# Airworthiness Directives; Rockwell Collins, Inc. Transponders
> **Rule** · Final rule. · Published 2014-03-28 · Effective 2014-05-02 · 79 FR 17397
## Document
- **Document number:** 2014-05202
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 79 FR 17397
- **Publication date:** 2014-03-28
- **Effective date:** 2014-05-02
- **FAA docket:** Docket No. FAA-2013-0966
## Abstract

We are adopting a new airworthiness directive (AD) for certain Rockwell Collins TPR-720 and TPR-900 Mode select (S) transponders that are installed on airplanes. This AD was prompted by the identification that the TPR-720 and TPR-900 Mode S transponders respond intermittently to Mode S interrogations from both ground-based and traffic collision avoidance system (TCAS-) equipped airplanes. This AD requires testing and calibration of the alignment of the transponders. We are issuing this AD to correct the unsafe condition on these products.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2014/03/28/2014-05202/airworthiness-directives-rockwell-collins-inc-transponders)
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