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CFR Citation: 14 CFR Part 25

Docket ID: [Docket No. NM351; Special Conditions No. 25-325-SC]

NOTICE: RULES

ACTION: Airworthiness standards:

DOCUMENT ACTION: Final special conditions; request for comments.

SUBJECT CATEGORY: Special Conditions: Gulfstream Aerospace Corporation Model G150 Airplanes; High-Intensity Radiated Fields (HIRF)

DATES: The effective date of these special conditions is September 8, 2006.
We must receive your comments on or before October 18, 2006.

DOCUMENT SUMMARY: The FAA issues these special conditions for Gulfstream Aerospace Corporation Model G150 airplanes modified by Gulfstream Aerospace Corporation, Dallas, Texas. These modified airplanes will have novel or unusual design features when compared with the state of technology envisioned in the airworthiness standards for transport category airplanes. The modification consists of installing an electronic laser inertial reference system. The applicable airworthiness regulations do not contain adequate or
[[Page 54577]]
appropriate safety standards for protecting these systems from effects of highintensity 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 established by the existing airworthiness standards.

SUMMARY: Gulfstream Aerospace Corp. Model G150 airplanes,

SUPPLEMENTAL INFORMATION

The FAA has determined that notice and opportunity for prior public comment for these special conditions is impracticable because these procedures would significantly delay certification and 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. We therefore find that good cause exists for making these special conditions effective upon issuance. However, we invite interested persons to take part in this rulemaking by submitting written comments. 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 about these special conditions. You may inspect the docket 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 preaddressed, stamped postcard on which the docket number appears. We will stamp the date on the postcard and mail it back to you.

Background

On June 9, 2006, Gulfstream Aerospace Corporation, Dallas, Texas, applied for a supplemental type certificate (STC) to modify Gulfstream G150 airplanes. The Gulfstream G150 is a lowwing, pressurized, transport category airplane with two fuselagemounted jet engines. It can seat up to 19 passengers, with a crew of two pilots. The modification consists of installing an electronic laser inertial reference system. These systems have a potential to be vulnerable to highintensity radiated fields (HIRF) external to the airplane. Type Certification Basis

Under provisions of 14 CFR 21.101, Gulfstream Aerospace Corporation must show that the Gulfstream G150 airplanes, as changed, continue to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. A16NM 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 specific regulations are 14 CFR part 25, as amended by Amendments 251 through 25108 with exceptions as indicated in the Type Certificate Data Sheet.

If the Administrator finds that the applicable airworthiness regulations (part 25, as amended) do not contain adequate or appropriate safety standards for the Gulfstream G150 airplanes 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, the G150 airplanes must comply with the fuel vent and exhaust emission requirements of 14 CFR part 34 and the noise certification requirements of 14 CFR part 36.

The FAA issues special conditions, as defined in Sec. 11.19, under Sec. 11.38, and they become part of the type certification basis under the provisions of Sec. 21.101.

Novel or Unusual Design Features

As noted earlier, the Gulfstream G150 airplanes modified by Gulfstream Aerospace Corporation will incorporate an electronic laser inertial reference system that will perform critical functions. This system may be vulnerable to highintensity radiated fields external to the airplane. Current airworthiness standards of part 25 do not contain adequate or appropriate safety standards for protecting this equipment from adverse effects of HIRF. So this system is considered to be a novel or unusual design feature.

Discussion

As previously stated, there is no specific regulation that addresses protection for electrical and electronic systems from HIRF. Increased power levels from radio frequency 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 Gulfstream G150 airplanes modified by Gulfstream Aerospace Corporation. 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 because of HIRF.

HighIntensity Radiated Fields (HIRF)

Highpower radio frequency transmitters for radio, radar, television, and satellite communications can adversely affect operation of airplane electric and electronic systems. Therefore, the immunity of critical avionics/electronics and electrical systems to HIRF must be established.

Based on surveys and an analysis of existing HIRF emitters, an adequate level of protection exists when airplane system immunity is demonstrated when exposed to the HIRF environments in either paragraph 1 or 2 below:

1. A minimum environment of 100 volts rms (rootmeansquare) per meter electric field strength from 10 KHz to 18 GHz.

a. System elements and their associated wiring harnesses must be exposed to the environment without benefit of airframe shielding. [[Page 54578]]

b. Demonstration of this level of protection is established through system tests and analysis.

2. An environment external to the airframe of the field strengths shown in the table below for the frequency ranges indicated. Immunity to both peak and average field strength components from the table must 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 environment levels identified above are the result of an FAA review of existing studies on the subject of HIRF and of the work of the Electromagnetic Effects Harmonization Working Group of the Aviation Rulemaking Advisory Committee.

Applicability

These special conditions are applicable to Gulfstream G150 airplanes modified by Gulfstream Aerospace Corporation. Should Gulfstream Aerospace Corporation apply at a later date for a supplemental type certificate to modify any other model included on Type Certificate No. A16NM to incorporate the same or similar novel or unusual design feature, these special conditions would apply to that model as well under provisions of Sec. 21.101.

Conclusion

This action affects only certain novel or unusual design features on Gulfstream G150 airplanes modified by Gulfstream Aerospace Corporation. 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.

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
Therefore, under the authority delegated to me by the Administrator, the following special conditions are issued as part of the supplemental type certification basis for the G150 airplanes modified by Gulfstream Aerospace Corporation.

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 continued safe flight and landing of the airplane.

Issued in Renton, Washington, on September 8, 2006. Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. E615401 Filed 91506; 8:45 am]
BILLING CODE 491013P

FOR FURTHER INFORMATION CONTACT Greg Dunn, FAA, Airplane and Flight Crew Interface Branch, ANM111, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington 980573356; telephone (425) 2272799; facsimile (425) 227 1320.