Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to supersede Airworthiness Directive (AD) 2011-15- 09, which applies to certain Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes. AD 2011-15-09 currently requires repetitive inspections for proper operation of the main landing gear (MLG) alternate extension system (AES), and corrective actions if necessary. Since we issued AD 2011-15-09, we have determined that, for certain airplanes not affected by AD 2011-15-09, a different MLG AES cam mechanism assembly was installed resulting in input lever fractures and inability to open the MLG door; those assemblies could be subject to the same unsafe condition in AD 2011-15-09. This new proposed AD would require, for certain airplanes, new repetitive inspections for proper operation of the MLG AES, and corrective actions if necessary. This proposed AD would also require eventually replacing the MLG AES cam mechanism assembly with a new assembly, which would terminate the repetitive inspections for those airplanes. We are proposing this AD to prevent improper operation of the cam mechanism or rupture of the door release cable, which could result in loss of control of the airplane during landing.