DATE 

ALERT SERVICE BULLETIN 

REVISION NOTICE 

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

IF OWNERSHIP OF AIRCRAFT HAS CHANGED PLEASE FORWARD TO NEW OWNER

Nov 17, 2009 

TO: All Owners/Operators of Bell 427 Helicopters

SUBJECT: REVISION A TO ALERT SERVICE BULLETIN 427-09-29: 

 TAIL ROTOR DRIVESHAFT HANGER BEARING BRACKET P/N 427-

044-223-101, REWORK OF. 

Revision A to this bulletin is issued to change the bracket web minimum thickness from 

0.140 to 0.130 inch after rework. 
NO. 

 

DATE 

PAGE 

 DATE 

 REV 

ALERT SERVICE BULLETIN 

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

IF OWNERSHIP OF AIRCRAFT HAS CHANGED PLEASE FORWARD TO NEW OWNER

427-09-29 

 Nov 17, 09 Oct 19, 2009 

A 1 of 7 

MODEL AFFECTED: 427

SUBJECT: TAIL ROTOR DRIVESHAFT HANGER BEARING 

BRACKET P/N 427-044-223-101, REWORK OF. 

HELICOPTERS AFFECTED: Model 427 helicopters serial number 56001 

through 56073, 56077, 58001, 58002 and all 

spares. 

 Model 427 helicopters serial numbers 56074 through 

56076, 56078 and subsequent and 58003 and 

subsequent will have the intent of this bulletin 

accomplished prior to delivery.] 

COMPLIANCE: As soon as possible but no later than next 

scheduled inspection or December 31, 2009 

whichever comes first

DESCRIPTION: 

Bell Helicopter received a report of a broken tail rotor driveshaft hanger bearing 

bracket P/N 427-044-223-101. Investigation revealed that the part fractured due to 

fatigue. The crack originated in the radius near an area where a tool had cut into the 

bracket for a flat faying surface. Refer to Figure 1 for details. 

This Bulletin introduces a one time inspection of the bracket and provides rework 

procedures for the polishing of both sides of the bracket. The rework will eliminate the 

tooling marks and increase the fatigue strength to reduce the potential for cracking in 

service. 

APPROVAL: 

The engineering design aspects of this bulletin are Transport Canada Civil Aviation 

(TCCA) approved. 
ASB 427-09-29 

Page 2 of 7 

MANPOWER: 

Approximately 4.0 man-hours are required to complete this bulletin. Man-hours are 

based on hands-on time, and may vary with personnel and facilities available. 

WARRANTY: 

Owners / Operators of Bell Helicopters who comply with the instructions in this Bulletin 

will be eligible to receive a labor credit of $300.00 towards the accomplishment of this 

bulletin. 

To receive this credit: 

• Comply with the instructions contained in this Bulletin no later 

than the applicable hours in the “compliance section” of this ASB, 

or before December 31 2009. 

• Submit an MMIR to the Bell Warranty Department. 

Customers who fail to comply with the instructions in this Bulletin after the December 

31 2009 are not eligible for the special warranty credit listed above. 

MATERIAL: 

No material required 

Consumable Material: 

The following material is required to accomplish this bulletin, but may not require 

ordering, depending on the operator’s consumable material stock levels. This material 

may be obtained through your Bell Helicopter Textron Supply Center.

Part Number Nomenclature Quantity Reference

 

Alodine Chemical film material A/R C-100 

Scotchbrite TY A Scotchbrite A/R C-407

 

SPECIAL TOOLS: 

None required 

WEIGHT AND BALANCE: 

Not affected 
ASB 427-09-29 

Page 3 of 7 

ELECTRICAL LOAD DATA: 

Not affected 

REFERENCES: 

BHT-427-IPB Illustrated Parts Breakdown 

BHT-427-MM Maintenance Manual, Chapter 53 

BHT-427-CR&O Component Repair and Overhaul Manual 

PUBLICATIONS AFFECTED: 

None affected 

ACCOMPLISHMENT INSTRUCTIONS:

1. Prepare the helicopter for maintenance. 

2. Remove the necessary fairing and cowl assembly to gain access to the blower 

housing assembly. Refer to BHT-427-MM, Chapter 53 

3. Support forward end of aft shaft assembly P/N 427-040-325-105. Remove bolts, 

washers and nuts attaching link assemblies P/N 406-040-318-107 to aft fan shaft 

bearing hanger P/N 406-040-317-101 and hanger bracket P/N 427-044-223-101. 

-NOTEDo not disturb the shims bonded on top of the support P/N 

427-030-609-101. 

4. Remove bolts, washers and nuts attaching hanger bracket P/N 427-044-223-101 to 

the support. Remove hanger bracket from the aircraft. 

5. Clean hanger bracket. Refer to BHT-ALL-SPM. 

6. Using Fluorescent Penetrant Inspection method, inspect affected areas of the 

bracket to detect crack(s). Refer to BHT-ALL-SPM. 
ASB 427-09-29 

Page 4 of 7 

7. Rework both side of bracket P/N 427-044-223-101 as follows: 

a) Using 180 grit sand paper, polish out the noted machining step smooth with 

the adjacent surfaces. Remove minimum material needed to remove the 

machining marks in the radius area. Maintain existing 0.50 radius and 

minimum web thickness of 0.130 inch. Refer to Figure 2. 

b) Polish reworked area using 280 grit sand paper. Final polish smooth reworked 

area using scotchbrite (C-407). 

c) Apply chemical film material (C-100) to reworked areas. Refer to BHT-ALLSPM. Refer to Figure 3. 

8. Reinstall bracket on the aircraft. Refer to BHT-427-MM, Chapter 53. 

9. Reinstall link assemblies P/N 406-040-318-107 to aft fan shaft bearing hanger P/N 

406-040-317-101 and hanger bracket P/N 427-044-223-101. Refer to BHT-427-

MM, Chapter 53. 

10. Reinstall previously removed fairing and cowl assembly. 

11. Annotate the aircraft records to reflect compliance with this bulletin. 

A
ASB 427-09-29 

Page 5 of 7 

Machining marks on bracket P/N 427-044-223-101 

Figure I 
ASB 427-09-29 

Page 6 of 7 

Bracket P/N 427-044-223-101 

View looking forward 

Figure 2 

A
ASB 427-09-29 

Page 7 of 7 

View of reworked bracket assembled on aircraft 

Bracket P/N 427-044-223-101 

Figure 3