Service Information Letters – Piston

Service Information Letter (SIL) is used to transmit information, recommendations, and general service instructions to the aircraft owner/operator and maintenance personnel.

The information provided in the SILs will be incorporated into the maintenance manual as needed at a later date.

PISTON SERVICE INFORMATION LETTER INDEX

  1. SIL0001 – Engine Crankcase Vent (2/28/1996)
  2. SIL0002 – Fuel Line (02/28/1968) 
  3. SIL0003 – CXL (10/06/2000)
  4. SIL0004 – CXL (9/11/2000)
  5. SIL0005 – Exhaust Stack Cracks (02/10/1969)
  6. SIL 0006 – CXL (10/12/2017)
  7. SIL0007 – Inspection of Cabin Door Handle Attachment Pins (2/12/1969)
  8. SIL0008 – CXL (9/11/2000)
  9. SIL0009 – Belt Idler Shaft (06/04/1969)
  10. SIL0010 – CXL (10/06/2000)
  11. SIL0011 – CXL (9/11/2000)
  12. SIL0012 – Roll Pin – Friction Lock Handle – Collective Control (09/19/1969)
  13. SIL0013 – Inlet Air Ducting (09/25/1969)
  14. SIL0014A – Proper Lubrication of Lower Jack Strut Bearing (05/11/1973)
  15. SIL0015 – Chafing of Pressure and Vent Lines, Main Cabin Area (12/19/1969)
  16. SIL0016-R1 – Removal of Alternator Cooling Fan (10/06/2000)
  17. SIL0017 – Inspection of Tail Rotor Teetering Hinge Bearings (04/14/1970)
  18. SIL0018 – Inspection of 28-11222 Stabilizer Attach. Tube (05/05/1970)
  19. SIL0019 – Inspection of Tail Rotor Gearbox Housing Drawing No. 28-13502F (11/13/1970)
  20. SIL0020 – Revision to Electrical Distribution System (02/18/1971)
  21. SIL0021 – Inlet Air Ducting (04/13/1971)
  22. SIL0022 – R.F. Interference with Engine Instrument Cluster (04/30/1971)
  23. SIL0023 – CXL (10/06/2000)
  24. SIL0024 – Main Rotor Blade Leading Edge Protection (09/24/1971)
  25. SIL0025 – Rod End Assembly – P/N 28-16143 – Swash Plate Assembly (06/26/1972)
  26. SIL0026 – Safety Lock Washer on Damper Rod End (05/18/1972)
  27. SIL0027A – Inspection of Over-Center Mount Pad 28-11100-83 (04/30/1974)
  28. SIL0028 – CXL (10/06/2000)
  29. SIL0029 – CXL (10/06/2000_
  30. SIL0030 – Collective Control Assembly (Pilot Stick) (10/10/1972)
  31. SIL0031 – Collective Friction Lock Assembly (05/31/1973)
  32. SIL0032 – Field Phasing of Main Rotor Controls by Field Mechanics (06/04/1973)
  33. SIL0033 – Blade Damper Bleeding Procedure (07/25/1973)
  34. SIL0034 – Abnormal Airframe Vibration (09/20/1973
  35. SIL0035 – Field Installation of the Tail Rotor Blades to the Splined Tail Rotor Output Shaft (12/17/1973)
  36. SIL0036 – Oil Sump Quick Drain Hose Assemblies (02/04/1974)
  37. SIL0037A – Inspection of Spindle Nylatron Sleeve (10/01/1983)
  38. SIL0038 – Lubrication of Seal (03/14/1974)
  39. SIL0039 – Setting Autorotative RPM (05/22/1974)
  40. SIL0040 – CXL (04/26/2017)
  41. SIL0041 – CXL (10/06/2000)
  42. SIL0042 – Recommended Procedure for Operation of Ground Handling Wheels (01/17/1975)
  43. SIL0043 – Inspection of 28-16192 and 28-16339 Push-Pull Control Rods (02/20/1975)
  44. SIL0044 – CXL (04/26/2017)
  45. SIL0045 – Possible Interference of Blade Grip and Spindle (08/11/1975)
  46. SIL0046 – Damper Modification (03/19/1976)
  47. SIL0047 – Title Changes for Enstrom Service Communications (03/11/1976
  48. SIL0048 – Foam Tape Separation from Cooling Fan Shroud (03/30/1976)
  49. SIL0049 – CXL (06/14/1976)
  50. SIL0050 –  CXL (09/05/2018)
  51. SIL0051 – Improved Teetering Bearing (01/27/1977)
  52. SIL0052 – Improved Narrow-Chord Tail Rotor Spindle Design (01/27/1977)
  53. SIL0053 – CXL
  54. SIL0054R2 – Induction System Hose Clamps (10/21/2025)
  55. SIL0055 – CXL
  56. SIL0056 – Tail Rotor Input Shaft Nut Torque (01/27/1977)
  57. SIL0057 – Main Rotor Gearbox Retention Bolts (01/27/1977)
  58. SIL0058 – CXL
  59. SIL0059 – Inspection and Packing of Sealed Bearings (02/15/1977)
  60. SIL0060 – Instructions for Obtaining Reworked Tail Rotor Spindle and New Teeter Stop (03/10/1977)
  61. SIL0061 – Helicopter Weight and Balance Fulcrum (04/25/1977)
  62. SIL0062 – Fuel Line Insulation (Lagging) (06/22/1977)
  63. SIL0063 – Improved Turbocharger Oil Inlet Adapter (05/27/1977)
  64. SIL0064 – Idler Stabilizer Installation Kit (06/01/1977)
  65. SIL0065 – CXL (04/26/2017)
  66. SIL0066 – CXL (04/26/2017)
  67. SIL0067 – Configuration of Helicopters Delivered to Australia (07/27/1977)
  68. SIL0068 – Oleo Boot Kit (08/23/1977)
  69. SIL0069 – Engine Troubleshooting Procedures for Turbo Installations and Idle Adjustments
    to Correct Engine Roughness and/or Inadvertent Stoppage (10/07/1977)
  70. SIL0070 – CXL (04/26/2017)
  71. SIL0071 – CXL
  72. SIL0072 – Eligibility for Certification in Republic of West Germany (05/01/1978)
  73. SIL0073A – O-Ring Main Rotor Retention Assembly, Reference Service Information Letter
    No. 0073 (05/24/1979)
  74. SIL0074R2 – Drive Belt inspection (04/27/2016)
  75. SIL0075A – Main Rotor Blade Damper (11/20/1980)
  76. SIL0076 – CXL
  77. SIL0077 – Torque, Main Rotor Transmission, Pinion Shaft Nut SLN 3045 (12/12/1978)
  78. SIL0078 – Fire Wall Inspection (12/13/1978)
  79. SIL0079A – Over-Running Clutch Lubrication (02/14/1980)
  80. SIL0080R2 – Clutch Control Rigging (03/28/2025)
  81. SIL0081 – Inspection of Turbocharger for Oil Leakage Between Bearing Housing Flange
    and Bearing Housing (12/12/1978)
  82. SIL0082 – Replacement Oil Lines (12/13/1978
  83. SIL0083 – Modification to Static Vent System (12/14/1978)
  84. SIL0084 – Inspection, Pinion Shaft Run-Out (12/19/1978)
  85. SIL0085 – Recommended Transmission Overhaul Interval (12/19/1978)
  86. SIL0086 – Tail Rotor Rigging Tool Markings (T-0080) (03/05/1978)
  87. SIL0087 – Tail Rotor Blade Bearing Inspection & Lubrication (03/06/1979)
  88. SIL0088R2 – Special Inspection for Main and/or Tail Rotor Blade Strike/Sudden Stoppage (11/13/2019)
  89. SIL0089 – Inspection of Main Rotor Blade Leading Edge Tape(01/22/1979)
  90. SIL0090 – Fuel Nozzle Air Vent Modification (05/23/1979)
  91. SIL0091A – Modification to Engine Starting System (09/26/1980)
  92. SIL0092 – Monitoring EGT System (02/14/1980)
  93. SIL0093 – Starter Ring Gear Clearance (02/13/1980)
  94. SIL0094 – Preflight Control System Check (02/25/1980)
  95. SIL0095 – Corrosion on Main and Tail Rotor Blades (07/17/1980)
  96. SIL0096 – Inspection of P/N 28-12462 Fuel Lines (07/1980)
  97. SIL0097 – CXL
  98. SIL0098 – Turbocharger Gasket Replacement (08/06/1980)
  99. SIL0099 – Corrosion Control on Low Usage Aircraft (08/06/1980)
  100. SIL0100 – Main rotor Flapping Bearing Lubrication (08/06/1980)
  101. SIL0101 – Position and Strobe Light Assembly Light Shields 908/08/1980)
  102. SIL0102 – Tail Rotor Teeter Bearing P/N KRP8A-C (09/26/1980)
  103. SIL0103 – Improved Overrunning Clutch (11/13/1980)
  104. SIL0104 – CXL (04/14/2019)
  105. SIL0105 – Change of Retard Timing on Bendix D-2000/3000 Shower of Sparks Magnetos (11/13/1980)
  106. SIL0106 – Cockpit Mixture Control Friction Adjustment (11/13/1980)
  107. SIL0107 – CXL (04/02/2019)
  108. SIL0108 – Improved Lower Jack Strut (03/17/1981)
  109. SIL0109 – Slinger Rings for Rain Protection on Main Rotor Shaft and Tail Rotor Input Shaft (03/10/1981)
  110. SIL0110B – Swashplate Lubrications (03/18/1983)
  111. SIL0111 – Improved Engine Starting Characteristics (03/11/1983)
  112. SIL0112R1 – Tolerance Fit on Main Rotor Gearbox Pinion Drive Key (03/14/1983)
  113. SIL0113 – Landing Light Modification (04/23/1981)
  114. SIL0114 – Recommended Optional Safety Equipment (04/28/1981)
  115. SIL0115 – Improved Main Rotor Blade Damper (03/19/1981)
  116. SIL0116R8 – Service Life Limits (11/13/2019)
  117. SIL0117 – Hot Weather Auxiliary Oil Cooler Kit (08/26/1981)
  118. SIL0118 – Engine Lubricating Oil – Recommendations for all Temperature Operation (08/26/1981)
  119. SIL0119 – Internal Timing of 2200/3300 Series Dual Bendix Magneto with Shower of
    Sparks (12/02/1981)
  120. SIL0120 – Teeter Bearing Lubrication and Inspection (12/02/1981)
  121. SIL0121 – Troubleshooting and Tracking Enstrom Articulated Rotor System (12/02/1981)
  122. SIL0122 – Improved Starter Installation (04/14/1982)
  123. SIL0123 – Improved Oil Cooler Access (04/14/1982)
  124. SIL0124 – Fuel System Ice Prevention (04/14/1982)
  125. SIL0125 – Change of Overboost Warning System (07/27/1982)
  126. SIL0126 – Inspection of Flapping Bearing Preload and Condition (07/27/1982)
  127. SIL0127A – Preventative Maintenance of Main & Tail Rotor Blades for Corrosion Control in the Field (12/15/1987)
  128. SIL0128 – CXL
  129. SIL0129 – Minor Maintenance & Repair of Main and Tail Rotor Blades (11/12/1982)
  130. SIL0130 – Eligibility for Normal Category 2600 Pound Gross Weight (10/01/1984)
  131. SIL0131 – Engine Damage from Improper Operation (10/01/1984)
  132. SIL0132  – CXL (03/06/2000)
  133. SIL0133 – Installation of Matched Angular Contact Bearings In The Tail Rotor Retention
    Systems (06/08/1987)
  134. SIL0134 – CXL (04/26/2017)
  135. SIL0135  – CXL (04/26/2017)
  136. SIL0136 – Applicability of Lubrication Engineering Greases, Almagard 3751 and Almaplex
    1275 (10/18/1985)
  137. SIL0137 – CXL (09/25/2012)
  138. SIL0138 – Pinion Nut Torque and Upper Jack Strut Bearing Adaptor Inspection (09/11/1985)
  139. SIL0139R1 – Inspection of Rotor Tachometer Drive Belts (10/14/2008)
  140. SIL0140R1 – Inspection and Proper Installation of Seat Belts (11/04/2025)
  141. SIL0141 – New Improved Tail Rotor Teeter Bearing Assembly (09/11/1995)
  142. SIL0142R1 – New Tail Rotor Assembly Bumpers (02/15/2002)
  143. SIL0143 – Inadvertent Trim Motor Operation on 24 Volt D.C. Systems (05/28/1997)
  144. SIL0144 – Main and Tail Rotor Transmission Chip Indications on New or Recently Overhauled Transmissions (10/03/1997)
  145. SIL0145 – Vibration and/or Main Rotor Tracking Problems on F-28C/280C, F-28-C-2, and F-28F-280F, Helicopters equipped with Floats, and/or operationg at Gross Weights Exceeding 2350 Pounds, or Operation with Large Lateral Moment Arm (10/3/1997)
  146. SIL0146 – Improved Main Rotor Control Rod Assembly (10/03/1997)
  147. SIL0147R1 – Modified Flapping Bearing Installation Procedure (05/29/2015)
  148. SIL0148 – Low Rotor Speed Warning Switch (03/31/1999)
  149. SIL0149 – Lamiflex Bearing, PN 28-14320-15_Usage (05/03/1999)
  150. SIL0150R1 – Lower Swashplate Assembly, P/N 28-16101-101 (09/30/2025)
  151. SIL0151 – Low Rotor Warning Tone Generator “Shelf Life” (03/06/2000)
  152. SIL0152R1 – Idler Pulley Alignment and Snubber Roller (03/28/2025)
  153. SIL0153 – Tail Rotor Assembly, P/N 28-150000, Configurations (02/15/2002)
  154. SIL0154 – Starter Circuit Wiring Modification (09/05/2002)
  155. SIL0155R1 – Drive Belt Compound Change (09/10/2003)
  156. SIL0156 – Main Rotor Push-Pull Rod, P/N 28-16253-“X”, Serviceability Inspection
    Criteria (12/09/2003)
  157. SIL0157 – Installation Torque for Main Rotor Damper Relief Valve, P/N 28-14367-7 (01/31/2005)
  158. SIL0158 – CXL (05/12/2015)
  159. SIL0159 – F-28A and 280 Left Side Tail Rotor Installation (01/31/2005)
  160. SIL0160 – Modified Procedure for Attaching Main Rotor Control Rods to the Lower
    Swashplate Assembly (10/30/2006)
  161. SIL0161 – Main Rotor Damper Oil Part Number (05/04/2007)
  162. SIL0162 – Tail Rotor Thrust Bearings, P/N ECD002-11
  163. SIL0163R1 – Turbocharger Adapter Assembly (04/02/2019)
  164. SIL0164 – Cyclic Trim System Configurations (07/24/2007)
  165. SIL0165R4 – Tail Rotor P/C Link Installation Inspection (11/10/2017)
  166. SIL0166 – Main Rotor Gearbox Bolt Retorque (05/21/2008)
  167. SIL0167R1 – Sliding Window Installation (01/05/2010)
  168. SIL0168 – Grease Recommendations for Rotor System Bearings (01/20/2009)
  169. SIL0169 – Identifying Corrosion Severity Zone for Operating Environment (04/28/2009)
  170. SIL0170 – Application of Corrosion Prevention Compound (03/22/2010)
  171. SIL0171R1 – Proper Servicing of Fuel Filter Screen (11/04/2025)
  172. SIL0172 – Blade Tape Repair (01/20/2011)
  173. SIL0173 – 09/02/2010)
  174. SIL0174 – Blade Interchangeability and Identification (01/2/2011)
  175. SIL0175 – Turbocharger Adapter Assembly (04/08/2011)
  176. SIL0176 – Alternative Lubrication Method for ECD016 and ECD018 Bearings (07/11/2011)
  177. SIL0177 – Main Rotor System Tracking (08/19/2011)
  178. SIL0178R1-Upper Swashplate Bearing Housing (09/30/2025)
  179. SIL0179R1 – Copilot Flight Controls Removal (12/20/2017)
  180. SIL0180 – Hi-Lo RPM Switch (11/30/2012)
  181. SIL0181 – Enstrom Helicopter Corporation Production Certificate Reissue (04/15/2014)
  182. SIL0182R1 – Fuel Management (11/07/2017)
  183. SIL0183 – Collective Stick Socket (08/19/2015)
  184. SIL0184R3 – Collective Trim Adjustment Rod Assembly (05/16/2023)
  185. SIL0185 – CXL (11/04/2025)
  186. SIL0186 – Wastegate Linkage and Throttle Cable Installation (003/30/2016)
  187. SIL0187  -Universal Block (11/09/2016)
  188. SIL0188 – Oil Pressure Gauge Troubleshooting (12/01/2016)
  189. SIL0189 – Magneto Retard Terminal P-Lead Insulator (02/04/2019)
  190. SIL0190 – Cabin Door Removal (11/04/2025)
  191. SIL0191 – Lamiflex Bearing Discontinuation (08/14/2019)
  192. SIL0192 – Tail Rotor Cable Assembly (12/09/2019)
  193. SIL 0193R1- TRGB Oil Check and Servicing (05/09/2023)
  194. SIL 0194 – Tail Rotor Gearbox Gear Wear (06-24-2025)

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