ENSTROM F-28F Series User manual

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Revision 11, dated Oct 25/19, applies to the Enstrom F-28F/280F Series Maintenance Manual,
1985 Edition/1990 2nd Edition. Place this cover sheet behind the “Record of Revisions” card after
removing and inserting the pages listed below.
Remove Pages Insert Pages
iii through x iii through x
xiii through xiv xiii through xiv
MM-1-3 through MM-1-4 MM-1-3 through MM-1-4
MM-2-11 through MM-2-20 MM-2-11 through MM-2-20
MM-4-3 through MM-4-4 MM-4-3 through MM-4-4
MM-4-9 through MM-4-12 MM-4-9 through MM-4-12
MM-4-21 through MM-4-22 MM-4-21 through MM-4-22
MM-4-31 through MM-4-32 MM-4-31 through MM-4-32
MM-4-47 through MM-4-48 MM-4-47 through MM-4-48
MM-4-51 through MM-4-56 MM-4-51 through MM-4-56
MM-4-65 through MM-4-66 MM-4-65 through MM-4-66
MM-4-77 through MM-4-78 MM-4-77 through MM-4-78
MM-6-1 through MM-6-8 MM-6-0.1 through MM-6-8
MM-8-35 through MM-8-36 MM-8-35 through MM-8-36
MM-9-1 through MM-9-48 MM-9-1 through MM-9-48
MM-10-1 through MM-10-50 MM-10-1 through MM-10-68
MM-12-1 through MM-12-71 MM-12-1 through MM-12-80
None MM-13-0.1 through MM-13-0.2
MM-13-31 through MM-13-32 MM-13-31 through MM-13-32
MM-13-35 through MM-13-38 MM-13-35 through MM-13-38
MM-13-49 through MM-13-50 MM-13-49 through MM-13-50
MM-13-67 through MM-13-72 MM-13-67 through MM-13-72
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ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 8
iii Sep 20/17
TABLE OF CONTENTS
Section 1 – Introduction
Table of Contents......................................................................................MM-1-1
1-1. Manual Arrangement.................................................................................MM-1-3
1-2. Aircraft Effectivity ......................................................................................MM-1-3
1-3. Maintenance Manual Supplements...........................................................MM-1-3
1-4. Maintenance Manual Changes and Revisions..........................................MM-1-3
1-5. Service Document Publications ................................................................MM-1-4
1-6. Application of Warnings, Cautions, and Notes..........................................MM-1-5
Section 2 – General Information
Table of Contents......................................................................................MM-2-1
2-1. General Description ..................................................................................MM-2-3
2-2. General Arrangement................................................................................MM-2-3
2-3. Principal Dimensions.................................................................................MM-2-3
2-4. Airframe.....................................................................................................MM-2-3
2-5. Landing Gear ............................................................................................MM-2-9
2-6. Engine.......................................................................................................MM-2-9
2-7. Engine Cooling..........................................................................................MM-2-9
2-8. Flight Controls...........................................................................................MM-2-9
2-9. Power Train.............................................................................................MM-2-10
2-10. Main Rotor Assembly..............................................................................MM-2-10
2-11. tail Rotor Assembly.................................................................................MM-2-10
2-12. Operating Limitations and Restrictions ...................................................MM-2-10
2-13. Placards..................................................................................................MM-2-10
2-14. Vendor Manuals......................................................................................MM-2-11
2-15. Special Tools...........................................................................................MM-2-13
2-16. Torque Data............................................................................................MM-2-16
2-17. Consumable Parts List............................................................................MM-2-20
Section 3 – Airworthiness Limitations
FAA Cover Page.......................................................................................MM-3-1
Log of Revisions........................................................................................MM-3-2
Table of Contents......................................................................................MM-3-3
3-1. Retirement Life Items................................................................................MM-3-5
3-2. Mandatory Inspection Items......................................................................MM-3-5
Section 4 – Servicing, Recommended Overhauls, Inspections, and General Maintenance
Table of Contents......................................................................................MM-4-1
4-1. Servicing ...................................................................................................MM-4-5
4-2. Description.......................................................................................MM-4-5
4-3. Fuel System............................................................................................MM-4-25
4-4. Servicing........................................................................................MM-4-25
4-5. Draining .........................................................................................MM-4-26
4-6. Engine Oil System...................................................................................MM-4-26
4-7. Servicing........................................................................................MM-4-26
4-8. Draining .........................................................................................MM-4-27

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
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4-9. Overrunning Clutch.................................................................................MM-4-27
4-10. Servicing........................................................................................MM-4-27
4-11. Main Rotor Transmission........................................................................MM-4-28
4-12. Servicing........................................................................................MM-4-28
4-13. Draining .........................................................................................MM-4-29
4-13.1 Flushing.........................................................................................MM-4-29
4-14. Tail Rotor Transmission..........................................................................MM-4-30
4-15. Servicing........................................................................................MM-4-30
4-16. Draining .........................................................................................MM-4-31
4-16.1 Flushing.........................................................................................MM-4-31
4-17. Main Rotor Dampers...............................................................................MM-4-32
4-18. Servicing (Bleeding).......................................................................MM-4-32
4-19. Oleos.......................................................................................................MM-4-33
4-20. Servicing........................................................................................MM-4-33
4-21. Battery.....................................................................................................MM-4-34
4-22. Servicing........................................................................................MM-4-34
4-23. Lubrication...............................................................................................MM-4-34
4-24. Description.....................................................................................MM-4-34
4-25. Lower Pulley (Jackstrut) Bearing ............................................................MM-4-34
4-26. Lubrication.....................................................................................MM-4-34
4-27. Main Rotor Blade Grip..........................................................................MM-4-34.1
4-28. Lubrication..................................................................................MM-4-34.1
4-29. Main Rotor Flapping Bearings.................................................................MM-4-36
4-30. Lubrication.....................................................................................MM-4-36
4-31. Tail Rotor Pitch Control Bearing..............................................................MM-4-36
4-32. Lubrication.....................................................................................MM-4-36
4-33. Lubrication, Preferred Method.......................................................MM-4-36
4-34. Lubrication, Alternate Method........................................................MM-4-36
4-35. Upper Pulley (Jackstrut) Bearing ............................................................MM-4-37
4-36. Lubrication.....................................................................................MM-4-37
4-37. Collective Guidetube Bearing..................................................................MM-4-37
4-38. Lubrication.....................................................................................MM-4-37
4-39. Cyclic Swashplate Bearing......................................................................MM-4-37
4-40. Lubrication.....................................................................................MM-4-37
4-41. Idler Pulley Bearings...............................................................................MM-4-38
4-42. Lubrication.....................................................................................MM-4-38
4-43. Lubrication, Preferred Method.......................................................MM-4-38
4-44. Lubrication, Alternate Method........................................................MM-4-38
4-45. Recommended Overhaul Cycles ............................................................MM-4-39
4-46. Periodic Inspections................................................................................MM-4-40
4-47. General Information ................................................................................MM-4-40
4-48. Daily Inspection.......................................................................................MM-4-40
4-49. Periodic Inspection Checklists ................................................................MM-4-40
4-50. 50 Hour Inspection Guide..............................................................MM-4-41
4-51. 100 Hour/Annual Inspection Guide................................................MM-4-42
4-52. 200 Hour Inspection Guide............................................................MM-4-57
4-53. 400 Hour Inspection Guide............................................................MM-4-58
4-54. Special Scheduled Inspection Guide.............................................MM-4-59
4-55. Special Instructions.................................................................................MM-4-60
4-56. General..........................................................................................MM-4-60
4-57. Main Rotor Blade Strike/Sudden Stoppage (Minor).......................MM-4-60
4-58. Main Rotor Blade Strike/Sudden Stoppage (Major).......................MM-4-61

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 11
v Oct 25/19
4-59. Tail Rotor Blade Strike/Sudden Stoppage.....................................MM-4-62
4-60. Hard Landing.................................................................................MM-4-62
4-61. Main Rotor Overspeed...................................................................MM-4-63
4-62. Main or Tail Rotor Transmission Chip Indication...........................MM-4-64
4-63. Engine Overboost..........................................................................MM-4-65
4-64. Engine Overspeed.........................................................................MM-4-66
4-65. Maintenance Ground Run.......................................................................MM-4-66
4-66. Ground Handling.....................................................................................MM-4-68
4-67. Ground Handling Wheels........................................................................MM-4-68
4-68. External Power........................................................................................MM-4-69
4-69. Parking....................................................................................................MM-4-69
4-70. Leveling...................................................................................................MM-4-69
4-71. Hoisting...................................................................................................MM-4-70
4-72. Cleaning..................................................................................................MM-4-70
4-73. Exterior ..........................................................................................MM-4-70
4-74. Interior ...........................................................................................MM-4-72
4-75. Plexiglass.......................................................................................MM-4-72
4-76. Aircraft Preservation and Storage...........................................................MM-4-73
4-77. General..........................................................................................MM-4-73
4-78. Low Usage.....................................................................................MM-4-73
4-79. Storage up to 45 Days...................................................................MM-4-74
4-80. Storage from 45 Days to 6 Months................................................MM-4-75
4-81. Storage for longer than 6 Months..................................................MM-4-75
4-82. Preventive Maintenance for Corrosion Control.......................................MM-4-76
4-83. General Information.......................................................................MM-4-76
4-84. Scheduled Field Preventive Maintenance Program................................MM-4-76
4-85. Component Preservation and Storage....................................................MM-4-77
4-86. Main Rotor Transmission...............................................................MM-4-77
Section 5 – Weight and Balance
5-1. General Information ..................................................................................MM-5-1
5-2. Approved Center of Gravity Envelopes.....................................................MM-5-1
5-3. Weighing the Helicopter............................................................................MM-5-3
5-4. Loading .....................................................................................................MM-5-6
Section 6 – Electrical System
6-1. Electrical System.......................................................................................MM-6-1
6-2. Battery.......................................................................................................MM-6-2
6-3. Alternator...................................................................................................MM-6-4
6-4. Voltage Regulator .....................................................................................MM-6-8
6-5. Overvoltage Relay...................................................................................MM-6-10
6-6. Starter .....................................................................................................MM-6-10
6-7. Fuel Boost Pump.....................................................................................MM-6-13
6-8. Lighting....................................................................................................MM-6-14
6-9. Clutch Disengage Warning Light.............................................................MM-6-16
6-10. Manifold Pressure Overboost Caution Light ...........................................MM-6-16
6-11. Hourmeter...............................................................................................MM-6-17
6-12. Trim Motors.............................................................................................MM-6-17
6-13. Ammeter – Charging System..................................................................MM-6-18
6-14. Instrument Cluster Troubleshooting........................................................MM-6-19
6-15. Charts......................................................................................................
MM-6-25

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 11
vi Oct 25/19
Section 7 – Instruments
7-1. Instrument Panel.......................................................................................MM-7-1
7-2. Altimeter....................................................................................................MM-7-1
7-3. Airspeed Indicator.....................................................................................MM-7-4
7-4. Engine and Rotor Tachometer..................................................................MM-7-5
7-5. Fuel Quantity Indicator..............................................................................MM-7-5
7-6. Engine Oil Pressure Gauge ......................................................................MM-7-6
7-7. Main Rotor Transmission Temperature Indicator......................................MM-7-7
7-8. Engine Oil Temperature Indicator.............................................................MM-7-7
7-9. Ammeter....................................................................................................MM-7-8
7-10. Cylinder Temperature Indicator.................................................................MM-7-9
7-11. Exhaust Gas Temperature Indicator (EGT) ..............................................MM-7-9
7-12. Manifold Pressure and Fuel Flow Indicator.............................................MM-7-11
7-13. Outside Air Temperature Indicator..........................................................MM-7-12
7-14. Magnetic Compass (F-28F) ....................................................................MM-7-12
7-15. Magnetic Compass (280F)......................................................................MM-7-12
7-16. Hourmeter...............................................................................................MM-7-12
7-17. Pitot Static System..................................................................................MM-7-13
7-18. Replacement of Instruments...................................................................MM-7-13
7-19. Inspection of Instruments........................................................................MM-7-15
Section 8 – Structures
8-1. Cabin.........................................................................................................MM-8-1
8-2. Windshields and Windows........................................................................MM-8-4
8-3. [Reserved]
8-4. Cabin Doors............................................................................................MM-8-11
8-5. [Reserved]
8-6. [Reserved]
8-7. Seat Belts – Lap Type.............................................................................MM-8-17
8-8. Seat Deck and Bulkheads.......................................................................MM-8-18
8-9. Landing Gear ..........................................................................................MM-8-19
8-10. Pylon.......................................................................................................MM-8-39
8-11. Baggage Compartment...........................................................................MM-8-39
8-12. Tailcone Assembly..................................................................................MM-8-42
8-12.1. Tubular Tail Rotor Guard ........................................................................MM-8-44
8-12.2. Tail Rotor Driveshaft Cover.....................................................................MM-8-45
8-13. Torque Tube Extension...........................................................................MM-8-46
8-14. Horizontal Stabilizers (F-28F Pre-1986)..................................................MM-8-48
8-15. Horizontal Stabilizers (280F)...................................................................MM-8-49
8-16. Horizontal and Vertical Stabilizers (F-28F Post 1986; 280FX)................MM-8-50
8-17. Airscoop (280FX)....................................................................................MM-8-59
Section 9 – Main Rotor
9-1. Main Rotor System....................................................................................MM-9-3
9-2. Main Rotor Hub.........................................................................................MM-9-3
9-3. Retention Assembly................................................................................MM-9-16
9-4. Universal Block Assembly.......................................................................MM-9-31
9-5. Dampers..................................................................................................MM-9-34

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 11
vii Oct 25/19
9-6. Main Rotor Blades...................................................................................MM-9-49
9-7. Description.....................................................................................MM-9-49
9-8. Removal.........................................................................................MM-9-49
9-9. Inspection ......................................................................................MM-9-52
9-10. Repair............................................................................................MM-9-62
9-11. Refinishing.....................................................................................MM-9-74
9-12. Corrosion Prevention.....................................................................MM-9-75
9-13. Installation......................................................................................MM-9-76
Section 10 – Tail Rotor
10-1. Tail Rotor Assembly................................................................................MM-10-3
10-2. Static Balance.......................................................................................MM-10-25
10-3. Tracking and Dynamic Balance ............................................................MM-10-27
10-4. Tail Rotor Pitch Control Assembly ........................................................MM-10-37
10-5. Tail Rotor Gearbox................................................................................MM-10-45
10-6. Tail Rotor Driveshaft and Flex Coupling ...............................................MM-10-48
10-7. Tail Rotor Control System.....................................................................MM-10-60
10-8. Tail Rotor Control Cables......................................................................MM-10-61
Section 11 – Drive Belt System
11-1. Clutch Control Rigging............................................................................MM-11-1
11-2. Clutch Cable............................................................................................MM-11-5
11-3. Clutch Control Lever ...............................................................................MM-11-8
11-4. Jackstrut and Pulley Assembly ...............................................................MM-11-9
11-5. Drive Belt...............................................................................................MM-11-15
11-6. Main Rotor Gearbox..............................................................................MM-11-23
11-7. Overrunning Clutch and Pulley Assembly.............................................MM-11-26
11-8. Idler Pulley – Troubleshooting...............................................................MM-11-36
11-9. Belt Tension Assembly..........................................................................MM-11-53
Section 12 – Flight Controls
12-1. Troubleshooting the Articulated Rotor System........................................MM-12-3
12-2. Main Rotor Blade Tracking......................................................................MM-12-5
12-3. Collective Pitch Control Stick................................................................MM-12-19
12-4. Collective Trim System .........................................................................MM-12-22
12-5. Cyclic Pitch Control Stick......................................................................MM-12-27
12-6. Lateral and Longitudinal Trim Actuators ...............................................MM-12-28
12-7. Flight Control Rigging............................................................................MM-12-34
12-8. Cyclic Azimuth Check ...........................................................................MM-12-42
12-9. Cyclic Trim Springs Rigging Procedure ................................................MM-12-44
12-10. Lower Swashplate Assembly................................................................MM-12-46
12-11. Upper Swashplate Assembly................................................................MM-12-58
12-12. Main Rotor Push Pull Rods...................................................................MM-12-70
12-13. Flight Test Procedure............................................................................MM-12-75
Section 13 – Powerplant and Associated Systems
13-1. Powerplant (General Information)...........................................................MM-13-1
13-2. Engine.....................................................................................................MM-13-3
13-3. Engine Exhaust System........................................................................MM-13-19
13-4. Fuel Injection System............................................................................MM-13-23

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13-5. Turbocharger.........................................................................................MM-13-47
13-6. Turbocharger Static Air Fuel Nozzle Pressure System.........................MM-13-49
13-7. Primary Airflow System.........................................................................MM-13-52
13-8. Cooling System.....................................................................................MM-13-57
13-9. Ignition System......................................................................................MM-13-64
13-10. Fuel System..........................................................................................MM-13-72
13-11. Lubricating System................................................................................MM-13-88
13-12. Correlator..............................................................................................MM-13-94
Section 14 – Utility Systems
14-1. Cabin Heat..............................................................................................MM-14-1
MAINTENANCE MANUAL SUPPLEMENT 280FX & 1986 F-28F – SECTIONS 15 THROUGH 25
Section 15 – Supplemental Procedures
15-1. Introduction .............................................................................................MM-15-1
15-2. Table of Contents....................................................................................MM-15-1
15-3. Manual Changes and Revisions .............................................................MM-15-1
Section 16 – [Reserved]
Section 17 – [Reserved]
Section 18 – Powerplant
18-1. General ...................................................................................................MM-18-1
Section 19 – Main Rotor Transmission
19-1. General ...................................................................................................MM-19-1
19-2. Main Rotor Gearbox Chip Detector.........................................................MM-19-1
19-3. Lubricant Change....................................................................................MM-19-2
Section 20 – Belt Drive System
20-1. General Information ................................................................................MM-20-1
Section 21 – Electrical Systems and Components
21-1. General ...................................................................................................MM-21-1
21-2. Combined Anticollision and Navigation Lights........................................MM-21-1
21-3. Annunciator Panel...................................................................................MM-21-1
21-4. Anticollision and Navigation Light and Annunciator Panel
Troubleshooting Chart.............................................................................MM-21-6
21-5. Lamp/Assembly Replacement Guide Chart............................................MM-21-8
21-6. Ampere Load Conditions.........................................................................MM-21-8
21-7. Hi/Lo Rotor RPM Warning System........................................................MM-21-11
21-8. Schematic Diagrams.............................................................................MM-21-14

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
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ix Oct 25/19
21-9. Illuminated Panels.................................................................................MM-21-33
Illuminated Collective Switch Panel.............................................MM-21-33
Illuminated Switch and Circuit Breaker Panel..............................MM-21-35
Section 22 – [Reserved]
Section 23 – [Reserved]
Section 24 – Instruments
24-1. Engine Monitor........................................................................................MM-24-1
24-2. Description.....................................................................................MM-24-1
24-3. Maintenance..................................................................................MM-24-2
24-4. Programming Alarm Limits ............................................................MM-24-2
24-5. Troubleshooting.............................................................................MM-24-2
24-6. Clock.......................................................................................................MM-24-7
24-7. Outside Air Temperature Indicator (OAT)...............................................MM-24-7
24-8. Magnetic Compass .................................................................................MM-24-7
24-9. Rotor RPM Magnetic Pickup...................................................................MM-24-8
Section 25 – Tail Rotor Drive Assembly
25-1. General ...................................................................................................MM-25-1
25-2. Tail Rotor Driveshaft ...............................................................................MM-25-1
25-3. Tail Rotor Gearbox Chip Detector...........................................................MM-25-1

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ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 11
xiii Oct 25/19
REV. NO REV DATE DESCRIPTION DATE FAA APPROVED
10 Feb 7/19
Cover
ix, xiii, xiv
MM-4-40, MM-4-42
MM-8-0 through MM-8-0.2
MM-8-12 through MM-8-16.2
MM-12-18 through MM-12-22
MM-21-1 through MM-21-4
MM-21-6 through MM-21-8, MM-21-14
MM-21-33 through MM-21-58
MM-24-7 through MM-24-8
N/A N/A
11 Oct 25/19
Cover
iv through vii, ix, xiii
MM-1-3
MM-2-11, MM-2-12
MM-2-14 through MM-2-20
MM-4-3, MM-4-9, MM-4-11
MM-4-22, MM-4-32
MM-4-47, MM-4-51 through MM-4-56
MM-4-65, MM-4-66, MM-4-77, MM-4-78
MM-6-0.1, MM-6-0.2
MM-6-1 through MM-6-8
MM-8-36
MM-9-1 through MM-9-48
MM-10-1 through MM-10-68
MM-12-1 through MM-12-80
MM-13-0.1, MM-13-0.2, MM-13-31
MM-13-35, MM-13-37, MM-13-49
MM-13-67 through MM-13-71
MM-13-93 through MM-13-100
MM-21-15, MM-21-16
MM-24-0.1, MM-24-0.2
MM-24-8 through MM-24-10
N/A N/A

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ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 11
MM-1-3 Oct 25/19
SECTION 1
INTRODUCTION
1-1. Maintenance Manual Arrangement
The maintenance manual sections divide the aircraft into major systems and related
subsystems to provide maintenance procedures required for proper system function and
optimum component service life. Each section details the following maintenance functions
for the associated subsystems and components, if applicable:
General Description
Troubleshooting
Adjustment/Rigging
Removal
Disassembly
Inspections (other than Periodic Inspections)
Repair
Assembly
Installation
1-2. Aircraft Effectivity
The maintenance data presented in this manual is applicable to all F-28F, 280F, and 280FX
model Enstrom helicopters with standard equipment. Optional equipment maintenance
procedures are included in the F-28F/280F Series Maintenance Manual for common
optional equipment that is installed before aircraft delivery (This does not include avionics
installations).
1-3. Maintenance Manual Supplements
Maintenance procedures for optional equipment may be provided in maintenance manual
supplements. These supplements are part of the F-28F/280F Series Maintenance Manual
when an aircraft is equipped with optional equipment which requires a maintenance manual
supplement. The following optional equipment supplements are applicable to the F-
28F/280F Series Maintenance Manual.
Supplement 1: Avionic Systems, Revision 8, Dated: Jan 15/19.
1-4. Maintenance Manual Changes and Revisions
Subsequent to the publication of the initial issue of the Enstrom F-28F/280F Series
Maintenance Manual, changes in aircraft equipment, support concepts and procedures, as
well as information developed by experience, may affect the contents of the manual. To
ensure that coverage in the manual continues to reflect such changes, revised information
is released by one of the following methods:
(1) Revision - A revision alters portions of the manual by replacement, addition, and/or
deletion of pages. A revision cover page lists the page(s) to be removed and/or
inserted.

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
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MM-1-4 Sep 20/17
(2) Reissue - Where large numbers of changes are involved, a complete reissue of the
manual is warranted. Preceding issues of the manual then become obsolete and
should be discarded.
1-5. Service Document Publications
(1) Service Directive Bulletins – Used to direct the owner/operator and/or maintenance
personnel to make mandatory changes, improvements, or inspections to the aircraft
applicable to the entire fleet or a segment of the fleet that are typically
safety/airworthiness related. The information provided in the Service Directive
Bulletins will be incorporated in the maintenance manual as needed at a later date. At
the time of incorporation, the Service Directive Bulletin is superseded by the
maintenance manual, and accomplishment or sign-off of the Service Directive Bulletin
in the maintenance records book is no longer required. A detailed entry should be
made in the maintenance records to indicate that the Service Directive Bulletin is
superseded by the maintenance manual.
(2) Service Information Letters – Used to transmit information, recommendations, and
general service instructions to the aircraft owner/operator and/or maintenance
personnel applicable to the entire fleet or a segment of the fleet. The information
provided in the Service Information Letters will be incorporated into the maintenance
manual as needed at a later date.
(3) Service Instructions – Used to provide the owner/operator and/or maintenance
personnel with information that is applicable to specific aircraft and does not meet the
criteria of a Service Information Letter or Service Directive Bulletin. Service
Instructions will not be distributed to the entire fleet.
Service Information Letters and Service Directive Bulletins incorporated into the
maintenance manual are logged in the Service Information Letter Index or the Service
Directive Bulletin Index (as appropriate) located on the Enstrom Helicopter website:
www.enstromhelicopter.com (follow the applicable link under the Tech Publications section
of the Technical Support page). Each index numerically lists all Service Information Letters
and Service Directive Bulletins, respectively, and identifies those which have been
incorporated into the maintenance manual. All Service Information Letters and Service
Directive Bulletins are also located under the Tech Publications section of the website.
Enstrom distributes maintenance manual reissues and revisions in hardcopy form via mail
to owners and operators who are registered with Enstrom. Notice of recently released
Service Information Letters and Service Directive Bulletins is provided via a postcard
mailing. Registration to receive publication mailings can be coordinated through Enstrom
Product Support.

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 11
MM-2-11 Oct 25/19
2-14. Vendor Information
The following components listed in Table 2-2 are to be maintained I/A/W the manufacturer's
instructions to ensure the continued airworthiness of the aircraft. The owner/operator is
responsible for ensuring that current maintenance publications are available to ensure
continued airworthiness of the aircraft.
Table 2-2. Vendor Contact Information
Component Part Number* Manufacturer*
Engine M/N HIO-360-F1AD Textron-Lycoming
625 Oliver Street
Williamsport, PA 17701
[phone]
www.lycoming.com
Magneto SYS P/N 66E21585-70
Hartzell Engine Technologies
2900 Selma Highway
Montgomery, AL 36116
[phone]
www.hartzell.aero
P/N 10-682605-13
Alternator P/N 32C19553 (24V)
P/N ALX-8521LS (12V)
P/N ALU-8521LS (24V)
Fuel Pump P/N 62D26035
Turbocharger M/N 3BT5EE10J2
P/N 600700-0000
Starter Vibrator P/N 10-382780-123
(12V)
P/N 10-400608-243
(24V)
Teledyne Continental Motors
2039 Broad Street
Mobile, AL 36615 [phone]
www.aviall.com
Fuel Servo M/N RSA-5AB1
P/N 2524858-5 Precision Airmotive Corporation
14800 40th Avenue, North East
Marysville, WA. 98271
[phone]
www.precisionairmotive.com
Fuel Boost
Pump P/N A-10019-D (12V)
P/N A-10019-E (24V) Weldon Pump
640 Golden Oak Parkway
Oakwood Village, Ohio 44146
[phone]
www.weldonpumps.com
Scavenge Oil
Pump P/N 101678-0002 Kelly Aerospace Power Systems
1404 E. South Blvd.
Montgomery, AL 36116
[phone]
www.hartzell.aero
Starter P/N 149-12HT (12V)
P/N 149-24HT (24V) Sky-Tec
350 Howard Clemmons Road
Granbury, TX 78230
[phone]
www.hartzell.aero
Battery P/N RG-35A (12V)
P/N RG24-11M (24V) Concorde Battery Corporation
2009 San Bernardino Road
West Covina, CA 91790
[phone]
www.concordebattery.com
EGT Indicator P/N 45817 Alcor
300 Breesport
San Antonio, TX 78216
[phone]
www.alcorinc.com
Graphic Engine
Monitor M/N GEM 603
M/N GEM 610 Insight Instrument Corporation
Box 194
Buffalo, NY 14205-0194
[phone]
www.insightinstruments.com
M/N EDM-700 J. P. Instruments Inc.
P.O. Box 7033
Huntington Beach, CA 92646
[phone]
www.jpinstruments.com

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 11
MM-2-12 Oct 25/19
Table 2-2. Vendor Contact Information
Component Part Number* Manufacturer*
Tension-Torson
(TT) Straps
P/N AA-ECD-084-280
(STC SR03465CH) Airwolf Aerospace LLC
15369 Madison Rd.
Middlefield, OH 44062-8404
[phone]
[phone] Fax
www.airwolfaerospace.com
[email protected]
* The manufacturer of the component may differ depending on the time the aircraft was manufactured or
overhauled. Refer to the manufacturer’s data plate affixed to the component for accurate part number
information.

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 6
MM-2-13 Apr 7/15
2-15. Special Tools
The special tools listed in Table 2-2 are used for removal, installation, and overhaul of
components used on the F-28F/280F series aircraft:
NOTE
The special tools listed in Table 2-2 are available through Enstrom’s Tool Rental
Program. Contact Enstrom Helicopter Product Support for details.
Table 2-3. Special Tools
Part Number Nomenclature
T-0003 Main Rotor Lead/Lag Lower Nut Tool
T-0005 Damper Rod End Removal Tool
T-0009 Main Rotor Blade Bolt Guide Bullet
T-0011 Main Rotor Hoist Sling
T-0013 Main Rotor Lamiflex Nut Socket
T-0014 Needle Point Grease Adapter
T-0016 Lower Swashplate Gimbal Tool
T-0017 Transmission Hoist Eye
T-0022 Collective Spring Capsule Retainer Tool
T-0026 Main Rotor Blade Tab Bending Tool
T-0027 Main Rotor Blade Tab Angle Tool
T-0029-SET Idler Assembly/Disassembly Tool
T-0035 Oleo Disassembly Tool
T-0036 Blade Grip Seal Installation Tool
T-0044 Pulley Alignment Tool
T-0045-1 Lower Swashplate Dogleg Puller
T-0048 Main Rotor Mast Nut Tool
T-0051-3 Main Rotor Flapping Nut Tool
T-0054 Swashplate Dogleg Alignment Tool
T-0056-3 Tail Rotor Thrust Bearing Retention Nut Tool
T-0057 Damper Bleeding Fixture
T-0068-3 Tail Rotor Transmission Output Shaft Runout Tools
T-0078 Engine Adapter Installation Tool
T-0079-1 Bearing Swagging Tool

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 11
MM-2-14 Oct 25/19
Table 2-3. Special Tools
Part Number Nomenclature
T-0080 Tail Rotor Rigging Tool
T-0086 Upper Guidetube Nut Tool
T-0087-15 Tail Rotor Assembly Static Balance Mandrel
T-0088 Tail Rotor Driveshaft Alignment Tool
T-0092-5 Taper Pin Removal Tool
T-0095 Damper Tool
T-0100-1 Swashplate DU Bushing Removal Tool
T-0102-1-SET Guidetube Disassembly Tool
T-0104-1 Swashplate Bushing Installation Tool
T-0111-SET Correlator Rigging Tool
T-0121-1 Tail Rotor Static Balance Stand
T-0127 Magnetic Pickup Bracket
T-0133-1 Pulley Restraint Tool Assembly
T-0134 Plate Assembly (Lower Swashplate Assembly)
T-0135-1-SET Main Rotor Transmission Pinion Crows Foot
T-0140 Tail Rotor Rigging Tool
T-0151-1 Universal Block Bearing Tool Set (Grease Lubricated)
T-0152 Tail Rotor Balance Tool (Photo Cell Bracket)
T-0156 Oil Filler Tube Adapter Wrench
T-0160-1 Damper Ring Seal Installation Tools
T-0168-1 Tail Rotor Assembly Holder
T-0169-1 Oleo Disassembly Tool
T-0174-1 Hub Puller
T-0179 Magneto Spring Installation Tool
T-0197-7 MR Hub Nut Torque Multiplier Wrench
T-0198-11 Enabler, Oil Drain MRGB
T-0204 Fan Shroud Alignment Tool

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 11
MM-2-15 Oct 25/19
Table 2-3. Special Tools
Part Number Nomenclature
T-1575 Swashplate Centering Tool
T-1709 Guidetube Bearing Collar Tool
T-1758 Guidetube Clamps
T-1775 Cyclic Centering Rigging Tool
T-1794 Weight and Balance Datum Tool
T-2893 Tail Rotor Needle Teeter Bearing Removal/Installation Tool Kit
T-2896-1 Damper Bleeding/Servicing Tool (2 Required)
* Main Rotor Transmission Stand
* Main Rotor Hub Stand
* Sprag Clutch Purge Tool
ATP761 Digital Mast Torque Multiplier
* Contact the Enstrom Helicopter Product Support for assistance in obtaining these tools.

ENSTROM F-28F/280F SERIES MAINTENANCE MANUAL
Rev. 11
MM-2-16 Oct 25/19
2-16. Torque Data
Unless specified in Table 2-4 and/or in this manual’s maintenance procedures or as called
out in the component manufacturer’s specifications, all hardware should be torqued to
standard torque values listed in Tables 2-5 through 2-12.
Table 2-4. Special Torque Values
Location Torque Value
1. Main rotor mast nut 400 ft-lb/542.3 Nm
2. Main rotor transmission pinion nut 250 ft-lb/339 Nm
3. Main rotor blade attachment nuts 50 ft-lb/68.2 Nm
4. Main rotor blade drag link nuts 140 in-lb/15.9 Nm
5. Main rotor damper pivot nut 190 in-lb/21.6 Nm
6. Main rotor hub U-block lower nut 50 ft-lb/67.8 Nm
7. Main rotor hub U-block upper nut 20 ft-lb/27.1 Nm
8. Lamiflex bearing retention nut 12-15 in-lb/1.4-1.7 Nm
9. Upper swashplate guidetube nuts 240 in-lb/27.1 Nm
10. Engine mount nut 460-500 in-lb/52-56.5 Nm
11. Tailcone attachment bolts 240 in-lb/27.3 Nm
12. Tail rotor assembly retention bolt 300 in-lb/34.1 Nm
13. Tail rotor blade grip nuts175 in-lb/8.5 Nm
14. Tail rotor thrust bearing retention nut 80-90 ft-lb/108.5-122.0 Nm
15. Lower engine pulley to crankshaft bolts 50 ft-lb/67.8 Nm
16. Pitch change bellcranks
a. Push/pull rod bolt
b. Push/pull rod bolt with floating bushing
40 in-lb/4.5 Nm
75 in-lb/8.5Nm
17. Landing gear pivot points (all) 40-60 in-lb/4.5-6.8 Nm
18. Landing gear oleo pivots points (all) 2 lb/0.9 kg drag (2)
19. Tail rotor driveshaft taper pins 25 in-lb/2.8 Nm
20. Dogleg nut 130-140 in-lb/14.7-15.9 Nm
21. Dogleg to swashplate nut 40-60 in-lb/4.5-6.8 Nm
22. Idler yoke/shaft jam nut 40-45 in-lb/4.5-5.1 Nm
23. Fuel pump and fuel injector attach nuts 204 in-lb/23.1 Nm
24. Main Rotor Transmission Magnetic Pick-up 60-65 in-lb/6.8-7.3 Nm
1 Foot-Pound (ft-lb) = 1.3558 Newton Meter (Nm)
1 Inch-Pound (in-lb) = 0.113 Newton Meter (Nm)
1 Nm = 0.7376 ft-lb
1 Nm = 8.851 in-lb
1Torque for oversize bolts: 140 in-lb/15.9 Nm maximum.
2Refer to paragraph 8-9.D.5.