Source: https://www.federalregister.gov/documents/2006/12/06/E6-20276/special-conditions-learjet-25-25a-25b-25c-25d-and-25f-airplanes-high-intensity-radiated-fields-hirf
Timestamp: 2017-08-22 05:25:42
Document Index: 601961273

Matched Legal Cases: ['art 25', 'art 25', '§\u200921', 'art 34', 'art 36', 'art 25', '§\u200921']

Federal Register :: Special Conditions: Learjet 25, 25A, 25B, 25C, 25D, and 25F Airplanes; High-Intensity Radiated Fields (HIRF)
Special Conditions: Learjet 25, 25A, 25B, 25C, 25D, and 25F Airplanes; High-Intensity Radiated Fields (HIRF)
The effective date for these special conditions is November 13, 2006. We must receive your comments on or before January 5, 2007.
70646-70648 (3 pages)
Docket No. NM360
Special Conditions No. 25-337-SC
https://www.federalregister.gov/d/E6-20276 https://www.federalregister.gov/d/E6-20276
The FAA issues these special conditions for Learjet 25, 25A, 25B, 25C, 25D, and 25F airplanes modified by Envoy Aerospace, LLC. 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 Universal Avionics EFI-890 Electronic Flight Displays and Rockwell Collins AHS-1000A Attitude Heading Reference Systems. The applicable airworthiness regulations do not contain adequate or appropriate safety standards for protecting these systems from 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 established by the existing airworthiness standards.
You may mail or deliver comments on these special conditions in duplicate to: Federal Aviation Administration, Transport Airplane Directorate, Attention: Rules Docket (ANM-113), Docket No. NM360, 1601 Lind Avenue, SW., Renton, Washington 98057-3356. You must mark your comments Docket No. NM360.
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, Start Printed Page 70647explain the reason for any recommended change, and include supporting data. We ask that you send us two copies of written comments.
On June 3, 2006, Envoy Aerospace, LLC of Naperville, Illinois, applied to the FAA Chicago Aircraft Certification Office for a supplemental type certificate to modify Learjet Model 25, 25A, 25B, 25C, 25D, and 25F airplanes approved under Type Certificate No. A10CE. These are transport category airplanes powered by two turbofan engines with maximum takeoff weights of up to 15,000 pounds. The airplanes operate with a 2-pilot crew and can seat up to 8 passengers. The proposed modification incorporates the installation of Universal Avionics EFI-890 Electronic Flight Displays and Rockwell Collins AHS-1000A Attitude Heading Reference Systems. These systems have a potential to be vulnerable to high-intensity radiated fields (HIRF) external to the airplane.
Under provisions of 14 CFR 21.101, Envoy Aerospace, LLC must show that the Learjet 25, 25A, 25B, 25C, 25D, and 25F airplanes, as changed, continue to meet the applicable provisions of the regulations incorporated by reference in Type Certificate No. A10CE 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 original type certification basis for the modified Learjet 25, 25A, 25B, 25C, 25D, and 25F airplanes includes 14 CFR Part 25, as amended by 25-2 and 25-4, and FAA Special Conditions as set forth in a letter to Learjet dated March 1, 1967. For further details refer to Type Certificate No. A10CE.
If the Administrator finds that the applicable airworthiness regulations (part 25, as amended) do not contain adequate or appropriate safety standards for the Learjet 25, 25A, 25B, 25C, 25D, and 25F 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 Learjet 25, 25A, 25B, 25C, 25D, and 25F 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.
As noted earlier, the Learjet 25, 25A, 25B, 25C, 25D, and 25F airplanes modified by Envoy Aerospace, LLC will incorporate digital flight display and attitude reference systems that will perform critical functions. These systems may be vulnerable to high-intensity 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 these system are considered to be novel or unusual design features.
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 Learjet 25, 25A, 25B, 25C, 25D, and 25F airplanes modified by Envoy Aerospace, LLC. 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.
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. Start Printed Page 70648
These special conditions are applicable to Learjet 25, 25A, 25B, 25C, 25D, and 25F airplanes modified by Envoy Aerospace, LLC. Should Envoy Aerospace, LLC apply at a later date for a supplemental type certificate to modify any other model included on Type Certificate No. A10CE to incorporate the same or similar novel or unusual design feature, these special conditions would apply to that model as well under provisions of § 21.101.
This action affects only certain novel or unusual design features on Learjet 25, 25A, 25B, 25C, 25D, and 25F airplanes modified by Envoy Aerospace, LLC. It is not a rule of general applicability and affects only the applicant which applied to the FAA for approval of these design features on the airplane.
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 Learjet 25, 25A, 25B, 25C, 25D, and 25F airplanes modified by Envoy Aerospace, LLC.
[FR Doc. E6-20276 Filed 12-5-06; 8:45 am]