Summary
We propose to supersede an existing airworthiness directive (AD) that applies to Turbomeca S.A. Arrius 2F turboshaft engines with P3 air pipe (first section) part number (P/N) 0 319 71 918 0, installed. The existing AD currently requires inspections of the P3 air pipe (first section) and right-hand (RH) rear half-wall for proper clearance, and readjustment of the pipe if necessary. Since we issued that AD, Turbomeca S.A. has redesigned the RH rear half-wall to ensure sufficient clearance between the P3 air pipe (first section) and RH rear half-wall. This proposed AD would require the same inspections for installed engines, eliminate readjusting of the P3 air pipe (first section), require replacement of the RH rear half-wall under certain conditions, and adding an optional terminating action. We are proposing this AD to prevent an uncommanded power loss to flight idle, which could result in an emergency autorotation landing or accident.