Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Raytheon (Beech) Model MU-300-10, 400, 400A, and 400T series airplanes; and certain Raytheon (Mitsubishi) Model Beech MU-300 airplanes. This proposed AD would require a one-time inspection of certain panels in the spoiler mixer bay for the presence of drain holes, and the addition of at least one new drain hole; and a one-time inspection for discrepancies of the sealant on the relief cutout on the aft pressure bulkhead, and on certain baffles; and corrective actions if necessary. This proposed AD is prompted by a report of fuel leaking from components in the spoiler mixer bay of several Raytheon (Beech) Model 400A series airplanes. We are proposing this AD to prevent the accumulation of fuel and/or fuel vapor in the spoiler mixer bay and/or the aft fuselage compartment, which could result in a fire in the airplane.