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CFR Citation: 14 CFR Part 25

Docket ID: [Docket No. NM265, Special Conditions No. 25-247-SC ]

NOTICE: RULES

ACTION: Airworthiness standards:

DOCUMENT ACTION: Final special conditions; request for comments.

SUBJECT CATEGORY: Special Conditions: Douglas Models DC-8-61, -61F, -63, -63F, -71, -71F, -72, -72F, -73, and -73F Airplanes; High Intensity Radiated Fields (HIRF)

DATES: The effective date of these special conditions is September 10, 2003. Comments must be received on or before October 20, 2003.

DOCUMENT SUMMARY: These special conditions are issued for Douglas Models DC-8- 61, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F airplanes
modified by ABX Air, Inc. These airplanes, as modified by ABX Air, 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 the Innovative Solutions and Support (IS&S) Duplex Reduced Vertical Separation Minimum (RVSM) system which will allow for the removal of the existing altitude alerter, encoding altimeters, air data computer, and standby altimeter. The applicable airworthiness 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 contain the additional safety standards that the Administrator considers necessary to establish a level of safety equivalent to that provided by the existing airworthiness standards.

SUMMARY: Special conditions—; Douglas Models DC-8-61, -61F, -63, -63F, -71, -71F, -72, -72F, -73, and -73F airplanes,

SUPPLEMENTAL INFORMATION

The FAA has determined that notice and opportunity for prior public comment are 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, the FAA invites interested persons to participate in this rulemaking by submitting 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. The docket is available for public inspection 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 4:00 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 November 25, 2002, ABX Air Inc. applied for a supplemental type certificate (STC) to modify Douglas Models DC861, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F airplanes. These models are
currently approved under Type Certificate 4A25. The modification incorporates the installation of the IS&S Duplex RVSM system which will allow for the removal of the existing altitude alerter, encoding altimeters, air data computer, and standby altimeter. This system uses two Air Data Display Units (ADDU) and a single Analog Interface Unit (AIU) to replace altitude displays and the air data computer. These displays can be susceptible to disruption to both command and response signals as a result of electrical and magnetic interference. This disruption of signals could result in the loss of all critical flight information displays and annunciations or the presentation of misleading information to the pilot.

Type Certification Basis

Under the provisions of 14 CFR 21.101, ABX Air Inc. must show that Douglas Models DC861, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F airplanes, as changed, continue to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. 4A25, 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 certification basis for the modified Douglas Models DC861, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F
airplanes include 14 CFR part 25 effective February 1, 1965 as described in Type Certificate Data Sheet 4A25.

[[Page 54801]]

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 Douglas Models DC861, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F 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 Douglas Models DC861, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F 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.

Special conditions, as defined in Sec. 11.19, are issued in accordance with Sec. 11.38 and become part of the type certification basis in accordance with Sec. 21.101.

Special conditions are initially applicable to the models for which they are issued. Should ABX Air, Inc., apply at a later date for a supplemental type certificate to modify any other models included on Type certificate No. 4A25 to incorporate the same or similar novel or unusual design feature, the special conditions would also apply to the other model under the provisions of Sec. 21.101.

Novel or Unusual Design Features

The modified Douglas Models DC861, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F airplanes will incorporate a new altitude display system, the Innovative Solutions and Support (IS&S) Duplex Reduced Vertical Separation Minimum (RVSM) system, which was not available at the time of certification of these airplanes, that performs critical functions. This system may be vulnerable to high intensity radiated fields (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 groundbased 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 Douglas Models DC861, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F airplanes, modified by ABX Air, Inc. These special conditions require that new electrical and electronic systems, such as the ADDU, 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, and the advent of space and satellite communications, coupled with electronic command and control of the airplane, the immunity of critical digital avionic/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 (rootmeansquare) 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 indicated in the table below for the frequency ranges indicated. Both peak and average field strength components from the table below 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 Douglas Models DC861, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F
airplanes modified by ABX Air Inc. Should ABX Air Inc. apply at a later date for a supplemental type certificate to modify any other model included on Type Certificate No. 4A25 to incorporate the same or similar novel or unusual design feature, these special conditions would apply to that model as well under the provisions of Sec. 21.101. Conclusion

This action affects only certain novel or unusual design features on Douglas Models DC861, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F airplanes modified by ABX Air 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 these airplanes.

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 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. [[Page 54802]]
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 Douglas Models DC861, 61F, 63, 63F, 71, 71F, 72, 72F, 73, and 73F airplanes modified by ABX Air Inc.

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 September 10, 2003. Ali Bahrami,
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 0323970 Filed 91803; 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, 980554056; telephone (425) 2272799; facsimile (425) 227 1149.