AD 96-11-08 61 FR 26429

This amendment supersedes an existing airworthiness directive (AD), applicable to Robinson Helicopter Company (Robinson) Model R22 helicopters, that currently requires installing a low-rotor RPM caution light and resetting the low-RPM warning unit to activate the warning horn and caution light at 94% to 96% revolutions-per-minute (RPM). This amendment requires installation of an improved throttle governor; an adjustment to the low RPM warning unit threshold to increase the RPM at which the warning horn and caution light activate; and, revisions to the R22 Rotorcraft Flight Manual that prohibit flight with the improved throttle governor selected off, except in certain situations. This amendment is prompted by an FAA Technical Panel review of Model R22 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 this AD are intended to minimize the possibility of pilot mismanagement of the M/R RPM, which could result in unrecoverable M/R blade stall and subsequent loss of control of the helicopter.