# Airworthiness Directives; Bombardier, Inc. Airplanes
> **Rule** · Final rule. · Published 2016-12-08 · Effective 2017-01-12 · 81 FR 88623
## Document
- **Document number:** 2016-28210
- **Category:** airworthiness
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 81 FR 88623
- **Publication date:** 2016-12-08
- **Effective date:** 2017-01-12
- **FAA docket:** Docket No. FAA-2016-4224
## Abstract

We are adopting a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-400 series airplanes. This AD was prompted by reports of cracked and corroded barrel nuts found at the mid-spar location of the horizontal-stabilizer-to-vertical-stabilizer attachment joint. This AD requires repetitive detailed inspections of each barrel nut and cradle, a check of the bolt torque of the preload indicating (PLI) washers, and corrective action if necessary. We are issuing this AD to address the unsafe condition on these products.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2016/12/08/2016-28210/airworthiness-directives-bombardier-inc-airplanes)
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