RC::U:3ENSUN 

HELICOPTER COMPANY 

2901 Airport Drive, Torrance, California 90505 Phone (310) 539-0508 Fax (310) 539-5198 

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R44 SERVICE BULLETIN SB-72 

DATE: 30April2010 

TO: R44 and R44 II owners, operators, and maintenance personnel 

SUBJECT: Main Rotor Blade Bond Inspection 

ROTORCRAFT AFFECTED: R44 helicopters with C016-2 main rotor blades, and R44ll 

helicopters with C016-5 main rotor blades. 

TIME OF COMPLIANCE: At next 100-hour inspection, annual inspection, or by 31 July 

2010, whichever occurs first, and at each 1 00-hour and annual inspection thereafter. 

BACKGROUND: Debonding of rotor blade skins can occur when the bond line is 

exposed due to erosion of the blade finish, or when corrosion occurs on the internal 

aluminum tip cap. Proper inspection and protection (refinishing) of bonded areas is 

required. Debonding resulting from improper inspection and maintenance could cause 

a catastrophic accident. 

COMPLIANCE PROCEDURE: 

NOTE 

To facilitate inspection, blade may be teetered down, collective fully 

raised, and cyclic stick positioned to apply maximum up pitch. 

1. Refer to Figures 1 and 2. Remove both main rotor blade tip covers and clean the 

blades. 

2. Using 1 Ox magnification, visually inspect uncovered skin-to-tip cap bond joints. Using 

a 1965-or-later United States quarter-dollar coin, tap test skin-to-tip cap bond joints on 

both upper and lower surfaces. If corrosion, separation, or voids are detected, blade is 

unairworthy. Tap test tutorial video is available at: www.robinsonheli.com/support.htm. 

3. Using 1 Ox magnification, visually inspect any exposed skin-to-spar bond line for gaps 

(empty space between skin and spar). Blade is unairworthy if any gap, including "pin 

hole(s)", is detected in the bond line. 

4. Refer to Figure 2. Mark outboard 135 inches of blade lower surface as shown to 

identify skin-to-spar bond joint area. 

(OVER) 
R44 SB-72 

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5. Verify no visible dents within the bond joint area. Blade is unairworthy if bond joint 

area is dented. 

6. Tap test the lower skin-to-spar bond joint and verify no voids exist. Blade is unairworthy 

if a void is detected. 

7. Refinish all exposed bare metal per R44 SL-32B. 

8. Install blade tip covers, ensuring cover edges are flush with blade profile. 

9. Make appropriate maintenance record entries. 

Approximate Cost: 

Parts: $5 for Kl-200 Kit if ordered by 31 July 2010. 

Kl-200 Kit includes: 

1 ea MT332-44 tool 

1 ea SAN30001 Sharpie® marker 

Labor: Less than 1 man-hour. 

GAP in bond line requires 

blade replacement (example). 

PIN HOLE in bond line requires 

1 

__ -..:::.::::.::~ replacement (example). 

SKIN-TO-SPAR BOND LINE, located 

1.1 5 inch from leading edge of blade 

(requires inspection and evaluation if 

exposed, see text) 

REMOVABLE 

TIP COVER 

SKIN-TO-TIP CAP 

CRITICAL BOND JOINT 

1 .37 inches for P/N C016-2 & C016-5 

FIGURE 1 TIP AREA AND LOWER SURFACE 

(Example, Blade with Excessive Paint Erosion) 

EXPOSED PAINT 

PRIMER (example) 

YELLOW PAINT 
Hold MT332-44 (R44-series) tool 

against main rotor blade surface 

and leading edge while moving 

it spanwise. 

Lines 

Insert felt tip of Sharpie® (brand) 30000-series 

"FINE POINT PERMANENT MARKER" thru holes 

in tool and mark two spanwise lines along lower 

surface from tip inboard 135 inches. 

R44 SB-72 

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FIGURE 2 MARKING LOWER SKIN-TO-SPAR BOND JOINT AREA 

THE DESIGN ENGINEERING ASPECTS OF THIS BULLETIN HAVE BEEN SHOWN TO COMPLY WITH 

APPLICABLE FEDERAL AVIATION REGULATIONS AND ARE FAA APPROVED.