# Special Conditions: Learjet Model 24/25 Series Airplanes; High Intensity Radiated Fields (HIRF)
> **Rule** · Final special conditions; request for comments. · Published 2003-04-29 · Effective 2003-04-14 · 68 FR 22578
## Document
- **Document number:** 03-10450
- **Category:** other
- **Type:** Rule
- **Action:** Final special conditions; request for comments.
- **Citation:** 68 FR 22578
- **Publication date:** 2003-04-29
- **Effective date:** 2003-04-14
- **FAA docket:** Docket No. NM247, Special Conditions No. 25-232-SC
## Abstract

These special conditions are issued for the Learjet Model 24/ 25 series airplanes, as modified by LJSC Ltd. These airplanes 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 dual IS&S air data display units (ADDU) and a single IS&S analog interface unit (AIU). 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.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2003/04/29/03-10450/special-conditions-learjet-model-2425-series-airplanes-high-intensity-radiated-fields-hirf)
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