Federal Aviation Administration May 2, 2006 – Federal Register Recent Federal Regulation Documents

We propose to supersede Airworthiness Directive (AD) 2005-17- 19, which applies to certain Cirrus Design Corporation (CDC) Models SR20 and SR22 airplanes. AD 2005-17-19 currently requires you to measure and adjust the crew seat break-over bolts and to replace the crew seat recline locks on both crew seats. Since we issued AD 2005-17- 19, CDC developed new crew seat break-over pins to replace the old crew seat break-over bolts. Consequently, this proposed AD would retain the action from AD 2005-17-19 of replacing the crew seat recline locks on both seats and would add the action of replacing the crew seat break- over bolts with the new crew seat break-over pins on both seats. We are proposing this AD to prevent the crew seats from folding forward during emergency landing dynamic loads with consequent occupant injury.

This document proposes adopting a new airworthiness directive (AD) for Sikorsky Aircraft Corporation (Sikorsky) Model S-76A, B, and C helicopters. The AD would require inspecting all installed HR Textron main rotor servo actuators (servo actuators) for a high rate of leakage and also inspecting for contaminated hydraulic fluid. The AD would also require reducing the time-in-service (TIS) interval for overhauling the servo actuators. This proposal is prompted by a National Transportation Safety Board (NTSB) Safety Recommendation written in response to an accident involving a Model S-76 helicopter in which the performance of an HR Textron servo actuator was questioned as a result of piston head seal leakage and piston head plasma spray flaking. The actions specified by the proposed AD are intended to detect a high rate of leaking from a servo actuator and contamination of the hydraulic fluid, which could lead to degraded ability to maneuver the cyclic and collective controls and could result in subsequent loss of control of the helicopter.

This document proposes to revise an existing airworthiness directive (AD) for Eurocopter France (Eurocopter) Model AS-365N2, AS 365 N3, EC 155B, EC155B1, SA-365N, N1, and SA-366G1 helicopters. That AD currently requires inspecting the main gearbox (MGB) base plate for a crack and replacing the MGB if a crack is found. This action would increase the time intervals for inspecting the MGB base plate. This action would also include minor editorial changes throughout the AD. This proposal is prompted by crack growth tests that indicate that the inspection intervals can be increased without affecting safety. The actions specified by the proposed AD are intended to detect a crack in an MGB base plate and prevent failure of one of the MGB attachment points to the frame, which could result in severe vibration and subsequent loss of control of the helicopter.