Airworthiness Directives; Bombardier, Inc. Model DHC-8-200 and DHC-8-300 Series Airplanes

摘要

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: During a recent production fuel system test, it was found that all three flapper valves located in each collector tank did not conform to the design requirements, due to the fact that a valve spring was installed on the flapper hinge pin. This valve spring should have been removed prior to installation of the valves. With the valve spring installed, the flapper valve is held closed by the valve spring, preventing gravity feed. In the event of scavenge system failure, the collector tank fuel level can no longer be maintained, potentially leading to an in-flight engine shutdown. The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.