EASA AD No.: 2013-0187 

TE.CAP.00110-003 © European Aviation Safety Agency. All rights reserved. 1/2 

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EASA AIRWORTHINESS DIRECTIVE 

AD No.: 2013-0187 

Date: 16 August 2013 

Note: This Airworthiness Directive (AD) is issued by EASA, acting in accordance with Regulation 

(EC) No 216/2008 on behalf of the European Community, its Member States and of the 

European third countries that participate in the activities of EASA under Article 66 of that 

Regulation.

This AD is issued in accordance with EU 748/2012, Part 21.A.3B. In accordance with EC 2042/2003 Annex I, Part M.A.301, the 

continuing airworthiness of an aircraft shall be ensured by accomplishing any applicable ADs. Consequently, no person may operate an 

aircraft to which an AD applies, except in accordance with the requirements of that AD, unless otherwise specified by the Agency [EC 

2042/2003 Annex I, Part M.A.303] or agreed with the Authority of the State of Registry [EC 216/2008, Article 14(4) exemption]. 

Design Approval Holder’s Name: 

AgustaWestland S.p.A 

Type/Model designation(s): 

AB 412 helicopters

TCDS Number: ENAC Italy SO/A 375 

Foreign AD: Not applicable 

Supersedure: None 

ATA 66 Power Train – Rotor Brake Pinion – Inspection / Replacement 

Manufacturer(s): AgustaWestland S.p.A (formerly Agusta S.p.A.). 

Applicability: AB412 and AB412EP helicopters, all serial numbers. 

Reason: One case of a cracked pinion, part number (P/N) 412-040-301-101, installed in 

the Rotor Brake Quill P/N 412-040-123-103 of an Agusta AB412 helicopter, has 

been reported. This crack was discovered through a magnetic inspection 

accomplished during a scheduled overhaul of the rotor brake quill. 

The results of the investigation revealed that this crack was due to residual 

stress, generated during the pinion manufacturing process. AgustaWestland is 

working to identify the cause of stress, with the aim to modify this 

manufacturing process. 

This condition, if not detected and corrected, could lead to the failure of the 

pinion with detachment of parts inside the transmission that could cause its 

malfunction or jamming, finally resulting in loss of control of the helicopter. 

To address this potential unsafe condition, AgustaWestland issued Bollettino 

Tecnico (BT) 412-135 to provide instructions for a one-time inspection of the 

rotor brake pinion. 

For the reasons described above, this AD requires a magnetic particle 

inspection (MPI) of the rotor brake pinion and, depending on findings, 

replacement with a serviceable part. 
EASA AD No.: 2013-0187 

TE.CAP.00110-003 © European Aviation Safety Agency. All rights reserved. 2/2 

Proprietary document. Copies are not controlled. Confirm revision status through the EASA-Internet/Intranet.

Effective Date: 30 August 2013 

Required Action(s) 

and Compliance 

Time(s): 

Required as indicated, unless accomplished previously: 

(1) Within 100 flight hours or 5 months, whichever occurs first after the 

effective date of this AD, for a rotor brake quill assembly P/N 412-040-123-

103 which has never been overhauled, accomplish a MPI of the rotor brake 

pinion P/N 412-040-301-101 in accordance with the instructions of 

AgustaWestland BT 412-135 Rev A. 

(2) If, during the inspection as required by paragraph (1) of this AD, a crack is 

detected, before next flight, replace the rotor brake pinion P/N 412-040-

301-101 with a serviceable part in accordance with the instructions of 

AgustaWestland BT 412-135 Rev A. 

(3) From the effective date of this AD, installation on a helicopter of a rotor 

brake pinion P/N 412-040-301-101 is allowed, provided it is new, or it is 

overhauled, or it has passed the inspection in accordance with the 

instructions of AgustaWestland BT 412-135 Rev A. 

Ref. Publications: AgustaWestland BT 412-135 Rev. A dated 29 July 2013. 

The use of later approved revisions of this document is acceptable for 

compliance with the requirements of this AD. 

Remarks: 1. If requested and appropriately substantiated, EASA can approve 

Alternative Methods of Compliance for this AD. 

2. Based on the required actions and the compliance time, EASA have 

decided to issue a Final AD with Request for Comments, postponing the 

public consultation process until after publication. 

3. Enquiries regarding this AD should be referred to the Safety Information 

Section, Executive Directorate, EASA. E-mail: ADs@easa.europa.eu. 

4. For any question concerning the technical content of the requirements in 

this AD, please contact: 

AgustaWestland S.p.A. Customer Support 

Via del Gregge, 100 - 21015 Lonate Pozzolo (VA) – Italy 

Telephone + 39 0331-664873 ; Fax: + 39 0331-664680 

E-mail: absereng@agustawestland.com.