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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

- 136

DATE August 13
, 20 1 3

REV.

Compliance with
this bulletin is:

DERIVED FROM BELL ALERT SERVICE BULLETIN 412-13-155 DATED FEBRUARY 4, 2013

SUBJECT: TAIL ROTOR BLADE P/N 2 12

- 010

- 7 50

- ALL , INSPECTION OF.

REASON: I nspect the subject tail rotor blade s for presence of damages

.

HELICOPTERS AFFECTED:

COMPLIANCE:
Within the next 25 hours time

- in

- service (TIS) or 30 days, whichever occurs first, and
thereafter at intervals not to exceed 25 hours TIS or 30 days, whichever occurs first

.

DESCRIPTION:
Some cases of failured tail rotor blades have b een reported by Bell Helicopter; the investigations conducted by Bell determined that the failure originated from a crack deriving from surface damages. A periodic inspection of the blade surfaces has been required by Bell.
Even if no similar failure has ever been reported on blades installed on AW helicopters , due to the P/N commonality this BT is issued to introduce the same inspection on TR blades installed on AW helicopters. This Bollettino requires a 3X magnifying glass inspecti on of the tail rotor blade surface for damages (crack, corrosion, nick, scratch, or dent) every 25 hours or 30 days. Any damage isB.T. 412-136

Page 2 of 6 to be investigated by removing paint and inspecting skin condition with 10X magnification. Due to the critical nature of this inspection and requirements to fully comply, a further local inspection with 10X magnifying glass of blade between stations 20.00 to 35.00 from the leading edge to the trailing edge is also required. This is in addition to the 3X requirement for the full blade. If anomalies are noted during the 3X/10X inspections of the blade surface, this Bollettino requires to remove the paint and check skin condition again with 10X magnification. Skin damages exceeding limits reported in the Maintenance Manual or presence of crack requires blade removal from service.

MANPOWER REQUIRED: Approximately 2 man-hours are required to complete this Bollettino.

WARRANTY:

N.A.

MATERIAL REQUIRED: The following material is required for the accomplishment of this Bollettino.

Consumable Material:

P/N DENOMINA TION Q.TY

----------- Abrasive cloth or paper 240 grit and 400 grit A.R.

----------- Wax pencil / piece of chalk A.R.

SPECIAL TOOLS:

N.A.

WEIGHT AND BALANCE CHANGE:

N.A.

REFERENCES: AB412-IPC Illustrated Parts Catalogue AB412EP-IPC Illustrated Parts Catalogue BHT-412-CR&O Component Repair and Overhaul ManualB.T. 412

- 136

Page 3 of 6 AB412

- MM Maintenance Manual

PUBBLICATIONS AFFECTED:

AB412

- MPM Maintenance Planning Manual Chapter 5

ACCOMPLISHMENT INSTRUCTIONS:

1. Prepare helicopter for safe ground maintenance, disconnect battery and all the electric power source and/or the external power supply.
NOTE

Removal of the tail rotor blades is not required for this inspection.

2. Clean each tail rotor blade by hand using mild soap and cheesecloth in a spanwise direction. Dry thoroughly.

3. Carry out a detailed visual inspection of both sides of the entire blade with a 3X magnifying glass and bright light. Inspect the tail rotor blade skin, leading edge spar, doublers, grip plates and trailing edge for cracks, corrosion, nicks, dents and scratches. Refer to Maintenance Manual Chapter 64

- 11

- 01 step 7 for damage limits.

4. Create a proper control grid on the blade surface (see an example in figure 1 ) to be used as a reference during the inspection. C arry out a further detailed visual inspection with 10X magnifying glass of t he shaded area shown in figure 2 between stations 20.00 to 35.00 of both sides of the blade with a bright light. During the check tick every grid square inspected.

5. If any blistering, peeling, flaking, bubb l ing or cracked paint is detected, remove the paint from the affected area by sanding in a span wise direction only with an abrasive cloth or paper 240 grit or finer and a final sanding using an abrasive cloth or paper 400 grit or finer. After paint removal, wipe area with a clean cloth damp ened with alcohol and dry thoroughly, visually inspect the affected area for damage using a 10X magnifying glass. Damage beyond the limits of the Maintenance Manual Chapter 64

- 11

- 01 step 7 requires
blade removal from service.

6. Only superficial corrosion that can be removed with aluminum wool o r very fine grade abrasive pad is permissible. Corrosion on the spar 0,076 mm (0.003 inch) deep or less is acceptable when polished out. Replace any blade that has corrosion on the spar greater than 0,076 mm (0.003 inch).

7. If a nick, scratch or dent is foun d, visually inspect for crack using a 10X magnifying glass or higher and measure the depth of the damage. (A digital optical micrometer is one tool that can be used for this measurement).B.T. 412-136

Page 4 of 6 8. Repair damage and/or corrosion found on tail rotor blades in accordance with the Maintenance Manual Chapter 64-11-01 step 8.

9. Replace any blade that has a crack. No cracks are permitted.

10. If paint was removed during the above steps, carry out paint touch up/refinishing as per Component Repair and Overhaul Manual Chapter 64.

11. Return the helicopter to flight configuration and make an entry in helicopter applicable documentations to indicate accomplishment of this Bollettino. Enter exact location of blend repair (if applicable), location shall include blade station as well as distance from the leading edge.B.T. 412

- 136

Page 5 of 6 FIGURE 1 Example of inspection reference gridB.T. 412-136

Page 6 of 6 FIGURE 2

409.6 mm (16.125 inches)

790.6 mm (31.125 inches)Note: Remarks:

Informazioni: Information: Al fine 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.