Federal Aviation Administration (FAA), DOT.
Final special conditions; request for comments.
These special conditions are issued for Sabreliner Model NA-265 series airplanes, modified by Sabreliner Corporation. 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 Air Data systems that perform critical functions by providing altitude, airspeed, or other critical data. 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.
The effective date of these special conditions is August 28, 2003. Comments must be received on or before October 9, 2003.
Comments on these special conditions may be mailed in duplicate to: Federal Aviation Administration, Transport Airplane Directorate, Attn: Rules Docket (ANM-113), Docket No. NM263, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; or delivered in duplicate to the Transport Airplane Directorate at the above address. All comments must be marked: Docket No. NM263.Start Further Info
FOR FURTHER INFORMATION CONTACT:
Mark Quam, FAA, Standardization Branch, ANM-113, Transport Airplane Directorate, Aircraft Certification Service, 1601 Lind Avenue SW., Renton, Washington, 98055-4056; telephone (425) 227-2145; facsimile (425) 227-1149.End Further Info End Preamble Start 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 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 pre-addressed, stamped postcard on which the docket number appears. We will stamp the date on the postcard and mail it back to you.
On May 21, 2003, Sabreliner Corporation, Pierre Laclede Center, 7733 Forsyth Boulevard, Suite 1500, St. Louis, Missouri 63105-1821, applied for a supplemental type certificate (STC) to modify Sabreliner Model NA-265 series airplanes. These airplanes are approved under Type Certificate No. A2WE. The Model NA-265 series are small transport category airplanes powered by two aft-mounted Pratt and Whitney Turbo Wasp JT12A engines, with the exception of the Model NA-265-65, which has two Air Research TFE731 turbofan engines, and the Model NA-265-80, which has two GE Model CF700 turbofan engines. These airplanes operate with a 2-pilot crew and can hold from 4 to 10 passengers depending on the model within the series. The NA-265 series have a maximum takeoff weight of 17,450 to 24,000 pounds, depending on the brake installation and model within the series.
The modification incorporates the installation of Air Data systems (combinations of Air Data Display Units, Air Computer, Air Data Sensor, and/or Altimeter) that perform critical functions by providing altitude, airspeed, or other critical data. These systems use electronics to a far greater extent than the original instrument systems, and may be more susceptible to electrical and magnetic interference caused by high-intensity radiated fields (HIRF). The disruption of these signals could result in loss of altitude, or present misleading information to the pilot.
Type Certification Basis
Under the provisions of 14 CFR 21.101, Sabreliner Corporation must Start Printed Page 53027show that the Model NA-265 series airplanes, as changed, continue to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. A2WE, 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 Sabreliner NA-265 series airplanes includes Civil Air Regulation (CAR) 4b, dated December 31, 1953, as amended by Amendments 4b-1 through 4b-9. In addition, under § 21.101(b)(1), Amendment 25-69, the following sections of 14 CFR part 25 apply to the air data, altimeter, and display systems installed on the Sabreliner NA-265 series airplanes: §§ 25.1309(a), (c), (e), (f), and (g), 25.1321(a), (b), (d), and (e), 25.1331, and 25.1335 as amended by Amendment 25-41; and § 25.1316, as amended by Amendment 25-80. The certification basis also includes other amendments and special conditions, as noted in Type Certificate Data Sheet (TCDS) No. A2WE, that are not relevant to these special conditions.
If the Administrator finds that the applicable airworthiness regulations (that is, CAR 4b, as amended) do not contain adequate or appropriate safety standards for the Sabreliner Model NA-265 series airplanes because of a novel or unusual design feature, special conditions are prescribed under the provisions of § 21.16.
In addition to the applicable airworthiness regulations and special conditions, the Sabreliner Model NA-265 series airplanes must comply with the fuel vent and exhaust emission requirement of SFAR 27 (now codified as 14 CFR part 34) and the noise certification requirements of 14 CFR part 36.
Special conditions, as defined in 14 CFR 11.19, are issued in accordance with § 11.38, and become part of the type certification basis in accordance with § 21.101.
Special conditions are initially applicable to the model for which they are issued. Should Sabreliner Corporation apply at a later date for a supplemental type certificate to modify any other model included on Type Certificate No. A2WE to incorporate the same or similar novel or unusual design features, these special conditions would also apply to the other model under the provisions of § 21.101.
Novel or Unusual Design Features
As noted earlier, the Sabreliner Model NA-265 series airplanes modified by Sabreliner Corporation will incorporate the installation of Air Data systems that perform critical functions. Because these advanced systems use electronics to a far greater extent than the original altimetry system, they may be more susceptible to electrical and magnetic interference caused by high-intensity radiated fields (HIRF) 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, these systems are considered to be a novel or unusual design feature.
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 Model NA-265 series airplanes, modified by Sabreliner to include the new Air Data systems. These special conditions require that the Air Data systems, which 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 (HIRF)
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 digital 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)|
|10 kHz-100 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|
|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|
|Note.—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.
As discussed above, these special conditions are applicable to Sabreliner Model NA-265 series airplanes modified by Sabreliner. Should Sabreliner Corporation apply at a later date for a supplemental type certificate to modify any other model included on Type Certificate No. A2WE 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 § 21.101.
This action affects only certain novel or unusual design features on Sabreliner Start Printed Page 53028Model NA-265 series airplanes modified by Sabreliner 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.
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.Start List of Subjects
List of Subjects in 14 CFR Part 25End List of Subjects
The authority citation for these special conditions is as follows:
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 Sabreliner Model NA-265 series airplanes modified by Sabreliner Corporation.
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.Start Signature
Issued in Renton, Washington, on August 28, 2003.
Kalene C. Yanamura,
Acting Manager, Transport Airplane Directorate, Aircraft Certification Service.
[FR Doc. 03-22798 Filed 9-8-03; 8:45 am]
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