Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to certain Saab Model SAAB SF340A and SAAB 340B series airplanes. This proposal would require repetitive operational tests of the valve limit switch of the propeller brake. This proposal also provides for an optional terminating action for the repetitive tests. This proposal is prompted by a report that when the propeller brake was not properly engaged the crew did not receive a ``PROP BRAKE'' warning due to a faulty valve limit switch. The actions specified by the proposed AD are intended to prevent a valve limit switch from failing to send input to the warning system; absence of a ``PROP BRAKE'' warning could result in the crew being unaware that the propeller brake is not properly engaged and the propeller may turn without warning.