Summary
We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc. Model DHC-8-400, -401, and -402 airplanes. This proposed AD was prompted by reports of an in-service incident where the propeller de-icing system became unavailable due to burnt/ chafed wires within the alternating current contractor box (ACCB). This proposed AD would require inspection for chafing, damage, and loose wiring within an ACCB and repair if necessary; and would require rework and re-identification of the wiring installation within each ACCB. We are proposing this AD to detect and correct damaged, chafed, or loose wiring within an ACCB, which could affect the operation of the windshield heater, ice detector, angle of attack (AOA) vane heater, pilot probe heater, engine intake heater, or propeller de-icing system, and subsequently adversely affect the airplane's flight characteristics in icing conditions.