Service Letters

Please contact SB47 if you wish to obtain a specific document.
Letter # Rev. Issue Date  Subject  Status 
         
1   22-Sep-58 Issuing of Service Letters Inactive
2 1-Jan-61 Technical Manual Illustration Inactive
3 7-Nov-55 Use of Surplus Parts Inactive
4 27-Apr-56 Rework of 47-120-183-3 Main Rotor Blade
Steel Yoke Adapter		 Inactive
5 3-May-56 Dual Tachometers Inactive
6 15-Mar-66 Ordering 47-661-041 Fan Belts Inactive
7 23-May-57 Control Rod End Bearing Substitutions Inactive
8 3-Jul-57 1. Generator Output Voltage with
Silvercel Battery Installed 2. Operational Check		 Inactive
9 20-Sep-57 Hydraulic Boost System Operating Pressure Inactive
10 A 10-Dec-68 Repair of Swashplate Link Part No. 47-150-113-3 Inactive
11 4-Apr-58 Inspection of the Forward Fuel Tank Strap Supports Inactive
12 30-Jul-58 Installation of Proper Bolts in Swashplate Scissors and Link Attachment Inactive
13 B 28-Apr-66 Helicopter Parts Returned to Bell Helicopter Company Inactive
14 25-Oct-58 Magnaflux Inspection of Engine Mounts Inactive
15 17-Oct-58 Inspection of Tail Rotor Extension Tube Part No. 47-640-055-1,-3, or -5 Inactive
16 18-Nov-58 Replacement of Flight Limitation Placard Inactive
17 A Cancelled Inspection of Scissors Lever Pivot Bolts and Bolt Holes (Sup. by SB129 Rev. B) Inactive
18 15-Jan-59 Inspection of Cable Cutter for good Trigger Lug Engagement (if hoist is installed) Inactive
19 29-Jan-59 Inspection of Lateral Hydraulic Cylinder for Lock and Load Valve Installation Inactive
20   9-Feb-59 Inspection of AN174-22A Bolts in the Fore and Aft Bellcrank Part No. 47-724-135-1 for Correct Installation Inactive
21 24-Feb-59 Modification of Synchronized Elevator Control Pulley Bracket Part No. 47-325-055-3 Inactive
22 27-Feb-59 Engine Starting Inactive
23 2-Mar-59 Inspection of Manifold Pressure Line 45 Degree Elbow at Carburetor for Restricted Orifice Inactive
24 5-Mar-59 Inspection of Bolt, Part No. 47-691-093-1 on Left Side of Lateral Hydraulic Cylinder Inactive
25 A 30-Jan-64 Helicopter Status Survey Inactive
26 18-Mar-59 Inspection of Synchronized Elevator for Freedom of Operation and Cracks in Main Tubular Spar Inactive
27 A 14-Apr-59 Modification of Carburetor Control Support Bracket for Removal of Carburetor Finger Screw Inactive
28 A 18-Sep-59 Hydraulic Power Cylinder No. 1450 Inactive
29 A 27-Sep-61 Drilling Hole in Engine Adapter Pad for Starter Inactive
30 23-Jun-59 Freewheeling Plate, P/N 47-620-617-1 Inactive
31 D 10-Dec-68 Electroless Nickel Build Up of Splines on
T/R Shaft Part No. 47-645-216-3		 Inactive
32 15-Jul-59 Static Stop for Metal M/R Blades Inactive
33 21-Jul-59 Rework of S6RN-20 and S6RN-21 Magnetos to Incorporate Rechargeable
Rotating Magnet with Heavier Shaft		 Inactive
34 29-Jul-59 Transmission Gears with Backlash Markings Inactive
35 30-Jul-59 Lubrication Inactive
36 31-Aug-59 Engine Mounts, 47-612-135-1 N13 Inactive
37   30-Oct-59 Installation of Induction Vibrator to
Facilitate Starting Weather		 Inactive
38 1-Oct-59 Inspection of Flexible Hose at Hydraulic
Cylinders for Correct Length		 Inactive
39 6-Oct-59 New Heavier Stabilizer Bar Damper
Frames, Part No. 47-140-251-1		 Inactive
40 27-Oct-59 Stabilizer Bar Damper Frame Part No.
47-140-134-1		 Inactive
41 A 29-Oct-59 Replacement of Pitch Control Link
Assemblies, Tail Rotor		 Inactive
42 K 1-Jun-66 Commercial Helicopter
Technical Manuals		 Inactive
43 18-Nov-59 New 47D1, 47G, 47G-2, M & 0 Manuals Inactive
44 18-Nov-59 Fabroid Tail Rotor Pitch Links 47B
Through 47G-2		 Inactive
45 24-Nov-59 Vibration Absorber Weights in Longi-
tudinal Tubes of Float Installation		 Inactive
46 18-Dec-59 Identification of Parts
With Limited Service Life		 Inactive
47 A 4-Mar-60 New Chuck Plug Assembly for Tail Rotor Inactive
48 19-Jan-60 Fan Belts Inactive
49 1-Feb-60 Extension of Major Inspection Period
From 600 to 1200 Hours		 Inactive
50 25-Feb-60 Replacement of Aluminum Cable Control Pulleys,
with Phenolic Cable Control Pulleys		 Inactive
51 2-Mar-60 Oil Seal Leakage Inactive
52 29-Mar-60 Rework Exhaust Stack Bracket, 47J Inactive
53 29-Mar-60 Reaming Bushings (Ref: 129 SB) Inactive
54 29-Mar-60 Removing Ears from 47-110-275 Spacing
Assembly		 Inactive
55 20-May-60 Lubrication of Sprag Swivel Plate, Part
No. 47-612-155-1		 Inactive
56   31-May-60 Rework of 473 Synchronized Elevator Inactive
57 3-Jun-60 Provision of Additional Locking for
AN320-10 Nut on Tail Rotor Yoke		 Inactive
58 3-Aug-60 Modification of T101372 Tail Rotor
Rigging Fixture for G-3 Helicopter		 Inactive
59 4-Aug-60 Installation of Gas Tank Caps Inactive
60 26-Sep-60 Shielded Oil Pressure Line Inactive
61 26-Sep-60 Installation of Heavier Stabilizer Bar
Damper Frames, Part No. 47-140-251-1		 Inactive
62 6-Oct-60 Distribution of Lycoming Technical Data Inactive
63 A 12-Nov-63 Use of Loc Tite Sealant to Prevent
Movement of Bearing Races		 Active
64 22-Nov-60 Dual Tachometers Inactive
65 21-Nov-60 Repair of Air Intake Scoop Inacti-
66 1-Mar-65 Proper Procedure for Setting Engine
Idle Speed-2. Recommended Method for
Engaging Clutch on Model 47 Helicopters		 Inactive
67 27-Jan-61 Deletion of 25 & 75 Hour inspection of All
47 Helicopters		 Inactive
68 17-Feb-61 Add Weight to Tail Rotor Guard to Reduce
Vibration		 Inactive
69 A 18-Apr-61 Installation of Trim Tabs Metal Blades Inactive
70 24-Apr-61 Rework of Cushion, Part No.47-620-674-1 Inactive
71 8-May-61 Lycoming Engine Starting Procedure
With Dual Breaker Magneto and Vibrator Coil		 Inactive
72 21-Jun-61 Auxiliary Cooling for Super-Chargers (at Shut Down) Inactive
73 B 22-Apr-64 Inspection & Shimming of Saddle Straps,
Part No. 47-322-259-1		 Inactive
74 17-Jul-61 Inspection of Wood Main Rotor Blades,
Part No. 47-110-120-30 & -50
Purchased as Military Surplus		 Inactive
75 A 27-Oct-61 Alternate Method for Timing Stabilizer
Bar Damper P/N A-13965		 Inactive
76   25-Jul-61 Aircooled Motors Inactive
77 C 14-Jun-63 New Stabilizer Bar Dampers, Part No.
CSC-870-3		 Inactive
78 A 30-Oct-61 Fabrication of a New Cover for Carburetor
Air Filter Housing Assembly		 Inactive
79 13-Oct-61 Slotting Tailboom Cable Fairlead Brackets
to Facilitate Tailboom Removal		 Inactive
80 8-Nov-61 Slip Covers (Seat and Floor) Inactive
81 15-Nov-61 Substitution of Thrust Bearings in Main
Rotor Grips		 Inactive
82 A 22-Jan-62 Tachometer Generators Inactive
83 29-Apr-62 Turbo Supercharger Operation and
Maintenance		 Inactive
84 A 14-Aug-62 Installation of 47-641-105 Trunnion Inactive
85 A 27-Jul-64 Maintenance and Operation of the Rotor
Brake		 Inactive
86 C 8-Oct-65 Installation of Rod End Bearings Inactive
87 D 15-Dec-65 Fuel System Cross Over Assembly
Replacement of Bellows Type Hose Assembly		 Inactive
88 A 21-Mar-63 Clutch Shoe Exchange (all models) Inactive
89 11-Jul-62 Fan Drive Sleeves, Part No. 47-620-538 Inactive
90 11-Jul-62 Stabilizer Bar Dampers, (Houdaille A13965) Inactive
91 8-Nov-62 Retainer Installation, Part No. 47-612-
172-7 in Engine Mount,
Part No. 47- 612-171		 Inactive
92 E 28-Aug-65 Hydraulic Cylinder Exchange Procedure Inactive
93 A 21-Mar-63 Use of 47-620-485-9 Shear Screws in
200 and 600 Series Transmissions		 Inactive
94 A 15-Jun-63 Sprag Lord Mounts, (Natural Rubber) Inactive
95 A 3-Jun-63 Adapter Plate Pin (Rework) Inactive
96 A 25-Apr-63 Engine Cooling Fan Inactive
97 B 24-Oct-67 Clutch Shoe Exchange Program Active
98 28-May-63 Cargo Sling (Ref: 308SI) Inactive
99 9-Jul-63 Installation of Safety Washers to Lateral
Torque Tube		 Inactive
100 A 17-Nov-64 Anderol 456H All Climate Synthetic
Aircraft Engine Lubricant		 Inactive
101 A 2-Sep-66 T101426 Tail Rotor Balance Fixture Inactive
102 C 30-Nov-65 The Centrifugal Clutch Inactive
103 16-Aug-63 Sargent Damper Exchange Inactive
104 H 27-Aug-65 Announcement of Authorized Service
Facility for Garwin Instruments		 Inactive
105 28-Oct-63 Shock Mounting, Rotating Beacon Inactive
106 30-Oct-63 Main Rotor Counterweights Inactive
107 A 16-Mar-64 Lubrication of Main Rotor Grips Inactive
108 12-Nov-63 Mixing Lever, Part No. 47-140-242-3 Inactive
12-Nov-63 Lubricatiion of Splined Coupling,
Transmission Tail Rotor Drive		 Inactive
B 18-Nov-65 Tail Rotor Blades Tip Play Inactive
111 27-Jan-64 Modification of Engine Starters to the
Latest Configuration		 Inactive
112 14-Apr-64 Retirement Life of Short Metal Blades Inactive
113 23-Jun-64 Trimming of Laminate Tips on Main Rotor
Blades (Metal Main Rotor Blades)		 Inactive
114 8-May-64 Alternate Engine Installation for
Model 47G-2		 Inactive
115 PART I 18-Jan-65 47J-2A and 47J-2 Fixed Elevators Inactive
115 PART II 10-Feb-66 47J-2A and 47J-2 Fixed Elevators Inactive
116   24-Jul-64 Preventative Maintenance - Model 47
Metal M/R Blades		 Inactive
117 A 1-Mar-65 Improved Transmission Lower Case
Bearing Part No. 47-620-680-1		 Inactive
118 26-Aug-64 Improved Pillow Block Bearings Part
No. 47-120-190-5		 Inactive
119 A 1-Mar-65 Transmission Maintenance and Operational Recommendations Inactive
120 A 22-Mar-65 Installation of Safety Washers on
Tail Rotor Pitch Links		 Inactive
121 A 5-May-65 Installation of a Swashplate Link Swivel
'Assembly Washer		 Inactive
122 15-May-65 Improved Heavy Duty Freewheeling
Assembly Part No. 47-620-536-7		 Inactive
123 A 16-Aug-65 Improved Mast Thrust Bearing Part No.
47-620-973-1		 Inactive
124 A 2-Nov-72 Mast Exchange Active
125 21-Jun-65 Tail Rotor Water Strike Indicator Inactive
126 3-Aug-65 Improved Cooling Fan Shroud Strips Inactive
127 5-Aug-65 Transmission Lower Sun Gear
Centering Tool		 Inactive
128 17-Aug-65 Increased Candlepower Requirement
For Navigation Lights (Tail Lamp)		 Inactive
129 5-Nov-65 Removal of Sharp Edge on Clutch Pivot
Pin Part No. 47-620-619		 Inactive
130 18-Nov-65 Puncture Resistant Wrapped Fuel
Tank Program		 Inactive
131 15-Dec-65 Installation of Bushings Into 47-120-
126 Pitch Change Horns		 Inactive
132 15-Feb-66 Wear Limits and Rework of Mast Driving
Flange Part No. 47-620-521		 Inactive
133 13-Dec-65 Milling Generator Sleeve Part
No. 47-620-625 (50 Amp)		 Active
134 Not Issued Improved Trans. Lower Case Bearing Ret. Inactive
135   20-Dec-65 Installation of Bolts and Rivets in
Synchronized Elevator Assembly		 Inactive
136 31-Aug-66 Repair of Sprag Spindles,
Part No. 47 612-167-13 by Installing a Bushing		 Active
137 28-Feb-66 Repair of Engine Cooling Fan Support,
Part No. 47-669-130		 Active
138 28-Mar-66 Improved Transmission Fan Drive Inactive
138A 1-Aug-66 Gear Shim and Heavy Duty Clutch
Washer		 Inactive
139 1-Apr-66 Elimination of Return Log Sheets on
Model 47 Helicopters		 Inactive
140 15-Apr-66 Inspection of Instrument Panel Fuel and
Oil Pressure Flexible Hoses		 Inactive
141 15-Dec-66 Rotor Brake Cylinder Rework to Prevent
Locking		 Inactive
142 29-Mar-67 Clutch Drum Modification, Add Oil Holes
P/N 47-620-691-1 and 47-620-941-1		 Active
143 28-Mar-67 Oil Cooler Support Improvement Active
144 12-Apr-67 Fuel Tank Support Improvement Active
145 14-Apr-67 Solid Shim Set P/N 47-620-498 Inactive
146 19-May-67 Fan Gear Set P/N 47-620-497-1 for 600
& 200 Series Transmissions		 Inactive
147 1-Aug-67 Installation of Rubber Washers In Cyclic
Control Systems		 Inactive
148 B 17-May-68 Relocation of Carburetor Heat Control
to Pedestal Position		 Inactive
149 15-Sep-67 Weston Instruments, Inc. Service
Bulletin No. 600-0002		 Inactive
150 15-Feb-68 Installation of Scotch Brand Y9265
Abrasion Resistant Polyurethane Tape		 Inactive
151 30-Jan-68 Inspection of Engine Cooling Fan Inactive
152   5-Apr-68 Cabin Door Kit (Reference SI 400) Inactive
153 A 17-Sep-68 Restraint Cable for
AG-Master Spray Kits		 Active
154 14-May-69 Revised Setting of Turbosupercharger
Waste Gate & Revised Marking of
Cylinder Head Temperature Gage		 Inactive
155 12-Aug-68 Transmission Lower Case, 47-620-991-5 Inactive
156 Missing
157 23-Sep-70 Improved Freewheeling Assembly
& Planetary Assembly		 Active
158 14-Aug-69 Replacement of Bearings in Idler Assys Inactive
159 22-Aug-69 Alternate Carburetor Setting
No. 10- 4975		 Inactive
160 10-Mar-70 Replacement of Leach Battery Relay
With Cutler-Hammer Relay		 Active
161 7-Nov-69 Main Rotor Blade Lease/Rental Program Inactive
162 9-Sep-71 Modification of Cargo Sling Kit Active
163 12-Mar-70 Sealing Inertia Reel Shoulder Harness
Shoulder Harness Kit Attachment
Holes In Center Frame		 Active
164 A 1-Oct-70 Inspection of Covered Oil Lines on
Helicopter Used for Agricultural
Chemical Applications		 Active
165 9-Jul-70 Warranty Claim Procedure Inactive
166 31-Jul-70 New Individual Stack Exhaust Assembly,
P/N 47-614-060-61 (Left Hand)
& P/N 47-614-060-63 (Right Hand)		 Inactive
167 21-Oct-70 Rotor Brake, Drum & Coupling Assembly,
P/N 47-620-644-11,
Alternate Rivet Installation		 Inactive
168 A 7-Jan-71 Damper Overhaul and/or Exchange Inactive
169 7-Apr-71 Carburetor Heat Control Cable Seal Inactive
170 15-Sep-71 M/R Blade Repair, Metal - Amarillo,TX Inactive
171 B 11-Mar-74 Historical Records Forms Active
172 A 25-Oct-71 Adj. of Stabilizer Bar Plugs P/N
47-140-138-1		 Inactive
173 27-Sep-71 Rework of Scissors Levers P/N
47-150-249-9		 Active
174 3-Apr-72 Preventive Maintenance Main Rotor
and Tail Rotor Blades		 Inactive
175 15-Jun-72 Dynamic Stop Cables, Removal of Inactive
176 2-Oct-72 Replacement of Fan Belts P/N
47-661-041-3		 Inactive
 
NOTE
 
Effective January 1973 Service Letters were replaced by Technical Bulletins.

 

Return to Service Letters