On May 18, the FAA published a Notice of Proposed Rulemaking (NPRM) proposing to require an Airworthiness Directive repetitively inspecting and adjusting the throttle linkage on the following Scotts-Bell 47 Inc. aircraft models: 47, 47B, 47B3, 47D, 47D1, 47E, 47G, 47G-2, 47G-2A, 47G-2A-1, 47G-3, 47G-3B, 47G-3B-1, 47B3B-2, 47G-3B-2A, 47-G4, 47G-4A, 47G-5, 47G-5A, 47H-1, 47J-2, 47J-2A and 47K helicopters with certain Marvel Schebler carburetors installed. The carburetors are the Model MA-3, MA-3A, MA3-PA, MA-3SPA, MA4-SPA, MA4-5, MA4-5AA, MA-5, MA-5AA, MA-6AA or MA6AA.      

This proposed AD is prompted by reports of the throttle linkage separating from the engine carburetor shaft, which could result in loss of throttle control. The proposal would require the following:

• Before further flight, inspect the throttle linkage connection at the engine carburetor for condition, security and correct safety wire installation.
• Before the first flight of each day, visually check the throttle-linkage to carburetor attachment for installed safety wire and for intact anti-sabotage lacquer. This can be accomplished by the owner/operator (pilot), but an entry must be made in the maintenance records.
• Within 100 hours time-in-service or at the next annual inspection, whichever occurs first, and thereafter at each annual or 100-hour inspection, whichever occurs first, adjusting, safety wiring and applying anti-sabotage lacquer to the throttle.

You may examine the AD docket at regulations.gov by searching for and locating FAA-2018-0440. The docket contains this proposed AD, the economic evaluation, any comments received and other information.