The National Transportation Safety Board has issued a formal recommendation directing the Federal Aviation Administration to take immediate regulatory action regarding safety concerns with Chandler Evans Company MFP-261 and -265 fuel pumps. The board advises that an emergency airworthiness directive be issued to mandate inspections of the internal splines on the fuel pump driveshaft and the external splines on the fuel pump driver gear. This requirement applies specifically to these pumps when used in single-engine applications for a specified number of hours since overhaul. The directive would require replacement if wear exceeds a specified amount, with the inspection interval based on failure history. Inspections must include a magnified visual examination of the driver gear splines to detect degraded conditions. The recommendation is marked as urgent.

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