Summary
We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-102, -103, and -106 airplanes. This proposed AD was prompted by a report of cracking in a lower longeron in a nacelle. This proposed AD would require repetitive inspections for cracking of the lower longerons in the nacelles and replacement with new longerons or repair if necessary. Additionally, this proposed AD specifies an optional terminating action. We are proposing this AD to detect and correct such cracking, which could result in degradation of the structural integrity of the nacelle and possible collapse of the main landing gear (MLG).