Summary
We propose to adopt a new airworthiness directive (AD) for Model R22, R22 Alpha, R22 Beta, and R22 Mariner helicopters with certain fuel shut-off valves installed. This proposed AD would require replacing the fuel shut-off valve with a newer design fuel shut-off valve. This proposed AD is prompted by three accidents that occurred because the fuel shut-off valve was inadvertently moved to the ``off'' position. The proposed actions are intended to prevent inadvertent closing of the fuel valve, which could result in engine power loss and subsequent loss of control of the helicopter.