Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain De Havilland Aircraft of Canada Limited Model DHC-8-400 series airplanes. This proposed AD was prompted by reports of broken P- clamps on the pressure relief line and the motive flow line in the fuel tanks, and a subsequent determination that certain service information lacked instructions for maintaining appropriate clearance between certain fuel tubes and their support brackets, and may also have led to incorrect installation of certain Teflon<SUP>TM</SUP> sleeves. This proposed AD was also prompted by a determination that new or more restrictive airworthiness limitations are necessary. This proposed AD would require inspecting the motive flow line, vent line, and related parts, and adding support or additional clearance if necessary. This proposed AD would also require inspection, and replacement or relocation if necessary, of affected Teflon<SUP>TM</SUP> sleeves on the vent line, and installation of Teflon<SUP>TM</SUP> sleeves on the vent line at additional wing stations. This proposed AD would also require revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations. The FAA is proposing this AD to address the unsafe condition on these products.