Airworthiness Directive · Amendment 39-18365 · Propeller/rotor anti-ice/de-ice system
Agusta S.p.A. Helicopters
This AD applies to Model AB139 and AW139 helicopters, certificated in any category, with a Full Icing Protection System tail rotor slip ring (slip ring) part number (P/N) 4G6420V00151, P/N 4G6420V00152, or P/N 4G6420V00153 installed, except a slip ring with a letter “T” after the serial number or marked with “MOD 1.”
We are adopting a new airworthiness directive (AD) for Agusta S.p.A. (Agusta) Model AB139 and AW139 helicopters. This AD requires inspecting each full ice protection system tail rotor slip ring (slip ring) for chatter marks, witness marks, or scoring, and determining the depth of each mounting hole. Based on the findings from the inspection, this AD requires either re-identifying the slip ring or replacing the slip ring. This AD is prompted by two incidents of the slip ring body separating from the supporting flange due to improper torque. These actions are intended to prevent separation of the mounting flange from the slip ring body and subsequent loss of 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.
Within 25 hours time-in-service:
(1) Remove each slip ring from the helicopter. Remove each lockwire, fastener, and washer by following the Compliance Instructions, paragraphs 3 through 5, of Moog Service Bulletin SB 14-02, Revision D, undated, included as Annex A to Agusta Westland Bollettino Tecnico (BT) No. 139-404, dated December 22, 2014, except you are not required to discard parts.
(2) Inspect the wall of the mounting plate hole for a chatter mark, witness mark, or scoring. If there is a chatter mark, witness mark, or scoring, replace the slip ring with a slip ring that is not listed in paragraph (a) of this AD.
(3) Determine the depth of the mounting plate hole. If the depth exceeds the grip length of the screw, replace the slip ring with a slip ring that is not listed in paragraph (a) of this AD.
(4) Re-identify the slip ring by marking a letter “T” after the serial number with permanent black pen and applying acrylic lacquer (CO81 or equivalent).
(5) Do not install an affected slip ring on any helicopter unless the slip ring has passed the inspections in accordance with this AD.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
