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SIL Turbine Index

ENSTROM 480B TURBINE · Service Bulletins

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Overview

This document is a Service Information Letter (SIL) for the Enstrom 480B Turbine helicopter, detailing various service bulletins and their effectivity on the aircraft. It includes a comprehensive index of service letters, their dates, and titles, along with notes on incorporation into maintenance manuals.

  • The document supersedes the previous version dated June 24, 2025.
  • It includes a list of service information letters relevant to the Enstrom 480 and 480B models.
  • Several service letters have been canceled or incorporated into maintenance manuals.
  • The document provides maintenance and operational updates for various components.
  • It covers topics such as generator switch operation, fuel system upgrades, and rotor transmission inspections.
  • The latest revision is dated April 8, 2026.

Document

Source

Originally published by enstromhelicopter.com. Sprinkle hosts a reference copy with an added summary, specifications and searchable full text.

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Document details

Type
·
Service Bulletins
Year
·
2026
File size
·
144 KB
Publisher
·
enstromhelicopter.com
Language
·
en
About this document
What is the SIL Turbine Index?

The SIL Turbine Index is a service bulletins for the ENSTROM 480B TURBINE, dated 2026.

Where does the SIL Turbine Index come from?

This copy of the SIL Turbine Index was originally published by enstromhelicopter.com and is hosted on Sprinkle as a free, searchable reference copy.

What year was the SIL Turbine Index published?

The SIL Turbine Index — the ENSTROM 480B TURBINE service bulletins on file — is dated 2026.

Documentation completeness
3/7

Most owners only have the POH. Here's the essential set for the ENSTROM 480B TURBINE.

More ENSTROM 480B TURBINEmanuals & documents

In this document

Service Information Letters

The document lists various service information letters (SILs) with their respective dates and titles, indicating their relevance to the Enstrom 480 and 480B models.

Effectivity

The effectivity section indicates which models the service letters apply to, specifically the TH-28, 480, and 480B.

Canceled Letters

Several service letters have been canceled, indicating they are no longer applicable or have been replaced by newer information.

Incorporation Notes

The document includes notes on how certain service letters have been incorporated into the TH-28/480 Series Maintenance Manual.

Maintenance Updates

It provides updates on maintenance procedures and inspections for various helicopter components.

Revision History

The document outlines the revision history, showing the evolution of the service information letters over time.

Full document text

INDEX – SERVICE INFORMATION LETTERS, TURBINE April 8, 2026 Superseding June 24, 2025 Page 1 of 3 SIL # DATE REV. DATE TITLE EFFECTIVITY TH-28 480 480B CANCELED T-001 09/11/95 GENERATOR SWITCH OPERATION X X T-002R8 CXL SERVICE LIFE LIMITS X X X X10 T-003 06/21/96 ENGINE OIL WARNING PLACARD X X T-004 CXL IMPROVED TAIL ROTOR FEATHERING AXIS BUMPER, P/N 28- 15033-13 X X X T-005 CXL MAIN AND TAIL ROTOR TRANSMISSION CHIP INDICATIONS ON NEW OR RECENTLY OVERHAULED TRANSMISSIONS X X X T-006 10/03/97 IMPROVED FUEL SHUTOFF VALVE OPERATION X X T-007 12/11/97 DRAIN HOLE INSTALLATION IN CABIN DOORS X X T-008 12/10/98 ALTERNATIVE SPAR FITTING ATTACHMENT X X T-009 CXL ALLISON ENGINE MODEL 250-C20W X X X T-010 CXL CYCLIC STICK SOCKET INSTALLATION REPAIR X X X T-011 03/31/99 MAIN ELECTRICAL RELAYS X X T-012 03/31/99 MAIN ROTOR TRANSMISSION PINION NUT RETORQUE X X T-013 04/06/99 SERIALIZATION OF VIBRATION ABSORBER BEAMS X X T-014 03/20/00 GENERATOR CONTROL UNIT RELOCATION X T-015 02/15/02 TAIL ROTOR TRANSMISSION IDENTIFICATION X X X T-016 CXL DRIVE BELT TENSION X X X X9 T-017 08/05/02 ELECTRICAL SYSTEM PYLON GROUNDS X X X T-018 06/16/03 FUEL CELL LEAKS X X X T-019 CXL MAIN ROTOR PUSH-PULL ROD, P/N 4140532-“X”, SERVICEABILITY INSPECTION X X X X8 T-020 CXL FIXED LENGTH TAIL ROTOR PITCH CHANGE LINK, P/N 28-16391- 1 X X X X7 T-021 CXL ELASTOMERIC MAIN ROTOR DAMPER KIT X X X T-022 01/31/05 OIL LUBRICATED LOWER PULLY BEARINGS X X X T-023 CXL MODIFIED PROCEDURE FOR ATTACHING MAIN ROTOR RODS TO THE LOWER SWASHPLATE ASSEMBLY X X X X6 T-024 05/02/07 ENGINE COOLING KIT X T-025 05/04/07 MAIN ROTOR DAMPER OIL PART NUMBER X X X T-026 05/08/07 TAIL ROTOR THRUST BEARING, P/N ECD002-11 X X X T-027R4 10/18/07 11/10/17 TAIL ROTOR P/C LINK INSTALLATION X X T-028R1 02/11/08 09/05/18 LANDING GEAR FAIRING ASSEMBLY X X X T-029 03/25/08 BELT TENSION AND PULLEY ALIGNMENT RECORD X X X T-030 05/12/08 MAIN ROTOR GEARBOX BOLT RETORQUE X X X INDEX – SERVICE INFORMATION LETTERS, TURBINE April 8, 2026 Superseding June 24, 2025 Page 2 of 3 SIL # DATE REV. DATE TITLE EFFECTIVITY TH-28 480 480B CANCELED T-031 11/06/08 RELAY KIT INSTALLATION X X X T-032 CXL 600 HOUR INSPECTION TERMINATION FOR SWASHPLATE AND CONTROL ROD ASSEMBLIES X X1 T-033 CXL GREASE RECOMMENDATIONS FOR ROTOR SYSTEM BEARINGS X X X X2 T-034R1 11/25/08 01/05/10 SLIDING WINDOW INSTALLATION X X X T-035 05/04/09 IDENTIFYING CORROSION SEVERITY ZONE FOR OPERATING ENVIRONMENT X X X T-036 03/19/10 BEARING TEMPERATURE WARNING UNIT X X X T-037 10/23/09 FAILURE OF THE ENGINE DRIVE SHAFT SUPPORT BEARING (ECD4017), THE OVERRUNNING CLUTCH DUPLEX SUPPORT BEARING (ECD4014), AND/OR THE P/N 23063426 DOUBLE LIP SEALS X X X T-038R1 03/22/10 04/08/26 APPLICATION OF CORROSION PREVENTION COMPOUND X X X T-039 03/22/10 HI/LO ROTOR RPM SWITCH INSTALLATION X X T-040 03/26/10 DUAL INDICATING VOLT-AMMETER X T-041R1 01/20/11 02/15/19 BLADE TAPE REPAIR X X X T-042 01/20/11 BLADE INTERCHANGEABILITY AND IDENTIFICATION X X X T-043 CXL TORQUE INDICATION CHECK PROCEDURE X X X X3 T-044 02/23/11 LINEAR ACTUATOR AND DROOP COMPENSATOR RIGGING X X X T-045 03/30/11 RESTRAINING CARGO IN THE CABIN X X X T-046 CXL LOWER DRIVE NUT TORQUE REQUIREMENT X X X X4 T-047 CXL TAIL ROTOR PITCH CHANGE BEARING LUBRICATION METHOD X X X X5 T-048 06/22/11 RETRACTION NOTICE, MAINTENANCE MANUAL SUPPLEMENT 4 X X T-049 07/07/11 SPECIAL INSPECTIONS FOR AGRICULTURAL AIRCRAFT X X T-050 08/19/11 MAIN ROTOR SYSTEM TRACKING X X X T-051R2 09/20/11 11/07/17 VENTED CLUTCH OIL RESERVOIR KIT P/N 4230001 X X X T-052 10/10/11 CLAMP INSTALLATION X X X T-053R1 09/28/12 09/22/15 7641-20 VRLA BATTERY OPTION X X T-054R1 10/31/12 11/16/22 FUEL CELL FOAM BAFFLE MAINTENANCE INSTRUCTIONS X X T-055R1 02/04/13 04/04/13 T-0139 CALIBRATION REFERENCE BAR X X T-056 04/15/14 UPPER SWASHPLATE BEARING HOUSING X X T-057 01/09/14 BREATHER TUBE ASSEMBLY X X T-058 01/23/14 INSPECTION AND REPAIR OF MINOR CABIN ROOF BUBBLES X T-059 CXL PRODUCTION CERTIFICATE X X X X11 INDEX – SERVICE INFORMATION LETTERS, TURBINE April 8, 2026 Superseding June 24, 2025 Page 3 of 3 SIL # DATE REV. DATE TITLE EFFECTIVITY TH-28 480 480B CANCELED T-060R2 03/07/14 8/21/19 LANDING LIGHT UPGRADE X T-061R2 07/31/15 08/07/17 FUEL QUANTITY TRANSMITTER UPGRADE X X T-062 08/20/15 FUEL SYSTEM, DIPSTICK TUBE REMOVAL X X T-063R1 07/08/15 09/05/18 MAIN ROTOR GEARBOX PUMP UPGRADE X T-064 12/10/15 MAIN ROTOR TRANSMISSION 600-HOUR INSPECTION X T-065 03/30/16 BLEED AIR RESTRICTOR X X X T-066R1 06/21/16 05/19/17 GROUND HANDLING WHEEL SADDLE X X T-067R2 11/09/16 5/1/2024 UNIVERSAL BLOCK, P/N 28-14117-11 and P/N 28-14117-13 X X T-068 05/24/17 EASA REGISTRATION OF G1000H-EQUIPPED MODEL 480B HELICOPTERS X T-069 05/24/17 EASA REGISTRATION OF GMA 350H-EQUIPPED MODEL 480B HELICOPTERS X T-070 09/05/18 MAIN ROTOR GEARBOX PUMP UPGRADE X T-071 08/14/19 LAMIFLEX BEARING DISCONTINUATION X T-072 12/02/19 G1000H SYSTEM LOADER CARD SOFTWARE VERSION 1852.05 RELEASE X T-073 10/13/20 PYLON REINFORCEMENT DOUBLER INSTALLATION X X T-074R1 08/12/24 FUEL CELL (BLADDER) ASSEMBLY X X T-075 01/16/25 UPPER PULLEY, P/N 4130538-11 X X T-076 06/24/25 TAIL ROTOR TRANSMISSION (GEARBOX), PREMATURE GEAR WEAR X X Notes 1 Incorporated into the TH-28/480 Series Maintenance Manual (para. 3-2 and 4-40). 2 Incorporated into the TH-28/480 Series Maintenance Manual (para. 4-2). 3 Incorporated into the TH-28/480 Series Maintenance Manual (para. 4-60, B, and 4-61, B). 4 Incorporated into the TH-28/480 Series Maintenance Manual (para. 11-23, P). Incorporated into the TH-28/480 Series Illustrated Parts Catalog (Figure 7-4, Item 22, and Figure 7-5, Item 25).

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5 Incorporated into the TH-28/480 Series Maintenance Manual (para. 4-39 and 4-39.1). 6 Incorporated into the TH-28/480 Series Maintenance Manual (para. 12-80). 7 Incorporated into SIL T-027 Revision 2. 8 Incorporated into the TH-28/480 Series Maintenance Manual (para. 12-86.1 through 12-86.4). 9 Incorporated into the TH-28/480 Series Maintenance Manual (para. 11-29, E). 10 Incorporated into the TH-28/480 Series Maintenance Manual (Table 3-1). 11 Previously published data is contained in the latest revision of TCDS H1CE.