# Airworthiness Directives; NARCO Avionics Inc. AT150 Transponders
> **Rule** · Final rule. · Published 2004-04-26 · Effective 2004-06-01 · 69 FR 22386
## Document
- **Document number:** 04-9104
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 69 FR 22386
- **Publication date:** 2004-04-26
- **Effective date:** 2004-06-01
- **FAA docket:** Docket No. 2002-NE-32-AD
## Abstract

The FAA is adopting a new airworthiness directive (AD) for certain serial numbers (SNs) of NARCO Avionics Inc. AT150 transponders. This AD requires modification to the transponder by adding a resistor and transistor to the circuit board. This AD results from reports of AT150 transponders not recognizing and responding properly to Mode S interrogations from Mode S ground stations and Traffic Alert and Collision Avoidance System (TCAS-II) airborne equipment. We are issuing this AD to prevent loss of aircraft airspace separation and the possibility of mid-air collision.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2004/04/26/04-9104/airworthiness-directives-narco-avionics-inc-at150-transponders)
---
*AI Analytics · CC0 1.0*