# Airworthiness Directives; Airbus Model A319, A320, and A321 Series Airplanes
> **Rule** · Final rule. · Published 1999-01-08 · Effective 1999-02-12 · 64 FR 1106
## Document
- **Document number:** 99-50
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 64 FR 1106
- **Publication date:** 1999-01-08
- **Effective date:** 1999-02-12
- **FAA docket:** Docket No. 98-NM-07-AD
## Abstract

This amendment adopts a new airworthiness directive (AD), applicable to certain Airbus Model A319, A320, and A321 series airplanes, that requires modification of the airplane wiring to separate the electrical inputs sent by the engine interface units (EIU) to certain probe heat computers (PHC). This amendment is prompted by the issuance of mandatory continuing airworthiness information by a foreign civil airworthiness authority. The actions specified by this AD are intended to prevent simultaneous loss of heating to pitot probes 1 and 3, which could result in incorrect airspeed indications to both the pilot's and first officer's airspeed indication systems. Malfunction of these systems could result in reduced controllability of the airplane.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/1999/01/08/99-50/airworthiness-directives-airbus-model-a319-a320-and-a321-series-airplanes)
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