Airworthiness standards: Special conditions 800 airplane,
[Federal Register: August 18, 1999 (Volume 64, Number 159)]
[Rules and Regulations]
[Page 44817-44819]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr18au99-1]
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[[Page 44817]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. NM161, Special Conditions No. 25-146-SC]
Special Conditions: GEC-Marconi; Boeing Model 737-800 Airplane; 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 the Boeing Model 737- 800 airplane, as modified by GEC-Marconi. The Model 737-800 is equipped with a high-technology digital avionics system that performs critical functions. The applicable type certification regulations do not contain adequate or appropriate safety standards for the protection of this system from the effects of high-intensity radiated fields (HIRF). These special conditions provide the additional safety standards that the Administrator considers necessary to ensure that the critical functions this system performs are maintained when the airplane is exposed to HIRF.
DATES: The effective date of these special conditions is July 29, 1999. Comments must be received on or before October 4, 1999.
ADDRESSES: Comments on these special conditions may be mailed in duplicate to: Federal Aviation Administration, Transport Airplane Directorate, Attention: Rules Docket (ANM-114), Docket No. NM161, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; or delivered in duplicate to the Transport Airplane Directorate at the above address. Comments must be marked: Docket No. NM161. Comments may be inspected in the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.
FOR FURTHER INFORMATION CONTACT: Gerry Lakin, FAA, Transport Airplane Directorate, Aircraft Certification Service, Standardization Branch, ANM-113, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; telephone (425) 227-1187; 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 issuance of the approval design 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.
Comments Invited
Interested persons are invited to submit such written data, views, or arguments, as they may desire. Communications should identify the regulatory docket and special conditions 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. These special conditions may be changed in light of the comments received. All comments submitted will be available in the Rules Docket for examination by interested persons, both before and after the closing date for comments. A report summarizing each substantive public contact with FAA personnel concerning this rulemaking will be filedin the docket. Persons wishing the FAA to acknowledge receipt of their comments submitted in response to this request must submit with those comments a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket No. NM161.'' The postcard will be date stamped and returned to the commenter.
Background
On September 28, 1998, the Los Angeles Aircraft Certification Office received an application from GEC-Marconi Avionics (GMA) Ltd., Airport Works, Rochester, Kent, England, for a supplemental type certificate to modify Type Certificate No. A16WE for the Boeing Model 737-800.
The Boeing Model 737-800 is a low-wing, pressurized airplane with twin, wing-mounted, jet engines that is configured for approximately 162 passengers. The airplane has a maximum standard takeoff weight of 155,500 pounds, a maximum landing weight of 146,300 pounds, a maximum operating altitude of 41,000 feet, and a range of 3370 nautical miles. The overall length of the Boeing Model 737-800 is 129 feet, 6 inches, the height is 41 feet, 2 inches, and the wing span is 112 feet, 7 inches. The modification incorporates a head up display (HUD) system for display of critical flight parameters (altitude, airspeed, and attitude) to the crew. The display can be susceptible to disruption to both command/response signals as a result of electrical and magnetic interference. This disruption of signals could result in loss of all critical flight displays and annunciations or present misleading information to the pilot.
Type Certification Basis
Under the provisions of 14 CFR 21.101, GEC-Marconi must show that the Model 737-800 airplane, as changed, continues to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. A16WE 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 certifications basis.'' The certification basis for the modified Boeing Model 737-800 airplanes is as follows:
For airworthiness and environmental standards for components and areas not affected by the change, the original certification basis for the Model 737-800 is shown on Type Certificate Data Sheet (TCDS) No. A15WE, revision 25, dated September 9, 1998. The Model 737-800 was certified to part 25, as amended by Amendments 25-1 though 25-77, with reversions to earlier Amendments, voluntary compliance to later Amendments, special conditions, equivalent safety findings and exemptions listed in the TCDS.
For airworthiness and environmental standards for components and areas affected by the change, the certification basis for the Model 737-800 is 14 CFR
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part 25, effective February 1, 1965, including Amendments 25-1 through 25-97, which is the amendment level in effect on the date of application.
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 Boeing Model 737-800 airplane because of novel or unusual design features, special conditions are prescribed under the provisions of Sec. 21.16.
In addition to the applicable airworthiness regulations and special conditions, the Model 737-800 must comply with the part 25 fuel and exhaust emission requirements of 14 CFR part 34 and the part 25 noise certification requirements of 14 CFR part 36.
Special conditions, as appropriate, are issued in accordance with Sec. 11.49, as required by Secs. 11.28 and 11.29, 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 GEC-Marconi 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 novel or unusual design feature, these special conditions would also apply to the other model under the provisions of Sec. 21.101(a)(1).
Novel or Unusual Design Features
Boeing Model 737-800 will incorporate a head up display (HUD) system that performs critical functions. This system may be vulnerable to 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 applicable regulations incorporated by reference, special conditions are needed for the Boeing Model 737-800, which require that new electrical and electronic systems, such as the HUD, 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, 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 paragraph 1 OR 2 below:
-
A minimum threat of 100 volts per meter peak electric field strength from 10 KHz to 18 GHz.
-
The threat must be applied to the system elements and their associated wiring harnesses without the benefit of airframe shielding.
-
Demonstration of this level of protection is established through system tests and analysis.
-
-
A threat external to the airframe of the following field strengths for the frequency ranges indicated.
Field strength (volts per meter) Frequency
--------------------- Peak Average
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 field strengths are expressed in terms of peak root-mean-square (rms) values.
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. In general, these standards are less critical than the threat level that was previously used as the basis for some earlier special conditions.
Applicability
As discussed above, these special conditions are applicable to Boeing Model 737-800 airplanes modified by GEC-Marconi. Should GEC- Marconi 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 novel or unusual design feature, these special conditions would apply to that model as well under the provisions of Sec. 21.101(a)(1).
Conclusion
This action affects only certain design features on Boeing Model 737-800 airplanes modified by GEC-Marconi. 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 the notice and comment procedure in several prior instances and has been derived without substantive change from those previously issued. It is unlikely that prior public comment would result in a significant change from the substance contained herein. For this reason, and 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. Therefore, these special conditions are being made effective 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 type certification basis for Boeing Model 737-800 airplanes modified by GEC-Marconi.
-
Protection from Unwanted Effects of High-Intensity Radiated Fields
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(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 external to the airplane.
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 July 29, 1999. Donald L. Riggin, Acting Manager, Transport Airplane Directorate, Aircraft Certification Service, ANM-100.
[FR Doc. 99-20858Filed8-17-99; 8:45 am]
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