ASB 412-13-155 Page 1 of 4

ECCN EAR99 ALERT SERVICE BULLETIN 412-13-155 4 February 2013

MODEL AFFECTED: 412/412EP

SUBJECT: TAIL ROTOR BLADE P/N 212-010-750-ALL,

INSPECTION OF

HELICOPTERS AFFECTED: Serial num bers 33001 through 33213, 34001 through 34036 and 36001 and subsequent.

COMPLIANCE: Within the next 25 hours and every 25 hours

thereafter

DESCRIPTION:

Bell Helicopter has recently examined a fractured tail rotor blade; the fracture originated from surfac e damage. Present BHT-412-MM Special Inspection requirements call for a 3X magnifying glass inspection of the tail rotor blade surface for damage every 25 hours. An y damage is to be investigat ed by removing paint and inspecting skin condition with 10X magnificati on. Due to the critic al nature of this inspection and requirements to fully comply, Bell Helicopter is adding a local inspection with 10X magnifica tion of blade between stations 20.00 to 35.00 from the leading edge to the trailing edge . This is in addition to the 3X requirement for the full blade. Operators are reminded that it is critical to investigate any paint and skin imperfections should the inspection warran t. If anomalies are noted during the 3X/10X inspections of the blade surface, remove the paint and check skin condition again with 10X magnification. Skin damage exceeding Maintenance M anual limits requires blade removal from service. Applicability of this bulletin to any spare part shall be determined prior to its instal lation on an affected helicopter.

APPROVAL:

The engineering design aspects of th is bulletin are FAA/ODA approved.ASB 412-13-155 Page 2 of 4

ECCN EAR99 CONTACT INFO:

For any questions regarding this bulletin, please contact:

Bell Helicopter Product Support E ngineering - Medium Helicopters
Tel: 450-437-6201 / 1-800-363-80 28 / psemedium@bh.com

MANPOWER:

Approximately 1.0 man-hour is required to complete this bul letin. This estimate is based on hands-on time, and may vary wit h personnel and facilities available.

WARRANTY:

There is no warranty credit applicable for parts or labor associated with this bulletin.

MATERIAL:

Required Material:

The following material may be required for the accomplishment of this bulletin and may be obtained through your Bell He licopter Textron Supply Center.

Part Number Nomenclature Qty

212-010-750-133 Bl ade A/R

Consumable Material:

The following material may be required to a ccomplish this bulletin, but may not require ordering, depending on the operator ’s consumable material stock levels. This material may be obtained through your Bell He licopter Textron Supply Center.

Part Number Nomenclature Qty Reference *

P-C-451 Abrasive Cloth or Paper,

Aluminum Oxide A/R C-406

* C-XXX numbers refer to the co nsumables list in BHT-ALL-SPM Standard Practices Manual

SPECIAL TOOLS:

None required.

WEIGHT AND BALANCE:

Not affected.ASB 412-13-155 Page 3 of 4

ECCN EAR99 ELECTRICAL LOAD DATA:

Not affected.

REFERENCES:

BHT-412-IPB Illustrated Parts Breakdown

BHT-412-MM Maintenance Manual
BHT-412-CR&O Component Repa ir and Overhaul Manual

PUBLICATIONS AFFECTED:

BHT-412-MM Maintenance Manual.

ACCOMPLISHMENT INSTRUCTIONS:

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

1. Upon completion of the 25-hour Special In spection of tail rotor blade per BHT-412-

MM

, Chapter 5 , carry out a further detailed visual inspection with 10X magnification of the shaded area shown in Figure 1 bet ween stations 20.00 to 35.00 of both

sides of the blade wit h a bright light.

2. If any blistering, peeling, flaking, bubbling or cracked paint is detected, remove the paint from the affected area by s anding in a spanwise direction only with an abrasive cloth or paper ( C -406 ) 240 grit or finer and a final sanding using an abrasive cloth or paper ( C- 406 ) 400-grit or finer. After paint removal, visually inspect the affected area for damage us ing a 10X magnifying glass. Damage beyond the limits of the Main tenance Manual requires blade removal from service.

3. Only superficial corrosion that can be re moved with aluminum w ool or very fine grade abrasive pad ( C-407 ) is permissible. Corrosion on the spar 0.003 inch deep or less is acceptable when polished out. R eplace any blade that has corrosion on the spar greater than 0.003 inch.

4. If a nick, scratch or dent is found, visu ally inspect for crack using a 10X magnifying glass or higher, and measure the dept h of the damage. (A digital optical

micrometer is one tool that c an be used for this measurement).

5. Repair damage and/or co rrosion found on tail rotor bl ades in accordance with the

Maintenance Manual.

6. Replace any blade that has a cr ack. No cracks are permitted.ASB 412-13-155 Page 4 of 4

ECCN EAR99 7. If paint was removed during the above steps , carry out paint touch up/refinishing as

per BHT-412-CR&O

, Chapter 64

.

8. Make an entry in the helicopter logbook a nd historical service record to indicate accomplishment of this ASB. Enter exact lo cation of blend repair (if applicable) in

the historical service record. Location shall include blade station as well as distance from the leading edge.

Figure 1