Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Raytheon Corporate Jets Models DH/BH/HS/BAe 125-1 to -700 series, BAe 125-800A, and Hawker 800 series airplanes. This proposal would require replacement of the existing standby static inverter with an inverter that incorporates a circuit board assembly sealed with a conformal coating. This proposal is prompted by reports of failure of the standby static inverter caused by electrical shorting from moisture condensing on the printed circuit boards (PCB), due to aberrations in the PCB conformal coating. The actions specified by the proposed AD are intended to prevent malfunction of the standby static inverter due to exposure to moisture caused by inadequate insulation coating of the circuit board assembly. Malfunction or failure of the standby static inverter, when its use is necessary, could result in the loss of electric power for certain equipment critical to safety of flight.