00-10912. Special Conditions: Boeing Model 747-200 (E-4B) Series Airplanes; 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 Boeing Model 747-200 (E-4B) airplanes. These airplanes, modified by S.I.P. Technical Services, Inc., will have novel and 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 a new Flight Management System (FMS) and an Electronic Flight Instrumentation System (EFIS). 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 (HIRF). These special conditions provide the additional safety standards that the Administrator considers necessary to ensure that the critical functions that this system performs are maintained when the airplane is exposed to HIRF.

DATES:

The effective date of these special conditions is April 24, 2000. Comments must be received on or before June 16, 2000.

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. NM172, 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. NM172. 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:

Ross Landes, FAA, Transport Airplane Directorate, Aircraft Certification Service, Standardization Branch, ANM-113, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; telephone [phone]; facsimile [phone].

SUPPLEMENTARY INFORMATION:

Comments Invited

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. 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 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. Persons wishing the FAA to acknowledge receipt of their comments submitted in response to these special conditions must include with those comments a self-addressed, stamped postcard on which the following statement is made: “Comments to Docket No. NM172.” The postcard will be date stamped and returned to the commenter.

Background

On November 10, 1998, S.I.P. Technical Services, Inc., 10107 McAllister Freeway, San Antonio, Texas 78216-4648, applied for a supplemental type certificate (STC) to modify Boeing Model 747-200 (E-4B) airplanes listed on Type Certificate A20WE. The modification incorporates the installation of a new Flight Management System (FMS) and an Electronic Flight Instrumentation System (EFIS). The new FMS consists of three Flight Management Computers (FMC) and three Multi-Purpose Control Display Units (MCDU). The new EFIS consists of Active Matrix Liquid Crystal Display (AMLCD) Electronic Flight Instrument (EFI) units with embedded symbol generators and new control panels. The installation of these systems may be vulnerable to high-intensity radiated fields (HIRF) external to the airplane.

Type Certification Basis

Under the provisions of 14 CFR 21.101, S.I.P. Technical Services, Inc. must show that Boeing Model 747-200 (E-4B) airplanes, as changed, continue to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. A20WE, 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 incorporated by reference in Type Certificate No. A20WE are as follows:

The certification basis for the modified Boeing Model 747-200 (E-4B) airplanes include title 14 Code of Federal Regulations (14 CFR), part 25, effective February 1, 1965, as amended by Amendments 25-1 through 25-8, plus Amendments 25-15, 25-17, 25-18, 25-20, and 25-39.

In addition to the applicable airworthiness regulations and special conditions, the Model 747-200 (E-4B) must comply with the part 25 fuel vent and exhaust emission requirements of 14 CFR part 34 and the part 25 noise certification requirements of 14 CFR part 36.

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 747-200 (E-4B) airplanes because of a novel or unusual design feature, special conditions are prescribed under the provisions of § 21.16.

Special conditions, as appropriate, are issued in accordance with § 11.49, as required by §§ 11.28 and 11.29(b), and become part of the type certification basis in accordance with § 21.101(b)(2).

Special conditions are initially applicable to the model for which they are issued. Should S.I.P. Technical Services, Inc. apply for a supplemental type certificate to modify any other model included on the same type certificate to incorporate the same novel or unusual design features, the special conditions would also apply to the other model under the provisions of § 21.101(a)(1).

Novel or Unusual Design Features

The modified Boeing Model 747-200 (E-4B) airplanes will incorporate the following new design features: the installation of new Flight Management System (FMS) and Electronic Flight Instrumentation System (EFIS). The new FMS consists of three Flight Management Computers (FMC) and three Multi-purpose Control Display Units (MCDU). The new EFIS consists of Active Matrix Liquid Crystal Display (AMLCD) Electronic Flight Instrument (EFI) units with embedded symbol generators and new control panels. The installation of these systems 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 regulations incorporated by reference, special conditions are needed for the Boeing Model 747-200 (E-4B) airplanes. These special conditions require that new electrical and electronic systems, such as the FMS and EFIS 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

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:

1. A minimum threat of 100 volts per meter root-mean-square (rms) 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.

Frequency	Field strength (volts per meter)
	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 of the root-mean-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 the Boeing Model 747-200 (E-4B) airplanes modified by S.I.P. Technical Services, Inc. Should S.I.P. Technical Services, Inc. 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 features, these special conditions would apply to that model as well under the provisions of § 21.101(a)(1).

Conclusion

This action affects only certain novel or unusual design features on Boeing Model 747-200 (E-4B) airplanes modified by S.I.P. Technical Services, Inc. It is not a rule of general applicability, and it 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 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 747-200 (E-4B) airplanes modified by S.I.P. Technical Services, 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.

Issued in Renton, Washington, on April 24, 2000.

Vi L. Lipski,

Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.