C-17 Globemaster III Block Upgrades
Block Upgrades is a technique that is used on major weapon systems to introduce multiple product improvement changes on a periodic basis. On the C-17 program this is an annual configuration update, although there is discussion on lengthening the block process to once every two years. Under the Block Change concept, all products within a given block have essentially the same configuration. This results in reduced sustainment costs by minimizing unique spare, tech order, support equipment and training requirements. Stable configurations within a block of aircraft or products improve manufacturing efficiency and quality. However, diligent manufacturing development and transition planning is required to minimize production line disruptions when introducing a new Block with configuration changes.
Block 9 aircraft features differences in its avionics, panels and design structures and in its Airlift Defensive System from earlier Block 8 C-17s. All of the Block 8 aircraft will eventually have software and hardware upgrades when they undergo depot repair by Boeing. Production models 49 and 50 are designated Block 9-plus versions since they have some upgrades from the later Block 10 models. The more modern Block 10 models, production models 52 to 87, were delivered to McChord AFB, WA. Charleston will remain at its current number of 40 assigned aircraft until October 2002 when P-88 is delivered. Eventually, the base will get 54 aircraft, including spares. In February 2001, P-49 and 50, initially possessed by Charleston, transfered to McChord as Charleston completed some modifications on the aircraft radios and McChord became ready to accept delivery. McChord's first C-17 acceptance ceremony was conducted when production model 51 (Block 10) was delivered.
The first 39 of the Air Force's 56 C-17s were delivered with an undetected design flaw that led to premature failures of the trunnion collar, a part of the main landing gear that guides gear rotation up and down. The collar attaches the main landing gear post to the fuselage. Durability testing failure in February 1997 showed the original collar design would not last the full 30-year service life of the C-17. Design of the C-17 landing-gear posts and trunnions had not been sufficiently stabilized to enable the C-17 System Program Office to fully project life-cycle management cost of landing-gear support. If the contractor is unable to extend the life of those parts, through redesign, past the 1.5 lifetimes of durability testing warranted in the contract, and those parts are declared life-limited, the Government costs for C-17 landing-gear support over the life of the C-17 fleet could increase $133.2 million for landing-gear posts and $5.2 million for trunnion collars. In addition, because of a much higher usage rate than anticipated in the original specifications, support costs could increase as much as $813.5 million for brakes and about $29 million for tires over the life of the C-17 fleet. The development of an improved main landing-gear tire could result in potential monetary benefits of approximately $1.8 million for FYs 1999 through 2005.
Easier access to patients and equipment, and improved functionality are among design enhancements the C-17 System Program Office incorporated into a new aeromedical litter station for the C-17. The design is based on changes in Air Force requirements for worldwide aeromedical evacuation that now mandate a minimum of 21 inches of space between litters. The old requirement was 16 inches. The additional space allows better interaction between medical personnel and the patient. The new patient litter system can accommodate up to 36 littered patients and 48 ambulatory patients. Design improvements were made to the litter arms, utility panel, oxygen lines, stanchions and overall set up and stowage placement and procedures. Quick disconnects, easy-operating litter arms, quick and unambiguous set up procedures, and quick access to emergency oxygen was designed to enhance the overall efficiency of the aeromedical mission. The first production C-17 with the new station, aircraft No. 41, was delivered to Charleston AFB in 1998.
All new aircraft, starting with the 40th, have new main landing gear trunnion collars. The plan was to retrofit the first 39 aircraft by December 2000, and 17 aircraft had received the new collars. But Air Mobility Command and the C-17 office decided to speed up the work. The team finished the remaining 18 cargo planes in a bit more than eight weeks.
The number one trend in the C-17 community is the quality of the landing gear. There have been numerous failures of landing gear assembly. There were at least six gear failures in 2000 year (two were ground jacking mishaps). The main problem seems to be centered around post assembly fractures on the main landing gear. These fractures have occurred on both operational and training missions. The landings ranged from normal to assault and all were within aircraft specifications and tolerances. Crews need to be aware that this problem has not been officially solved and that any landing could trigger another fracture of the post assembly. In addition, some of these failures were discovered during pre/post flight inspections.
The original C-17 main landing gear (MLG) pods were massive structures measuring over 60 feet in length, weighing more than 2,000 pounds and consisting of thousands of detailed parts and sub-assemblies. Due to design discrepancies, high scrap and rework, and time-consuming assembly practices, the cost of manufacturing the MLG pods was excessive. Aeronautical Systems Center engineers worked with the contractor to implement a Design For Manufacturing/Assembly project to reduce the part count and ease the assembly process. The team reduced the total part count by over 1,500 details (a 53% reduction) and eliminated 16,000 fasteners (a 47% reduction) greatly improving the producibility of the units. Fabrication and assembly costs were cut by $333,000 per shipset. Total installation time was reduced by 16 days and 10,000 hours per shipset for a savings of over $760,000 per aircraft.
All C-17 aircraft, from No. 51 onward, will have a newly designed tail. Aircraft No. 51 was delivered to McChord Air Force Base, WA in June 1999. Flight tests were completed in May 1999 for a new, lighter horizontal stabilizer for the C-17, and the component was installed on production aircraft at facilities of The Boeing Co. in Long Beach, CA. The hybrid composite/metal structure is 20 percent lighter than the all-metal tail. Additionally, the new tail component eliminates 90 percent of the parts, 81 percent of the fasteners, and 70 percent of the tools needed to produce the airlifter's tail. A majority of the structural savings was attributed to the large reduction in part count. Part integration included components such as the 'hat stiffeners'-- three sided structures that support the torque box skin-- that were co-cured to the tape-layed skin. Clips and brackets were virtually eliminated by incorporation into the machined aluminum ribs, and stiffeners also were integrated into the front spar by a co-bonding operation to the hand-layed composite spar. The new tails will be installed on the next 70 C-17 aircraft scheduled for delivery to the Air Force. Since the first 50 C-17s produced will not have the new tail design, the program will realize much less than the original goal of a 50 percent savings; however, additional cost savings will be realized should production numbers increase.
The 58th production C-17 was delivered to McChord AFB in early March 2000. It was the first of the Block XI C-17s. Block XI runs through production aircraft No. 70, which was delivered in early 2001. The upgrades affect all subsequent C-17s as well. Block XI includes a number of upgrades designed to increase ease of production and maintainability which include: automatic pressurization and depressurization; aircrew data transfer device (allows the automatic upload of worldwide navigational data, maintenance date and loadmaster software); chest-mounted oxygen regulator (allows loadmaster to move about the cabin during certain high-altitude airdrops); and electric production improvement project (rewiring of aircraft to make it easier and less costly to produce).
Block XI completes a two-phase cabin depressurization project. The new system is designed to depressurize the aircraft as soon as it lands. With the new system, depressurization is triggered by weight on the landing gear. It is a great safety improvement, since crews can egress more quickly in the event of a ground emergency. Another addition under Block XI is the aircrew data transfer device, a replacement for the current portable maintenance aid. The ADTD is a rugged, windows-based laptop computer used to transfer data, such as mission plans, navigational aids and communications data, to and from the aircraft avionics system. The system will also be used by loadmasters to compute weight and balance calculations. The new system provides greater capability and durability, explained Capt. Mitch Bradt, ADTD program manager at the C-17 SPO. It can operate at temperatures as low as minus 40 degrees and as high as 140 degrees Fahrenheit. It is also constructed to handle the shock and vibration of a rugged environment. The ADTD will be mounted at the loadmaster station, but is removable and can provide the standard computer tools found on any laptop. For C-17 loadmasters, this block introduces a new chest-mounted oxygen regulator, allowing loadmasters to move about the cargo bay during certain high-altitude parachute jumps. This will provide loadmasters more maneuverability in executing their mission. Previously loadmasters received oxygen from a stationary supply unit. Block XI includes 120 Class II changes, the most significant being the Electric Production Improvement project. This project involved the rewiring of most of the C-17's electrical systems, simplifying routing and changing connectors. The remainder of the fleet will receive retrofits for cabin pressurization and the chest-mounted oxygen regulator. C-17s will receive the new cabin pressurization at the Boeing Aerospace Support Center during the Global Reach Improvement Project (GRIP) cycle, Sept.-Dec. 2002. About half of the remaining fleet had already received the new oxygen regulator, which can be fitted very quickly in the field.
On 11 February 2000 Boeing was awarded a $12,285,602 modification to a time-and-materials contract to provide for retrofit of fifteen C-17 aircraft with the Global Air Traffic Management (GATM) system.
On 17 December 2001 Boeing made its final C-17 Globemaster III delivery for the year. It was the 80th C-17 delivered overall to the U.S. Air Force and the 10th in 2001. In addition, Boeing delivered four C-17s to the United Kingdom Royal Air Force this year. All C-17s delivered in 2001 have the extended range fuel containment system and other Block 12 upgrades. This year also marked the 10th anniversary of the C-17's first flight in September 1991.
Boeing planned to deliver 15 C-17s to the US Air Force in 2002. All deliveries have been ahead of schedule since early 1994.
In early 2002 the C-17 flare pattern effectiveness was improved over threefold, and the resulting new flare pattern is being instituted AMC-wide to support ongoing operations. Flares are fired from aircraft to divert enemy anti-aircraft weapons such as heat-seeking missiles. The 46th Test Wing of the Air Armament Center continued its accelerated and quick reaction flight and ground testing with a 15-sortie Operational Utility Evaluation of advanced flares and flare dispense techniques for AMC's C-17 and C-130 aircraft. The unit conducted more than 77 missions to evaluate a number of flare combinations and testing involving 11 different flare types. This extensive evaluation safely and successfully expended more than 5,000 flares and yielded extremely valuable results. Since September 11, 2001, the 46th Test Wing has planned and conducted 25 quick reaction/accelerated tests and certifications.
C-17s have featured onboard extended-range tanks for 60,000 extra pounds of fuel since the Block 12 versions. The additional tanks allow about four to five more flying hours.
Block 13 versions include upgrades such as a Terrain Awareness Warning System, a reactive wind sheer warning system and follow-on improvements to various computer systems that enhance the aircraft's mission capability and safety. The new aircraft contains improvements to the onboard computers, to include a warning system that maps terrain and helps pilots avoid obstacles. The new aircraft also has a new reactive wind-shear warning system on the heads-up-display and its Station Keeping Equipment are updated to allow pilots to keep track of their location relative to up to 99 other aircraft flying in formation over a 100-square-mile area. Charleston Air Force Base was set to receive 12 Block 13 C-17s by spring of 2003.
Block XIII/XIV has software modifications and improved station-keeping equipment used in flying formation with testing scheduled to be complete in 2004. Block XV is planned to contain the upgraded on-board inert gas generating system along with navigation and safety modifications. The Block XVI will contain an avionics modernization package and a weather radar modification with testing to be complete in 2006. Additional enhancements, modifications, and corrections to existing deficiencies are concurrent and include a fuel system retrofit, main landing gear deficiency corrections, and a wheel brake and tire cost saving initiative. Detailed developmental and operational test planning is underway.
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