### Helicopter Technology Company, LLC 

# f\tlandatory Service Bulletin NOTICE No.: 3100-4R4 DATE: 10 May 2006 PAGE: 1 of4 

## TAIL ROTOR BLADE ABRASION STRIP TAP TEST AND MODIFICATION

SUMMARY: Procedures in this service notice provide owners and operators with information pertaining to the periodic inspection ofthe abrasion strip to skin bond integrity on tail rotor blades. PURPOSE: The purpose ofthis notice is to ensure the periodic inspection ofthe abrasion strip to skin bond integrity on tail rotor blades. Failure to comply with this bulletin may result in dis-bond or delamination ofthe tail rotor abrasion strip. Loss ofthe tail rotor abrasion strip could result in significant vibration, loss ofthe Tail Rotor, and ultimately loss ofdirectional control. REVISION: This document supercedes 3100-4R3. The Part 2- Modification may now be accomplished at an HTC Authorized Repair Station qualified to perfom1 this modification

. PART NUIVIDERS AND SERIAL NUMBERS AFFECTED: 500P3100-101 and

- 103, including "M" and "I" (SIC Number SR09213RC) All Serial Numbers. These blades are also known as MD Helicopters, Inc. Part Number 369D21640-501, -503 , and -505 and all references in MD Helicopters, Inc

. CSP-HMI-2 that pertain to part number 369D21640-501, -503 , and -505 pertain to HTC part number 500P3100-101 and -103 as well. 500P3100-301and -303, including "M" and "I" (SIC Number SR01282LA) All serial Numbers. These blades are also known as MD Helicopters, Inc. PartNumber 369D2164l-501, -503 , and -505 and all references in MD Helicopters, Inc. CSP-HMI-2 that pertain to part number 369D21641-501, -503, and -505 pet1ain to HTC part number 500P3100-301 and -303 as well. 500P3300-501 and -503, including "M" and "I" (SIC Number SRO 1282LA) All Serial Numbers. These blades are also known as MD Helicopters, Inc. Part Number 369D21643-50l, -503 , and -505 and all references in MD Helicopters, Inc. CSP-H-2 and CSP-H-4 that pertain to part number 369D21643-501, -503, and -505 pertain to HTC part number 500P3300-501 and -503 as well. 500P3500-701 and -703, including "M" and "I" (SIC Number SR01282LA) All Serial Numbers. These blades are also known as MD Helicopters, Inc. Part Number 369D21642-501, -503, and -505 and all references in MD Helicopters, Inc. CSP-HMI-2 that pertain to part number 369D21642-501, -503, and -505 pertain to HTC part number 500P3500-701 and -703 as well.

### Helicopter Technology Company, LLC 

# lVlandatory " 

# Service Bulletin NOTICE No.: 3100-4R4 DATE: 10 May 2006 PAGE: 2 of4 

## TAIL ROTOR BLADE ABRASION STRIP TAP TEST AND MODIFICATION

HELICOPTER MODELS AFFECTED: MD Helicopters, Inc. Models 369A, H, HE, HM, HS, D, E, and FF. TIME OF COMPLIANCE: This bulletin shall be accomplished within 25 hours ofreceipt ofthis notice and every 25 hours thereafter until PART 2 is implemented. PART 2 shall be accomplished not later than 31 January 2007. PART 2 constitutes terminating action ofthe periodic inspection requirements ofPart 1. MANPOWER: Approximately 0

. 1man-hours will be required to accomplish PART 1 ofthis bulletin. Approximately 2.0 man-hours will be required to Remove and Replace the Tail Rotor Blades to accomplish PART 2 ofthis bulletin. WARRANTY POLICY: N/A

. DISPOSITION OF PARTS REMOVED: N/A. REFERENCES:

1) MD Helicopters, Inc. Handbook ofMaintenance Instructions (CSP-H-2), Revision 17, dated May 15, 2001 or later 2) MD Helicopters, Inc. Appendix B (CSP-H-4), Revision 1, dated May 14, 2001 or later 3) MD Helicopters, Inc. Handbook ofMaintenance Instructions (CSP-HMI-2), Revision 29, dated May 11, 2001 or later 4) MD Helicopters, Inc

. Rotorcraft Log Book (CSP-RLB), Revision 2, dated February 17, 2000 or later 5) Maintenance Manual HTCM-002, Part Number 500P3100, 500P3300, 500P3500, 369D21640, 369D21641 , 369D21642, and 369D21643 Tail Rotor Blades (Installation and Maintenance), Revision B, dated 16 June 2003 or later 6) Federal Aviation Administration (FAA) Advisory Circular (AC) 43

. 13

### Helicopter Technology Company, LLC 

# lVlandatorv

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# Service Bulletin NOTICE No.: 3100-4R4 DATE: 10 May 2006 PAGE: 3 of4 

## TAIL ROTOR BLADE ABRASION STRIP TAP TEST AND MODIFICATION

PART 1- INSPECTION: Physically perform a tap test on both the upper and lower surfaces ofthe abrasion strip surfaces on each tail rotor blade. Inspect the abrasion strip to skin bond from the inboard end ofthe blade to the blade tip in the spanwise direction and from the leading edge to the aft edge ofthe abrasion strip in the chordwise direction. The allowable void size in the abrasion strip area is 0.2 square inches. There shall be a minimum of 1.0 inches between voids in this area. 75% ofthe abrasion strip bonded area shall be free from voids except that no voids shall break out to the edges ofthe abrasion strip. The upper and lower surfaces shall be considered separately. The tap inspection may be conducted using a coin (U.S. 25 cent piece or equivalent) or a small brass, steel, or aluminum hammer. Lightly tap the abrasion strip area as shown in the sketch below. A void will produce a tone change. The tone will be lower over the void. A method of"tuning" your ear is to tap from the leading edge ofthe blade towards the trailing edge. As you move pass the aft edge ofthe abrasion strip and over the unsupported skin, you will notice a distinctive lowering ofthe tone produced. Tap in a pattem with no more than 0.13 inches between taps in any direction. Any blade that is outside ofthe above specification shall be replaced with an airworthy blade.**~** 

# TF' T F

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### Helicopter Technology Company, LLC 

# 1\'landatory Service Bulletin NOTICE No.: 3100-4R4 

### DATE: 10 May 2006 

### PAGE: 4 of4 

## TAIL ROTOR BLADE ABRASION STRIP TAP TEST AND MODIFICATION

PART 2- MODIFICATION: Fielded Tail Rotor Blades are to be returned to the HTC Factory or an HTC Authorized Repair Station qualified to perform this modification. This modification consists ofthe installation ofa 500P3124-13 Titanium Rivet installed in the tip ofthe blade in accordance with the following Engineering Drawing as applicable: 

### 500P3100, Revision F, dated 11/22/04, 500P3300, Revision B, dated 11/22/04, or 500P3500, Revision B, dated 10/22/04 or Standard Repair Instruction: 

### SRI #3100-006 as described in HTCQ-012, Revision B, dated 05/10/06 or later FAA Approved revisions. The Identification "T" shall signify that the aforementioned procedure has been accomplished. Installation ofthe -13 Rivet and theRe-Identification shall constitute compliance and repeating 

### PART 1 is no longer required. Newly builtblades shall already comply. 

### RECORDING AND COMPLIANCE: Record compliance ofthis Service Bulletin in the Technical Directives and Bulletins section ofthe rotor blade Serviceable Component Record

. 

### POINTS OF CONTACT: For further information and rotor blade disposition, contact HTC at (310) 523-2750, or FAX (310) 523-2745.



### THIS SERVICE BULLETIN IS FAA APPROVED