Summary
We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-102, -103, -106, -201, -202, -301, -311, and -315 airplanes. This proposed AD was prompted by reports of the loss of the fixed frequency system, leading to the loss of power to the left and right buses and all systems serviced by these buses. This proposed AD would require modification of the wiring and changes to existing airworthiness limitations. We are proposing this AD to prevent loss of the fixed frequency system, which could lead to loss of a number of the pilot's and co-pilot's flight instruments, in addition to other avionics systems.