Aviation Missile Command (AMCOM) Aviation Safety Action Message Summaries

 

 

In brief format, this page gives the Summary of Problem as indicated in the appropriate Aviation Safety Action Message (ASAM) issued by Commander, Aviation Missile Command (AMCOM). Note: ASAMs do not expire unless revised, rescinded, superceded, or incorporated and reprinted as a Technical Bulletin, becoming permanent additions to the Quality Control Library.

 

 

 

CH-47-06-ASAM-01, 9 January 2006: Title: Upper Boost Actuators. Summary: A Quality Discrepancy Report (QDR) shows that the end caps of an Upper Boost Actuator (UBA) were inadvertently swapped (reversed). There are 4 (ea) UBAs installed on the aircraft (Forward Pivoting, Forward Swiveling, Aft Pivoting, and Aft Swiveling Actuators). The UBAs have 2 (ea) servocylinders which are machined with different sized return ports so that the #1 and #2 hydraulic systems cannot be crossfed into one another. When crossed, this deficiency would eliminate aircraft hydraulic system redundancy. [Full Text ]

 

CH-47-05-ASAM-06, 14 September 2005: Title: Hydraulic Fluid System Maintenance. Summary: CH-47-99-ASAM-02 required hydraulic purification every 200 flight hours and CH-47-00-ASAM-03 required aircraft hydraulic system sampling every 50 flight hours. Experience has shown this additional maintenance has achieved the expected system cleanliness. It has been determined the interval for hydraulic purification can safely be extended and the requirement for periodic hydraulic sampling rescinded. These changes will reduce the maintenance burden while maintaining the desired level of system cleanliness. [Full Text ]

 

 

CH-47-05-ASAM-05, 8 August 2005: Title: Hydraulic Check Valves and Fluid Parts. Summary: Over the service life of H-47 aircraft, Category I Quality Discrepancy Reports (QDR) have documented the failure of hydraulic check valves (PN 4C3074) manufactured by Crissair Company. Some of these failures have exposed hydraulic pumps to excess heat from hot hydraulic return fluid or caused reverse rotation of pump rotor blades, either of which can cause premature wear and possible failure of the pumps. The vendor has designed a new check valve (PN 4C5202) to replace the PN 4C3074 valve. Additionally, several discrepancies were found in the CH-47D parts manual (TM 55-1520-240-23P), two of which could lead to degraded hydraulic system performance or premature failure of the Power Transfer Unit (PTU) pump. It has also been determined that some premature pump failures were caused by cavitation (air in the system). [Full Text ]

 

 

CH-47-05-ASAM-04, 28 July 2005: Title: Aft Transmission Retainer. Summary: An unknown number of H-47 aft transmissions omitting the Liner (PN 145D2304-4) or with the ball bearing outer race retention key mechanically removed from the liner. The Liner is a subcomponent of the Seal Retainer Assembly (PN 145D2304-9). Installation of the Seal Retainer assembly is identified in DMWR 55-1615-324 with a Warning to be an Installation Critical, Critical Safety Item but is not included in the TM. [Full Text ]

 

 

CH-47-05-ASAM-03, 21 July 2005: Title: Vertical Hinge Pin Bearings. Summary: Twenty four vertical hinge pin upper bearings have been found that were marked incorrectly as vertical hinge pin lower bearings. The DA Form 2410 for these parts correctly identified them as upper bearings, but the parts themselves and their packaging were marked as lower bearings. Additionally, 20 of the bearings had corrosion on the inner diameter vertical hinge pin mating surface. The upper bearing inner diameter is larger than the lower bearing inner diameter. The bearing manufacturer has isolated the problem to one set of 78 bearings. As many as 54 mislabeled bearings could still be installed or in stock. [Full Text ]

 

 

CH-47-05-ASAM-02, 21 July 2005: Title: Aft Rotary Wing Head. Summary: CH-47-05-ASAM-01, issued on 14 October 04, directed the demilitarization of some Aft Rotary Wing Heads (PNs 145R2004-18 and -20). The original intent of the ASAM was to only demilitarize the suspect Pitch Housings (PNs 145R2075-2,-12,-14 and -16) from the aft rotary wing head serial numbers listed in the ASAM. [Full Text ]

 

 

 

CH-47-05-ASAM-01, 14 October 2004: Title: Aft Critical Dynamic Components. Summary: CH-47-04-ASAM-02 was issued on 29 April 04 to advise flight crews on the operational limits of the Cruise Guide Indicator (CGI), to remark the CH-47D CGI and to require the inspection of the instrumented aft fixed link. This ASAM provides additional inspections and corrective action. [Full Text ]

 

 

CH-47-04-ASAM-02, 29 April 2004: Title: Transient and avoid bands on the Cruise Guide Indicator. Summary: Following combat operation of CH-47D aircraft in Iraq and in the mountains of Afghanistan, pilots reported that continuous flight operations were conducted with the cruise guide indicator (CGI) in the transient region, accompanied by excursions into the avoid region, usually encountered in turbulence. [Full Text ]

 

 

CH-47-04-ASAM-01, 3 February 2004: Title: Aft Fuselage Bellcrank Fastener. Summary: The baseline version of the CH-47D and the MH-47E Maintenance Manuals contain figures that are either incorrect or lack proper resolution, possibly causing incorrect Aft Fuselage Bellcrank fastener installation, and consequently causing reduced clearance between control system linkages. [Full Text ]

 

 

CH-47-03-ASAM-02, 7 August 2003: Title: Performance Planning During Desert Combat Operations. Summary: Current Operating Limits outlined in aircraft Operator Manuals impose established, specific environmental, temperature, and time limits. Aircraft operating in extreme environmental zones may experience conditions that clearly exceed the prescribed standard limits. To assist units deployed in support of desert combat operations, Air Worthiness Releases (AWR) have been prepared to provide instructions on completing performance planning when Free Air Temperatures (FAT) exceed 50 degrees Centigrade. [Full Text ]

 

 

CH-47-03-ASAM-01, 25 Mar 2003: Title: Engine Drive Shaft. Summary: Application of MWO 55-1520-240-50-43 replaced three piece engine drive shaft, P/N 145D3500-15, with a one piece engine drive shaft, P/N 145D3504-2. At that time an interim retirement life of 2000 hours was established. The interim retirement life was to remain in effect until fatigue testing was conducted and verified. Based on fatigue test results, the retirement life of P/N 145D3504-2 can safely be increased to 6000 hours for all but 49 of these shafts. These 49 shafts were flown on certain aircraft during a specific time frame which cannot allow their retirement lives to be increased. These 49 specific serial numbered shafts will remain at the 2000 hour retirement life. [Full Text ]

 

 

CH-47-02-ASAM-04, 24 Jul 2002: Title: Inspection for untested Critical Safety Item (CSI), P/N 114C3044-2, Aft Yoke Support Shaft. Summary: The original qualification (fatigue testing) of Critical Safety Items (CSI) was done by Boeing Helicopters under Army direction. The fatigue testing of these parts substantiated their service life and the parts design was considered qualified. In October 1995, a change in the Army Flight Safety Part (FSP) policy required that parts manufactured by authorized vendors/suppliers and originally qualified by the prime contractor must be fatigue tested. The H-47 Aft Yoke Support Shaft, P/N/ 114C3044-2 is a Critical Safety Item (CSI). The 114C3044-2 shaft is used to attach the Yoke Assembly, P/N 114c3043-6 to the airframe. Failure of this shaft would result in loss of control to the Aft Rotor Head. Some 114C3044-2 shafts were fielded without being qualified as an alternate source by fatigue testing. [Full Text ]

 

 

CH-47-02-ASAM-03, 12 June 2002: Title: Inspect for improperly manufactured/assembled Fuel Control Relay Boxes. Summary: This ASAM results from a Category I Deficiency Report. A CH-47D experienced an inoperative Right Hand Side Main Aft Fuel Boost Pump during flight caused by improper manufacture/assembly of the wiring harness in the Fuel Control Relay Box. The wiring did not have terminal lugs installed, wire identification was improperly marked, and wire ends were directly wrapped and attached to the relay screws. In this particular relay box, six (6) wires were completely broken and one (1) wire was partially broken. [Full Text ]

 

 

CH-47-02-ASAM-02, 26 December 2001: Title: Forward Yoke Shaft replacement date extension. Summary: CH-47-00-ASAM-08 (TB 1-1520-240-128) was issued to require inspection for insufficient paint coverage and/or corrosion on the inside bore of the Forward Yoke Shaft (P/N 145C3051-1). If either condition was found, Corrosion Preventive Compound (CPC) was to be applied and the shaft was to be replaced NLT 31 DEC 2001. It has been determined that an insufficient number of shafts are available to allow all units to be in full compliance with the ASAM. [Full Text]

 

 

CH-47-02-ASAM-01, 4 October 2001: Title: Inspection of the Tunnel Cover Strut Assemblies. Summary: A report has been received from the field documenting that the Pin in a Tunnel Cover Strut Assembly was not staked. If the Pin becomes dislodged from the Strut Assembly, the Strut halves and/or the Pin can cause damage to the hydraulic lines and Sync Shafts. [Full Text]

 

 

CH-47-01-ASAM-09, 6 September 2001: Title: Inspection for untested Flight Safety Part (FSP) Bolts (Drive Arm and Aft Rigid Link). Summary: The original qualification (fatigue testing) of Flight Safety Parts was done by Boeing Helicopters under Army direction. The fatigue testing of these parts substantiated their service life and the parts design was considered qualified. In October 1995, a change in the Army Flight Safety Part policy required that parts manufactured by authorized vendors/suppliers and originally qualified by the prime contractor must be fatigue tested. The 114R3650-9 and BACB30ST10-40 bolts are Flight Safety Parts. The 114R3650-9 Bolt Assembly is used for attachment of the Drive Scissors Upper Arm to the Drive Collar Assembly on both the Forward and Aft Rotor Heads. The BACB30ST10-40 Self-Retaining Bolt is used for attachment of the Fixed Link to the Yoke Assembly in the Aft Pylon Controls installation. Some of the 114R3650-9 and BACB30ST10-40 Bolts were fielded without being qualified by fatigue testing as an alternate source. [Full Text]

 

 

CH-47-01-ASAM-08, 9 August 2001: Title: Inspection of Flight and Utility Boost Hydraulic Control Modules. Summary: A Deficiency Report investigation identified that a Power Control Module was missing its Shut-Off Diaphragm hardware. [Full Text]

 

 

CH-47-01-ASAM-07, 12 February 2001: Title: Inspection for untested Flight Safety Part (FSP) Bolts (Pitch Change Link). Summary: The original qualification (fatigue testing) of Flight Safety Parts was done by Boeing Helicopters under Army direction. The fatigue testing of these parts substantiated their service life and the parts design was considered qualified. In October 1995, a change in the Army Flight Safety Part policy required that parts manufactured by authorized vendors/suppliers and originally qualified by the prime contractor must be fatigue tested. The 114R3650-13 and 114R3650-15 Bolts are Flight Safety Parts. The 114R3650-13 Bolt (three per Rotor Head) is superseded and replaced by the improved 114R3650-16 Bolt, and is used to attach the upper end of each Pitch Link to the Pitch Arm on both the Forward and Aft Rotor Heads. The 114R3650-15 Bolt (three per Rotor Head) is superseded and replaced by the improved 114R3650-17 Bolt, and is used to attach the lower end of each Pitch Link to the Swashplate on both the Forward and Aft Rotor Heads. Some of the 114R3650-13 and -15 bolts were fielded without being qualified as an alternate source by fatigue testing. [Full Text]

 

 

CH-47-01-ASAM-06, 22 December 2000: Title: Revision to CH-47-01-ASAM-04, inspection for untested Flight Safety Part (FSP) Tie Bar Pin Assemblies. Summary: CH-47-01-ASAM-04 (TB 1-1520-240-20-133) was issued on 14 December 2000 requiring the inspection of Flight Safety Parts (FSP) 114R2168-3 and 114R2168-4, Tie Bar Pin Assemblies. Paragraphs 8a(3) and 8b(3) of the ASAM provided a listing of Cage codes to identify serviceable Tie Bar Pins. It has since been determined that serviceable Tie Bar Pins can be identified by an additional Cage code number. [Full Text]

 

 

CH-47-01-ASAM-05, 14 December 2000: Title: Inspection of Rotor Head Assembly Droop Stop Bolts for proper length. Summary: An accident occurred during shutdown of a CH-47D. Investigation was conducted and findings indicated that 2 incorrect bolts were installed in the Droop Stop on the Red Blade of the Aft Rotor Head Assembly. A shorter Bolt P/N NAS624H5 was installed instead of the correct Bolt P/N NAS624H7 (1/8 inch difference). It appears the excessive force on the threads along with loads seen during droop stop contact caused the threads on the bolts to fail. [Full Text]

 

 

CH-47-01-ASAM-04, 14 December 2000: Title: Inspection for untested Flight Safety Part (FSP) Tie Bar Pin Assemblies. Summary: The original qualification (fatigue testing) of Flight Safety Parts was done by Boeing Helicopters under Army direction. The fatigue testing of these parts substantiated their service life and the parts design was considered qualified. In October 1995 a change in the Army Flight Safety Part (FSP) policy required that parts manufactured by authorized vendors/suppliers and originally qualified by the prime contractor must be fatigue tested. The 114R2168-3 and 114R2168-4 Tie Bar Pin Assemblies are Flight Safety Parts. The Pins (3 of each per Rotor Head) secure the ends of the Tie Bars to the Pitch Shaft and the Pitch Varying Housing. Some of the Tie Bar Pin Assemblies were fielded without being qualified as an alternate source by fatigue testing. [Full Text]

 

 

CH-47-01-ASAM-03, 8 November 2000: Title: Forward and Aft Rotor Hub Lightening Hole inspections. Summary: A Category I Deficiency Report was received which revealed cracks extending from the Lightening Holes in the Vertical Web Area of the Rotor Head Center Hub. When discovered, these cracks were greater than one inch in length. Further investigation revealed the cracks went undiscovered during several phased maintenance visual inspections. Research revealed three other Rotor Hubs that have been found with similar cracks. [Full Text]

 

 

CH-47-01-ASAM-02, 19 October 2000: Title: Inspection for untested Flight Safety Part (FSP) Bolts (Forward LCT and Aft Drive Arm). Summary: The original qualification (fatigue testing) of Flight Safety Parts was done by Boeing Helicopters under Army direction. The fatigue testing of these parts substantiated their service life and the parts design was considered qualified. In October 1995 a change in the Army Flight Safety Part (FSP) policy required that parts manufactured by authorized vendors/suppliers and originally qualified by the prime contractor must be fatigue tested. The 114R3650-6 and 114R3650-11 Bolt Assemblies are Flight Safety Parts. Tthe 114R3650-6 Bolts (2 per Forward Rotor Head) attach the Forward Cyclic Trim Actuator, and Fixed Link, to the Swashplate. The 114R3650-11 Bolt (1 per Forward and Aft Rotor Head) attach the Drive Scissors Upper Arm to the Drive Scissors Lower Arm. Some of the 114R3650-6 and 114R3650-11 Bolts, manufactured by Boeing authorized vendors/suppliers, were fielded before they were qualified as an alternate source by fatigue testing. [Full Text]

 

 

CH-47-01-ASAM-01, 11 October 2000: Title: Inspect for installation of MA-16 Inertia Reels. Summary: The Inertia Reels function in concert with the Crew Restraint Harness to minimize flailing injuries to aircew personnel in the event of an aircraft mishap. Based upon sampling tests at Fort Rucker of various Inertia Reels, an estimated 24 percent of the old MA-6 and MA-8 Inertia Reels failed to automatically lock in low forward velocity crashes as required by MIL-R-8236F. Additional sampling tests conducted by the Navy revealed that 50 percent of the old MA-6 and MA-8 Inertia Reels tested failed to lock during high velocity forward crashes. Clearly, older design Inertia Reels do not afford the maximum degree of protection from flailing injuries, thereby increasing the risk of serious injuries in survivable helicopter accidents. [Full Text]

 

 

CH-47-00-ASAM-08, 28 September 2000: Title: Inspection of Forward Yoke Shaft, P/N 145C3051-1, for corrosion. Summary: A Category I Deficiency Report was received which reported corrosion on the inside surface of the Forward Yoke Shaft, P/N 145C3051-1. The inside surface is required to be painted with primer. Inspection revealed that the primer only covered the first 3 or 4 inches of the inside bore with the unpainted portion exhibiting corrosion. [Full Text]

 

 

CH-47-00-ASAM-07, 26 September 2000: Title: Inspection of untested Flight Safety Part (FSP) Bolts (Aft LCT and Fixed Link). Summary: The original qualification (fatigue testing) of Flight Safety Parts was done by Boeing Helicopters under Army direction. The fatigue testing of these parts substantiated their service life and the parts design was considered qualified. A change in the Army Flight Safety Part (FSP) policy in October 1995 required that parts originally qualified by the prime contractor be fatigue tested for all of the prime contractor's authorized vendors/suppliers. The 114R3650-7 Bolt assembly is a Flight Safety Part which attaches the Aft Cyclic Trim Actuator, and Fixed Link, to the Swashplate. Some of the 114R3650-7 Bolts manufactured by Boeing authorized vendors/suppliers were fielded before they were qualified as an alternate source by fatigue testing. [Full Text]

 

 

CH-47-00-ASAM-06, 21 September 2000: Title: Inspection for defective Full Authority Digital Electronic Control (FADEC) P3 Drain Cartridge. Summary: Modification Work Order (MWO) 1-1520-240-50-83 installs T55-GA-714A Engines on the H-47 aircraft. Part of the installation is a P3 Signal Line from the Engine Hydro-Mechanical Assembly (HMA) to the Digital Electronic Control Unit (DECU). This line has a water drain cartridge. The Drain Cartridge incorporates a plastic sight tube for detecting water that may accumulate in the line. The plastic sight tubes have not been stress relieved and minute axial cracks develop easily which can cause P3 air leaks. In primary mode, the P3 signal is used to calculate a fuel flow limit. If the cartridge leaks, the P3 signal to the DECU may decrease enough to cause a lowering of fuel flow but not enough to engage the software fault detection logic. This will result in a partial or complete loss of engine power while in primary mode. [Full Text]

 

 

CH-47-00-ASAM-05, 26 July 2000: Title: Inspection of Forward and Aft Slider Shaft Seals. Summary: A unit reported receipt of a defective Slider Shaft Seal Assembly from the supply system. The metal portion of the seal assembly extended out to the edge of the rubber seal. This condition places the metal portion of the seal assembly unacceptability close to the vertical rotor shafts. [Full Text]

 

 

CH-47-00-ASAM-04, 26 July 2000: Title: Horizontal Hinge Pin Inspection. Summary: A Horizontal Hinge Pin failed hardness and tensile strength tests during a routine quality assurance destructive test. It has been determined that some Horizontal Hinge Pins with serial numbers UW2407 and prior may not have been properly heat treated. Horizontal Hinge Pins with these serial numbers are required to be hardness tested at the next overhaul or no later than 4800 flight hours total time since new (TTSN). The hardness test will be conducted by the overhaul facility. Horizontal Hinge Pins that pass the hardness test will be re-identified with a suffix "A" vibro engraved after the serial number. [Full Text]

 

 

CH-47-00-ASAM-03, 1 July 2000: Title: Hydraulic Fluid sampling from Flight Control and Utility Systems. Summary: The H-47 community has reported several incidents in which the aircraft experienced uncommanded maneuvers or flight control lock up while in flight. Contaminated Hydraulic Fluid is a factor which has been present and may have contributed to the uncommanded maneuvers or flight control lock up. To resolve this hydraulic fluid contamination factor, a periodic sampling interval of 50 flight hours or 100 calendar days for the Number One, Number Two, and Utility Hydraulic Systems will be initiated. [Full Text]

 

 

CH-47-00-ASAM-02, 10 May 2000: Title: Initial and recurring inspections and replacement of Horizontal Hinge Pin Shouldered Bolts. Summary: During Post Flight Inspection a Horizontal Hinge Pin Shouldered Bolt, P/N 114R2201-1, was found to have the bolt head separated. Failure analysis determined a crack had initiated at the groove between the shank and the head of the bolt. The crack propagated until the bolt head broke off. A redesigned Bolt, P/N 114R2201-2, which does not have a groove is now being procured. [Full Text]

 

 

CH-47-00-ASAM-01, 27 April 2000: Title: Inspection of Fuel Pods for corrosion and electrical bonding. Summary: A unit reported finding corrosion where the Fuel Pod skin attaches to the T-Cap. Further investigation revealed this to be galvanic corrosion. The manufacturer of the pods misinterpreted the drawings and painted bare aluminum with a carbon filled paint. The dissimilar materials set up the environment for the galvanic corrosion. Corrosion products can reduce conductivity and make electrical bonding ineffective. [Full Text]

 

 

CH-47-99-ASAM-05, 22 April 1999: Title: Extension for replacement of the Aft Landing Gear Drag Link Assemblies that are susceptible to stress corrosion cracking. Summary:    A. Several instances have been reported of failed Aft Landing Gear Drag Links. The investigation revealed the cause to be stress corrosion cracking. New Drag Links are now made from a material which is not susceptible to stress corrosion cracking.       (1) AMCOM issued TB 1-1520-240-20-80 (CH-47-96-ASAM-01) to inspect and identify Aft Drag Links which had either a "3" or "5" stamped or painted on them. The Drag Links identified with a "3" were made of a material which is susceptible to stress corrosion cracking and were required to be replaced by 6 NOV 97. The Drag Links identified with a "5" were made of a material which is not susceptible to the same stress corrosion cracking failure mode and were not required to be replaced.       (2) AMCOM issued TB 1-1520-240-20-100 (CH-47-98-ASAM-02) to extend the operational life and allow continued use of the Aft Landing Gear Drag Links identified with a "3" until 30 April 99. The risk for this extension was determined to be medium. Roll-On landings of aircraft with links identified with a "3" were restricted IAW TB 1-1520-240-20-100 (CH-47-98-ASAM-02).       (3) After conducting a thorough review of past accidents, it had been determined the likelihood of a Rotor Blade/Fuselage strike was improbable if a Landing Gear Drag Link failure occurred during a Roll-On landing. As a result, AMCOM issued TB 1-1520-240-20-101 (CH-47-98-ASAM-05) to rescind the Roll-On landing restriction imposed by TB 1-1520-240-20-100 (CH-47-98-ASAM-02). [Full Text]

 

 

CH-47-99-ASAM-04, 15 March 1999: Title: Forward and Aft Longitudinal Cyclic Trim Yoke Bushing inspections and Aircraft Maintenance Manual changes. Summary:    A. Two instances have been reported of Bushings being left out during installation of Longitudinal Cyclic Trim (LCT) Yokes. The first was corrected before any damage occurred. The second instance resulted in damage to the Yoke Assembly Mounting Lug on the Forward Transmission. A review of the Maintenance Manual confirms that two bushings (Part Numbers NAS75-20-206 and NAS75-20-123) are not sufficiently represented in the text or diagrams.       (1) Forward LCT Yoke assembly: in TM 55-1520-240-23, Task 11-217, Step 5.1, Item 9.1 is installed (Bushing, TM 55-1520-240-23P, Figure 372, Item 78, Part Number NAS75-20-206). Prior to Change 22 in TM 55-1520-240-23, this part was not represented in the associated diagram. As a result, this bushing was omitted because it was confused with the press-fit sleeve bushing on the transmission housing (TM 55-1520-240-23P, Figure 180, Item 22, Part Number 145D0121-14).       (2) Aft LCT Yoke Assembly: in TM 55-1520-240-23, Task 11-233, Steps 7 and 8 have omitted the installation of the sleeve bushing (TM 55-1520-240-23P, Figure 137, Item 135, Part Number NAS75-20-123). As a result, the sleeve bushing was not installed. [Full Text]

 

 

CH-47-99-ASAM-03, 24 February 1999: Title: Inspection of Hoist/Cargo Hook Control Panel and Water Intrusion in the Cockpit. Summary: Investigations have revealed that the Hoist/Cargo Control Panel has chaffed wires and corrosion on the terminal lugs. These conditions could cause electrical shorting and inadvertent jettison of external cargo. [Full Text ]

 

 

CH-47-99-ASAM-02, 16 February 1999: Title: Actions to reduce susceptibility to Flight Control lock-up and/or uncommanded maneuvers. Summary: The H-47 community has reported several incidents in which the aircraft experienced uncommanded maneuvers or Flight Control lock up in flight. The USASC, AMCOM, and Boeing are conducting an investigation into this hazard. The investigating agencies analyzed suspect components and performed analytical tear-downs. AMCOM issued CH-47-98-ASAM-01 and CH-47-96-ASAM-06 as a result of the reported incidents. Factors which have been present and may contribute to uncommanded maneuvers or Flight Control lock-up include, but are not limited to: contamination of hydraulic fluid, internal parts out of tolerance, corrosion on internal parts, high barium content in preservative hydraulic fluids, hands off flying, and internal FOD created by wear of aluminum parts. The investigation team conducted simulations to analyze the interaction of these factors with aircraft flight. The simulations demonstrated that when such factors are present and actual hands on flying is not being observed, the aircraft may perform uncommanded movements with a slow degradation in flight capabilities. The computer simulation is not sophisticated enough at this time to produce the exact maneuvers of the incident aircraft, therefore we have not been able to establish a rigorous cause and effect relationship between any single factor or combination of factors for which the specific flight control anomalies have occurred. To resolve corrosion hazards with the Integrated Lower Control Actuator (ILCA) control valve, the CH-47 PMO will fund and request an engineering change to manufacture the control valve from corrosive resistant material. [Full Text]

 

 

CH-47-99-ASAM-01, 8 February 1999: Title: Inspection of Lag Dampners. Summary: An investigation of cracked Rod Ends on Blade Lag Dampeners with Elastomeric Bearings revealed that the Rod Ends had been adjusted to the length applicable to the older, teflon Rod End Bearings. Improper adjustment increases fatigue stresses which can cause the Banjo portion of the Rod End Assembly to crack. The Lag Dampeners were not properly identified by part number 114H6800-11 as required upon application of MWO 1-1520-240-50-64 or upon other maintenance action. The Maintenance Manuals require different adjustment lengths for the 9 and 11 Lag Dampeners. Without the correct part number identified on the part, incorrect adjustment lengths may have been applied to the lag dampeners. [Full Text]

 

 

CH-47-98-ASAM-05, 17 September 1998: Title: Revision to CH-47-98-ASAM-02 (Aft Gear Drag Link). Summary:    A. Failure of the Aft Landing Gear Drag Link may cause minor aircraft damage, depending upon flight crew detection of the failure and actions taken after the failure is detected. Investigations have revealed that side impact loading forces may cause the Aft Drag Link to fail on "-3" equipped Aft Landing Gear Assemblies. These side impact forces are generated during Roll-On landings, slope operations, rear wheel taxi operations, and landing the aircraft from a hover with a slight yaw rate.       (1) AMCOM issued TB 1-1520-240-20-80 (CH-47-96-ASAM-01) to inspect and identify Aft Drag Links identified with either a stamped or painted "-3" or "-5". The "-3" Drag Link is made of a material which is susceptible to stress corrosion cracking. The "-5" is the new configuration and is made of a different material which is not susceptible to the same stress corrosion cracking failure mode.       (2) AMCOM issued TB 1-1520-240-20-100 (CH-47-98-ASAM-02) to extend the operational life to allow continued use of the "-3" Aft Landing Gear Drag Link and restrict the aircraft from conducting Roll-On landings if the "-3" Drag Link was installed. Field visits have indicated that some unit trainers and evaluators were not aware of the Roll-On landing restriction. A system safety risk assessment was processed and continued use of the "-3" link, until the "-5" replacement links are available, was determined to be a medium risk. It has also been determined that the Roll-On landing restriction would adversely affect ATM training and pilot qualifications. [Full Text]

 

 

CH-47-98-ASAM-04, 14 May 1998: Title: Inspection for Aft Transmissions with suspected improperly shimmed Input Pinion Gear Assembly. Summary: Detailed investigation has identified twenty three Aft Transmissions that have been overhauled with improper shimming of the Input Shaft. This deficiency causes excessive vibration of the Transmission and premature wear of the Input Pinion Gear and its mating gear. The shimming procedure has been corrected by tool modification, and all Aft Transmissions overhauled after 8 Dec 97 are not considered suspect. The reference message/memorandum in paragraph 13 was sent in attempt to locate these specific transmissions and expedite the process. It had some success in locating some of the twenty three transmissions. This message requires a visual check of the transmission data plate. [Full Text]

 

 

CH-47-98-ASAM-03, 28 April 1998: Title: Mandatory torque check and replacement of Auxiliary Power Unit (APU) Bolts. Summary: In two separate incidents since October 1997, one Bolt of six which secure the APU Turbine Assembly to the Reduction Drive Assembly has backed out and been ingested into the APU Compressor causing FOD damage but no uncontained failures. The original Depot Maintenance Work Request (DMWR) and Tech Manuals specified a Self-Locking Bolt (P/N M4DS428-22C, NSN 5306-00-9867200). However, the current DMWR and TM specify a new Bolt (P/N AN101118, NSN 5306-00-638-5332) which is also listed as Self-Locking but, in reality, is not. Any T-62T-2B APU which has been subject to a Special Repair Activity (SRA) since 1 Jan 92 is suspect for having these non-self-locking bolts. (Note: Cherry Point has never used these bolts.) To prevent further incidents, the DMWR and TM will be corrected to specify a Bolt which is truly Self-Locking. Also, because it is difficult to identify the suspect bolts based only on head markings, all six of these bolts in each suspect T-62T-2B APU need to be replaced, one at a time. The new Bolt (P/N NK4-13, NSN 5306-00-117-9897) is currently used by the Navy and is provisioned for Army use. Also, a limited number of the original Self-Locking Bolts will be available from DLA. Until replacement Bolts arrive, each Bolt will be torque checked, torque-striped, and re-inspected every 50 flight hours to ensure proper torque (50 to 70 pound-inches torque). [Full Text]

 

 

CH-47-98-ASAM-02, 23 October 1997: Title: Extension for replacement of the Aft Landing Gear Drag Link Assemblies that are susceptible to stress corrosion cracking. Summary: Aviation Safety Action Message CH-47-96-ASAM-01 (TB 1-1520-240-20-80) was issued to inspect and remove Aft Landing Gear Drag Links that were susceptible to stress corrosion cracking. Susceptible drag links were identified with a number 3 painted/marked on the Drag Link. Drag Links with a number 5 were not susceptible and did not require replacement. CH-47-96-ASAM-01 required that the susceptible Drag Links be replaced within 24 months from the date of the ASAM. This coincides to a final replacement date of 6 Nov 97. [Full Text]

 

 

CH-47-98-ASAM-01, 15 October 1997: Title: Uncommanded Control Inputs. Summary: A recent CH-47D incident is under investigation by the U.S. Army Safety Center. A CH-47D, while in cruise flight, entered an uncommanded nose down and left roll that failed to respond to the pilots corrective inputs. The crew reported that the aircraft completed a 360 degree roll. The aircraft landed in an open field with the fuselage and power train intact. Flight control incidents with other aircraft have also been reported and investigated with no conclusive findings. These reports include uncommanded inputs and control lock-up. [Full Text]

 

 

CH-47-97-ASAM-10, 29 September 1997: Title: Inspection of ANVIS/HUD Power Supply. Summary: The AN/AVS-7 Heads Up Display provides Operational Symbology to pilots during Aviator's Night Vision Imaging System (ANVIS) operations by overlaying the Symbology on the image provided by the ANVIS. It was recently discovered that a component part power supply was changed by the vendor without approval, causing the AN/ANVIS-7 to be susceptible to some power line transients. The AN/ANVIS system will reset when certain power spikes are received, causing the display to blank for a ten to fifteen second interval while completing the power-up sequence. Upon completion of the power up sequence, the system will return to its normal start up condition of full dim on the display and display page 1N. [Full Text]

 

 

CH-47-97-ASAM-09, 29 May 1997: Title: Operation of T-62T-2B Auxiliary Power Unit (APU) and report of APU flight hours. Summary: A Category I Quality Deficiency Report on the Sundstrand APU T-62T-2B has been submitted. The APU Compressor Wheel failed during the start up sequence. The wheel failed in three equal sections, sending pieces through the APU Air Inlet Housing. Two pieces were retrieved from the aircraft Aft Pylon. The third section appeared to have exited the aircraft. Investigations determined that fatigue cracks emanating from Bolt Holes on the back face of the APU Compressor Wheel caused the failure. Actions are still in process to address risk reduction alternatives. [Full Text]

 

 

CH-47-97-ASAM-08, 22 April 1997: Title: Inspection and lubrication of the Flight Control Rod End Bearings in the Flight Control Closet Area. Summary: TB 1-1520-240-20-77 was issued to have specific Rod End Bearings inspected and lubricated at the next Phase and every 1st and 3rd Phase thereafter. Since this TB, several bearings in the closet area have been identified as also requiring lubrication. [Full Text]

 

 

CH-47-97-ASAM-07, 14 April 1997: Title: Inspection of power distrubution feeder wiring for fraying/chaffing and arcing/burning; certain Power Distribution Panel (PDP) Circuit Breakers (CBs) for water intrusion induced corrosion or arcing and burning, and installation of Circuit Breaker covers/seals. Summary:    A. The CH-47 helicopter is designed with two redundant three-phase 400 hertz AC electrical power distribution systems. Fault protection is provided through magnetic type CBs and generator control units. The two AC systems are normally isolated and operate independently of each other. If one generator goes off-line, the generator contactor relays and bus tie CBs act to interconnect the systems (Number 1 and Number 2 main AC busses), allowing the remaining generator to supply all AC power requirements. DC power is also supplied off each AC system through voltage rectifiers.    B. Inherent cockpit water intrusion is subjecting the Power Distribution Panel (PDP) main CBs ([i.e. Phase A/B/C Number 1 and Number 2 AC auxiliary (aux) PDP feed CBs (MH-47E installation only) and phase A/B/C Number 1 and Number 2 AC bus tie CBs]) to water entry. Subsequent, moisture/salt water induced corrosion is causing a conductive path buildup between individual CB phase case lower power studs and the metal restraint pin which mechanically secures the 3 case CB gang bar assembly together. If a sufficient conductive path develops, arcing occurs, resulting in a short circuit between phases. [Full Text]

 

 

CH-47-97-ASAM-06, 2 April 1997: Title: Informational update and possible solution for NAVSTAR AN/ASN-149(V1) Global Positioning System Control Display Unit lockup whenever the receiver is tracking Satellite PRN 30. Summary: A software problem exists in the AN/ASN-149(V1) Global Positioning System Receiver that manifests itself as a Control Display Unit (CDU) lockup whenever the receiver is tracking Satellite PRN 30. The receiver continues to navigate, however the operator cannot control the CDU and therefore is unable to change the data displayed. The problem occurs only when Satellite PRN 30 is in view. For most of the world, Satellite PRN 30 is visible twice daily for about four hours each time. See also General Aviation Safety Action Message GEN-97-ASAM-03. [Full Text]

 

 

CH-47-97-ASAM-05, 13 March 1997: Title: Inspection for and replacement of AN320-12 Castellated Nuts made by Greer Stop Nut Inc. (Lag Dampners and Drive Arm) Summary:    A. There have been three reported instances of AN320-12 Castellated Nuts found cracked. One during pre-flight inspection of a CH-47D helicopter where a Lag Damper Attachment Nut at the Rotor Head connection was found cracked. The second during post-flight inspection of a MH-47E helicopter. Both nuts were forwarded to Corpus Christi Army Depot (CCAD) for failure analysis which revealed the nuts were cracked at the manufacturers designation (logo) impression stamp. The defective nuts were both double impression stamped with the letter capital G, which is the registered logo of Greer Stop Nut Inc. (Cage 27687). A third instance involving a MH-47E helicopter was very recently reported and is being investigated.    B. The CCAD failure analyses concluded that there were three contributing causes of failure. The double stamp impression on the cracked nuts and the excessive depth of the impressions provided an area of stress concentration that assisted in the cracking. The torque value for the Nut in the TMs were too high in the drive arm attachment installation and needed to be lowered to not to exceed 3000 inch-pounds. Also, the grain structure contained islands of Pearlite and Ferrite, both of which are characteristic of soft phases of steel. The nuts should have been quenched and tempered steel. [Full Text]

 

 

CH-47-97-ASAM-04, 13 March 1997: Title: Inspection and replacement of a certain P/N 4C3074 Crissair, Inc. Check Valve installed in Power Control Module Assemblies in the port marked "FLT CONT PUMP" only. Summary:    A. Recent field reports revealed that a certain P/N 4C3074 Hydraulic Check Valve, manufactured by Crissair, Inc. (Cage 99240), in Power Control Modules P/N AE-A620-14 (145H1201-5) or P/N AE-A620-15 (145H1201-6) is being found with a Rivet missing from the Valve's Poppet. Failure of the Valve during Auxiliary Power Unit (APU) or External Ground Power Unit (GPU) operation could cause the rotors to turn in the opposite direction of normal rotation during operation of the No. 1 or No. 2 Power Transfer Units (PTU). The missing Rivet can enter the Hydraulic System causing damage to the Flight Control Pump when the power source to the hydraulic system is either the APU or an External GPU.    B. The failure occurs when the drive system is shut down and the flight control systems are being powered by either the APU through the PTU pump or a ground power unit. Therefore, the failure poses no safety of flight condition. After compliance with this ASAM, do not control substitute/cannibalize from the modules identified in para 8c.    C. To eliminate the problem, the valve has been redesigned to replace the three-piece assembly (rivet, washer, and poppet) with a one-piece poppet. There are two locations where the Power Control Module P/N AE-A620-14 (145H1201-5) or P/N AE-A620-15 (145H1201-6) is used on the aircraft. Each Power Control Module has three check valves. However, only the Check Valve that is installed into the port marked "FLT CONT PUMP" can cause the above problem. If any of the other four(4) check valves fail, the rivet becomes trapped or lodged in the hydraulic system without causing any damage or failure of other components. [Full Text]

 

 

CH-47-97-ASAM-03, 4 February 1997: Title: Inspection of Cabin Floor and Ramp 5,000 Pound Tie-Down Fittings. Summary:    A. In 1993, several incidents were reported of the 5,000 Pound Tie-Down Rings unscrewing and pulling loose from the Cabin Floor. These Tie-Down Fitting Rings are routinely used to secure the Flight Engineer/Crew Member Safety Harness. Investigation revealed that the cause of the problem was missing MIL-S-22473 Sealant on the Retaining Bushing Threads, and seizure of the Bushing due to paint overspray, allowing the Tie-Down Ring to unscrew on rotation.    B. Referenced message, CH-47-94-ASAM-05 (TB 1-1520-240-20-71), 25 Apr 94, was issued to inspect fielded CH/MH-47 aircraft, and action was to be taken by Boeing Helicopters (BH) to inspect aircraft on the production line prior to delivery.    C. Recently, during flight operations of an Australian CH-47D aircraft, the Forward Right Hand Tie-Down Fitting on the Ramp backed out of the adapter while the Flight Engineer was using the Tie-Down fitting to secure his Safety Harness. Investigation revealed the absence of sealant on the threads of the adapter and bushing, and no conclusive evidence that the aircraft had been inspected/corrected prior to delivery by BH. [Full Text]

 

 

CH-47-97-ASAM-02, 30 December 1996: Title: Installation of Guard around Cargo Hook Release Switch on Winch/Hoist Operators Grip Assembly. Summary: Several reports have been received of the Flight Engineer inadvertently releasing an External Load by accidentally actuating the Cargo Hook Release Switch (button) on the Winch/Hoist Operators Control Grip Assembly. Inadvertent jettisoning of the External Load has also occurred when the Flight Engineer has laid down the Control Grip Assembly and the surface contact has inadvertently actuated the Cargo Hook Release Switch and jettisoned the External Load. [Full Text]

 

 

CH-47-97-ASAM-01, 10 October 1996: Title: Inspection for, and removal of, certain Serial Numbered 145D3400-23/-25/-32 Forward Synchronizing Drive Shaft Assemblies. Summary:    A. Corpus Christi Army Depot (CCAD) has announced a recall due to a process deviation concerning rework procedures and the assembly of the Retainer Assembly to some 145D3400-23/-25/-32 Forward Synchronizing Drive Shaft Assemblies.    B. For a limited period of time, the Teflon Inserts were erroneously being removed from the Retainer Assembly (Part Number 114D3207-3, NSN 1615-00-066-0285) prior to installation to the Forward Synchronizing Drive Shaft Assembly.    C. A total of 27 Forward Synchronizing Drive Shaft Assemblies are suspect. Of these, 16 were located locally at CCAD and have been reworked to conform to the correct technical criteria. The remaining 11 were requisitioned and issued to CH-47D field units world wide. [Full Text]

 

 

CH-47-96-ASAM-09, 12 September 1996 Title: Inspection and repair of Aft Pylon Clamshell Door Lower Latch to preclude wear and/or in-flight loss of Doors. Summary:    A. Several recent incidents have been reported of aircraft losing the Aft Pylon Clamshell Doors in-flight due to failure from vibration of the Lower Latch Pin or Fitting which holds the doors together. In-flight separation of the Clamshell Doors from the aircraft has caused damage to the Rotor System, Engine Tail Cones, and Airframes.    B. MWO 55-1520-240-50-8 (ECP-D082R1) and MWO 1-1520-240-50-62 (ECP D190R1) were issued to improve the latch system. Although the incident rate of Doors separating in-flight has decreased, there have been several reports of Clamshell Latch Fittings cracked and broken. [Full Text]

 

 

CH-47-96-ASAM-08, 21 August 1996: Title: Inspection for and removal of certain Serial Numbered 145DS102-3 Forward Transmission Main Lubrication Pumps. Summary:    A. Two (2) 145DS102-3 Forward Transmission Main Lubrication Pump Shafts have failed in service. The Pump Shaft fractured causing the output pressure of the pump to decrease. The failures consisted of a fracture of the Pump Shaft between the two (2) Gerotors resulting in only one Gerotor being driven and a reduction of main oil pressure to five (5) to seven (7) PSI. The Shaft failures were determined to be the result of bending fatigue with the origin at a manufacturing defect (crack) in the Snap Ring Groove. Our investigation concluded that the cracks were caused by Shaft straightening after hardening.    B. Three (3) additional Pump Shafts inspected exhibited cracks. All five (5) of the above failures were from the same manufacturing work order (i.e. lot). Five (5) additional manufacturing lots of Pump Shafts have been inspected and no cracks have been found. The suspect lot of 145DS102-3 Forward Transmission Lubrication Pumps consists of Serial Numbers V534 through V598. The probability of a suspect Pump malfunction is increased over that of a non-suspect pump.    C. Based on data obtained during Forward Transmission Auxiliary Oil System testing, it is likely that after a Main Lubrication Pump Malfunction the Transmission Oil Pressure Master Caution Warning Light will illuminate followed by illumination of the Forward Transmission Oil Hot Master Caution Warning Light. Illumination of these warning lights requires compliance with published emergency procedures, i.e. Land As Soon As Practicable. It should be noted that malfunction of a Main Lubrication Pump will not affect Auxiliary Oil Pressure within the Forward Transmission.    D. The suspect Forward Transmission Lubrication Pumps are to be removed from service, reworked, and identified with the letters "RW" after the Serial Number on the Pump Identification Plate. [Full Text]

 

 

CH-47-96-ASAM-07, 9 July 1996: Title: Inspect the Bond Lines on the 114P8079-2 and -3 Strap Assemblies [on Engine FOD screens] for looseness around the edges. Summary: Following a Phase Maintenance Inspection, the MH-47E Prototype experienced a Compressor Stall of the No. 2 Engine. The Silicone Rubber Pad (P/N 114P8073-27) from the Strap Assembly (P/N 114P8079-3) [on the Engine FOD Screen] had been ingested into the Engine with subsequent Engine failure. The Strap Assembly was removed and returned to Boeing Helicopters for analysis. The results of that analysis showed that a Polysulfide Sealant (Pro-Seal 890) had been used on the Strap Assembly instead of the prescribed Adhesive. [Full Text]

 

 

CH-47-96-06, 27 June 1996: Title: Inspection and records check of the Upper Boost Actuators and pull test of Swashplates. Summary:    A. An analysis of a CH-47D aircraft which experienced unexplained Control Binding has identified two potential Flight Control problems. The first problem is an out of adjustment condition on Upper Dual Boost Actuators overhauled at Corpus Christi Army Depot (CCAD), and the second problem involves Swashplate binding due to increased friction.    B. The primary problems with the CCAD overhauled Actuators include Control Valve out of adjustment condition and the condition of the Actuator Control Valve Retainer Ring.       (1) The potential problem with the Control Valve out of adjustment condition is that parked blade loads could react through the housing of the Control Valve rather than through the Flight Control Linkage. This condition could lead to a failure of the internal components of the Valve Housing.       (2) The second potential problem with the Actuators involves the Retaining Ring used in the Actuators Control Valve. If the Retaining Ring is yielded or sprung open during installation, it is possible that the Inner Sleeve of the Control Valve will not reset after Secondary Valve operation. Secondary Valve operation can occur under certain parked blade load conditions.    C. The problem with the Flight Controls Swashplates binding is the result of increased friction on the Uniball which may cause wear, binding, and scoring of the Uniball. [Full Text]

 

 

CH-47-96-ASAM-05, 24 June 1996: Title: Inspection of the Forward Control Installation for the manufacturer of P/N 114R3650-3 Bolt Assemblies. Summary: The Rotary Wing Head Controls Bolt Assembly, P/N 114R3650-3, a Flight Safety Part, is being manufactured by a vendor, Accurate Tool Co., that is not listed as an approved source in the U.S. Army Aviation Troop Command Spares Technical Data Package (TDP). Bolt Assemblies, P/N 114R3650-3, that were manufactured by Accurate have been found in the field. Since they are not listed in TDP, none of their Bolts have gone through a rigid first article testing as those manufacturers listed in the TDP. [Full Text]

 

 

CH-47-96-ASAM-04, 6 June 1996: Title: Inspection of the Forward and Aft Rotary Wing Heads to ensure flow of Lubricating Oil to the Horizontal Hinge Pin Bearings. Summary: During the scheduled maintenance of a Rotor Head Assembly, Tape was discovered covering one of six Oil Lube Ports on the Upper Surface of the Rotor Hub. These Ports are used to provide Lubrication to the Horizontal Hinge Pin Bearings. The Tape is used to protect the Oil Passages during painting and may have been accidentally left in place during overhaul production. A complete or partial restriction of Lubricating Oil to the Horizontal Hinge Pin Bearings causes premature wear and results in damage to the Bearings and related components. [Full Text]

 

 

CH-47-96-ASAM-03, 25 January 1996: Title: Inspection of Pressure Gauges [APU Start Accumulator] for Identification Tape location. Summary: A mechanic on the CH-47D attached an air supply to the Auxiliary Power Unit (APU) Start Accumulator and increased the charge to 1400 PSI from 100 PSI. As the air supply was slowly opened, the Glass Cover blew off the Gauge causing lacerations to the mechanics face and arms. Corpus Christi Army Depot (CCAD) has evaluated 6 Pressure Gauges since the failure, and determined that the cause of the failure was the Metal Identification Tape covering the Pressure Relief Port. This prevents venting of air from an internal failure. [Full Text]

 

 

CH-47-96-ASAM-02, 20 November 1995: Title: Operation of the APU. Summary: A Category I Quality Deficiency Report on the Sunstrand APU T62T2B was submitted by Ft. Campbell. During the starting sequence of the APU, the APU exploded. Pieces of the Compressor Wheel went through the APU Air Inlet Housing. Two Compressor Wheel pieces were retrieved from the aircraft Aft Pylon. A third piece appeared to have exited the aircraft from the right side. An investigation has been initiated to determine the cause of the failure. [Full Text]

 

 

CH-47-96-ASAM-01, 6 November 1995: Title: Replacement of Aft Landing Gear Drag Link Assemblies that are susceptible to stress corrosion cracking. Summary:    A. Several instances have been reported of failed Aft Landing Gear Drag Links. The investigation revealed that the cause to be Stress Corrosion Cracking (SCC). The crack originated inside the bore, where the link mates with the large pin attached to the aircraft frame. The crack continued to propagate until the link failed by overload.    B. In some cases the link failed with the aircraft sitting on the ground. The crack originated inside the assembly and was not externally visible until the link had completely failed.    C. SCC can occur in aluminum alloys with certain combinations of the following factors: section thickness, temper, tensile stresses and environment. The new Drag Links (P/N 114L2323-5) are manufactured from aluminum alloys that are resistant to SCC. The Link Assembly (P/N 114L2329-2) includes the Drag Link (P/N 114L2323-5) and Sleeve Bushings (P/N 114L2357-1).    D. A team from Corpus Christi Army Depot (CCAD) has traveled to all the Chinook units and inspected the two Aft Drag Links. The inspection consisted of a conductivity measurement of the aluminum Link. The measurements will separate Links susceptible and those that are resistant to SCC. The Links that could fail from SCC were painted/marked with 1 1/2 inch high number "3". The Links that are resistant to SCC were identified with number "5". [Full Text]

 

 

CH-47-95-ASAM-08, 12 September 1995: Title: Inspection of the Aft Vertical Shaft. Summary: The 101st Airborne Division reported multiple aircraft that had rubbing damage to the Aft Vertical Shafts on the surface that is adjacent to the Dust Seal on the top of the Slider Shaft. [Full Text]

 

 

CH-47-95-ASAM-07, 6 September 1995: Title: Records check for MWO 1-1520-240-50-69, reinstallation of MWO 1-1520-240-50-69 for Rotor Heads that were modified in Europe, and recurring visual inspection for Slipped Bushings and/or cracked Pitch Housing Lugs for Rotor Heads that have MWO 1-1520-240-50-69 applied. Summary: After the application of MWO 1-1520-240-50-69 in Europe, a Daily Inspection found a Slipped Bushing in the Lower Lug of the Pitch Housing on an aircraft in Italy. The Slipped Bushing may have been caused by either improper interference between the Bushing and Lug or damage to the Bore caused by improper installation techniques of the previous and/or current MWO. [Full Text]

 

 

CH-47-95-ASAM-06, 21 August 1995: Title: Revision to Inspection and Lubrication of the Flight Control Rod End Bearings (Rolling Element) required by Aviation Safety Action Message CH-47-95-ASAM-05. Summary: Aviation Safety Action Message CH-47-95-ASAM-05 required an inspection at every 3rd Phase. As a result of engineering analysis, the requirements of CH-47-95-ASAM-05 need revising. Implement the requirements of this message at the next Phase Inspection as required by CH-47-95-ASAM-05. [Full Text]

 

 

CH-47-95-ASAM-05, 25 May 1995: Title: Inspection and Lubrication of the Flight Control Rod End Bearings (Rolling Element). Summary: A CH-47 Operator had an occurrence during ground check-out of the aircraft. Prior to Engine Start, unusual movements of the Cockpit Control were noted. During Single Boost Controls Motion Checks, the Controls exhibited abnormal cross-couplings between the various axes, and in some positions required abnormally high forces to move. When the Collective Mag Brake was released, the Thrust Control Lever rose to above its normal Detent position. Subsequent inspection revealed that a Flight Control Rod End Bearing Housing had separated. [Full Text]

 

 

CH-47-95-ASAM-04, 22 March 1995: Title: Inspection for Stratopower Pumps. Summary:    A. ATCOM has received numerous reports from the field of leaking and pressure fluctuations being experienced with the Stratopower Hydraulic Pumps. A typical scenario is the following: during normal flight, the Hydraulic System indicates pressure fluctuations from a maximum of 4000 PSI to a minimum of 2000 PSI, followed by illumination of the Hydraulic Flight Control Segment Light. Also, high temperatures in the Hydraulic System have been noted when aircraft is shut down.    B. An intensive investigation has been completed, resulting in design changes to the Stratopower Pump for improved reliability of the Pump. The investigation revealed friction between the Counter Balance Sleeve and Piston, failure of the Counter Balance Sleeve in fatigue that caused external leakage and prevented free movement of the Counter Balance piston, and failure of the Compensator Housing Mounting Screw(s) in fatigue. An engineering change proposal was developed to create a new Counter Balance Piston, Sleeve and Seat, Pump Housing, Control Piston, Compensator Assembly Mounting Screws, Compensator Housing and Pilot Spool, and matched Compensator Housing/Spool Assembly. Extensive bench testing (300 hours) and field testing (12 modified pumps have accumulated over 3000 flight hours and still on-going without failure) have resulted in a full qualification approval for the new design features. [Full Text]

 

 

CH-47-95-ASAM-03, 31 January 1995: Title: Aircraft with Engine Transmissions utilizing Speco manufactured Gears. Summary:    A. Two Safety-of-Flight Messages (CH-47-91-01) (TB 1-1520-240-20-55) and (CH-47-93-03) (TB 1-1520-240-20-66) were issued to identify the unserviceable Engine Transmissions, P/N 145D6300-(Series). These SOF Messages were generated by a 1991 Operation Desert Storm incident and by a 1993 Ft. Meade incident involving a CH-47D Engine Transmission. The failures were caused by gears manufactured by Speco Corporation. Since then the Gears have undergone a program of intensive inspection and changes in manufacturing processes to eliminate the cause of the problem. However, two memorandums, one from the Department of Defense Inspector General, 2 Dec 1994, Notification of Defective Transmission Gears for the Boeing CH-47, Chinook Helicopter and the other from the 515th Military Police Detachment (CID), 3 Jan 95, Subject: Criminal Alert Notice, have been published. These messages are incomplete and do not contain the most current information and measures that have been put in place to solve the problem. Therefore, the CID information/message does not reflect updated information. ATCOM is continuing the technical investigation of the allegations. At this time in the investigation, there has been no indication of a safety problem with these gears.    B. Two accidents were caused by the failed Speco Gears. One accident occurred in Saudi Arabia in 1991 and the other at Ft. Meade in 1993. Both accidents were thoroughly investigated and appropriate corrective actions were taken.    C. All Speco Gears went through an additional non-destructive inspection (NDI) following the Saudi accident. As a result the manufacturing processes and plans were changed to eliminate the cause of the cracks - post carburizing grinding of the damping ring grooves.    D. The Ft. Meade failure initiated in an area of a non-authorized rework for the removal of burrs. The manufacturing plan for the Gear, Boeing P/N 145D6302-2, did not have an approved procedure for deburring operation in the area of the gear that failed. This was the only part number and the only area on the Gear where the deburring operation was not controlled. Changes in the manufacturing plan were addressed and all P/N 145D6302-2 Gears were inspected again. The Gears are used in the CH-47D, MH-47D and MH-47E Transmissions, P/N 145D6300 Series.    E. The inspections resulted in some Gears being rejected. The DMWRs were revised to include more stringent inspections. There has been no reoccurrence of these failures in the thousands of flying hours subsequent to the inspections. [Full Text]

 

 

 

CH-47-95-ASAM-02, 18 January 1995: Title: Torque verification of the Nuts securing the No.1 and No.2 PTU Motor/Pump. Summary: An inspection at Boeing Helicopters revealed that the Nuts securing the Motor to the Pump on the Power Transfer Unit, P/N 145HS140-8, were not properly torqued. Loose Motor/Pumps could possibly cause cracks in the unit and eventual component failure. [Full Text]

 

 

CH-47-95-ASAM-01, 13 December 1994: Title: Recurring Daily Inspection of Thrust Idler Assembly. Summary: Recent field reports indicate that the Thrust Idler Assemblies P/N 145C1408-1 are being discovered with bent inboard arms. At least one case of in-flight failure has occurred which resulted in a loss of engine/rotor droop anticipation. The Thrust Idler Assemblies are not loaded laterally during their normal mode of operation, and consequently, are not designed to withstand abnormal lateral loading. However, drawings will be changed to reinforce the Thrust Idler Assembly. [Full Text]

 

 

CH-47-94-ASAM-06, 26 April 1994: Title: Recurring inspection of Pumping Unit, Hydraulic [Stratopower Hydraulic Pumps]. Summary:    A. ATCOM has received reports from the field of leaking and pressure fluctuations being experienced with the Strato-power Hydraulic Pumps. A typical scenario is as follows: during normal flight, the Hydraulic System pressure indicates pressure fluctuations from a maximum of 4000 PSI to a minimum of 2000 PSI, followed by illumination of the Hydraulic Flight Control Segment Light. Also, high temperatures in the Hydraulic System have been noted when aircraft is shut down. An intensive investigation is being conducted.    B. The suspect pumps are manufactured by Strato-power and the serial numbers have a suffix "BO", NSN 1650-01-249-4341, P/N 64WE075102 and or 938555. Further information and instructions will be disseminated as soon as it is available. Report all failures thru QDR system.    C. The CH-47 has 3 Hydraulic Pumps on board and any one is capable of powering the Flight Controls. Power Transfer Unit (PTU) can be utilized in emergency conditions when powered by Utility Hydraulic Pump or APU Motor Pump. In the event such a failure occurs, utilize current procedures of TM 55-1520-240-10 Para 9-49. [Full Text]

 

 

CH-47-94-ASAM-05, 25 April 1994: Title: Inspection of the 5000 Pound Tie-Down Receptacle Assemblies and provide instructions to correct defective Tie-Down Receptacle Assemblies. Summary: Two incidents have been reported of Crew Members Safety Harness becoming unsecured from the 5000 Pound Tie-Down Receptacle P/N 114S2893 when the Tiedown Adapter became unscrewed from the Tie-Down Fitting. Upon landing, the Tie-Down Fitting and Adapter were visually inspected, and it was found that the Tie Down Adapter had unscrewed from the Receptacle Retaining Bushing. There was no evidence of Sealant on the Adapter Stud Threads which is required to keep the Fitting from unscrewing. Additional investigation revealed that the exact cause of the problem was missing MIL-S- 22473 Sealant coating on the Retaining Bushing Threads, and seizure of the Bushing due to paint overspray, allowing the Tie-Down Ring to unscrew on rotation. [Full Text]

 

 

CH-47-94-ASAM-04, 8 February 1994: Title: Inspect Crew Seat Belt. Summary: The Pilot and Copilots Seat/Lap Belt has been discovered to be improperly secured to the Release Handle of the Seat Belt Assembly. If this Pin falls out, the Seat Belt Mechanism comes apart and becomes ineffective. [Full Text]

 

 

CH-47-94-ASAM-03, 24 January 1994: Title: Inspection of certain Rigid Connecting Links [Flight Control Closet Links]. Summary:    A. During Ground Run-Up, a Connecting Link, P/N 145C3340-10 was broken. Teardown analysis revealed that the tensile strength of the Connecting Link was below drawing requirements. Analysis also revealed a 3 inch lengthwise scrape mark on the failed Link which contributed to its failure. This scrape mark was attributed to a foreign object becoming lodged between the Link and an adjacent bulkhead.    B. The low strength was a result of faulty heat treat on approximately 148 Connecting Links, P/N 145C3340-10 with a manufacturing date of "1-2-91" and the word "Globe" ink stamped on the Link. Therefore, Connecting Links in this lot require a recurring Controls Check prior to each Engine Start until they are replaced. Replacement Connecting Links will be provided to the units as free issue. Representative samples of other lots will be required for testing. Serviceable Connecting Links, P/N 145C3340-10 will be furnished (subject to availability) by logistical POC. The inspection varies depending on aircraft serial number. See Para 8 for inspection procedures. All units shall report to logistical POC within 10 days from the date of this message per Para 14b. Future procurements of Connecting Links will be serialized and/or contain metalcals.    C. Pilots Information - These Links are subject to low forces during normal flight. The conditions of concern are:    (1) Blade flapping while parked (Hydraulics Off).    (2) Pilot induced force to overcome a jam.    (3) Improper shutdown procedure (Thrust not in Detent).    Caution: Critical Flight Control Components can be damaged if Thrust is not in Ground Detent. [Full Text]

 

 

CH-47-94-ASAM-02, 29 October 1993: Title: Amendment to One-Time and Recurring Inspections (ATCOM MSG DTG 171815Z OCT 93) of Rotary Wing Head Bushings. Summary: This Amendment to the basic ASAM is offered to avoid unnecessary downtime. The compliance time in the basic ASAM has been extended up to 50 additional flight hours after finding a Bushing which has slipped from its proper position IAW CH-47-94-ASAM-01. [Full Text]

 

 

CH-47-94-ASAM-01, 19 October 1993: Title: Recurring Inspections of Rotary Wing Head Bushings. Summary:    A.       (1) Field inspections have revealed in some instances that Rotary Wing Head Bushings (P/N 145R3116-10) have become loose. These Bushings are installed in the Upper Lag Damper Lug of the Pitch Housing. Loose Bushings can cause excessive wear in the Lugs which could result in having to scrap high cost Pitch Housings.       (2) The loose Bushings are the result of defective installations. Installations were performed by retrofit per MWO 1-1520-240-50-37 or converted in production or at overhaul.       (3) The new configuration, MWO 1-1520-240-50-37, was instituted because field reports indicated that the Bushing P/N 114R2096-2 was sometimes left out of the Lower Lug of the Pitch Housing. If the Bushing P/N 114R2096-2 is not present during torque-up of the Lag Damper, it could result in bending the Pitch Housing Lugs which would cause scrapping the part, and perhaps cracking or breaking the Lugs. [Full Text]

 

 

CH-47-93-ASAM-05, 16 August 1993: Title: Maintenance information on Fuel Cells. Summary: During field Fuel Cell Inspections, Blisters have been found in the interior of the Fuel Cell on the manufacturer's reworked areas. These Blisters may be repaired by units or supporting field activities. [Full Text]

 

 

CH-47-93-ASAM-04, 20 April 1993: Title: Maintenance information for T55-L-712 Engines [Hung Starts and other issues]. Summary: There have been numerous incidents of Hung Starts (failure of the Engine to accelerate to Ground Idle with high PTIT) and N1 Rollback (uncommanded deceleration of Gas Producer Turbine) which have been investigated and analyzed. [Full Text]

 

 

CH-47-93-ASAM-03, 12 March 1993: Title: Inspection of Pumping Unit, Hydraulic [Strato-Power]. Summary:    A. The CH-47D Fleet is currently experiencing Hydraulic System failures. A typical scenario is as follows: during normal flight, the Hydraulic System Pressure indicates pressure fluctuations from a maximum of 4000 PSI to a minimum of 2000 PSI, followed by illumination of the Hydraulic Flight Control Segment Light. Also, high temperatures in the Hydraulic System have been noted when aircraft is shut down. An intensive investigation is being conducted. The investigation is centered on the Flight Control/Utility Hydraulic Pump at this time, although it is not certain that the Pump is the root cause.    B. The suspect Pumps are manufactured by Strato-Power and the serial numbers have a suffix "BO", NSN 1650-01-240-4341, P/N 64WE075102 and or 938555. It should be noted that no abnormal problems have been reported with the Vickers pump, NSN 1650-01-115-3948, P/N PV3-075-20. Further information and instructions will be disseminated as soon as it is available. Report all failures thru QDR system to support investigations.    C. The CH-47 has 3 Hydraulic Pumps on board and any one is capable of powering the Flight Controls. Power Transfer Unit (PTU) can be utilized in emergency conditions when powered by Utility Hydraulic Pump or APU Motor Pump. In the event such a failure occurs, utilize current procedures of TM 55-1520-240-10 Para 9-49. [Full Text]

 

 

CH-47-93-ASAM-02, 2 March 1993: Title: Inspection of Hi-Lok Fasteners at Fuselage Station 83 to 120. Summary: CH-47-92-ASAM-05 required replacement of Hi-Lok Fasteners due to oversize holes and improper deburring during production. This replacement was not completed because of a shortage in replacement Hi-Lok Fasteners. Several waivers were granted providing interim instructions. This message provides criteria for correcting loose fasteners and requires a recurring inspection at each Phase Inspection. [Full Text]

 

 

* CH-47-93-ASAM-01, 3 December 1992: Title: Aft and Combiner Transmission Oil Cooler Fan Bearings. Summary: TM 55-1520-240-23-5 erroneously reads: Apply Syn-Tech Grease (E190.1) to the Aft and Combiner Transmission Cooler Fan Bearings. It should read: Apply WTR, MIL-G-81322 (E190) to the Aft and Combiner Transmission Cooler Fan Bearings. [Full Text]

 

 

CH-47-92-ASAM-06, 10 September 1992: Title: Extended Range Fuel System (ERFS) Tank Assembly. Summary: Four ERFS Tanks were recently returned to Corpus Christi Army Depot as unserviceable due to seepage in the vicinity of a weld in the tank skin. This seepage was only found on tanks with the lower skin doubler extending only to the inboard side of the skids. Tanks with the doubler extending outboard of the skids have the preferred configuration and have not seeped fuel. Units are reminded of the fuel leak inspection required before operation. [Full Text]

 

 

CH-47-92-ASAM-05, 16 June 1992: Title: Replacement of Hi-Lok Fasteners in L/H and R/H Butt Line 18 Beams at Fuselage Station 83 to 120. Summary: During manufacture of the CH-47D helicopter the subject Hi-Lok Fasteners were inadvertently installed in oversized holes. This may reduce the fatigue life of this part of the fuselage structure. Replacement of the Hi-Lok Fasteners by OLR Team/STIR Program assures that the proper size fastener for any particular hole is installed. [Full Text]

 

 

CH-47-92-ASAM-04, 22 April 1992: Title: Recurring Inspection of Cross Shaft Adapters. Summary: During a Daily Inspection, the Number Two (RH) Side Engine-Combiner Cross Shaft Steel Adapter Lug on the combiner end was found cracked. Investigation revealed that the crack was initiated from fretting in the bore of a bolt hole. The fretting is attributed to a loose bolt between the Thomas Couplings and the adapter. [Full Text]

 

 

CH-47-92-ASAM-03, 20 November 1991: Title: Rescission of Airworthiness Releases on Tank Assembly [600 Gallon Fuel Pods]. Summary: Many Airworthiness Releases have been issued to use the P/N 85SDSCC-D-0007-4 Six Hundred Gallon Metal Tanks for Forward Refueling and Extended Range Missions. An improved version of this tank and related hardware has been developed which standardizes the configuration. This improved Extended Range Fuel System (ERFS), P/N 85SDSCC-D-0007-2, its operation, and installation are defined in TM 55-1560-307-13 & P. This ERFS has a full Materiel Release and does not require an Airworthiness Release. [Full Text]

 

 

CH-47-92-ASAM-02, 20 November 1991: Title: Inspection of Generator Wire Harness at the Fire Extinguisher Discharge Tube. Summary: During flight, the Number One (1) Generator on a CH-47D aircraft failed and would not reset. The problem was found to be chafed wiring at the Discharge Tube for the Number One (1) Engine Fire Extinguisher from the Aft Bottle. [Full Text]

 

 

CH-47-92-ASAM-01, 16 October 1991: Title: Inspection of interference between the Engine Cross Shaft and the Right Hand Fairing Access Cover. Summary: There have been several reported occurrences of interferences between the One Piece Engine Cross Shaft and the Alignment Pin or Rivets installed in the Right Hand Drive Shaft Fairing Access Doors. This interference causes wear on the edges of the Cross Shaft Lugs. [Full Text]

 

 

Note: Several Aviation Safety Action Messages were issued prior to 1992, but we do not have a copy of them.

 

 

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