# Airworthiness Directives; Bombardier Model DHC-8-400 Series Airplanes
> **Rule** · Final rule. · Published 2006-12-15 · Effective 2007-01-19 · 71 FR 75409
## Document
- **Document number:** E6-21267
- **Category:** airworthiness
- **Manufacturer:** Bombardier Model DHC-8-400 Series
- **Type:** Rule
- **Action:** Final rule.
- **Citation:** 71 FR 75409
- **Publication date:** 2006-12-15
- **Effective date:** 2007-01-19
- **FAA docket:** Docket No. FAA-2006-25723
## Abstract

The FAA is adopting a new airworthiness directive (AD) for certain Bombardier Model DHC-8-400 series airplanes. This AD requires repetitive cleaning/inspecting of the drain hole of each pitot static probe and repetitive cleaning of the pitot lines in the pitot static system. This AD results from reports of incidents of airspeed mismatch between the pilot, co-pilot, and standby airspeed indications caused by contamination in the pitot static system. We are issuing this AD to prevent erroneous/misleading altitude and airspeed information from a contaminated pitot static system to the flightcrew, which could reduce the ability of the flightcrew to maintain the safe flight and landing of the airplane.

## Source
- [Federal Register document](https://www.federalregister.gov/documents/2006/12/15/E6-21267/airworthiness-directives-bombardier-model-dhc-8-400-series-airplanes)
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