ASB 412-11-148 Rev A 

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ECCN EAR99 

 

 ALERT SERVICE BULLETIN 412-11-148 

15 September 2011 

Revision A, 12 December 2011 

MODEL AFFECTED: 412/412EP

SUBJECT: COLLECTIVE LEVER 412-010-408-101, 100 HOUR 

SPECIAL INSPECTION INTRODUCTION OF 

HELICOPTERS AFFECTED: Serial number 33001 through 33213, S/N 34001 

through 34036 and 36001 through subsequent. 

 [Serial numbers 36571 and subsequent will have the 

intent of this bulletin accomplished prior to delivery. 

Recurring inspection will be required as indicated in 

the COMPLIANCE section] 

COMPLIANCE: Within the next 100 hours accumulated on the 

collective lever or 90 days after release of this bulletin 

whichever comes first and every 100 hours 

accumulated on the collective lever thereafter. 

 

DESCRIPTION: 

Revision A allows the lower side of the collective lever to be visually inspected with a 

mirror (no magnifying glass) due to difficult access. Other changes are also 

incorporated for clarity. 

Bell Helicopter has received a report of a fractured collective lever 412-010-408-101. 

The investigation has revealed that residual stresses induced during manufacturing may 

have contributed to the fatigue fracture. This anomaly in the forging that could lead to 

cracking cannot be detected using existing Non Destructive Inspection methods. This 

Alert Service Bulletin introduces a recurring 100 hrs 10 X magnifying glass inspection of 

the collective lever. The Maintenance Manual will be revised to include the intent of this 

Alert Service Bulletin as a 100 hour Special Inspection (Mandatory Structural 

Inspection). Applicability of this bulletin to any spare part shall be determined prior to its 

installation on an affected helicopter. 

APPROVAL: 

The engineering design aspects of this bulletin are FAA/ODA approved. 
ASB 412-11-148 Rev A 

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ECCN EAR99 

CONTACT INFO: 

For any questions regarding this bulletin, please contact: 

Bell Helicopter Product Support Engineering - Medium Helicopters 

Tel: 450-437-6201 / 1-800-363-8028 / psemedium@bellhelicopter.textron.com 

MANPOWER: 

The man-hours required to complete this bulletin are negligible. This estimate is based 

on hands-on time, and may vary with 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 Helicopter Textron Supply Center. 

Part Number Nomenclature Qty 

 

412-010-408-101 Collective lever assembly (Note) 

Note: Ordering will be required only if a crack is found. 

Consumable Material: 

The following material is required to accomplish this bulletin, but may not require 

ordering, depending on the operator’s consumable material stock levels. This material 

may be obtained through your Bell Helicopter Textron Supply Center.

Part Number Nomenclature Qty Reference * 

 

MILC87936TYI Cleaning Compound A/R C-318 

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

SPECIAL TOOLS: 

None required. 
ASB 412-11-148 Rev A 

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ECCN EAR99 

WEIGHT AND BALANCE: 

Not affected. 

ELECTRICAL LOAD DATA: 

Not affected. 

REFERENCES: 

BHT-412-MM, Maintenance Manual 

BHT-ALL-SPM 

PUBLICATIONS AFFECTED: 

BHT-412-MM, Maintenance Manual 

ACCOMPLISHMENT INSTRUCTIONS: 

Collective lever inspection.

1. Prepare helicopter for maintenance. 

a. Gain access to the collective lever. 

2. Using cleaning compound (C-318) or equivalent, thoroughly clean the collective 

lever in preparation for inspection. 

3. Using a strong light source and a 10X magnifying glass, inspect the collective lever 

in the area shown on Figure 1. Due to difficult access, it is acceptable to inspect the 

lower side of the affected area with a strong light source and a mirror only. 

4. Look for evidence of crack in the paint. 

5. If a crack is suspected, remove the collective lever from the swashplate assembly. 

(BHT-412-MM) 

a. Perform a Fluorescent Penetrant Inspection with local paint and primer removed 

in the suspected area. (BHT-ALL-SPM. 

6. If a crack is found, replace the collective lever with a serviceable part and contact 

Product Support Engineering to report the defect. 

7. If no crack is found, refinish as required per BHT-412-CR&O and make an entry in 

the helicopter records to indicate findings and compliance with this Alert Service 

Bulletin. 
ASB 412-11-148 Rev A 

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ECCN EAR99 

Figure 1. Collective lever inspection.