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CFR Citation: 14 CFR Part 25

Docket ID: [Docket No. NM181; Special Conditions No. 25-171-SC]

NOTICE: RULES

ACTION: Airworthiness standards:

DOCUMENT ACTION: Final special conditions; request for comments.

SUBJECT CATEGORY: Special Conditions: Dassault Aviation Mystere-Falcon 50; High- Intensity Radiated Fields (HIRF)

DATES: The effective date of these special conditions is December 20, 2000. Comments must be received on or before February 2, 2001.

DOCUMENT SUMMARY: These special conditions are issued for Dassault Aviation MystereFalcon 50 airplanes modified by Garrett Aviation Services. These modified airplanes will have a novel or unusual design feature when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. The modification incorporates the installation of dual attitude heading reference systems that perform critical functions. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for the protection of these systems from the effects of high intensityradiated fields (HIRF). These 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.

SUMMARY: Special conditions—; Dessault Aviation Mystere-Falcon 50 airplanes,

SUPPLEMENTAL INFORMATION

The FAA has determined that good cause exists for making these special conditions effective upon issuance; however, interested persons are invited to submit such written data, views, or arguments, as they may desire. Communications should identify the regulatory docket number and be submitted in duplicate to the address specified above. The Administrator will consider all communications received on or before the closing date for comments. These special conditions may be changed in light of the comments received. All comments received 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 filed in the docket. Commenters wishing the FAA to acknowledge receipt of their comments submitted in response to these special conditions must include a selfaddressed, stamped postcard on which the following statement is made: ``Comments to Docket No. NM181.'' The postcard will be date stamped and returned to the commenter.

Background

On November 1, 2000, Garrett Aviation Services, 1200 North Airport Drive Capital Airport, Springfield, IL, applied for a Supplemental Type Certificate (STC) to modify Dassault Aviation MystereFalcon 50 airplanes. The Model Falcon 50 is a small transport category airplane, powered by three AlliedSignal Model TFE 73131C turbofans with a maximum takeoff weight of 38,800 pounds. This airplane operates with a 2pilot crew and can hold up to 19 passengers. The modification incorporates the installation of dual Collins AHS3000 Attitude Heading Reference Systems. The AHS3000 is a replacement for the existing electromechanical vertical and directional gyro's, while also providing additional functional capability and redundance in the system. The avionics/electronics and electrical systems installed in this airplane have the potential to be vulnerable to highintensity radiated fields (HIRF) external to the airplane.

Type Certification Basis

Under the provisions of 14 CFR 21.101, Garrett Aviation Services must show that the Dassault Aviation MystereFalcon 50 airplanes, as changed, continue to meet the applicable provisions of the regulations [[Page 262]]
incorporated by reference in Type Certificate No. A46EU, 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 regulations included in the certification basis for the Dassault Aviation MystereFalcon 50 airplanes include Title 14, Code of Federal Regulations (14 CFR) part 25, as amended by Amendments 251 through 2534, plus additional requirements listed in the type certificate data sheet that are not relevant to these special conditions.

If the Administrator finds that the applicable airworthiness regulations (i.e., part 25, as amended) do not contain adequate or appropriate safety standards for an airplane because of a novel or unusual design feature, special conditions are prescribed under the provisions of Sec. 21.16.

In addition to the applicable airworthiness regulations and special conditions, these Dassault Aviation MystereFalcon 50 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 appropriate, are issued in accordance with Sec. 11.49, 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 Garrett Aviation Services 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

As noted earlier, the DassaultAviation MystereFalcon airplanes modified by Garrett Aviation Services will incorporate a new attitude heading reference system that will perform critical functions. This system may be vulnerable to highintensity radiated fields 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 groundbased 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 that is equivalent to that intended by the regulations incorporated by reference, special conditions are needed for the Dassault Aviation Mystere Falcon 50 airplanes modified by Garrett Aviation Services. 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.

HighIntensity Radiated Fields (HIRF)

With the trend toward increased power levels from groundbased transmitters, plus the advent of space and satellite communications coupled with electronic command and control of the airplane, 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 cockpitinstalled 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 of the following field strengths for the frequency ranges indicated. Both peak and average field strength components from the Table are to be demonstrated. Field strength (volts per meter) Frequency
Peak Average 10 kHz100 kHz................................ 50 50 100 kHz500 kHz............................... 50 50 500 kHz2 MHz................................. 50 50 2 MHz30 MHz.................................. 100 100 30 MHz70 MHz................................. 50 50 70 MHz100 MHz................................ 50 50 100 MHz200 MHz............................... 100 100 200 MHz400 MHz............................... 100 100 400 MHz700 MHz............................... 700 50 700 MHz1 GHz................................. 700 100 1 GHz2 GHz................................... 2000 200 2 GHz4 GHz................................... 3000 200 4 GHz6 GHz................................... 3000 200 6 GHz8 GHz................................... 1000 200 8 GHz12 GHz.................................. 3000 300 12 GHz18 GHz................................. 2000 200 18 GHz40 GHz................................. 600 200 The field strengths are expressed in terms of peak of the rootmean 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 Dassault Aviation MystereFalcon 50 airplanes modified by Garrett Aviation Services. Should Garrett Aviation Services 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 novel or unusual design features on the Dassault Aviation MystereFalcon 50 airplanes modified by Garrett Aviation Services. 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 these special conditions has been subjected to the notice and comment period 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
[[Page 263]]
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 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 Dassault Aviation MystereFalcon 50 airplanes modified by Garrett Aviation Services.

1. Protection from Unwanted Effects of HighIntensity 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 highintensity 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 December 20, 2000. Donald L. Riggin,
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 0189 Filed 1201; 8:45 am] BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT Meghan Gordon, FAA, Standardization Branch, ANM113, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington 980554056; telephone (425) 2272138; facsimile (425) 2271149.