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 of the abrasion strip to skin bond integrity on tail rotor blades. 

PURPOSE: 

The purpose of this notice is to ensure the periodic inspection of the abrasion strip to skin bond integrity on 

tail rotor blades. 

Failure to comply with this bulletin may result in dis-bond or delamination of the tail rotor abrasion strip. 

Loss of the tail rotor abrasion strip could result in significant vibration, loss of the Tail Rotor, and ultimately 

loss of directional 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: 

500P31 00-101 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 500P31 00-101 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. Part Number 369D2164l-50 1, -503 , and -505 and all 

references in MD Helicopters, Inc. CSP-HMI-2 that pertain to part number 369D21641-50 1, -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 369D21643-50 l, -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 369D21642-50 1, -503, and -505 and all 

references in MD Helicopters, Inc. CSP-HMI-2 that pertain to part number 369D21642-50 1, -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 of receipt of this 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 of the periodic inspection requirements of Part 1. 

MANPOWER: 

Approximately 0.1 man-hours will be required to accomplish PART 1 of this bulletin. 

Approximately 2.0 man-hours will be required to Remove and Replace the Tail Rotor Blades to accomplish 

PART 2 of this bulletin. 

WARRANTY POLICY: 

N/A. 

DISPOSITION OF PARTS REMOVED: 

N/A. 

REFERENCES: 

1) MD Helicopters, Inc. Handbook of Maintenance 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 of Maintenance 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 ... 

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 of the abrasion strip surfaces on each tail 

rotor blade. Inspect the abrasion strip to skin bond from the inboard end of the blade to the blade tip in the 

span wise direction and from the leading edge to the aft edge of the 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% of the abrasion strip bonded area shall be free from voids except that 

no voids shall break out to the edges of the 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 of the blade towards the trailing edge. As you move pass the aft edge of the abrasion strip 

and over the unsupported skin, you will notice a distinctive lowering of the tone produced. Tap in a pattem 

with no more than 0.13 inches between taps in any direction. 

Any blade that is outside of the above specification shall be replaced with an airworthy blade. 

~ T F' 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 of the installation of a 500P3124-13 

Titanium Rivet installed in the tip of the 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 of the -13 Rivet and theRe-Identification shall constitute 

compliance and repeating PART 1 is no longer required. Newly built blades shall already comply. 

RECORDING AND COMPLIANCE: 

Record compliance of this Service Bulletin in the Technical Directives and Bulletins section of the rotor blade 

Serviceable Component Record. 

POINTS OF CONTACT: 

For further information and rotor blade disposition, contact HTC at (31 0) 523-2750, or FAX (31 0) 523-2745. 

THIS SERVICE BULLETIN IS FAA APPROVED