Verification of the Production Safe Flight Instrument Corporation OV/RV- 1D Stall Warning System

A Safe Flight Instrument Corporation (SFIC) stall warning system and prototype normal acceleration (g) limit aural warning device were evaluated on an OV-1D(C). Fifteen productive test flight hours were completed. Interchangeability of the SFIC stall warning system between aircraft was demonstrated by the good correlation of data between Grumman's test on aircraft and U.S. Army Aviation Engineering Flight Activity's (AEFA's) test on aircraft. Grumman's data shows adequate warning margin for LSSS on. There were, inadequate stall margins with LSSS not installed for dual-engine unaccelerated stalls, drop tanks only, and no-stores configurations. Single engine warning margins were inadequate, especially with the right engine operating near maximum power. Accelerated stall warning margine were satisfactory for all wing stores configurations. If the SFIC system is installed on operational aircraft without LSSS, the SFIC system should be adjusted to provide approximately 3 knots more warning margin for low power stalls. Keywords: Stall warning indications; Angle of attack; Configurations; Interchangeability; Louvered scarfed shroud suppressor (LSSS), Prototype, Warning margin.