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### BOLLETTINO TECNICO
The technical content of this document is approved under the authority of DOA nr. EASA.21J.005. N° 

# 412 - 139

DATE February 19 , 20 1 4

REV.

Compliance with this bulletin is:

SUBJECT: INSPECTION OF THE FLANGED ADAPTER P/N 412-040-622-101 AND

P/N 412 -040-623 -101 INSTALLED ON TAIL ROTOR DRIVE SHAFTS.
REASON: Provide the necessary instructions to inspect the above mentioned flanged adapter s

installed on tail rotor drive shafts.

HELICOPTERS AFFECTED: Agusta AB412 helicopters S/N 25801 through 25900 and AB412EP helicopters S/N 25901 and subs.

COMPLIANCE: Within and not later than 5 flight hours after the issue of this Bollettino, and subsequently every 100 flight hours.

DESCRIPTION: AgustaWestland has recently received a report of a crack on a flanged adapter P/N 412-040

- 622-101 installed on the tail rotor drive shaft of an AB412 EP helicopter. The investigation to determine the root causes of the crack on the flanged adapter is in progress, then the requirements of this Bollettino could be updated according to the investigation results. This Bollettino is issued in order to prescribe an inspection of the adapter-flanged P/N 412- 040-622-101 and P/N 412-040-623-1 0 1 for presence of cracks.B.T. 412-139

Page 2 of 4 MANPOWER REQUIRED: Approximately 3 man-hours are required to complete this Bollettino.

WARRANTY: N.A. MATERIAL REQUIRED: N.A. SPECIAL TOOLS: N.A. WEIGHT AND BALANCE CHANGE: N.A.

REFERENCES: AB412-IPC Illustrated Parts Catalogue AB412EP-IPC Illustrated Parts Catalogue AB412

- MM Maintenance Manual

PUBBLICATIONS AFFECTED: AB 412-MPM Maintenance Planning Manual

ACCOMPLISHMENT INSTRUCTIONS: 1. Prepare the helicopter for safe ground maintenance. Disconnect battery and all the electric power source and/or the external power supply. 2. In accordance with AB412- MM Chapter 65 gain access to the tail rotor drive shaft. 3. Using a 5X magnifying glass and a source light visually inspect the adapter-flanged P/N 412- 040-622 -101 and P/N 412-040 -623 -101 for presence of cracks in proximity of the fixing bolts (Refer to Figures 1 and 2 ). 4. If cracks are found, before the next flight remove from the helicopter the affected drive shaft assy in accordance with AB412-MM Chapter 65 and replace it with a serviceable drive shaft assy. 5. Report to AgustaWestland Product Support Engineering at the following e-mail address: absereng@agustawestland.com any case of cracked adapter-flanged and send the affected parts for investigation. 6. If no cracks are found in ac cordance with AB412-MM Chapter 65 install the access panel and close the access doors removed/opened during step 2. 7. Return the helicopter to flight configuration and make an entry in helicopter applicable documentations to indicate accomplishment of this Bollettino.B.T. 412

- 139

Page 3 of 4 Figure 1

- C rack found during inspection FLANGED ADAPTER EXAMPLE OF CRA C K FOUND DURING INSPECTION AREA TO BE INSPECTED ON FLANGED ADAPTER TYP

. 3 P LACESB.T. 412

- 139

Page 4 of 4 Figure 2

– Detail of flanged a dapter (on both side s of driveshaft)

FLANGE D ADAPTERNote: Remarks:

Informazioni: Information: Al f ine di gestire le varianti alla configur azione base, in relazione all’emissione de l Bollettino Tecnico, preghiamo di voler compilare il presente modulo in tutte le sue parti e sped irlo all’indirizzo sopra indicato. Si ring razia per la gentile collaborazione data. We request your cooperation in filling this form, in order to keep out statistical data relevant to aircraft configuration up- to-date. The form should be filled in all its parts and sent to the above address. We thank you beforehand for the information given. **MODULO APPLICAZIONE BOLLETTINO TECNICO** TECHNICAL BULLETIN COMPLIANCE FORM Data: Date:

Numero: Number:

Revisione: Revision: Prego spedire a questo indirizzo: Please send to the following address: 

### AGUSTA **WESTLAND S.p.A.**  CUSTOMER SUPPORT & SERVICES - ITALY PRODUCT SUPPORT ENGINEERING DPT. Via del Gregge, 100 2101 5 Lonate Pozzolo (VA) - I T ALY T el

. : +39 0331 664905 Fa x : +39 0331 66468 4 Telefono: Telephone:

Fax:

Data Applicazione B.T.: B.T. Compliance Date: Denominazione Cliente ed Indirizzo: Customer Name and Address:

Modello Elicottero

Helicopter Model S/N Matricola Tail Number Ore Totali Total Hours Ore D.U.R. T.S.O.