Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Portions of DOT are affected by a lapse in appropriations. Website information may be outdated, transactions may be delayed, and inquiries may not be answered until funding is restored. Please monitor this page for updates.

Action

Notice of proposed rulemaking (NPRM).

Summary

We propose to adopt a new airworthiness directive (AD) for certain Bombardier Inc. Model DHC-8-400 series airplanes. This proposed AD was prompted by reports that the automatic de-icing mode became unavailable due to a failure of the timer and monitor unit (TMU). This proposed AD would require replacing the TMU. We are proposing this AD to prevent loss of the automatic de-icing mode and consequent increased workload for the flight crew, which, depending on additional failures, could lead to loss of control of the airplane.

Document

View PDF