Airworthiness Directives; Bombardier, Inc., Airplanes

We propose to adopt a new airworthiness directive (AD) for certain Bombardier, Inc., Model DHC-8-400 series airplanes. This proposed AD was prompted by reports of wear on fuel couplings, bonding springs, and sleeves as well as fuel tube end ferrules and fuel component end ferrules. This proposed AD would require repetitive inspections of the existing clamshell coupling bonding wires, fuel couplings, and associated sleeves for certain criteria and replacement as necessary. This proposed AD would also require repetitive inspections of the fuel tube end ferrules, fuel component end ferrules, and ferrule o-ring flanges for damage and wear, and rework as necessary. We are proposing this AD to address the unsafe condition on these products.