Marine Corps Medium Lift: How Do We Keep The H-46 Flying Into The Twenty-First Century? CSC 1995 SUBJECT AREA - Aviation EXECUTIVE SUMMARY Title: Marine Corps Medium Lift: How Do We Keep The H-46 Flying Into The Twenty-First Century? Author: Major Anthony M. Haslam, United Stated Marine Corps Thesis: To date the V-22 is the aircraft that will replace the H-46. In order for the H-46 to continue to bridge the critical gap in Marine Corps Medium lift, a dedicated effort is required to keep this thirty year old aircraft flying into the Twenty-First Century. Background: The H-46 Sea Knight is a product of Boeing Helicopter Division and was built for the Marine Corps in 1962 to replace the H-34. The H-46 has been the workhorse for the Marine Corps, providing assault support to the fleet for over thirty years. As one of the six functions of Marine Aviation, the assault support mission is defined as the transport of personnel, supplies, and equipment into or within the battle area. The Marine Corps has been trying to field a new medium lift replacement for the H-46. The V-22 Osprey is the aircraft that will replace the H-46, but the Initial Operational Capability (IOC) is not until 2001 with 425 expected aircraft deliveries through 2026. Recommendation: The aging H-46 will require special programs to ensure the integrity of its airframe, avionics, engines, and dynamic components. Some of these programs are currently funded with program deliveries commencing in December 1995. A dedicated effort must be focused on all funded H-46 programs to ensure on time deliveries. A Service Life Extension Program (SLEP) must be funded to capture all cost associated with the extension of a thirty year old aircraft into the Twenty-First Century. Marine Corps Medium Lift How Do We Keep The Marine Corps H-46 Flying Into The Twenty-First Century? The H-46 Sea Knight has been the workhorse for the Marine Corps for over thirty years. It has been an invaluable asset in the success of the Marine Corps mission, providing assault support to the Marine Air Ground Task Force(MAGTF). Under Title 10, U.S. Code and DOD Directive 5100.1, the Marine Corps has a long standing operational requirement to provide the capability to conduct assault support operations in support of our national military strategy. As one of the six functions of Marine Aviation, the assault support mission is defined as the air transport of personnel, supplies, and equipment into or within the battle area. To meet future assault support requirements, the Marine Corps has been trying to field a new medium lift replacement for the H-46. To date the V-22 Osprey is the aircraft that will replace the H-46, but the Initial Operational Capability (IOC) is not until 2001. The Initial Operational Capability will stand up HMT-204 with twelve (12) V-22 aircraft in 2001 for conversion training. The total of 425 V-22's will be delivered to the fleet over the next twenty- five years.1 In other words, the get-well for the Marine Corps is still twenty-five years away. I will address how to keep the H-46 flying into the Twenty-First Century to bridge a critical gap in the Marine Corps medium lift requirement until the V-22 can be successfully fielded in operational fleet squadrons. The H-46 is a product of Boeing Helicopter Division and was built for the Marine Corps in 1962 to replace an aging H-34. Six hundred and twenty-four H-46 helicopters were produced and the production line was shut down in 1971. The H-46 was tried and tested in the jungles of Vietnam and became a respected asset throughout the war. Since 1962 the H-46 has provided combat assault transport of Marines in the initial assault waves and follow-on stages of amphibious operations and subsequent operations ashore. Besides its primary mission of combat troop transport, it has provided a reliable platform to accomplish all missions associated with assault support to include: aerial delivery of cargo, search and air rescue, and medevac. Since 1962, 2.99 million flight hours have been flown by the H-46 fleetwide.2 The current utilization rate for the H-46 is 25.6 hours per month.3 In 1982 the H-46 reached the twenty year mark and its technology and capability began to be a limiting factor. The need for an aircraft that could conduct over the horizon missions, fly at an excess of 250 kts, carry twenty-four combat loaded Marines, remain airborne for over three hours, and have a range of over 2,000 miles were the requirements. In 1982 an operational requirement document (ORD) for a new medium lift replacement aircraft was formalized.4 The V-22 will be the new medium lift aircraft that will replace the H-46. This program has been in a state of uncertainty for the last ten years. The status is that the V-22 will be procured for the Marine Corps and delivery will commence to the fleet with an IOC of 2001.5 Over the last ten years the H-46 has suffered the neglect of a weapon system that should have reach its retirement age and sent to the desert five years ago. At that time all plans for logistic support of the H-46 stopped because it was an aircraft that was going away. It is 1995 and the V-22 is still six years away. The H-46 must continue to provide the essential assault support to the fleet. In order to extend the H-46 into the Twenty-First Century there are several areas that must be addressed. The first area concerns airframe service life. The H-46 service life was established at 10,000 hours that was recently extended to 12,500 hours. The average age of the Marine Corps H-46 fleet is 8,500 hours. The majority of the Navy's H-46 fleet has over 10,000 hours and approaching the extended service life of 12,500 hours.6 An official Service Life Assessment Program (SLAP) is underway at the Naval Aviation Depot, Cherry Point to determine what depot level rework must be performed to an H-46 airframe in order to extend its service life to 20,000 hours. With a new service life of 20,000 hours, this would enable the H-46 airframe to continue to operate for an additional twenty-five years.7 Once this study (SLAP) is completed then a Service Life Extension Program (SLEP) will have to be developed to accomplish what is needed to extend the H-46 service life to 20,000 hours. Funding for SLEP has not been identified but is a critical program for the survival of the H-46 in the future. The H-46, with an extended service life, will need to get established on a fixed Standard Depot Level Maintenance (SDLM) cycle. Current Navy and Marine Corps policy for SDLM induction states that the aircraft must be inspected by a depot level team. If the aircraft fails this inspection it is authorized to be sent to the depot for SDLM. This inspection process is called Aircraft Service Period Adjustment (ASPA) and is used to extend the service period of an aircraft if the material condition warrants extension. The service period for the H-46 is thirty months. This figure indicates the time that should elapse between SDLM inductions. The ASPA program extends the thirty month service period by twelve months every time the aircraft passes an ASPA inspection. The H-46 is averaging thirty-six months of extension time on the ASPA program. This results in an aircraft that does not get to the depot for SDLM until five and a half years. A five and a half year interval for SDLM is excessive for a thirty year old airframe that is subject to the constant exposure of a salt water environment on all deployments aboard amphibious ships. The ASPA program saves money, it enables an aircraft to be extended beyond its service period postponing SDLM induction cost. The current SDLM induction cost for the H-46 is $475,000 dollars.8 There comes a time when the age of an aircraft and its operating environment must be taken into account, especially when the aircraft is bridging a critical gap in Marine Corps medium lift. I recommend the H-46 be removed from the ASPA program and placed on a fixed thirty six month SDLM Phase Depot Maintenance (PDM) cycle. This move would enable the H-46 to receive depot level maintenance every three years and would help preserve a very tired airframe. NADEP Cherry Point has the capacity to handle the increased H-46 workload.9 This change would increase the H-46 SDLM inductions from fifty aircraft to approximately a hundred aircraft per year. This would generate a twenty-four million dollar increase in the funding required for the H-46 SDLM budget, a cost well worth the price for operating the H-46 safely into the Twenty-First Century. The next critical area that must be addressed is the dynamic components, which encompasses the components, subcomponents, and rotating flight controls of the drive system on rotary wing aircraft. The H-46 has been plagued with numerous dynamic components failures over the last five years, some of these resulting in aircraft mishaps and loss of life. Due to the problems associated with the dynamic components, the H-46 has been placed under weight and maneuver restrictions.10 These restrictions have drastically effected the operational capability of the Navy and the Marine Corps.11 Besides the restrictions, the requirement to perform Non Destructive Inspections (NDI) of rotor head components at intervals of three to ten hours has increased scheduled maintenance and decreased aircraft readiness. The Dynamic Component Upgrade Program (DCUP) is a $400 million dollar funded program which will start delivery in December 1995.12 The program is designed to replace current rotor heads with new corrosion resistant stainless steel rotor head components, replace synchronizing and vertical shafts, and install rate gyros in the AFCS computers. The DCUP program will eliminate all weight and maneuver restrictions and eliminate all dynamic component NDI inspections. The program commences in December 1995 and will complete all fleet aircraft by 2000.13 This program should ensure the safety of the H-46 dynamic components into the future. The next issue that must be addressed is the weight carrying capability of the H-46. The current maximum gross weight of a Marine H-46 is 24,300 pounds.14 The aircraft's basic weight, plus the weight of the fuel, passengers, and cargo cannot exceed the maximum gross weight of 24,300 pounds. Over the last fifteen years the aircraft's basic weight has increased over 2,000 pounds with new aircraft modifications. Along with this there has been an enhancement to the fuel capacity on the H-46, increasing the fuel tank capacity from 356 gallons to 660 gallons. This adds an additional 2,400 pounds of fuel that can be carried by the H-46. This increase in fuel capacity is a step in the right direction. This gives the H-46 longer range and more time on station which is critically needed. However, with an increased aircraft basic weight of 17,500 pounds plus 4,800 pounds of fuel this leaves only 2,000 pounds remaining to carry troops or cargo. This equates to only eight combat loaded Marines which is totally unsatisfactory when the requirement is for fifteen. The current procedures for the Bullfrog aircraft (H-46's with new extended range fuel tanks with 4,800 pounds of capacity) are to take on 3,000 pounds of fuel. This gives the aircraft an endurance of about two hours before it has to be refueled and enables the additional 1,800 pounds for carrying troops or cargo. This figure enables the H-46 to carry fifteen combat loaded Marines, fly for two hours before having to refuel, and stay below the maximum gross weight of the aircraft of 24,300 pounds. The goal should be to increase the carrying capability of the H-46. This can be accomplished in one of two ways. First, the basic weight of the aircraft can be reduced, giving a bigger delta between the aircraft's basic weight and the maximum gross weight. Due to new aircraft modifications, the aircraft's basic weight has been increasing vice decreasing over the years. Some options in this area are to replace the aircraft's steel armor plate with lightweight composite armor, remove armored seats and replace them with lightweight crash worthy armored pilot seats, and replace all analog avionics with new lightweight digitized avionics (i.e, the high frequency radio). These steps would reduce the aircraft's basic weight by 600 pounds.15 The second option to increase the carrying capability of the H-46 is to increase the maximum gross weight of the aircraft. After DCUP replaces the H-46's dynamic components with new stainless steel components the maximum gross weight could be increased 26,000 lbs. This increase would give an additional 1,700 lbs of payload capacity that would solve the H-46 payload problem. The aircraft has sufficient engine power to carry the additional weight but the drive train (transmissions and drive shafts) is torque limited not to exceed 24,300 lbs. In order to accomplish this the drive system would have to be tested to determine if these components could be rated at 26,000 lbs.16 If the drive train cannot be rated at the new weight, then a drive system upgrade would be required for this option to occur. The cost for a drive system upgrade has not been determined, but it could eliminate this option due to cost. The last option is to replace the existing rotor blades with new Boeing advance technology composite rotor blades that would generate an additional 1,200 lbs of lift for the same amount of torque at 24,300 lbs.17 This option cost $70,000 dollars per rotor blade (six blades per a/c) for a total cost $420,000 dollars per aircraft.18 This is a viable option, because new H-46 rotor blades will be needed for the fleet in the near future. Current pricing for a replacement rotor blade is $40,000 dollars per blade. However, this replacement blade does not generate the additional 1,200 lbs of lift needed. The avionics system currently on the H-46 is 1960 analog technology. The need for high tech digital technology is critical on the modern day battlefield. The areas of concern are in navigation and communication. GPS is the way of the future and without any other navigational aid except for tactical navigation (TACAN) the H-46's crews have to rely on detailed terrain navigation and time distance calculations. GPS technology, with accuracy down to 16 meters, will enable aircrews to concentrate on other aspects of the flight profile besides knowing exactly where they are and if they are dropping the troops off in the right zone. The Department of Defense is going to a standard GPS unit that will be procured for all aircraft. This system is scheduled for incorporation into the H-46 starting in December 1995.19 The ARC-210 radio will give the H-46 communication capabilities that are far superior to the current systems. It is a full digital radio that covers AM through UHF frequencies ranges. The ARC-210 will provide superb anti-jamming capability through its Have-Quick frequency hopping feature. The ARC-210 will also provide excellent secure voice capability through the KY-58's already installed in the aircraft. The current plan is to install two ARC-210 radios per aircraft with installations commencing in December 1995.20 The Communication Navigation Control System (CNCS) provides state of the art digital technology into the cockpit of the H-46. It minimizes cockpit workload by integrating all radios into a single control head. CNCS provides two flat panels that indicate an aircraft's heading along with navigational information from the GPS system. A prototype system has been installed and flown at NADEP, Cherry Point. The system is on contract with kit delivery and installation schedule to commence in December 1995.21 This system will cost $200,000 dollars per aircraft and require 1,400 depot level man-hours for installation.22 When the Marine Corps fights, it will fight at night. It is essential that all aircraft are modified to be compatible for night vision goggle operations. This process is already underway with a new blue light cockpit modification. This modification should be completed in all Marine H-46 aircraft by August 1995. The last step of this process is the fielding of the Night Vision Goggle Heads Up Display (NVG-HUD). This change will enable each pilot to view flight instrument and navigational information through his night vision goggles. The HUD will display attitude, altitude, heading and navigational information to each pilot. This configuration will eliminate the need for the pilot to look inside at his instruments and break his outside visual scan. The NVG-HUD will reduce cockpit workload and fatigue thus enhancing aircrew safety. Installation of the NVG-HUD is scheduled for March 1996 at a cost of twenty five thousand dollars per aircraft.23 The Marine H-46 is equipped with two General Electric T58-16 engines, each rated at 1870 shaft horsepower.24 These engines have been installed in Marine H-46 helicopters since 1977. Over the years there has been some degradation of power due to worn and loose tolerance of subcomponents within the engine. Most major components on an aircraft are placed on an overhaul cycle in which those components go through an overhaul process determined by specific Time Between Overhaul (TBO). Once that component reaches its TBO it is removed from the aircraft and sent to the depot for overhaul. At the depot the component is disassembled and reworked with new sub components and all tolerances are brought back to specification. When it leaves the depot it is like a new component. The T58-16 engine is not on an overall cycle, but an inspection cycle. These engines are removed from the aircraft every 1,200 hours and sent to a first degree repair facility which could be a depot, a Aircraft Intermediate Maintenance Activity (AIMD), or a Marine Aviation Logistic Squadron (MALS) that has first degree repair capability. This inspection is called a Hot Section Inspection. The compressor section is removed and disassembled, turbine blades inspected, bad blades removed and replaced, and the compressor section reinstalled. Next the engine is run on a test cell, if it meets required horsepower it is signed off and Ready For Issue (RFI). The horsepower required for an engine to be RFI has a wide range. If an engine does not meet the power requirements, further maintenance is performed on the engine until it can meet the published specifications. On occasion engines are RFI on the test cell and rejected by squadron functional check pilots for not meeting power required specifications during the test flight. This situation of low power engines in the fleet would not occur if the T58-16 engine was on an engine overall cycle. If the GE-T58-16 engine was on an overall cycle it would be sent to the depot at a specified interval for total overall. When the engine is run on the test cell it would have to meet the power required specifications of a new engine, which is much higher than what is currently tested to. If the H-46 is going to remain in service for another twenty-five years the engine program's funding must be increased in order to establish this engine on an overall cycle. The H-46 program office is currently researching this issue and trying to determine both the funding required and the capacity needed at NADEP Cherry Point to establish an overall process for the T58-16 engine.25 The installation of the above aircraft modifications can be conducted by two different methods. The first method is to have the aircraft modification conducted at the depot. The most cost effective means is to modify the aircraft when it is already at the depot for SDLM. During the SDLM process the aircraft is already disassembled, so it requires less man-hours to install most modifications. The other way is to send the aircraft to the depot specifically for the modification. This is called a Drive Inn Modification Program. The benefit of the Drive Inn Modification Program is selected aircraft can be modified and returned to a specific squadron for a standard aircraft configuration within that squadron. This program establishes a separate modification line at the depot that runs concurrently with the SDLM line. This program has been very successful in the past. It is an optimum way to get aircraft modified that has not been through SDLM or not scheduled to go to the Depot for SDLM for the next couple of years. The second method to modify aircraft is sending depot field modification teams out in the fleet to modify aircraft. This method is cheaper than the Drive Inn Modification Program but more expensive than the SDLM Modification Program.26 Field teams are sent from the depot to fleet activity where they set up shop in a hanger and conduct aircraft modifications until all aircraft are modified. This is another great program that is used extensively in the fleet. This program gives the fleet extra flexibility, it keeps the aircraft at home, and the squadrons usually get their aircraft back quicker. Despite these advantages, this program is limited to certain modifications. Some modifications require special tooling, specific depot facilities, and a significant amount of man-hours. These modifications are restricted from field team incorporation (i.e. CNCS). Besides NADEP, Cherry Point, there are other facilities that can perform the drive inn modification program or send out field modification teams. One is the Bluegrass Army Depot in Lexington, KY. This facility has performed depot level repair and modification incorporation on the H-53's and the UH-IN's and is available to the H-46 program office to provide services. So far the depot at Cherry Point has produced the best product at the lowest cost. Funding is the main driver in the solution. In a time of austere budget constraints all programs are under the microscope. The H-46 program has received a great deal of support within the Beltway and funding has been very positive over the last few years. Some of the major programs like the Dynamic Component Upgrade Program (DCUP) and the Communication Navigation Control System are fully funded and will commence delivery in December 1995. Funding must be identified for the Service Life Extension Program (SLEP) in order to extend the life of the H-46. The SLEP funding requirement should capture all cost associated with the extension of the service life of the aircraft. This should include the cost of purchasing Boeing's advance technology rotor blade, placing the GE-T58-16 engine on an engine overhaul cycle, and establishing the H-46 on a fixed thirty-six month SDLM Phase Depot Maintenance cycle. Another area of funding that must be addressed is supply support. The logistic effort that is needed to keep a thirty year old aircraft flying is tremendous. Funding is required not only to keep sufficient stock of current supply items but funding must be provided to purchase sufficient spares for all of the current and future air frame modifications. The last issue we need to discuss is the H-46 inventory. The question is with the H-46 being extended into the Twenty-First Century do we have enough H-46's in the current inventory to meet our requirements? The current H-46 inventory is 241 aircraft in the Marine Corps.27 The requirement is composed of the Primary Authorized Aircraft (PAA) plus pipeline aircraft. PAA for the H-46 is 231 aircraft, this gives each Marine tactical squadron twelve aircraft and the training squadron twenty aircraft.28 Pipeline aircraft are spare aircraft within the fleet. They are used to replace crash/damage aircraft or provide aircraft to squadrons when their PAA drops below twelve aircraft due to SDLM/modification programs. The number of pipeline aircraft is equal to nine percent of the H-46 PAA (231 times nine percent equals twenty one aircraft).29 With an inventory of 241 H-46's, the Marine Corps is eleven aircraft short of total requirement. This shortage in inventory has not been a major factor in being able to provide the required PAA to our deploying squadrons. Looking into the future, inventory could be a factor if the V-22 has any significant delays. The H-46 has an attrition rate of two point five (2.5) aircraft per year.30 With this attrition rate if the V-22 production is halted or delayed the H-46 inventory could fall below required PAA in Marine tactical squadrons. The H-46 production line at Boeing Helicopter Division has been closed for some time now, so there is no way to procure extra aircraft. To procure a different type of aircraft such as the H-60 or other medium lift alternative would not be cost effective since the V-22 will be the Marine Corps medium lift aircraft in the future. One option that is viable, if this situation develops, is to replace the Marine Reserve H-46's with CH-53D's. There are two Marine Reserve H-46 squadrons with a total of twenty-five H-46's assigned. If the inventory of the fleet tactical squadrons dropped below PAA, H-46's could be transferred from the Reserve squadrons and replaced with CH-53D's. Currently there is an excess of CH-53D's, twenty of which are in preservation in the desert at the Aircraft Management and Rejuvenation Center (AMARC), Davis Monthan AFB.31 I do not feel that the H-46 inventory will be a big issue in the future. Once V-22 deliveries commence in 1999 with an IOC of twelve V-22's to HMT-204 in 2001, H-46's will become available to fill any shortfall in aircraft inventory. In conclusion, it is a proven fact that the H-46 has been an invaluable asset to the Marine Corps for over thirty years providing assault support operations in the support of our national military strategy. The V-22 will replace the H-46 in the future, but until then the H-46 is the aircraft that can bridge this critical gap in Marine Corps medium lift until the V-22 is fielded in Marine operational squadrons. In order for the H-46 to be safe and productive in the Twenty-First Century, special programs must be formulated to ensure the integrity of its air frame, avionics, engines, and dynamic components. Programs and funding have already been established in some of these areas with fleet deliveries commencing in December 1995. A combined effort by all involved in the H-46 program will be required in order to champion the cause and battle through the budget constraints of the future. The H-46 can continue to provide assault support to the fleet only if a dedicated effort is focused on current funded H-46 programs and a Service Life Extension Program (SLEP). The SLEP must be fully funded to capture all cost associated with the extension of a thirty year old aircraft into the Twenty- First Century. ENDNOTES 1. Chief of Naval Operations (N880G), "U. S. Navy Aircraft Inventory Budget Exhibit A2," January 1995. 2. Michael Borowasky, Statistics Analyst at Naval Safety Center, interviewed by author, 10 February 1995. 3. Commander Naval Air Force Atlantic, "3M Aviation /SER / Utilization / Maintenance History Report," 25 November 1994. 4. Chief of Naval Operations, "Joint Services Advanced Vertical Lift Aircraft (JVX) Operational Requirement Document (ORD)," 14 December 1982. 5. Chief of Naval Operations (N880G), "U. S. Navy Aircraft Inventory Budget Exhibit A2," January 1995. 6. Naval Air Systems Command, PMA-226, "H-46 Program Review," Time Since New, January 1995. 7. Maj. Bob Hellar, H-46 Class Desk at Naval Air Systems Command, Det. PMA 226, interviewed by author, 12 January 1995. 8. Naval Aviation Depot Operations Center, "NADEP Cherry Pt., Aircraft SDLM Cost Report," January 1995. 9. LtCol. Gene Conti, Production Officer at Naval Aviation Depot, Cherry Pt., interviewed by author, 18 January 1995. 10. Commander Naval Air Systems Command message to the Commanders of Naval Air Forces, Subject: "Flight Restriction for H-46 Helicopters," 292007Z July 1993. 11. Commander Marine Forces Atlantic message to Commander Naval Air Systems Command, Subject: "COMNAVAIRSYSCOM Restriction on CH-46E," 131454Z August 1993. 12. Naval Air Systems Command, PMA-226, "H-46 Program Review," Dynamic Component Upgrade Status, January 1995. 13. Ibid. 14. NATOPS Flight Manual, Al-H46AE-NFM-000, 20 August 1993. 15. Boeing Defense and Space Group (Helicopter Division), "H-46 Payload Recovery Study," October 1994. 16. John Taylor, H-46 Chief Drive Systems Engineer at Product Support Division, NADEP Cherry Pt., interviewed by author 10 February 1995. 17. Boeing Defense and Space Group (Helicopter Division), "H-46 Payload Recovery Study," October 1994. 18. Maj. Bob Hellar, interviewed by author on 12 January 1995. 19. Naval Air Systems Command, PMA 226, "H-46 Program Review," Communication Navigation Control System, January 1995. 20. Ibid. 21. Ibid. 22. Maj. Bob Hellar, interviewed by author on 12 January 1995. 23. NASC Det. PMA-226 "H-46 Program Review," Night Vision Goggle Heads Up Display, (AFC-439), January 1995. 24. NATOPS Flight Manual, Al-H46AE-NFM-000, 20 August 1993, p.2-1. 25. LtCol. Gene Conti, interviewed by author 18 January 1995. 26. Mary Bender, Assistant Program Manger for Logistics at Naval Air Systems Command Det. PMA 226, interviewed by author 3 February 1995. 27. Maj. Rob Renken, Aviation Plans and Support Systems Officer at Chief of Naval Operations, interviewed by author 20 January 1995. 28. Naval Air Systems Command, "Weapons System Planning Document," NAVAIR Notice C13100. March, 1994. 29. Ibid. 30. Ibid. 31. Aircraft Management and Rejuvenation Center (AMARC20), "Inactive Navy Aircraft," NAVAIR 4850, January 1995. Bibliography Aircraft Management and Rejuvenation Center (AMARC). "Inactive Navy Aircraft." NAVAIR 4850, January 1995. Bender, Mary. Assistant Program Manager for Logistics at Naval Air Systems Command Det. PMA. Interviewed by author, 3 February 1995 Borowasky, Michael. Statistics Analyst at Naval Safety Center. Interviewed by author, 10 February 1995. Chief of Naval Operations. "Joint Services Advanced Vertical Lift Aircraft (JVX) Operational Requirement Document (ORD)." 14 December 1982. Chief of Naval Operations (N880G). "U. S. Navy Aircraft Inventory Budget Exhibit A2." January 1995. Commander Marine Forces Atlantic message to Commander Naval Air Systems Command. Subject: "COMNAVAIRSYSCOM Restriction on CH-46E." 131454Z August 1993. Commander Naval Air Force Atlantic. "3M Aviation / SER / Utilization / Maintenance History Report." 25 November 1994. Commander Naval Air Systems Command message to the Commanders of Naval Air Forces. Subject : "Flight Restriction for H-46 Helicopters." 292007Z July 1993. Conti, LtCol. Gene. Production Officer at Naval Aviation Depot, Cherry Pt. Interviewed by author, 18 January 1995. Hellar, Maj. Bob. H-46 Class Desk at Naval Air Systems Command. Det. PMA 226. Interviewed by author, 12 January 1995. NATOPS Flight Manual. A1-H46AE-NFM-000. 20 August 1993. Naval Air Systems Command. "Weapons System Planning Document." NAVAIR Notice C13100. March, 1994. Naval Aviation Depot Operations Center. "NADEP Cherry Pt., Aircraft SDLM Cost Report." January 1995. Renken, Maj. Rob. Aviation Plans and Support Systems Officer at Chief of Naval Operations. Interviewed by author, 20 January 1995. Taylor, John. H-46 Chief Drive Systems Engineer at Product Support Division, NADEP, Cherry Pt. Interviewed by author, 10 February 1995.
