ALERT SERVICE BULLETIN 

DATE

REVISION NOTICE 

A Subsidiary of Textron Inc.

Dec 01, 2004 

TO: All Owners/Operators of Bell 206L4 Helicopters

SUBJECT: REVISION “A” TO ALERT SERVICE BULLETIN 206L-04-129: 

(FREEWHEEL AFT BEARING CAP 406-040-509-101, INSPECTION 

AND REWORK OF) 

Revision “A” to this bulletin mandates the replacement of the output shaft 406-040-517-

101 and sprag and retainer 406-040-580-103 for freewheel with discrepant aft bearing 

cap installed. 

AN APPROPRIATE ENTRY SHOULD BE MADE IN THE AIRCRAFT LOGBOOK UPON ACCOMPLISHMENT 

IF OWNERSHIP OF AIRCRAFT HAS CHANGED PLEASE FORWARD TO NEW OWNER
NO. 

DATE 

PAGE 

DATE 

REV 

 

 

 

ALERT SERVICE BULLETIN 

A Subsidiary of Textron Inc.

AN APPROPRIATE ENTRY SHOULD BE MADE IN THE AIRCRAFT LOGBOOK UPON ACCOMPLISHMENT 

IF OWNERSHIP OF AIRCRAFT HAS CHANGED PLEASE FORWARD TO NEW OWNER

206L-04-129 

12-01-04 July 19, 2004 

“A” 1 of 13 

MODEL AFFECTED: 206L4

SUBJECT: Freewheel aft bearing cap 406-040-509-101, 

inspection and recall of 

HELICOPTERS AFFECTED: Model 206L4. 

Freewheel aft bearing cap P/N 406-040-509-101, 

serial numbers A-1833 thru A-1912. 

COMPLIANCE: PART I 

Upon receipt of this bulletin, determine if the aft 

bearing cap is affected. This applies to all spare aft 

bearing caps and freewheel assembly as well as 

those installed on the helicopter. 

PART II

-NOTEEngine cycle start average can be calculated by 

subtracting the actual engine start cycle count from 

the engine start cycles at which time the freewheel 

was installed and dividing by the freewheel time 

since new or time between overhaul. 

Example: 

 5000 cycles Total of actual engine cycle start 

- 3000 cycles Total of engine cycle start at the freewheel installation 

 2000 cycles Total of start cycle on freewheel assembly 

 2000 cycles Total of start cycle on freewheel assembly 

÷ 1000 hrs Freewheel (TSN) or(TSO) 

 2 cycles/hrs Engine cycle start average 
ASB 206L-04-129 

Page 2 of 13 

For freewheel assemblies with less than 3 engine 

start cycles per hour on average and helicopters that 

are not exclusively used for training, accomplish 

PART II of this bulletin within the next 50 flighthours. 

PART III 

For helicopters exclusively used for training, and for 

freewheel assemblies with 3 engine start cycles or

more per hour on average, accomplish PART III of 

this bulletin within the next 50 flight-hours. 

If the freewheel assembly is removed for any

reason, accomplish PART III of this bulletin. 

PART IV 

For freewheel assembly equipped with aft cap as 

described in the HELICOPTER AFFECTED section,

accomplish PART IV of this bulletin within the next

300 hours, but not later than 30 June 2005. 

A 

DESCRIPTION: 

Bell Helicopter has found that some freewheel aft bearing caps are missing the 

lubrication channel intended to allow oil flow into the aft bearing support assembly. 

These caps may have been delivered on production aircraft or as spares. 

PART I of this bulletin gives instructions how to identify the affected aft cap. 

PART II and III of this bulletin provides procedures required to return the freewheel 

assembly to service. 

PART IV of this bulletin mandates the replacement of the output shaft 406-040-517-

101 and sprag and retainer 406-040-580-103 for freewheel with discrepant aft bearing 

cap installed. 

A 

APPROVAL: 

The engineering design aspects of this bulletin are Transport Canada approved. 
ASB 206L-04-129 

Page 3 of 13 

MANPOWER: 

Approximately 0.5 man-hour is required to complete PART I of this bulletin. 

Approximately 3.0 man-hours are required to complete PART II of this bulletin. 

Approximately 16.0 man-hours are required to complete PART III of this bulletin. 

Approximately 16.0 man-hours are required to complete PART IV of this bulletin. 

Man-hours are based on hands-on time, and may vary with personnel and facilities

available. 

A

WARRANTY: 

Owner/Operators of the affected helicopters who comply with the instructions outlined 

in this bulletin will receive a special 100% warranty credit for the replacement parts 

contained in the “Required Material” section of this bulletin. 

Owner/Operators that comply with PART II of this ASB will receive $150.00 labor 

credit, Owner/Operators that comply with PART III of this ASB will receive $800.00 

labor credit. An additional $100.0 will be issued for customers that elect local rework of 

the aft bearing cap. 

Purchase the required parts from an approved BHTI supply source. Submit a 

completed Maintenance Malfunction Information Report (MMIR) to BHTI Warranty 

Department no later than 30 days after completion of this bulletin. 

MATERIAL: 

Required Material: 

The following material is required for the accomplishment of this bulletin and may be 

obtained through your Bell Helicopter Textron Supply Center. 

PART II 

Part Number Nomenclature Quantity

214-040-814-105 SLEEVE A/R (NOTE 1) 

214-040-841-101 SEAL 1

406-040-509-101 AFT BEARING CAP A/R (NOTE 2) 

406-040-532-103 BEARING A/R (NOTE 1) 

M83248/1-018 PACKING 1

M83248/1-021 PACKING 1

M83248/1-140 PACKING 1

MS24665-285 COTTER PIN 1
ASB 206L-04-129 

Page 4 of 13 

NOTE: 

1. Bearing and sleeve replacement may not be necessary depending on the parts 

condition. 

2. Aft bearing cap replacement may not be required depending on the option chosen 

by the operator. 

PART III 

Part Number Nomenclature Quantity

206-040-279-101 PACKING 1 

214-040-841-101 SEAL 1 

214-040-814-105 SLEEVE A/R (NOTE 1) 

406-040-509-109 AFT BEARING CAP A/R (NOTE 2) 

406-040-516-101 INPUT SHAFT A/R (NOTE 1) 

406-040-517-101 OUTPUT SHAFT 1 

406-040-530-103 BEARING A/R (NOTE 1and 3) 

406-040-532-103 BEARING A/R (NOTE 1 and 4) 

407-340-533-101 BEARING A/R (NOTE 1 and 5) 

406-040-580-103 SPRAG AND RETAINER 1 

M83248/1-011 PACKING 5 

M83248/1-016 PACKING 1 

M83248/1-018 PACKING 1 

M83248/1-021 PACKING 1 

M83248/1-033 PACKING 1 

M83248/1-034 PACKING 1 

M83248/1-036 PACKING 1 

M83248/1-140 PACKING 1 

M83248/1-240 PACKING 1 

M83248/1-238 PACKING 1 

M83248/1-903 PACKING 1 

M83248/1-906 PACKING 1 

M83248/1-907 PACKING 1 

MS24665-285 COTTER PIN 1 

NOTE: 

1. Replacement of bearing, input shaft, and sleeve, may not be necessary depending 

on the parts condition. 

2. Aft bearing cap may not be required depending on the option chosen by the 

operator. 

3. As an alternate, it is acceptable to use 406-040-530-105 or 206-040-206-001 in 

lieu of 406-040-530-103 bearing. 

4. As an alternate, it is acceptable to use 406-040-532-101 in lieu of 406-040-532-

103 bearing. 

5. As an alternate, it is acceptable to use 206-040-206-001 or 206-040-206-101 in 

lieu of 407-340-533-101 bearing. 
ASB 206L-04-129 

Page 5 of 13 

PART IV 

A

Part Number Nomenclature Quantity

206-040-279-101 PACKING 1

406-040-517-101 OUTPUT SHAFT 1 

406-040-580-103 SPRAG AND RETAINER 1 

M83248/1-011 PACKING 5

M83248/1-016 PACKING 1

M83248/1-018 PACKING 1 

M83248/1-021 PACKING 1

M83248/1-033 PACKING 1

M83248/1-034 PACKING 1

M83248/1-036 PACKING 1 

M83248/1-140 PACKING 1

M83248/1-240 PACKING 1 

M83248/1-238 PACKING 1

M83248/1-903 PACKING 1 

M83248/1-906 PACKING 1

M83248/1-907 PACKING 1 

MS24665-285 COTTER PIN 1

SPECIAL TOOLS: 

None required 

WEIGHT AND BALANCE: 

Not required 

ELECTRICAL LOAD DATA: 

Not affected

REFERENCES: 

BHT-206L4-MM, Rev. 4 – 22 December 2003 

Chapter 63, Main Rotor Drive System 

BHT-206L-CR&O, Reissue 0 – 18 June 1993 
ASB 206L-04-129 

Page 6 of 13 

 Chapter 63, Main Rotor Drive System 

PUBLICATIONS AFFECTED: 

None affected 

ACCOMPLISHMENT INSTRUCTIONS: 

PART I: Identification of the affected aft bearing cap, 406-040-509-101 

1. Open the engine access doors. 

2. Locate the serial number (1, Figure 1) of the freewheel aft bearing cap (2). 

a. If the cap serial number is not listed in the HELICOPTER AFFECTED section, 

no further action is required. Close the access doors and continue with Step 3. 

b. If the cap serial number is listed in HELICOPTER AFFECTED section, refer to 

the COMPLIANCE section and accomplish either PART II or III of this bulletin 

as directed. Contact Product Support Engineering Light Helicopters with the 

P/N, S/N, TSN, and TSO of the aft bearing cap and freewheel assembly: 

Product Support Engineering Light Helicopters 

Office: 450-971-6407 

Fax: 450-433-0272 

E-mail: pselight@bellhelicopter.textron.com

3. Make an entry in the helicopter Technical Records to show that PART I of the Alert 

Service Bulletin is completed. 

PART II. For freewheel assemblies with an average of less than 3 engine start 

cycle per hour and for helicopter that are not exclusively used for training 

1. Remove the engine cowling and transmission fairing assembly (BHT-206L4-MM, 

Chapter 53). 

2. Remove the forward short shaft (BHT-206L4-MM, Chapter 65). 

3. Remove the aft adapter (5, Figure 2) and aft bearing cap (2) (BHT-206L4-MM, 

Chapter 63). 
ASB 206L-04-129 

Page 7 of 13 

4. Remove bearing (1) from the aft bearing cap (2) (BHT-206L4-MM, Chapter 63). 

5. Remove and discard the support assembly seal (3). 

6. Inspect support assembly bearing (1) for condition (BHT-206L-CR&O). Replace 

bearing if defective. 

7. Inspect sleeve (4) for condition (BHT-206L-CR&O). 

8. Select from the following list, the rework option deemed most suitable for 

convenience: 

a. Order a replacement cap assembly through your Bell Helicopter Spares 

supplier. Please note that limited assets are available to support this bulletin, 

and spares will be issued on a first come, first served basis. 

b. Locally rework the aft bearing cap as shown in Figure 3. Use a vibrating stylus 

to identify locally-reworked cap assembly by adding letter "R" to the serial 

number on the cap. 

c. Provide the cap for rework to Bell Tennessee. This option permits the original 

cap to be reworked by Bell Tennesee, identified with the rework letter "R" suffix 

to the serial number, and returned for installation. 

d. Obtain a reworked cap from the rotable pool available through Bell Tennessee. 

This option will accept the rework candidate in exchange for a reworked item 

from the rotable pool. Please note that for this option due to limited assets, a 

rework candidate must be supplied in advance of shipment from the rotable 

pool. 

e. For option c or d above, contact Bell Tennesee for advance scheduling at: 

Bell Helicopter Tennessee Textron 

157 Industrial Park Road

Piney Flats, TN. 37686

Office: 423-538-5114 

Fax: 423-538-6198. 

9. Install the support assembly bearing (1) and seal (3) into the aft bearing cap (2) 

(BHT-206L4-MM, Chapter 63). 

10. Install the aft bearing cap (2) and adapter (5) (BHT-206L4-MM, Chapter 63). 

11. Install the forward short shaft (BHT-206L4-MM, Chapter 65). 
ASB 206L-04-129 

Page 8 of 13 

12. Check the freewheel and transmission chip detectors for presence of metal 

contamination (BHT-206L4-MM, Chapter 63). 

13. Install the engine cowling and transmission fairing assembly (BHT-407-MM, 

Chapter 53). 

14. Perform a 30 minute ground run as follow: 

a. Perform normal start as per Flight Manual. 

b. Operate the helicopter until it reaches 100% Nr then roll the throttle back to idle 

speed as you would do during normal operation. 

c. Repeat the above step one time every 2 minutes until the 30 minute ground run 

is completed. 

15. Perform a serviceability check to the transmission and freewheel assembly (BHT206L4-MM, Chapter 63). 

16. Make an entry in the helicopter Technical Records to show that PART II of this 

Alert Service Bulletin is completed. 

PART III: For helicopters exclusively used for training, for freewheel assemblies 

with an average of 3 engine start cycles or more per hour, or if the 

freewheel has to be removed for any reason. 

1. Remove freewheel assembly (BHT-206L4-MM-6, Chapter 63). 

-NOTEIt is not necessary to remove wear sleeves from the 

forward and aft adapters unless they are damaged. 

2. Disassemble the freewheel assembly (BHT-206L-CR&O, Chapter 63). 

3. Discard the sprag and retainer (7, Figure 2), the output shaft (10), and the aft seal 

(3). 

4. Visually inspect the remaining freewheel part details for condition (BHT-206LCR&O, Chapter 63). 

5. Select from the following list, the rework option deemed most suitable for 

convenience: 
ASB 206L-04-129 

Page 9 of 13 

a. Order a replacement cap assembly through your Bell Helicopter Spares 

supplier. Please note that limited assets are available to support this bulletin, 

and spares will be issued on a first come, first served basis. 

b. Locally rework the aft bearing cap as shown in Figure 3. Use a vibrating stylus

to identify locally-reworked cap assembly by adding letter "R" to the serial 

number on the cap. 

c. Provide the cap for rework to Bell Tennessee. This option permits the original 

cap to be reworked by Bell Tennesee, identified with the rework letter "R" suffix 

to the serial number, and returned for installation. 

d. Obtain a reworked cap from the rotable pool available through Bell Tennessee. 

This option will accept the rework candidate in exchange for a reworked item

from the rotable pool. Please note that for this option due to limited assets, a 

rework candidate must be supplied in advance of shipment from the rotable 

pool. 

e. For option c or d above, contact Bell Tennesee for advance scheduling at: 

Bell Helicopter Tennessee Textron 

157 Industrial Park Road

Piney Flats, TN. 37686

Office: 423-538-5114 

Fax: 423-538-6198 

6. Assemble the freewheel assembly (BHT-206L-CR&O, Chapter 63). 

7. Install the freewheel assembly (BHT-206L4-MM-6, Chapter 63). 

8. Make and entry in the helicopter Technical Records to show that PART III of the 

Alert Service Bulletin has been completed. 

PART IV: For freewheel assembly equipped with affected aft cap. 

-NOTESprag and retainer and the output shaft presently installed 

on freewheel affected by this bulletin, which have not run 

with a defective cap, may remain in service. 

1. For freewheel assembly equipped with the aft cap described in the HELICOPTER 

AFFECTED section of this bulletin, proceed as follow: 

A
ASB 206L-04-129 

Page 10 of 13 

A 

a. If the freewheel assembly is currently located in spare stock, continue with 

step 3. 

b. If the freewheel assembly has had PART II of this bulletin complied with, 

continue with step 2. 

c. If the freewheel assembly has had PART III of this bulletin complied with,

continue with step 8. 

2. Remove freewheel assembly (BHT-206L4-MM-6, Chapter 63). 

3. Disassemble the freewheel assembly (BHT-206L-CR&O, Chapter 63). 

4. Discard the sprag and retainer (7, Figure 2) and the output shaft (10). 

5. Visually inspect the remaining freewheel part details for condition (BHT-206LCR&O, Chapter 63). 

6. Assemble the freewheel assembly (BHT-206L-CR&O, Chapter 63). 

7. Install the freewheel assembly (BHT-206L4-MM-6, Chapter 63). 

8. Make and entry in the helicopter Technical Records to show that PART IV of the 

Alert Service Bulletin has been completed. 
ASB 206L-04-129 

Page 11 of 13 

Figure 1. Location of the lubrication channel and the serial number 
ASB 206L-04-129 

Page 12 of 13 

Figure 2. Parts affected by the missing lubrication channel 
ASB 206L-04-129 

Page 13 of 13 

Figure 3. Instructions required to modify the aft bearing cap 406-040-509-101