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Rule

Special Conditions: Raytheon Aircraft Company Model BAe.125 Series 800A; High-Intensity Radiated Fields (HIRF)

Action

Final Special Conditions; Request For Comments.

Summary

These special conditions are issued for Raytheon Aircraft Company Model BAe.125 Series 800A airplanes modified by Duncan Aviation Inc. These modified airplanes will have novel or unusual design features when compared to the state of technology envisioned in the airworthiness standards for transport category airplanes. The modification incorporates the installation of electronic flight and engine instrument systems. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for protecting these systems from the effects of high-intensity radiated fields (HIRF). These special conditions contain the additional safety standards the Administrator considers necessary to establish a level of safety equivalent to that established by the existing airworthiness standards.

 

Table of Contents Back to Top

DATES: Back to Top

The effective date of these special conditions is February 12, 2007. We must receive your comments by March 28, 2007.

ADDRESSES: Back to Top

You must mail two copies of your comments to: Federal Aviation Administration, Transport Airplane Directorate, Attention: Rules Docket (ANM-113), Docket No. NM369, 1601 Lind Avenue SW., Renton, Washington 98057-3356. You may deliver two copies to the Transport Airplane Directorate at the address indicated above. You must mark your comments: Docket No. NM369. You can inspect comments in the Rules Docket weekdays, except Federal holidays, between 7:30 a.m. and 4 p.m.

FOR FURTHER INFORMATION CONTACT: Back to Top

Greg Dunn, FAA, Airplane and Flight Crew Interface Branch, ANM-111, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-3356; telephone (425) 227-2799; facsimile (425) 227-1320.

SUPPLEMENTARY INFORMATION: Back to Top

Comments Invited Back to Top

The FAA has determined that notice and opportunity for prior public comment is impracticable because these procedures would significantly delay certification of the airplane 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; however, we invite interested persons to take part in this rulemaking by sending 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. 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 by 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 Back to Top

On October 27, 2006, Duncan Aviation, Inc., 15745 South Airport Road, Battle Creek, Michigan 49015, applied for a supplemental type certificate (STC) to modify Raytheon Aircraft Company Model BAe.125 Series 800A airplanes currently approved under Type Certificate No. A3EU. The Model BAe.125 Series 800A airplanes are small transport category airplanes. They are powered by two turbojet engines, with maximum takeoff weight of 31,000 pounds as modified by Modification No. 253379A or 26,866 pounds as modified by Modification No. 25B047A. These airplanes operate with 2-person crew and can seat up to 15 passengers. The proposed modification is to install the Rockwell Collins Pro Line 21 Integrated Display Systems. The avionics/electronics and electrical systems installed in this airplane have the potential to be vulnerable to high-intensity radiated fields (HIRF) external to the airplane.

Type Certification Basis Back to Top

Under 14 CFR 21.101, Duncan Aviation, Inc. must show the Raytheon Aircraft Company Model BAe.125 Series 800A aircraft, as changed, continue to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. A3EU. They must also continue to meet the applicable regulations in effect on the date of application for the change. We commonly refer to the regulations incorporated by reference in the type certificate as the “original type certification basis.” The regulations incorporated by reference in Type Certificate No. A3EU include Part 10 of the British Civil Airworthiness Requirements. This certification is equivalent to Civil Air Regulations (CAR) 4b dated December 1953, as amended by Amendment 4b-1 through Amendment 4b-11, exclusive of CAR 4b 350(e). It includes Special Regulation SR 422B. In addition, the certification basis includes certain later amendments to 14 CFR part 25 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 the Raytheon Aircraft Company Model Bae.125, Series 800A airplanes, because of a novel or unusual design feature, special conditions are prescribed under § 21.16.

Besides the applicable airworthiness regulations and special conditions, the Raytheon Aircraft Company Model BAe.125, Series 800A airplanes, must comply with the fuel vent exhaust emission requirements of 14 CFR part 34 and the noise certification requirements of 14 CFR part 36.

We issue special conditions, as defined in 14 CFR 11.19, under § 11.38 and they become part of the type certification basis under § 21.101.

Special conditions are initially applicable to the model for which they are issued. Should Duncan Aviation Inc., apply later for a supplemental type certificate to modify any other model included on Type Certificate No. A3EU to incorporate the same or similar novel or unusual design feature, these special conditions would also apply to the other model under § 21.101.

Novel or Unusual Design Features Back to Top

As noted earlier, the Raytheon Aircraft Company Model BAe.125 Series 800A aircraft, as modified by Duncan Aviation, Inc., will incorporate the Rockwell Collins Pro Line 21 Integrated Display Systems that will perform critical functions. These systems may be vulnerable to high-intensity 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. Therefore, we consider this system to be a novel or unusual design feature.

Discussion Back to Top

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/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 Raytheon Aircraft Company Model BAe.125 Series 800A airplanes modified by Duncan Aviation, Inc. 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 both the direct and indirect effects of HIRF.

High-Intensity Radiated Fields (HIRF) Back to Top

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 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 Average
The field strengths are expressed in terms of peak of the root-mean-square (rms) over the complete modulation period.
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 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 Back to Top

As discussed above, these special conditions are applicable to Raytheon Aircraft Company Model BAe.125 Series 800A airplanes modified by Duncan Aviation, Inc. Should Duncan Aviation, Inc. apply later for a supplemental type certificate to modify any other model included on Type Certificate No. A3EU to incorporate the same or similar novel or unusual design feature, these special conditions would apply to that model as well.

Conclusion Back to Top

This action affects only certain novel or unusual design features on Raytheon Aircraft Company Model BAe.125 Series 800A airplanes as modified by Duncan Aviation, Inc. 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 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 upon issuance. The FAA is requesting comments to allow interested persons to send views that may not have been sent in response to the prior opportunities for comment described above.

List of Subjects in 14 CFR Part 25 Back to Top

begin regulatory text

The authority citation for these special conditions is as follows:

Authority:

49 U.S.C. 106(g), 40113, 44701, 44702, 44704.

The Special Conditions Back to Top

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 Raytheon Aircraft Company Model BAe.125 Series 800A airplanes modified by Duncan Aviation, Inc.

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.

end regulatory text

Issued in Renton, Washington, on February 12, 2007.

Ali Bahrami,

Manager, Transport Airplane Directorate, Aircraft Certification Service.

[FR Doc. E7-3231 Filed 2-23-07; 8:45 am]

BILLING CODE 4910-13-P

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