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### ALERT SERVICE BULLETIN

AN APPROPRIATE ENTRY SHOULD BE MADE IN TH E AIRCRAFT LOGBOOK UPON ACCOMPLISHMENT

IF OWNERSHIP OF AIRCRAFT HAS CHANGED PLEASE FORWARD TO NEW OWNER 427-10-31

Mar 01, 2010

1 of 5

MODEL AFFECTED: 427

SUBJECT: TAILBOOM ATTACHMENT HARDWARE,

REPLACEMENT OF.

HELICOPTERS AFFECTED: 427 Helicopters serial number 56001 through

56084 and 58001 and 58002.

427 helicopters serial number 56085 and subsequent and 58003 and su bsequent will have the intent of this bulletin accomplished prior to delivery.

COMPLIANCE: Accomplish this bulletin within 150 hours of operation or 90 days, whichever comes first, following release date of this bulletin.

DESCRIPTION:

Bell Helicopter has reviewed the tailboom atta chment installation of the model 427. It has been determined that the torque values s pecified in the maintenance manual and used during assembly of the 427 for the tailboom attachment bolts exceed the specified torque range recomm ended for subject bolts.

This bulletin requires the removal of the existing tailboom attachment hardware and

installation of new hardware with reduced torque val ue. In addition, specific hardware installation/torquing procedure is provided fo r the tailboom to aft fuselage joint.

APPROVAL:

The engineering design aspects of this bulletin are Transport Canada Civil Aviation (TCCA) approved.ASB 427-10-31 Page 2 of 5

MANPOWER:

Approximately 2.0 man-hours ar e required to complete this bulletin. Man-hours are based on hands-on time, and may vary with pers onnel and facilities available. The

time estimated does not include the hardware retorque required after installation of the

new hardware.

WARRANTY:

Owners / Operators of Bell Heli copters who comply with the in structions in this Bulletin will be eligible to receive a credit for the replacement parts outlined in the material

section of this bulletin.

To receive this credit:

• Comply with the instructions contained in this Bulletin no later than the applicable hours in the “compliance sectio n” of this ASB, or before May 30,

2010.

• Purchase replacement parts as required in the materials section of this bulletin from a Bell approved source.

• Submit an MMIR to the Bell Warranty Department.

Customers who do not comply with the instructions in this Bulletin by May 30, 2010 are not eligible for the specia l warranty credit listed above.

There is no labor associated with this bulletin.

MATERIAL:

Required Material: The following material is required for the ac complishment of this bulletin and may be obtained through your Bell Helico pter Textron Supply Center.

Part Number Nomenclature Quantity

NAS627-27 Bolt 4

42FLW-720 Nut 4ASB 427-10-31 Page 3 of 5

Consumable Material: The following material is required to acco mplish this bulletin, but may not require ordering, depending on t he operator’s consumable material stock levels. This material may be obtained through your Bell He licopter Textron Supply Center.

Part Number Nomenclature Quantity Reference

CA1000 6OZ Compound 1 C-586 (Note 1)

Note 1: Mastinox 6856K (C- 128) may be used as an alternat e. Mastinox is available from Bell Helicopter Supply Centers under P/N: XMAS6856K/160CTG or from any Aviation Supply store.

SPECIAL TOOLS:

None required

WEIGHT AND BALANCE:

Not affected

ELECTRICAL LOAD DATA:

Not affected

REFERENCES:

BHT-427-IPB, Illustra ted Parts Breakdown BHT-427-MM, Maintenance Manual, Chapter 5 and 53 BHT-ALL-SPM, Chapter 2

PUBLICATIONS AFFECTED:

BHT-427-MM, Maintenance Manual, Chapter 53

ACCOMPLISHMENT INSTRUCTIONS:

1. Prepare helicopter for maintenance.

2. Remove access cover fr om the aft fuselage to gai n access to the tailboom

attachment hardware. Refer to BHT-427-MM, Chapter 53.ASB 427-10-31 Page 4 of 5

3. Support weight of the tailboom wit h an appropriate suppor t device or stand installed close to aft end of the tailboom assembly.

NOTE Discard hardware (mating nuts and bolts) every time

it is removed from t he tailboom/fuselage joint

4. Remove existing left upper attachment bolt, washers and nut. Discard removed bolt

and nut.

NOTE Replacement hardware (bolt and nut) shall be new.

5. Install new replacement bolt P/N NA S627-27, washer P/ N 140-007-29S25E6, washer(s) P/N NAS1149G0732P and new nut P/N 42FLW-720 per procedure below and BHT-427-MM, chapter 53, revision 13, dated 19 February 2010.

a) Coat shank of the new bolt with corrosion preventive compound (C-586). Do not apply compound on threads of bolt. b) Coat faying surfaces of the chamfered washer P/N 140-007-29S25E6 with corrosion preventive compound (C-586) and install washer on the

new bolt. Fit the bolt/washer thr ough the tailboom and the fuselage mating fitting. c) Install sufficient washers P/N NA S1149G0732P under th e nut to obtain a

minimum of 1 to a maxi mum of 3 threads showing beyond the nut after proper torque is obtained. Co at the faying surfaces of these washers with corrosion preventive compound (C-586) and fit over shank of the new

bolt.

NOTE
For the initial installation, the tare torque of a new nut with mating bolt must be measured and added to the specified torque range.

d) Coat new nut faying surface wit h corrosion preventive compound (C-586) prior to assembly. Do not apply compound on t he threads of the nut

and/or the bolt. Inst all nut on the bolt. e) Run the nut on the threads of the mating bolt with a di al indicator type torque wrench and measure existing tare . Minimum acceptable tare is 14 inch/lbs. Refer to BHT-ALL-SPM, Chapter 2. f) Torque the nut to 550 - 560 inch-l bs (62.1 to 63.3 Nm) plus measured
tare torque. g) Back the nut off at least 3⁄4 of a tu rn before re-applying the torque to 550 - 560 inch-lbs (62.1 to 63.3 Nm) plus measured tare torque.ASB 427-10-31 Page 5 of 5

h) After the torque is completed, coat bolt head, nut and washers with corrosion preventive compound (C-586) to fully seal the joint.

6. Repeat Step 4 and 5 at the th ree remaining bolt locations.

7. Reinstall aft fuselage access cover previously removed.

8. Insert BHT-427-MM Revision 13, dated 19 February 2010 in applicable

maintenance manual

9. Annotate the helicopter technical records to reflect compliance with this bulletin.

NOTE For torque check purposes, it is acceptable to use the minimum tare torque of 14 inch/lbs (1.58 Nm) per BHT-ALL-SPM added to the minimum specified torque range of 550-560 inch/lbs (62.1 to 63.3 Nm).

10. Perform a torque check of tailboom atta ching bolts/nuts every 1 to 5 flight-hours following initial installation until torque stabilizes at all positions. Refer to BHT-ALLSPM, Chapter 2, BHT-427-MM, Chapter 5, Special Inspections and BHT-427-MM, Chapter 53, revision 13, dated 19 February 2010.

NOTE For torque check purposes, it is acceptable to use the minimum tare torque of 14 inch/lbs (1.58 Nm) per BHT-ALL-SPM added to the minimum specified torque range of 550-560 inch/lbs (62.1 to 63.3 Nm).

11. Perform a torque check of tailboom attach ing bolts/nuts every 300 flight-hours of operation. Refer to BHT-ALL-SPM, C hapter 2, BHT-427-MM, Chapter 5, Scheduled Inspections or Airframe pr ogressive inspection and BHT-427-MM, Chapter 53, revision 13, dated 19 February 2010.