity of up to 289, and a maximum takeoff weight of 270,000 pounds (122,470 Kg). Type Certification Basis Under the provisions of Title 14 CFR 21.101, Boeing must show that the Model 757-300 meets the applicable provisions of the regulations incorporated by reference in Type Certificate No. A2NM, or the applicable regulations in effect on the date of application for the change to the Model 757-300. The regulations incorporated by reference in the type certificate are commonly referred to as the ``original type certification basis.'' The regulations incorporated by reference in Type Certificate No. A2NM include 14 CFR part 25, as amended by Amendments 25-1 through 25-45, and certain other later amended sections of part 25 that are not relevant to these proposed special conditions. Except for certain earlier amended sections of part 25 that are not relevant to these proposed special conditions, Boeing has chosen to comply with part 25 as amended by Amendments 25-1 through 25-85, the applicable regulations in effect on the date of application. In addition to the applicable airworthiness regulations and special conditions, the 757-300 must comply with the fuel vent and exhaust emission requirements of part 34, effective September 10, 1990, plus any amendments in effect at the time of certification; and the noise certification requirements of part 36, effective December 1, 1969, as amended by Amendment 36-1 through the amendment in effect at the time of certification. The special conditions that may be developed as a result of this notice will form an additional part of the type certification basis. 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 757-300 because of a novel or unusual design feature, special conditions are prescribed under the provisions of Sec. 21.16 to establish a level of safety equivalent to that established in the regulations. Special conditions, as appropriate, are issued in accordance with Sec. 11.49 of the FAR 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. 21.101(b)(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, or should any other model already included on the same type certificate be modified to incorporate 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 757-300 airplane avionics enhancement will utilize electronic systems that perform critical functions, including the following airframe Line Replaceable Units (LRU): Multi-Mode Receiver (MMR), Flight Control Computer (FCC), Yaw Damper Stabilizer Trim Module (YSM), Air Data Inertial Reference System (ADIRS), and the Allied Signal Radio Altimeter (RA). These systems may 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 electrical and electronic 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 757-300, which require that new technology electrical and electronic systems, such as the MMR, FCC, YSM, ADIRS, and RA, 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 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 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 paragraphs 1 or 2 below: 1. A minimum threat of 100 volts per meter peak 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 following field strengths for the frequency ranges indicated. ---------------------------------------------------------------------------------------------------------------- Field Strength (volts per meter) ----------------------------------------------------- Frequency US UK/European Consolidated ----------------------------------------------------- Peak Avg. Peak Avg. Peak Avg. ---------------------------------------------------------------------------------------------------------------- 10 kHz-100 kHz............................................ 30 30 50 50 50 50 100 kHz-500 kHz........................................... 40 30 60 60 60 60 500 kHz-2 MHz............................................. 30 30 70 70 70 70 2 MHz-30 MHz.............................................. 190 190 200 200 200 200 30 MHz-70 MHz............................................. 20 20 30 30 30 30 70 MHz-100 MHz............................................ 20 20 30 30 30 30 [[Page 14383]] 100 MHz-200 MHz........................................... 30 30 150 30 150 30 200 MHz-400 MHz........................................... 30 30 70 70 70 70 400 MHz-700 MHz........................................... 80 80 700 40 700 80 700 MHz-1 GHz............................................. 690 240 1700 80 1700 240 1 GHz-2 GHz............................................... 970 70 5000 360 5000 360 2 GHz-4 GHz............................................... 1570 350 4500 360 4500 360 4 GHz-6 GHz............................................... 7200 300 5200 300 7200 300 6 GHz-8 GHz............................................... 130 80 2000 330 2000 330 8 GHz-12 GHz.............................................. 2100 80 3500 270 3500 270 12 GHz-18 GHz............................................. 500 330 3500 180 3500 330 18 GHz-40 GHz............................................. 780 20 (\1\) (\1\) 780 20 ---------------------------------------------------------------------------------------------------------------- \1\ NA. The field strengths are expressed in terms of peak root-mean-square (rms) values. The threat levels identified above differ from those used in previous special conditions and 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. In general, these standards are less critical than the threat level that was previously used as the basis for earlier special conditions. Applicability As discussed above, these special conditions would be applicable initially to the 757-300 airplane. Should Boeing apply at a later date for a change to the type certificate to include another model incorporating the same novel or unusual design feature, the special conditions would apply to that model as well, under the provisions of Sec. 21.101(a)(1). Conclusion This action affects certain design features only on the Model 757- 300. It is not a rule of general applicability and affects only the manufacturer who applied to the FAA for approval of these features on this model. List of Subjects in 14 CFR Part 25 Aircraft, Aviation safety, Reporting and record keeping requirements. The authority citation for these proposed special conditions is as follows: Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704. The Proposed Special Conditions Accordingly, the Federal Aviation Administration (FAA) proposes the following special conditions as part of the type certification basis for the Boeing 757-300 series 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 March 17, 1998. Donald L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service. [FR Doc. 98-7826 Filed 3-24-98; 8:45 am] BILLING CODE 4910-13-P