Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Boeing Model 737-100 and - 200 series airplanes. This proposal would require replacement of the 250 volt-ampere (VA) rated static inverters with 410 or 500 VA rated static inverters, and an operational test of the standby electrical power system. This proposal is prompted by a report that accomplishment of a certain modification could result in overload of the static inverter on these airplanes. The actions specified by the proposed AD are intended to prevent overload of the static inverter, which could result in the loss of the 115 volt alternating current standby bus and the associated flight instruments when the airplane is operating on standby electrical power.