Airworthiness Directives; AlliedSignal, Instrument Landing System Navigation Receivers, as Installed in, but Not Limited to, Airbus Model A300 Series Airplanes and Boeing Model 747-100, -100B, -100B SUD, - 200B, -200F, -200C, -300, 747SR, and 747SP Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain instrument landing system (ILS) navigation receivers manufactured by AlliedSignal. This action requires replacement of certain resistors in the ILS navigation receiver with higher ohm resistors and replacement of the nameplate on the receiver with a new nameplate. This amendment is prompted by reports of ILS navigation receivers incorrectly indicating signals from the glideslope ground station during final approach. The actions specified in this AD are intended to ensure the ILS receiver provides the flight crew with accurate glideslope data. Inaccurate glideslope data could result in an approach off the glideslope, and, consequently, a landing short of the runway or a runway overrun.