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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 412-09-135 Aug 25, 2009 1 of 16
MODEL AFFECTED: 412 /412EP
SUBJECT: HIGH AFT CROSSTUBE ASSEMBLIES P/N 412- 050-011-101, / -103, / -105, / -107, 412-050-045- 105: MANDATORY INSPECTION
HELICOPTERS AFFECTED: Model 412 / 412EP helicopters serial numbers 33001 through 33213, 36001 and subsequent.
The intent of this bulleti n will be incorporated into the Model 412 Maintenance Manual at a future date.
COMPLIANCE: Within 6 months after receipt of this bulletin.
Part I Schedule and accomplish a reoccurring 12 month / 2500 landing Fluorescent Penetrant Inspection of aft high crosstube.
Part II Schedule and accomplish a reoccurring 12 month / 2500 landing Deflection Check of aft high crosstube Part III Establish a mandatory use of aft high crosstube towing retention kit per BH T-412-SI-58 at helicopter weight of 8900Ibs and higher.
ASB 412-09-135 Page 2 of 16
DESCRIPTION:
As a result of reported field failures, Bell Helicopter has completed a load survey, coupon testing and analysis of the high aft crosstubes. The results indicate repetitive cycle fatigue damage can occur during towing and landing operational events. These results warrant a 12 month / 2500 landing (which ever comes first) repetitive Fluorescent Penetrant Inspection, Deflection Check, and a mandatory use of the aft crosstube retention kit (BHT-412-SI-58) at helicopter weights at or above 8900 lb.
APPROVAL:
The engineering design aspects of this bulletin are FAA/DER approved.
MANPOWER:
Approximately 10 man-hours are required to co mplete this bulletin not including paint and primer cure times. Man-hours are based on hands-on time, and may vary with personnel and facilities available.
WARRANTY:
There is no warranty provided for this bulletin.
MATERIAL:
Required Material:
The following material is required for the ac complishment of this bulletin and may be obtained through your Bell Helicopter Textron Supply Center.
Part Number Nomenclature Quantity 412-050-045-117 Clamp Assembly A/R 206-050-301-111 Abrasion Strip A/R LARSON L101 Larson Film A/R 412-706-031-101* Towing Provisions A/R 412-250-100-101* Puller Equipment A/R 212-070-600-143** Decal 2
* See BHT-412-SI-58 ** Acceptable to locally manufacture per Figure 3
ASB 412-09-135 Page 3 of 16
Consumable Material:
The following material is required to a ccomplish this bulletin and may be obtained through your Bell Helicopter Textron Supply Center.
Part Number Nomenclature Quantity Reference AMS-S-8802 Sealant 1 C-308 LARSON L100 Adhesive A/R C-571 MIL-R-81294 Paint Remover A/R C-436 * EWDE072 3950 Scotchcal Primer Kit (1GAL,1QT) Edge Sealer A/R A/R C-246 C-349 MS-242N Quik-Freeze A/R C-137
* Customers may also use Turco 5351(T-5469)
SPECIAL TOOLS:
None required
WEIGHT AND BALANCE:
Not affected
ELECTRICAL LOAD DATA:
Not affected
REFERENCES:
BHT-412-IPB Illustrated Parts Breakdown BHT-412-MM Maintenance Manual, Rev 12 BHT OSN 412-07-32 BHT-ALL-SPM Standard Practices Manual BHT ASB 412-08-129 (AAI ASB AA-07109) BHT-ASB 412-99-97 BHT-412-SI-58 Gross Weight Towing Kit Provisions & Puller Equipment
PUBLICATIONS AFFECTED:
BHT-412-IPB Illustrated Parts Breakdown BHT-412-MM Maintenance Manual BHT-412-MD-1, 2, & 3 BHT-412-SI-2 Emergency Float Kit BHT-412-SI-40 High Skid Gear / High Crosstube
ASB 412-09-135 Page 4 of 16
BHT-412-SI-58 Gross Weight Towing Kit Provisions & Puller Equipment BHT-412-SI-60 Emergency Floats
ACCOMPLISHMENT INSTRUCTIONS
ESTABLISHING REQUIREMENTS:
1. Review the high landing gear aft cro sstube component history card and determine bulletin applicability as indicated in Table 1 below.
TABLE 1
Crosstube Assembly Part Number Sub Assembly Crosstube Part Number (See Note) Crosstube subassembly (Nonprocurable) (See note) Bare Crosstube (Non-procurable) 412-050-011-101 412-050-010-101 N/ A this level 412-050-010-103 412-050-011-103 412-050-010-107 412-050-010-109 412-050-010-103 412-050-011-105 412-050-010-107 412-050-010-109 412-050-010-103 412-050-011-107 412-050-010-111 412-050-010-113 412-050-010-115 412-050-045-105 412-050-045-107 N/ A this level 412-050-044-101 412-321-104 See AAI ASB AA-07109 / BHT ASB 412-08-129
Note: Sub-assemblies are indicated abov e for tracking purposes. Tracking is accomplished at the sub assembly par t number level on Bell 12-digit part numbers. The factory serial numbers or the company control serial numbers are visible in the cuff area above the skid tube saddle; refer to ASB 412-99-97.
2. Amend the component history card to reflect the bulletin requirements for a recurring 12 month / 2500 landing aft cro sstube Fluorescent Penetrant Inspection and a Deflection Check. Refer to acco mplishment instructions Part I & II respectively.
3. Establish maintenance practices to mandate towing with the aft crosstube retention kit. Refer to the Accomplishment Instructions Part III.
ACCOMPLISHMENT INSTRUCTIONS
PART I - Accomplish a reoccurring 12 month / 2500 landing aft crosstube Fluorescent Penetrant Inspection as indicated below.
ASB 412-09-135 Page 5 of 16
-NOTE-
The high aft crosstube Fluoresce nt Penetrant Inspection can be accomplished by any pers on meeting the personnel Qualification / Certification Requirements of the BHT-ALL- SPM (ref. Chapter 6, Section 6-5).
1. Remove the landing gear assembly from the helicopter as per BHT-412-MM.
CAUTION
TEMPORARILY INSTALLING A SECONDARY LANDING
GEAR OR MAINTAINING A CONNECTION TO AN
OVERHEAD CRANE IS RECOMMENDED DURING THIS MAINTENANCE ACTION.
2. Remove the aft crosstube fr om the landing gear assembly.
3. Remove the support beam from the aft crosstube as per BHT-412-MM
4. Remove the hardware retaining BL 14 clamp assemblies P/N 412-050-045-115 or / -117 (left & right hand) on the high aft crosstube. Refer to Figure 1 below.
CAUTION
CROSSTUBE TEMPERATURE NOT TO EXCEED 200ºF
(93.3ºC) WHEN USING HEAT GUN. EXCESSIVE HEAT WILL DAMAGE CROSSTUBE.
5. Use heat gun to soften sealant bonding t he clamp assembly to the crosstube.
Separate the clamp from crosstube and the abrasion strip (if installed).
-NOTE-
Crosstubes 412-050-011-ALL do not have the abrasion strips bonded to the under side at BL 14 or the Larson L101 material bonded to the under side at BL 00. Fluorescent Penetrant Inspection is requi red in these areas prior to reworking these crosstubes to meet the protective requirements of 412-050-045 crosstubes, containing the above mentioned items. Refer to “Rework” section below for the 412-050-011-ALL high aft crosstubes.
ASB 412-09-135 Page 6 of 16
-NOTE-
Crosstube 412-050-045-107 with AAI replacement lower support 604-026-003 at BL 00 re quire Fluorescent Penetrant Inspection in this area. Refer to “Rework” section
6. Remove abrasion strip P/N 206-050-301-11 1 at BL 14 from the crosstube lower surface only if it has become partially de- bonded; or, if further maintenance related investigation is deemed necessary. Removal of the abrasion strips from crosstubes 412-050-045-107 or reworked 412-050-011-ALL series crosstubes is not necessary to accomplish the Fluorescent Penetrant Inspection. If abrasion strips must be removed, use a plastic scraper to separat e the strip from the crosstube while cooling the strip with Quik-freeze C-137 to de-grade the bond line. Start at a corner and continue peeling carefully while mainta ining the bond line in a cool / frozen state.
-NOTE-
The upper support 412-050-006-101 on the aft crosstube is bonded with structural adhesive and is not designed to be removed.
7. Removal of the lower crosstube s upport P/N 412-050- 007-101 incorporating the abrasion strip at BL 0.0 is unnecessary unless there are signs of looseness or debonding. If the abrasion strip must be removed, use a plastic scraper to separate the strip from the crosstube while cooling the strip wi th Quik-freeze C-137 to degrade the bond line. Start at a corner and continue peeling carefully while maintaining the bond line in a cool / fr ozen state. Crosstube assembly 412-050- 045-107 and reworked crosst ubes 412-050-011-ALL have the abrasion strip under BL 0.0 support. Crosstubes P/N 412-050-011- ALL in the original condition without the Larson L101 under the lower support P/ N 412-050-007-101 at BL 0.0 require removal of the lower support for the first Fluorescent Penetrate Inspection (refer to Rework section for 412-050-011-ALL high aft crosstubes).
-NOTE-
Lower support P/N 604-026-00 3 comes with black nylon abrasion material bonded to the support. The Larson L101 abrasion strip shall not be used with this support.
8. Remove lower crosstube support P/N 604 -026-003 (if installed) from Crosstubes 412-050-011-ALL and 412-050-045-107 to accomplish the first Fluorescent Penetrant Inspection.
ASB 412-09-135 Page 7 of 16
9. Remove Larson L101 abrasion strip bonded to the crosstube at BL 0.0 if using AAI replacement support P/N 604-026-003 to accomplish the first Fluorescent Penetrant Inspection.
CLEANING AND PREPARATION
1. Use a plastic scraper to remove residual sealant on the crosstube. It is not required to remove the sealant bead around t he periphery of the 412-050-006-101 upper / 412-050-007-101 lower supports at BL 00 unless the sealing bead has been damaged on crosstube series 412-050-045. Residual sealant, Larson L101 film and Larson adhesive will need to be remov ed from crosstubes affected by the installation of spare r eplacement lower support 604-026- 003. Original crosstubes P/N 412-050-011-ALL without Larson L101 (adhesive film) under the lower support at BL 0.0 require the residual sealant to be removed for the first Fluorescent Penetrant inspection only.
CAUTION
PROTECT ABRASION STRI PS AND UPPER / LOWER SUPPORTS (BL 14, BL 00) FROM PAINT REMOVER
CONTAMINATION AS REQUIRED
2. Prepare crosstube for the inspection pr ocess by removing the paint on the crosstube in the area indicated in Figure 2.
a. Crosstube P/N 412-050-045 will require the paint to be removed in area depicted in Figure 2 wit h the exceptions of the abr asion strip areas and the 412-050-006-101 upper and 412-050-007-101 lower supports (BL 0.0). The paint and Larson abrasion strip will need to be removed in the lower support area at BL 00 if support P/N 604-026-003 has been installed.
b. Crosstube P/N 412-050-011- ALL which does not have the abrasion strip under the clamp assembly at BL 14 or Larson L101 material under the lower support at BL.0.0 will require the paint to be removed under the lower center support.
3. Apply chemical paint remover (C-436) to the crosstube with a brush following manufacturer’s directions and the BHT-ALL-SPM.
ASB 412-09-135 Page 8 of 16
CAUTION
A PLASTIC SCRAPER OR AB RASIVE PAD C-407 MAY BE
USED TO GENTLY ASSIST THE PAINT REMOVAL PROCESS. USE OF THE PLASTIC SCRAPER OR
ABRASIVE PAD IS TO BE ACCOMPLISHED IN A
LONGITUDINAL DIRECTION ENSURING NOT TO ABRADE THE CROSSTUBE METAL SURFACE.
4. Reapply the paint remover as required to completely remove the paint and primer.
Rinse crosstube surface clean using potable water and dry thoroughly. Inspect crosstube to ensure the bare metal of the cr osstube is clearly visible and free of paint and primer residue in the affected area.
5. Protect crosstube immediat ely after cleaning by applying corrosion preventive oil if the inspection process is delayed. Wrap in barrier material and secure with tape.
INSPECTION
CAUTION
USE CARE TO PREVENT CONTAMINATION FROM
FLUORESCENT PENETRANT CHEMICALS ON THE
ABRASION STRIPS AND UP PER / LOWER SUPPORT (BL14, BL 00) AS APPLICABLE.
-NOTE-
The aft crosstube Fluorescent Penetrant Inspection can be accomplished by any person meeting the personnel Qualification / Certification Requirements of the BHT-ALL- SPM (ref. Chapter 6, Section 6-5).
1. Inspect the crosstube, with the exception of the areas covered by the protective abrasion strips (if installed) and upper c enter support using Fluorescent Penetrant method per ASTM E1417, Type 1 Method B, C or D using a penetrant sensitivity level of 2 or 3 (Refer to BHT-ALL-SPM Chapter 6).
2. All penetrant inspection materials utilized shall be compatible, and shall meet requirements of SAE AMS 2644.
ASB 412-09-135 Page 9 of 16
-NOTE-
The use of visible dye systems is prohibited.
3. Inspect crosstube damage per limits spec ified in the Maintenance Manual (BHT- 412-MM-5, Chapter 32) to determine allo wable damage and cleanup. No cracks are permitted. To determine the appropriat e Inspection Criteria Table in the Maintenance Manual for a specific high a ft crosstube, refer to cross reference Table 2 below.
TABLE 2
Crosstube Assembly Part Number Sub Assembly Crosstube Part Number Crosstube With 10,000 Takeoff/ Landing Limit using Standard Inspection Criteria Crosstube With 20,000 Takeoff/ Landing Limit using Improved Inspection Criteria 412-050-011-101 412-050-010-101 X 412-050-011-103 412-050-010-107 X 412-050-011-105 412-050-010-107 X 412-050-011-107 412-050-010-111 X 412-050-045-105 412-050-045-107 X 412-321-104 X See AAI ASB AA-07109 / BHT ASB 412-08-129
REPAIR
1. Repair all damaged crosstubes that are found to be within acceptable limits as indicated in BHT-412-MM-5 Standard or Im proved inspection criteria Tables, record all repairs.
2. Replace crosstubes that are beyond t he maximum allowable damage limits as indicated in the inspection Tables.
REWORK OF CROSSTUBES
-NOTE-
High aft crosstubes 412-050-011 -ALL shall incorporate the bonding procedures and abrasion strips at BL 00 and BL14 locations, to provide an equival ent level of protection as used on replacement cro sstubes P/N 4 12-050-045-105/- 107/-107A.
ASB 412-09-135 Page 10 of 16
-NOTE-
It is required to omit the Larson L101 abrasion strip on the 412-050-011-ALL and 412-050-045-107 crosstubes at BL 00 when installing lower support 604-026-003.
1. Apply primer (C-246) to areas where paint has been removed for inspections as per BHT-ALL-SPM.
CAUTION
DO NOT SAND CROSSTUBE IN A CIRCUMFERENTIAL DIRECTION. SAND CROSSTU BE IN A LONGITUDINAL DIRECTION ONLY.
-NOTE-
It is required to complete the first Fluorescent Penetrant Inspection before installation of the abrasion strips at BL 0.0 and BL 14 on the crosstubes 412-050-011-ALL.
-NOTE-
Abrasion strip bonding is ac complished prior to the installation of the BL 14 band clamp P/ N 412-050-045-115 and BL 00 lower support P/N 412-050-007-101 installation.
2. Lightly abrade the primer on the crosst ube common to the abrasion strip taking care not to expose bare material.
-NOTE- Replacement of abrasion strip material on the under side of the crosstubes at station BL 0.0 and BL 14 locations on 412- 050-045-ALL high aft crosstubes is not required if it has not been damaged during inspection.
3. Install the abrasion strip material on the under side of the crosstubes at both BL 0.0 and BL 14 locations on all high aft cr osstubes series 412-050-011-ALL and 412- 050-045-107 per the BHT-412-MM, as requi red. Abrasion strip removal for subsequent Fluorescent Penetrant Inspecti ons is not required. When installing replacement lower support 604-026-003 at BL 00 the Larson L101 abrasion strip is not required. The replacement support has a black nylon abrasion material bonded to the support.
ASB 412-09-135 Page 11 of 16
-NOTE-
All BL14 band clamps shall have an adhesive film on the inner surface prior installation.
4. Use band clamp assembly 412-050-045-115 (replaced by 412-050-045-117) or prepare band clamp P/N 330 C400-338-S (alt. P/N 333C 400-338-S) by adding the adhesive film as indicated in the BHT- 412-MM, BL 14 clamp preparation. Clamp assembly 412-050-045-117 and clamp 333C400-338-S both have longer “T” bolts to ease installation.
CAUTION
CONFIRM BAND CLAMP POSITIONING PRIOR TO INSTALLATION AS PER BHT-412-MM. DO NOT POSITION
BAND CLAMP OVERLAP AT CENTER OF RETENTION CAP RUBBER BUMPER. OVER ROTATION OF THE
CLAMP ASSEMBLY COULD RESULT IN DAMAGE TO THE AIRFRAME TUNNEL FROM THE CLAMP “T” BOLTS.
CAUTION
DO NOT SAND CROSSTUBE IN A CIRCUMFERENTIAL DIRECTION.
5. Lightly abrade the primer on the cro sstube and abrasion strip common to the band clamp (P/N 412-050-045-117) taking care not to expose bare material.
CAUTION
REMOVE PROTECTIVE BACK ING FILM TO EXPOSE ADHESIVE FILM PRIOR TO BONDING CLAMP.
6. Install band clamp assembly P/N 412- 050-045-117 using sealan t (C-308) as per the BHT-412-MM. Ensure complete sealant coverage of the inner clamp surface, avoiding air pockets.
7. Trim the “T” bolts on the clamp asse mbly 412-050-045-117 to provide adequate clearance from fuselage tunnel, as require d. Normally the “T” bolt should have approximately ½ inch of threads visible afte r installation. Deburr as required. Prime (C-246) and paint (as required) bare metal on “T” bolt for corrosion protection.
ASB 412-09-135 Page 12 of 16
8. Lightly abrade the abrasion strip or the crosstube primer on the crosstube at BL 0.0 common to the lower support P/N 412-050-007-101 or 604-026-003 taking care not sand through abrasion strip or primer on crosstube expo sing bare material. The Larson L101 abrasion strip is not requi red when installing replacement lower support 604-026-003.
9. Install lower support P/ N 412-050-007-101 or 604-026-003 using sealant (C-308) per the BHT-412 Maintenance Manual. Prio r to bonding the replacement lower support 604-026-003 with sealant (C-308) light ly abrade the black nylon abrasion material taking care not to expose bare metal.
10. Repaint crosstube as required per BHT-ALL-SPM.
11. Annotate component records to indicate incorporation of abrasion strips on 412- 050-011 series crosstubes by the addition of “FM” to the end of the part number sequence (e.g. 412-050-011-107FM), for future reference.
12. Annotate helicopter / component records to indicate Part I of this bulletin has been accomplished.
ACCOMPLISHMENT INSTRUCTIONS
PART II - ACCOMPLISH AFT CROSSTUBE DEFLECTION CHECK AND ESTABLISH A RECURRING 12 MONTH / 2500 LANDING DEFLECTION CHECK (WHICH EVER COMES FIRST).
CAUTION
ENSURE HELICOPTER IS STABILIZED ON JACKS
BEFORE PROCEEDING TO ACQUIRING MEASUREMENTS.
1. Hoist or jack the helicopter until the weight is removed from the landing gear.
2. Determine the BL 0.0 from the walking beam pivot point position and hang a plumb line to obtain the measurement from BL 0.0 to the outside edge of the skid tubes as indicated.
3. Confirm aft crosstube is within deflections limits indicated in the BHT-412-MM.
4. Replace aft crosstubes that exceed t he dimensional tolerances indicated.
5. Annotate helicopter / component records to i ndicate Part II of this bulletin has been accomplished.