Airworthiness Directives; Bombardier, Inc. Airplanes

We are superseding Airworthiness Directive (AD) 2015-10-01 for certain Bombardier, Inc. Model DHC-8-400 series airplanes. AD 2015-10- 01 required inspection for correct assembly of the main landing gear (MLG) alternate extension system reservoir lid, and corrective action if necessary. This new AD revises the applicability. This AD was prompted by the discovery of two errors in the applicability of AD 2015-10-01. We are issuing this AD to, in the event of a failure of the primary MLG extension system, prevent failure of the alternate MLG extension system to fully extend the MLG into a down-and-locked position, which could result in collapse of both left-hand and right- hand MLG sides during touchdown.