Airworthiness Directive · Amendment 39-18170 · Tail rotor drive shaft
Agusta S.p.A. Helicopters
This AD applies to Model AB412 helicopters with a serial number (S/N) 25801 through 25900, and Model AB412 EP helicopters with a S/N 25901 and larger, certificated in any category.
We are adopting a new airworthiness directive (AD) for certain Agusta S.p.A. Model AB412 and AB412 EP helicopters. This AD requires inspecting the tail rotor (T/R) drive shaft flanged adapter (adapter) for a crack and removing the adapter from service if there is a crack. This AD is prompted by a report of a crack found in an adapter. These actions are intended to detect a crack in the adapter and prevent failure of the T/R drive shaft, which could result in reduced control of the helicopter.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
(1) Within 5 hours time-in-service (TIS) and thereafter at intervals not to exceed 100 hours TIS, using a 5X power magnifying glass and a light source, visually inspect each flanged adapter, part number (P/N) 412-040-622-101 and P/N 412-040-623-101, for a crack as shown in Figures 1 and 2 of AgustaWestland Bollettino Tecnico No. 412-139, dated February 19, 2014.
(2) If there is a crack in a flanged adapter, before further flight, remove the flanged adapter from service.
(3) Do not install a flanged adapter, P/N 412-040-622-101 or P/N 412-040-623-101, unless it has been inspected in accordance with the requirements of paragraphs (e)(1) and (e)(2) of this AD.
