# Airworthiness Directives; Bombardier, Inc. Airplanes
> **Rule** · Final rule. · Published 2013-07-22 · Effective 2013-08-26 · 78 FR 43761
## Document
- **Document number:** 2013-17210
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 78 FR 43761
- **Publication date:** 2013-07-22
- **Effective date:** 2013-08-26
- **FAA docket:** Docket No. FAA-2012-1222
## Abstract

We are superseding airworthiness directive (AD) 2011-13-08 for certain Bombardier, Inc. Model DHC-8-400 series airplanes. AD 2011-13- 08 required a free-play check for excessive free-play of the shaft swaged bearing installed in the tailstock end of each elevator power control unit (PCU), and replacing any PCU on which the bearing exceeds allowable limits with a serviceable PCU. This new AD adds airplanes to the applicability from that of AD 2011-13-08. This AD was prompted by a determination that additional airplanes are affected by the identified unsafe condition. We are issuing this AD to detect and correct excessive free-play of the swaged bearings, which could lead to excessive airframe vibrations and difficulties in pitch control, and consequent loss of controllability of the airplane.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2013/07/22/2013-17210/airworthiness-directives-bombardier-inc-airplanes)
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