Airworthiness Directives; Raytheon (Beech) Model MU-300-10, 400, 400A, and 400T Series Airplanes; and Raytheon (Mitsubishi) Model Beech MU-300 Airplanes

The FAA is adopting 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 AD requires 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 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 issuing 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.