Summary
This document proposes the adoption of a new airworthiness directive (AD) that is applicable to Robinson Helicopter Company (Robinson) Model R44 helicopters. This proposal would require an adjustment to the low-RPM warning unit threshold to increase the revolutions-per-minute (RPM) at which the warning horn and caution light activate, and revisions to the R44 Rotorcraft Flight Manual that prohibit flight with the throttle governor (governor) selected off, except in certain situations. This proposal is prompted by an FAA Technical Panel Review of Robinson accident history data which revealed that main rotor (M/R) blade stall at abnormally low M/R RPM resulted in accidents. The actions specified by the proposed AD are intended to minimize the possibility of pilot mismanagement of the M/R RPM, which could result in unrecoverable M/R stall and subsequent loss of control of the helicopter.