Source: https://www.federalregister.gov/articles/2005/10/13/05-20459/special-conditions-learjet-model-35-series-high-intensity-radiated-fields-hirf
Timestamp: 2016-07-24 22:21:58
Document Index: 339922676

Matched Legal Cases: ['art 25', '§ 25', 'art 25', 'art 25', '§ 21', 'art 34', 'art 36', '§ 11', '§ 21', '§ 21', 'art 25', '§ 21']

Federal Register | Special Conditions: Learjet Model 35 Series; High-Intensity Radiated Fields (HIRF)
Dates: The effective date of these special conditions is October 4, 2005. Comments must be received on or before November 14, 2005.
-59631 (2 pages)
Document Number: 05-20459
Shorter URL: https://federalregister.gov/a/05-20459 Related Topics
These special conditions are issued for Learjet Model 35 series airplanes modified by Avcon Industries Inc. 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 new Kollsman 24771 Air data computers and Thommen AD30 displays. 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 established by the existing airworthiness standards.
Comments on these special conditions may be mailed in duplicate to: Federal Aviation Administration, Transport Airplane Directorate, Attention: Rules Docket (ANM-113), Docket No. NM331 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. NM331.
On August 5, 2005, Avcon Industries, Inc., P.O. Box 748, Newton, Kansas, 67114, applied for a supplemental type certificate (STC) to modify Learjet Model 35 series airplanes currently approved under Type Certificate No. A10CE. The Learjet Model 35 airplanes are small transport category airplanes powered by two turbojet engines, with maximum takeoff weight of up to 18,000 lbs. These airplanes operate with 2-person crew and can seat up to 8 passengers. The proposed modification incorporates the installation of Kollsman 24771 Air Data Computers and Thommen AD30 displays. The avionics/electronics and electrical systems installed in this airplane are flight critical and have the potential to be vulnerable to high-intensity radiated fields (HIRF) external to the airplane.
Under the provisions of 14 CFR 21.101, Avcon Industries, Inc., must show that the Learjet Model 35 series 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 certification basis for the Learjet Model 35 series airplanes includes 14 CFR part 25 effective February 1, 1965, as amended by Amendments 25-1, 25-2, 25-4, 25-7, 25-18, and § 25.571(d) of Amendment 25-10, Special Conditions set forth in FAA letter to Learjet dated March 1, 1967, and Special Conditions No. 25-50-CE-6 dated April 18, 1973, and Amendment 1 dated September 18, 1973. The certification basis for Models 35A also includes Special Conditions No. 25-72-CE-8 dated November 3, 1976, and Amendment 1 dated March 14, 1978. The certification basis for Model 35A (C-21A), in addition to the basis listed above, includes Special Conditions 25-ANM-28 dated May 3, 1989. In addition, the certification basis includes certain later amended sections of the applicable part 25 regulations 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 Learjet Model 35 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 Learjet Model 35 series 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 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 Avcon Industries Inc., 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 also apply to the other model under the provisions of § 21.101.
As noted earlier, the Learjet Model 35 series airplanes, as modified by Avcon Industries, Inc., will incorporate Kollsman 24771 Air data computers and Thommen AD30 displays. The Thommen displays and air data sensor 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. Accordingly, this system is considered to be a novel or unusual design feature.
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 Model 35 series airplanes as modified by Avcon Industries, 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 due to both the direct and indirect effects of HIRF.
As discussed above, these special conditions are applicable to Learjet Model 35 series airplanes modified by Avcon Industries, Inc. Should Avcon Industries, Inc., 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 the provisions of § 21.101.
This action affects only certain novel or unusual design features on Learjet Model 35 series airplanes modified by Avcon Industries, 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.
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 Learjet Model 35 series airplanes modified by Avcon Industries, Inc.
Issued in Renton, Washington, on October 4, 2005.
[FR Doc. 05-20459 Filed 10-12-05; 8:45 am]