Summary
We propose to supersede an existing airworthiness directive (AD) that applies to all Turbomeca S.A. Arriel 1E2, 1S, and 1S1 turboshaft engines. The existing AD currently requires a one time inspection and torque check of a certain 3-way union plug installed on all fuel control units (FCUs). Since we issued that AD, the applicability has been reduced to certain FCUs and the referenced service bulletin has been updated with additional detailed information to identify the non-compliant ``red disk'' plug. This proposed AD would still require a one time inspection and torque check of the 3-way union plug, would require replacement of the plug before further flight if it is found to be non-compliant, and would prohibit installation of FCUs that have not passed the 3-way union plug inspection and torque check. We are proposing this AD to prevent fuel leaks, which could result in a fire and damage to the helicopter.