ALERT SERVICE BULLETIN

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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 407-10-93 Aug 30, 2010 May 03, 2010 A 1 of 11 MODEL AFFECTED: 407 SUBJECT: TAILBOOM ATTACHMENT HARDWARE, REPLACEMENT OF. HELICOPTERS AFFECTED: Model 407 Helicopters serial number 53000 through 53990. [Model 407 helicopters serial number 53991 and subsequent will have the intent of this bulletin accomplished prior to delivery.] COMPLIANCE: For helicopters with cumulative flight time of 7,000 flight-hours or less: Accomplish this bulletin at the next 600 Hour scheduled inspection but no later than December 31st , 2010. For helicopters with cumulative flight time of more than 7,000 flight-hours: Accomplish this bulletin within 150 hours or 90 days, whichever comes first, following release date of this bulletin. DESCRIPTION: Bell Helicopter has reviewed the tailboom attachment installation of the Model 407. It has been determined that the torque values specified in the maintenance manual and used during assembly of the 407 for the tailboom attachment bolts exceed the specified torque range recommended for subject bolts. This bulletin mandates the removal of the existing tailboom attachment hardware and the installation of new hardware with reduced torque values. In addition, specific hardware installation/torquing procedure is provided for the tailboom to aft fuselage joint. ASB 407-10-93 Page 2 of 11 APPROVAL: The engineering design aspects of this bulletin are Transport Canada Civil Aviation (TCCA) approved. MANPOWER: Approximately 2.0 man-hours are required to complete this bulletin. Man-hours are based on hands-on time, and may vary with personnel and facilities available. This time estimated does not include post installation torque checks as required. WARRANTY: Owners / Operators of Bell Helicopters who comply with the instructions in this Bulletin will be eligible to receive a credit for the replacement parts outlined in the materials 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 section” of this ASB, or before December 31st , 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 fail to comply with the instructions in this Bulletin after December 31 st , 2010 are not eligible for the special warranty credit listed above. There is no labor credit associated with 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 Number Nomenclature Quantity NAS627-30 Bolt 2 42FLW-720 Nut 2 NAS626-26 Bolt 2 42FLW-624 Nut 2 A ASB 407-10-93 Page 3 of 11 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 CA1000 6OZ Anti-corrosion compound 1 C-586( Note 1) Note 1: Mastinox 6858KD (C-128) can be used as an alternate as prescribed in the current maintenance manual. This product can be obtained from BHT- approved supply sources under P/N XMAS6856K/160CTG. SPECIAL TOOLS: Socket P/N 407-230-001-101 or equivalent Note: an equivalent tool may be locally fabricated using a commercial 12-point socket. Refer to Figure 1. WEIGHT AND BALANCE: Not affected ELECTRICAL LOAD DATA: Not affected REFERENCES: BHT-407-IPB Illustrated Parts Breakdown BHT-407-MM Maintenance Manual BHT-ALL-SPM Standard Practices Manual PUBLICATIONS AFFECTED: BHT-407-MM Maintenance Manual A ASB 407-10-93 Page 4 of 11 ACCOMPLISHMENT INSTRUCTIONS: 1. Prepare helicopter for maintenance. 2. Remove the access panel from the right aft fuselage to gain access to the tailboom attachment hardware. Refer to BHT-407-MM, chapter 53 3. Support weight of the tailboom with an appropriate support device or stand. Replacement of tailboom attachment bolts and nuts; NOTE To prevent using the discrepant hardware again, it is recommended to use a hacksaw or an equivalent tool and make a .125 to .250 inch (3.175 to 6.35 mm) deep cut at any location on the bolt (1) and the nut (2) removed before discarding. 1. (Ref. Figure 2) Remove left upper attachment bolt (1) and nut (2) but retain the chamfered washer (4) and the regular washers (3). Discard the nut (2) and the bolt (1) you have removed. NOTE Replacement hardware (bolt (1) and nut (2)) shall be new. Hardware with unknown origin should not be used and must be discarded appropriately to prevent further usage. 2. Install a new bolt (1) procured from a BHT-Approved supply source as follows: a) Coat the shank of the new bolt (1) and the faying surfaces of the chamfered washer (4) with anti-corrosion compound (C-586). Do not apply compound on any threads of the bolt (1). b) Fit the new bolt (1) (with the chamfered washer (4) against head of bolt (1)) through the tailboom and the fuselage upper mating fittings. c) Select a sufficient number of washers (3) for opposite end of bolt (1) to obtain a minimum of 1 to a maximum of 3 threads showing beyond the nut (2) after proper torque is obtained. Coat the faying surfaces of these washers (3) with anti-corrosion compound (C-586) and fit over shank of the new bolt (1). A ASB 407-10-93 Page 5 of 11 NOTE Upper nut (2) must have a minimum tare value of 14 inch/lbs (1.58 Nm) or more. 3. Install a new nut (2) on the forward end of the bolt (1) as follows; a) Coat the nut (2) faying surface prior to assembly. Do not apply compound on any threads of the nut (2).