Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to all Raytheon (Beech) Model MU-300, MU-300-10, 400, and 400A series airplanes. This proposal would require repetitive inspections of the bleed air supply tube assemblies for discrepancies; and replacement of the bleed air tube assembly with a new bleed air tube assembly, if necessary. In lieu of accomplishing the repetitive inspections, this proposal also would provide for a revision of the Airworthiness Limitations to incorporate, among other things, certain inspections and compliance times to detect discrepancies of the subject area; and corrective action, if necessary. This proposal is prompted by reports of broken wire braiding in the bellows assembly of the bleed air supply tube assembly due to premature failure from loading. The actions specified by the proposed AD are intended to prevent the bleed air supply tube assembly from disconnecting and contacting other pneumatic or electrical systems of the airplane or expelling high temperature air on surrounding systems and structure. Such a condition could reduce the functional capabilities of the airplane or the ability of the flight crew to cope with adverse operating conditions.