F-35 Joint Strike Fighter: Assessment Needed to Address Affordability Challenges
Published: 2015-04-14T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: With estimated acquisition costs of nearly $400 billion, the F-35 Lightning II—also known as the Joint Strike Fighter—is DOD's most costly and ambitious acquisition program. The U.S. portion of the program will require annual acquisition funding of $12.4 billion on average through 2038 to complete development and procure a total of 2,457 aircraft. GAO's prior work has found that the program has experienced significant cost, schedule, and performance problems.
In 2009, Congress mandated that GAO review the F-35 acquisition program annually for 6 years. This report, GAO's sixth, assesses the program's (1) development and testing progress, (2) cost and affordability, and (3) manufacturing and supply chain performance.
GAO reviewed and analyzed the latest available manufacturing, cost, testing, and performance data through December 2014; program test plans; and internal DOD analyses; and interviewed DOD, program, engine and aircraft contractor officials.
section_title: What GAO Found
paragraphs: The F-35 Joint Strike Fighter program had to make unexpected changes to its development and test plans over the last year, largely in response to a structural failure on a durability test aircraft, an engine failure, and software challenges. At the same time, engine reliability is poor and has a long way to go to meet program goals. With nearly 2 years and 40 percent of developmental testing to go, more technical problems are likely. Addressing new problems and improving engine reliability may require additional design changes and retrofits. Meanwhile, the Department of Defense (DOD) has plans to increase annual aircraft procurement from 38 to 90 over the next 5 years. As GAO has previously reported, increasing production while concurrently developing and testing creates risk and could result in additional cost growth and schedule delays in the future.
Cost and affordability challenges remain. DOD plans to significantly increase annual F-35 funding from around $8 billion to nearly $12 billion over the next 5 years (see figure) reaching $14 billion in 2022 and remaining between $14 and $15 billion for nearly a decade. Over the last year, DOD reduced near-term aircraft procurement by 4 aircraft, largely due to budget constraints. While these deferrals may lower annual near-term funding needs, they will likely increase the cost of aircraft procured in that time frame and may increase funding liability in the future. It is unlikely the program will be able to sustain such a high level of annual funding and if required funding levels are not reached, the program's procurement plan may not be affordable. DOD policy requires affordability analyses to inform long-term investment decisions. The consistent changes in F-35 procurement plans indicate that DOD's prior analyses did not adequately account for future technical and funding uncertainty.
Manufacturing progress continued despite mixed supplier performance. The aircraft contractor delivered 36 aircraft as planned in 2014, despite a fleet grounding, added inspections, and software delays. In contrast, the labor hours needed to manufacture an aircraft and the number of major design changes have continued to decline over time. Because supplier performance has been mixed, late aircraft and engine part deliveries could pose a risk to the program's plans to increase production. The contractors are taking steps to address these issues.
section_title: What GAO Recommends
paragraphs: GAO recommends that DOD assess the affordability of F-35's current procurement plan that reflects various assumptions about technical progress and future funding.

section_title: Letter
paragraphs: With estimated acquisition costs of nearly $400 billion, the F-35 Lightning  II—also known as the Joint Strike Fighter—is the Department of  Defense’s (DOD) most costly and ambitious acquisition program. Through  this program, DOD is developing and fielding a family of next generation  strike fighter aircraft, integrating low observable (stealth) technologies  with advanced sensors and computer networking capabilities for the  United States Air Force, Navy, and Marine Corps, as well as eight  international partners. The F-35 family is comprised of the F-35A  conventional takeoff and landing variant, the F-35B short takeoff and  vertical landing variant, and the F-35C carrier-suitable variant. According  to current projections, the U.S. portion of the program will require  acquisition funding of $12.4 billion a year, on average, through 2038 to  complete development and procure a total of 2,457 aircraft. In addition,  DOD and program office estimates indicate that the F-35 fleet could cost  around $1 trillion to operate and support over its lifetime, which will pose  significant affordability challenges.
We have reported on F-35 issues for many years. Over time, we have  reported significant cost, schedule, and performance problems and have  found those problems, in part, can be traced to (1) decisions made at key  junctures without adequate product knowledge and (2) a highly  concurrent acquisition strategy with significant overlap among  development, testing, and manufacturing activities. We have made  numerous recommendations for improvement in our previous reports.  DOD has taken action to address many of our recommendations to  varying degrees.
The National Defense Authorization Act for Fiscal Year 2010 requires  GAO to review the F-35 acquisition program annually for 6 years. This is  the sixth and final report under that mandate, and in this report we assess  program (1) development and testing progress, (2) cost and affordability  and (3) manufacturing and supply chain performance.
To conduct our work, we reviewed and analyzed program briefings,  management reports, test data and results, and internal DOD program  analyses. We collected data on and discussed key aspects of F-35  development and test progress with program management and contractor  officials as well as DOD test officials and program test pilots. We  collected and analyzed program acquisition cost estimates and reviewed  total program funding requirements to project annual funding  requirements through 2038. To assess the reliability of the cost data, we  reviewed the supporting documentation and discussed the development  of those estimates with DOD officials instrumental in producing them. We  collected and analyzed production and supply chain performance data  from DOD, Lockheed Martin, and Pratt & Whitney. We assessed the  reliability of the data by reviewing supporting documentation and  interviewing knowledgeable agency officials. We determined that all of the  data we used were sufficiently reliable for the purposes of this report. We  also discussed ongoing manufacturing process improvements with  contracting and Defense Contract Management Agency officials.  Appendix Il contains a more detailed description of our scope and  methodology.
We conducted this performance audit from July 2014 to April 2015 in  accordance with generally accepted government auditing standards.  Those standards required that we plan and perform the audit to obtain  sufficient, appropriate evidence to provide a reasonable basis for our  findings and conclusions based on our audit objectives. We believe that  the evidence obtained provides a reasonable basis for our findings and  conclusions based on our audit objectives.
subsections: section_title: Background
paragraphs: DOD began the F-35 acquisition program in October 2001 without  adequate knowledge about the aircraft’s critical technologies or design. In  addition, DOD’s acquisition strategy called for high levels of concurrency  between development, testing, and production. In our prior work, we  have identified the lack of knowledge and high levels of concurrency as  major drivers in the significant cost and schedule growth as well as  performance shortfalls that the program has experienced since 2001. The  program has been restructured three times since it began: first in  December 2003, again in March 2007, and most recently in March 2012.  The most recent restructuring was initiated in early 2010 when the  program’s unit cost estimates exceeded critical thresholds established by  statute—a condition known as a Nunn-McCurdy breach. DOD  subsequently certified to Congress in June 2010 that the program was  essential to national security and needed to continue. DOD then began  efforts to significantly restructure the program and establish a new  acquisition program baseline. These restructuring efforts continued  through 2011 and into 2012, during which time the department increased  the program’s cost estimates, extended its testing and delivery schedules,  and reduced near-term aircraft procurement quantities by deferring the  procurement of 450 aircraft into the future—total procurement quantities  did not change. Figure 1 shows how planned quantities in the near-term  have steadily declined over time.
The new F-35 acquisition program baseline was finalized in March 2012,  and since that time costs have remained relatively stable. Table 1 shows  the significant cost, quantity, and schedule changes from the initial  program baseline and the relative stability since the new baseline was  established.
In March 2012, when the new acquisition program baseline was finalized,  DOD had not yet identified new initial operating capability dates for the  military services. The following year, DOD issued a memorandum stating  that the Marine Corps and Air Force were planning to field initial operating  capabilities in 2015 and 2016 respectively, and that the Navy planned to  field its initial operating capability in 2018, which represented a delay of 5  to 6 years since the program’s initial baseline.
DOD is currently conducting developmental flight testing to verify that the  F-35 system’s design works as intended and can reliably provide the  capabilities needed for the services to field their respective initial  operational capabilities. The program’s flight testing is separated into two  key areas referred to as mission systems and flight sciences. Mission  systems testing is done to verify that the software and systems that  provide warfighting capabilities function properly and meet requirements,  while flight science testing is done to verify the aircraft’s basic flying  capabilities. For the F-35 program, DOD is developing and fielding  mission systems capabilities in software blocks: (1) Block 1, (2) Block 2A,  (3) Block 2B, (4) Block 3i, and (5) Block 3F. Each subsequent block builds  on the capabilities of the preceding blocks. Blocks 1 and 2A are  essentially complete. The program is now focused on completing Block  2B testing to support Marine Corps initial operating capability, but some  testing of specific Block 3i and Block 3F capabilities is also being  conducted. Blocks 2B and 3i will provide initial warfighting capabilities  while Block 3F is expected to provide the full suite of warfighting  capabilities. Figure 2 identifies the sequence of software blocks and  capabilities expected to be delivered in each.
As developmental flight testing continues, DOD is concurrently  purchasing and fielding aircraft. The F-35 airframe and engine are  managed as one program, but they are manufactured in separate  facilities by different contractors. The airframe is being manufactured by  Lockheed Martin, the prime contractor, in Fort Worth, Texas, while the  engine—which is designated the F135—is manufactured by Pratt &  Whitney in Middletown, Connecticut. The engines are purchased by the  government directly from Pratt & Whitney and delivered as government  furnished equipment to Lockheed Martin for integration into the airframes  during production. As a result, engine development and testing activities  are managed by Pratt & Whitney and not Lockheed Martin.
section_title: Recent Technical Challenges Will Likely Result in Cost Growth and Schedule Delays
paragraphs: The F-35 program continued to experience development and testing  discoveries over the past year, largely due to a structural failure on the F- 35B durability test aircraft, an engine failure, and more mission system  test growth than expected. Together, these factors led to adjustments in  the program’s test schedule. Test resources and some aircraft capabilities  were reprioritized, and test points were deferred or eliminated. While  these actions mitigated some of the schedule risk, ultimately the  completion of key developmental test activities had to be delayed.  Decisions were also made to restructure an early operational test event  that likely would have reduced operational risk for the Marine Corps. The  event will now be conducted over time and will not be completed as  originally scheduled. Instability in the development program is likely to  continue with more complex and demanding development testing still to  go. As the program continues to discover problems in development and  testing, it also faces a significant challenge to improve the reliability of the  engine. Program data show that the reliability of the engine is very poor  (less than half of where it should be) and has limited the program’s  progress toward its overall reliability targets. The engine contractor, Pratt  & Whitney, has identified a number of design changes that it believes will  help improve engine reliability, but some of those changes have not yet  been implemented. With complex and challenging developmental testing  remaining and engine reliability challenges ahead, DOD still plans to  increase procurement rates by nearly threefold over the next 5 years.  This same highly concurrent strategy has already proven to have  negatively impacted the program. According to program reports, $1.7  billion could be incurred in costs associated with retrofits to already  delivered aircraft. This cost will likely increase, as more aircraft are  purchased and delivered before development ends.
subsections: section_title: Test Failures and Software Challenges Forced Program Changes
paragraphs: A significant structural failure on the F-35B durability test aircraft, an  engine failure, and a higher than expected amount of test point growth  largely to address software rework, over the past year, delayed key test  activities and forced unexpected adjustments to the program’s  development schedule and test plans. Each of these three factors is  discussed in more detail below.
At around 9,000 hours of durability testing—about half of the 16,000  hours required—a major airframe segment, known as a bulkhead, on  the F-35B durability test aircraft severed, and one other bulkhead was  fractured as a result. Durability testing on the F-35B was halted for  more than a year as program officials conducted a root cause analysis  and Lockheed Martin worked to repair the durability test aircraft. The  root cause analysis determined that the bulkhead severed because its  design did not take into account appropriate factors in the  manufacturing processes, resulting in a bulkhead that had less  durability life than expected. According to officials, the fracture in the  other bulkhead was caused by the added weight it had to bear after  the first bulkhead severed. Lockheed Martin is currently redesigning  the bulkheads to strengthen the aluminum and plans to incorporate  the updated designs into the ninth low-rate initial production lot. A total  of 50 aircraft will have to be modified using additional structural  reinforcement techniques. According to program and contractor  officials, because the incident occurred halfway through durability  testing, retrofits will not be required until the aircraft reach about half  of their expected service life, or about 10 years. According to officials,  the total costs of related modifications are yet to be determined at this  time.
In June 2014, an F-35A engine caught fire during take-off. As a result,  the entire F-35 fleet was grounded for nearly one month and then  placed under flight restrictions for several additional months. A root  cause analysis conducted by Pratt & Whitney determined that  excessive heat caused by rubbing between engine fan components  ultimately led to parts of the engine breaking free at a high rate of  speed, resulting in a fire. The program could not execute any planned  flight test points while the fleet was grounded. After flying resumed  there were still hundreds of planned test points that could not be  executed because the fleet was restricted from flying at the speeds  and conducting the maneuvers necessary to execute those points.  Despite these obstacles, the program was able to keep its test aircraft  productive and accomplished some test points that had been planned  to be done in the future. Follow-up inspections conducted by the  contractor identified 22 engines with evidence of overheating. Officials  have identified a short-term fix that they believe will allow the fleet to  return to normal flight test operations. As of January 31, 2015, 18 of  22 engines had received the short-term fix and were cleared to return  to normal flight operations. Pratt & Whitney has identified several  potential long-term fixes but no final determination has been made.
While the program’s test plan for 2014 reflected an allowance of 45  percent growth in mission system software test points for the year— largely to address software rework that might be needed—officials  from the Office of the Secretary of Defense noted that the program  experienced around 90 percent growth, or nearly twice the planned  amount. As of January 2015, 56 percent of the Block 2B functionality  had been verified by program officials, which was about 10 percent  short of its goal. According to DOD and contractor officials, the higher  than anticipated amount of rework was largely due to the fact that  portions of the Block 2B software did not function as expected during  flight testing. To address these deficiencies, changes were made to  the software and this extended the Block 2B test schedule by  approximately 3 months. As of January 2015, all of the updated  software was in flight testing.
DOD continued to address other key technical risks that we have  highlighted in the past including the Helmet Mounted Display, Arresting  Hook System, and the Autonomic Logistics Information System (ALIS). A  new helmet design was developed and integrated that includes previously  developed updates and addresses shortfalls in night vision capability.  Test pilots we spoke with noted that while testing of the new helmet  design has just begun, some improvements over the previous design are  evident, but more testing is needed. A redesigned Arresting Hook System  was also integrated on the aircraft. While sea trial testing of the  redesigned system was slightly delayed, the testing took place in  November 2014 and the system performed very well with a 100 percent  arrestment rate. Lastly, program officials began testing a more capable  version of ALIS in September 2014 and expect to begin testing a  deployable version in February 2015. Although DOD plans to release the  deployable version in time for Marine Corps initial operational capability, it  faces tight timeframes. A portion of the system’s capabilities, Prognostics  Health Management downlink, has been deferred to follow-on  development.
In response to the challenges faced in 2014, program officials  reprioritized test resources and aircraft capabilities, deferred or eliminated  test points, and ultimately delayed completion of some developmental test  activities. Personnel and facilities that had been dedicated to developing  and testing Block 3i and Block 3F—software blocks required by the Air  Force and the Navy to field initial operational capabilities in 2016 and  2018 respectively—were reassigned to focus on delivering Block 2B to  support the Marine Corps’ initial operational capability in 2015. In  addition, program officials eliminated over 1,500 test points from the  overall Block 2B developmental test plan, and deferred some Block 2B  capabilities. According to program officials, they chose to delay some test  points that had been scheduled to be accomplished in 2014, and  accomplish other test points that they had scheduled to be done in the  future. In addition, program officials, in conjunction with officials from the  Director, Operational Test and Evaluation, restructured a Block 2B early  operational test event that had been planned for 2015. The restructured  event will now be conducted over time as resources allow but will not be  completed as originally scheduled. While these changes allowed the  program to accomplish nearly the same number of test points it had  planned for the year, officials stated that not all of the specific test  activities scheduled were completed. In the end, the completion of Block  2B developmental testing is 3 months behind schedule, Block 3i testing is  about 3 months behind schedule, and Block 3F could be as much as 6  months behind schedule.
section_title: Need to Improve Engine Reliability Presents Additional Challenges
paragraphs: The program has a long way to go to achieve its engine reliability goals.  Reliability is a function of how well a system design performs over a  specified period of time without failure, degradation, or need of repair.  During system acquisition, reliability growth should occur over time  through a process of testing, analyzing, and fixing deficiencies through  design changes or manufacturing process improvements. Once fielded,  there are limited opportunities to improve a system’s reliability without  additional cost increases and schedule delays. Currently, the F-35  engine’s reliability is very poor and overall aircraft reliability growth has  been limited. Improving engine reliability will likely require additional  design changes and retrofits.
The program uses various measures to track and improve reliability,  including the mean flying hours between failures (design controlled).  Data provided by Pratt & Whitney indicate that the mean flight hours  between failure for the F-35A engine is about 21 percent of where the  engine was expected to be at this point in the program. The F-35B engine  is about 52 percent of where the engine was expected to be at this point.  This means that the engine is failing at a much greater rate and requiring  more maintenance than expected. Pratt & Whitney has identified a  number of design changes that officials believe will improve the engine’s  reliability and is in the process of incorporating some of those changes  into the engine design, production, and retrofitted to already built aircraft;  however, other design changes that Pratt & Whitney officials believe are  needed, such as changes to engine hoses and sensors, are not currently  funded. Figure 3 shows the trend in the engine’s mean flight hours  between failures (design controlled).
Poor engine reliability has limited the F-35’s overall reliability progress.  The overall reliability of the aircraft, which includes engine reliability data,  has been improving over the past year. Contractor officials attribute the  improvements in reliability to having an increasing number of aircraft in  flight operations that have received design changes to address previously  identified problems. For example, design changes in the way certain  metal plates—known as nut plates—are bonded to the aircraft, and  changes to fix problems with contamination of the On-board Oxygen  Generating System have been incorporated into 62 aircraft that were  delivered and began flying throughout 2013 and 2014. While overall  reliability has increased, engine reliability over the last year has remained  well below expected levels. Improving the F-35 engine reliability to  achieve established goals will likely require more time and resources than  originally planned.
In addition, in September 2014, we reported problems with the F-35  software reliability and maintainability. Specifically, we reported that the  program continues to experience both hardware and software reliability  issues, but DOD had no processes or metrics that provide sufficient  insight into the impact of software reliability and maintainability  contributing to the overall aircraft reliability. We recommended that DOD  develop a software reliability and maintainability assessment process with  metrics, and DOD concurred with this recommendation.
section_title: Unexpected Technical Issues and Ongoing Reliability Challenges Amplify Concurrency Risk
paragraphs: While DOD has taken steps over the past few years to reduce  concurrency, the program’s strategy still contains a noteworthy overlap  between the completion of flight testing and the increase in aircraft  procurement rates. With about 2 years and 40 percent of the  developmental test program remaining and significant engine reliability  growth needed, DOD plans to continue increasing procurement rates.  Over the next 5 years, procurement will increase from 38 aircraft per year  to 90 aircraft per year, and by the time developmental testing is finished— currently expected to occur in 2017—DOD expects to have purchased a  cumulative total of 340 aircraft. During this time, there are plans to  conduct testing to prove that the F-35 can provide full warfighting  capabilities—Block 3F—needed to perform in more demanding and  stressing environments. In addition, DOD plans to complete operational  testing in early 2019 and at that time will have procured 518 aircraft or 21  percent of its total planned procurement quantities. At the same time,  efforts will be ongoing to improve F-35 engine reliability.
As of June 2014, DOD estimated that at that point about $1.7 billion in  funding was needed to rework and retrofit aircraft with design changes  needed as a result of test discoveries. This concurrency cost estimate  does not include any costs related to the most recent failures. According  to DOD officials, the estimate takes into account some unexpected costs  and they believe that the estimate will not exceed $1.7 billion. However,  with more complex and demanding testing ahead and engine reliability  improvements needed, it is almost certain that the program will encounter  more discoveries. Depending on the nature and significance of the  discoveries, the program may need additional time and money, beyond  the current $1.7 billion estimate, to incorporate design changes and  retrofit aircraft at the same time that it increases procurement.
section_title: Affordability Challenges Will Likely Continue to Affect Program Plans to Increase F-35 Procurement
paragraphs: As of December 2014, the program office estimated that the total  acquisition cost of the F-35 will be $391.1 billion, or $7.4 billion less than  DOD reported in December 2013. Our analysis indicates that the program  will require an average of $12.4 billion per year, which represents around  one-quarter of DOD’s annual funding for major defense acquisition  programs over the next 5 years. From fiscal years 2015 to 2019, DOD  plans to increase annual development and procurement funding for the F- 35 from around $8 billion to around $12 billion, an investment of more  than $54 billion over that 5-year period, while competing with other large  programs for limited acquisition resources. This funding reflects the U. S.  military services’ plans to significantly increase annual aircraft  procurement buys from 38 in 2015 to 90 in 2019. International partners  will also increase procurement buys during this time, and the combined  purchases will peak at 179 aircraft in 2021, with the United States  purchasing 100 aircraft and the international partners purchasing an  additional 79 aircraft. DOD projects that the program’s acquisition funding  needs will increase to around $14 billion in 2022. Funding needs will  remain between $14 and $15 billion for nearly a decade and peak at  $15.1 billion in 2029 (see figure 4). Given resource limitations and the  funding needs of other major acquisition programs such as the KC-46A  tanker, the DDG-51 Class Destroyer, the Ohio Class submarine  replacement, and a long-range strike bomber, in addition to the high  estimated costs of sustaining the fleet over the next several years, we  believe funding of this magnitude will pose significant affordability  challenges.
Since the 2012 re-baselining, DOD has made changes to its F-35  procurement plans on an annual basis. In 2013, DOD reduced the  number of aircraft that it planned to purchase between 2015 and 2019 by  37 aircraft and extended the procurement timeline by one year. In 2014,  DOD deferred the purchase of 4 more aircraft over that same timeframe.  DOD officials attribute this decision to affordability concerns due to  budget constraints, among other factors. Although this action may reduce  near-term funding requirements as well as concurrency risks, it will likely  increase the average unit cost of the aircraft purchased over that time and  may increase funding liability in the future. DOD policy requires  affordability analyses to inform long-term investment decisions. The  consistent changes in F-35 procurement plans, made during the annual  DOD budget process, indicate that the analysis done to support the  program’s 2012 baseline did not accurately account for future technical  risks or funding realities. Changes in procurement plans are also  impacted by adjustments to military service and DOD priorities.
Program office data indicates that after accounting for quantity changes,  the program is unlikely to achieve the affordability unit cost targets set by  the Under Secretary of Defense for Acquisition, Technology, and  Logistics in 2012. The aircraft deferrals will also reduce the number of F- 35s fielded over the next several years, which could force the military  services to invest in extending the life of their current aircraft fighter fleets,  including the Air Force A-10 Thunderbolt II and the Navy F/A-18 Hornet.  We believe maintaining the level of sustained funding required to build an  F-35 fleet in addition to incurring costs to extend the life of current aircraft  will be difficult in a period of austere defense budgets.
Officials from the Office of Secretary of Defense have stated that the  current sustainment strategy is not affordable. Both the program office  and the Cost Assessment and Program Evaluation (CAPE) office, within  the Office of the Secretary of Defense, estimate sustainment costs will be  about $1 trillion over the life of the F-35 fleet. Since 2012, CAPE’s  sustainment cost estimate has decreased by nearly $100 billion. CAPE  attributes the bulk of this decrease to updated cost estimating ground  rules and assumptions related to the cost of spare parts, labor rates, and  fuel efficiency. The program office has also issued a separate  sustainment cost estimate of approximately $859 billion, which is $57.8  billion less than it estimated last year. The CAPE and program estimates  differ primarily in assumptions about reliability, depot maintenance,  personnel, and fuel consumption. However, as we reported in September  2014, the current estimates are still higher than the current operation and  support costs of the existing aircraft the F-35 is expected to replace, and  according to officials from the Office of Secretary of Defense, remain  unaffordable. In addition, we reported that DOD’s sustainment cost  estimates may not reflect the most likely costs that the F-35 program will  incur.
While the F-35 program office and contractors have initiatives underway  to improve affordability, those initiatives have a specific focus on reducing  procurement and sustainment costs but do not assess the affordability of  the program’s overall procurement plan within budget constraints. These  initiatives include the “War on Cost,” “Cost War Room,” and “Blueprint for  Affordability” that are intended to identify ways to reduce procurement  and sustainment costs of the aircraft and engine. The initiatives are still  ongoing and the total cost savings related to these initiatives is yet to be  determined.
section_title: While Manufacturing Progress Remains Steady, Planned Production Increases Could Be a Challenge
paragraphs: As Lockheed Martin continues to deliver more aircraft, the number of  hours needed to build each aircraft has declined and efficiency rates have  improved despite increases in the time spent on scrap, rework, and  repairs. Supplier performance has been mixed as late deliveries have  resulted in increases to part shortages. Supplier quality defects have also  increased while scrap, rework, and repair attributable to suppliers have  remained steady. Pratt & Whitney is experiencing problems with quality  and late deliveries from its suppliers.
subsections: section_title: Manufacturing Efficiency Remains Steady
paragraphs: The number of aircraft produced in the Lockheed Martin’s final assembly  facility has remained relatively stable over the last 3 years. The contractor  has delivered a total of 110 aircraft since 2011—9 in 2011, 30 in 2012, 35  in 2013, and 36 in 2014. None of the aircraft delivered currently possess  initial warfighting capability and are being used primarily for training  purposes. As a result, delivered aircraft will have to be retrofitted with 2B  initial warfighting capabilities prior to becoming operational. Although  aircraft continued to be delivered later than contracted delivery dates— averaging 3.6 months late in 2014—Lockheed Martin officials believe they  are closing the gap and expect to begin delivering to contract dates in  2015. Figure 5 shows actual aircraft deliveries compared to contracted  delivery dates over the last 2 years. In 2014, Lockheed Martin achieved  its goal of delivering 36 aircraft despite multiple setbacks throughout the  year, such as late software deliveries, a fleet grounding, and increased  engine inspections.
As Lockheed Martin produces more aircraft and learns more about its  manufacturing processes, it continues to reduce the number of labor  hours needed to manufacture aircraft. The reduction in labor hours  remained relatively steady over the last year; however, in the case of the  F-35B, labor hours briefly trended upward. Officials stated that a gap in  production of the F-35B variant between lots four and six and part  shortages drove the increased labor hours. The number of labor hours to  produce the last F-35B delivered in 2014 was lower than previous aircraft,  and officials believe labor hours will continue to decrease as production  quantities for the F-35B increase. Figure 6 identifies the trend in reduction  of labor hours per aircraft since the beginning of low-rate initial  production.
The number of major engineering design changes has also continued to  decline over time, and is currently tracking to the program’s plan. The  reduction in labor hours and engineering design changes over time has  allowed Lockheed Martin to increase manufacturing efficiency rates as  measured by the hours it takes to complete certain production tasks  compared to the number of hours established by engineering standards.  The efficiency rate increased from about 16 to about 20 percent over the  last year, nearly achieving Lockheed Martin’s goal of about 22 percent.
Labor hours and efficiency rates improved despite increases in time spent  on scrap, rework, and repair over the last year. The time spent on scrap,  rework, and repair increased from 13.8 percent in production lot four to  14.9 percent in production lot five, falling short of Lockheed Martin’s goal  of 12.8 percent. At 14.9 percent, Lockheed Martin’s scrap, rework, and  repair rates are nearly equal to percentages experienced in the third  production lot. According to Lockheed Martin officials, a majority of the  scrap, rework, and repair hours are associated with fixing mislocated  brackets and mismatched seams. Figure 7 shows the trend in percent of  labor hours spent on scrap, rework, and repair along with the goal for the  fifth production lot. If these trends continue, Lockheed Martin could have  difficulty improving its manufacturing efficiency at its expected rates.
Lockheed Martin reports that less than 40 percent of its critical  manufacturing processes are considered in statistical control which  means that for those processes it can consistently produce parts within  quality tolerances and standards. Statistical control is a measure of  manufacturing maturity. The best practice standard is to have 100 percent  of the critical manufacturing processes in control by the start of low-rate  initial production, which began in 2011 for the F-35 program. According to  Lockheed Martin officials, only 54 percent of its F-35 critical  manufacturing processes will provide enough data to measure statistical  control. As a result, they do not expect to achieve 100 percent.
section_title: Late Deliveries from Suppliers Continue, and Could Challenge Planned Production Increases
paragraphs: Suppliers continue to deliver late parts to Lockheed Martin resulting in  part shortages. Since 2013, the average number of part shortage  occurrences at Lockheed Martin’s facility has increased. The severity of  part shortages is measured in five categories, category 1 being the least  severe, and category 4 and above being the most severe with those  shortages requiring a major workaround or work stoppage. Figure 8  identifies changes in the average number of part shortage occurrences at  Lockheed Martin’s facility over the last year.
According to Lockheed Martin officials, suppliers are delivering late parts  for several reasons. Those reasons include the need for suppliers to fix  faulty parts and the inability of some suppliers to handle large amounts of  throughput. In addition, Lockheed Martin officials stated that some delays  are a result of late request for proposals, late responses to those  proposals, and delayed contract negotiations with the government that  result in late contract awards. Officials do not expect to begin making  authorizations with appropriate lead time until the end of low-rate initial  production in 2019. Part shortages will likely remain problematic and  could be amplified as production rates increase over the next 5 years.
Supplier quality at Lockheed Martin has been mixed. Lockheed Martin  uses a reactive approach to managing most of its supplier base because,  according to officials, they do not have access to supplier specific  manufacturing data. The company uses internal metrics to track supplier  performance such as the number of quality defects—known as non- conformances—discovered at the Lockheed Martin facility and the  amount of scrap, rework, and repair driven by poor supplier performance.  Over the last year, the number of supplier related non-conformances has  slightly increased and Lockheed Martin continues to experience supplier  related non-conformances for things like hole-drilling and bracket  placement, among others. Lockheed Martin officials identified 22 of their  more than 1,500 suppliers that contributed to 75 percent of the non- conformances. In order to address these non-conformances, Lockheed  Martin developed a management team aimed at improving quality  management at those suppliers. Lockheed Martin reported a 58 percent  improvement in non-conformances for those suppliers over the last year,  which it attributes to the work of its team. For example, the key supplier of  the aircraft weapons bay door experienced quality problems in 2013.  Over the last year, Lockheed Martin sent more personnel to the supplier’s  facility to work with the supplier’s management team to identify problems  in their production processes and solutions to those problems. As a  result, the supplier adjusted its tooling and modified its quality  management techniques, and the number of defects and part shortages  from that supplier decreased. In addition, the percent of time spent on  scrap, rework, and repair for supplied parts has remained steady.  Supplier deliveries requiring scrap, rework, and repair averaged 1.3  percent of the hours spent building an aircraft over the last 2 years.
Pratt & Whitney is also experiencing challenges with part shortages and  supplier quality. Nearly 45 percent of Pratt & Whitney’s key suppliers  have delivered late parts over the past year. In order to mitigate some of  the risk, Pratt & Whitney has pulled or borrowed some parts meant for  spare engines to use in place of the late parts. According to Pratt &  Whitney officials, they have taken steps to reduce the number of parts  that are borrowed; however, the number of borrowed parts remains high,  which could lead to further part shortages and late engine deliveries if  production rates increase over the next several years as planned. In  addition, in 2014, poor supplier quality negatively impacted engine  performance. For example, improper lubrication of an oil valve adapter by  the valve supplier resulted in an in-flight emergency in June 2014. As a  result, the oil valves on 136 F-35 aircraft—28 of which were in production  and 108 of which were delivered—had to be removed and replaced.  According to Pratt & Whitney officials, the associated retrofit costs were  borne by the valve supplier. The supplier also made changes to its  procedures to prevent future incidents.
section_title: Conclusions
paragraphs: The F-35 remains DOD’s most costly and ambitious programs and one of  its highest priority acquisition programs. The program began with an  acquisition strategy that called for high levels of concurrency between  developmental testing and aircraft procurement. Since then, however, the  program has experienced significant technical problems that have  resulted in schedule delays and additional unplanned, or latent,  concurrency. With more than 100 production aircraft delivered as of  December 2014, the program continues to encounter significant technical  problems like the engine and bulkhead failures that require design  changes. Programs in developmental testing are expected to encounter  technical problems that require design changes. However, in a concurrent  acquisition environment, the destabilizing effects of design changes are  amplified as more systems are produced and delivered, thus requiring  costly retrofits, and rework. With around 40 percent of developmental  testing remaining, additional unanticipated changes are likely as much of  that testing will be very challenging. At the same time, DOD plans to  steeply increase its procurement funding requests over the next 5 years  and projects that it will need between $14 and $15 billion annually for  nearly a decade. It is unlikely that the program will be able to receive and  sustain such a high and unprecedented level of funding over this  extended period, especially with other significant fiscal demands weighing  on the nation. This poses significant affordability challenges to DOD as  other costly, high priority acquisition efforts, including the KC-46A Tanker  and the DDG 51 Class Destroyer, compete for limited resources at the  same time. DOD continues to adjust its F-35 procurement plans on an  annual basis. This reactionary approach indicates that DOD may not be  accurately accounting for the future technical and funding uncertainty it  faces, and thus may not fully understand the affordability implications of  increasing F-35 procurement funding at the planned rates.
section_title: Recommendations
paragraphs: As DOD plans to significantly increase F-35 procurement funding over the  next 5 years, we recommend that the Secretary of Defense conduct an  affordability analysis of the program’s current procurement plan that  reflects various assumptions about future technical progress and funding  availability.
section_title: Agency Comments and Our Evaluation
paragraphs: We provided a draft of this report to DOD for comment. In its written  comments, which are reprinted in appendix III, DOD concurred with our  recommendation. DOD also provided technical comments which we  incorporated as appropriate.
We are sending copies of this report to appropriate congressional  committees; the Secretary of Defense; the Secretaries of the Air Force,  Army, and Navy; the Commandant of the Marine Corps; and the Director  of the Office of Management and Budget. The report is available at no  charge on the GAO website at http://www.gao.gov.
If you or your staff have any questions about this report, please contact  me at (202) 512-4841 or sullivanm@gao.gov. Contact points for our  Offices of Congressional Relations and Public Affairs may be found on  the last page of this report. Staff members making key contributions to  this report are listed in Appendix IV.
section_title: Appendix I: Prior GAO Reports on F-35 Joint Strike Fighter (JSF) and Department of Defense (DOD) Responses and Subsequent Actions
subsections: section_title: Estimated Development Costs Development Length Aircraft unit cost Key program event $34.4 Billion 10 years $69 Million
paragraphs: Start of system  development and  demonstration approved.
Primary GAO  Conclusion/Recommendation   DOD response and actions   Critical technologies needed for  key aircraft performance elements  are not mature. Program should  delay start of system development  until critical technologies are  mature to acceptable levels.
DOD did not delay start of  system development and  demonstration, stating  technologies were at  acceptable maturity levels  and stated it would manage  risks in development.
The program underwent a  re-plan to address higher  than expected design  weight, which added $7  billion and 18 months to  development schedule.
We recommended that the DOD  reduce risks and establish an  executable business case that is  knowledge-based with an  evolutionary acquisition strategy.
DOD partially concurred but  did not adjust strategy,  believing that its approach  was balanced between cost,  schedule, and technical risk.
Program set in motion a  plan to enter production in  2007 shortly after first  flight of the non- production representative  aircraft.
The program was entering  production with less than 1  percent of testing complete. We  recommended that  DOD delay investing in production  until flight testing shows that JSF  performs as expected.
DOD partially concurred but  did not delay start of  production because it  believed the risk level was  appropriate.
Congress reduced  funding for first two low- rate production buys  thereby slowing the ramp  up of production.
Progress was being made but  concerns remained about undue  overlap in testing and production.  We recommended limits to annual  production quantities to 24 a year  until flying quantities were  demonstrated.
DOD non-concurred and felt  that the program had an  acceptable level of  concurrency and an  appropriate acquisition  strategy.
DOD implemented a Mid- Course Risk Reduction  Plan to replenish  management reserves  from about $400 million to  about $1 billion by  reducing test resources.
We found the new plan increased  risks and recommended that DOD  should revise the plan to address  concerns about testing,  management reserves, and  manufacturing. We determined  that the cost estimate was not  reliable and that a new cost  estimate and schedule risk  assessment was needed.
DOD did not revise risk plan  or restore testing resources,  stating that it will monitor the  new plan and adjust it if  necessary. Consistent with  one of our  recommendations, a new  cost estimate was prepared,  but DOD did not conduct a  risk and uncertainty analysis.
section_title: Estimated Development Costs Development Length Aircraft unit cost Key program event $44.4 Billion 13 years $104 Million
paragraphs: The program increased  the cost estimate and  added a year to  development but  accelerated the  production ramp up.  Independent DOD cost  estimate (JET I) projects  even higher costs and  further delays.
Primary GAO  Conclusion/Recommendation   DOD response and actions   Moving forward with an  accelerated procurement plan and  use of cost reimbursement  contracts is very risky. We  recommended the program report  on the risks and mitigation  strategy for this approach.
DOD agreed to report its  contracting strategy and  plans to Congress and  conduct a schedule risk  analysis. The program  reported completing the first  schedule risk assessment  with plans to update semi- annually. The Department  announced a major program  restructure, reducing  procurement and moving to  fixed-price contracts.
The program was  restructured to reflect  findings of recent  independent cost team  (JET II) and independent  manufacturing review  team. As a result,  development funds  increased, test aircraft  were added, the schedule  was extended, and the  early production rate  decreased.
Costs and schedule delays  inhibited the program’s ability to  meet needs on time. We  recommended the program  complete a full comprehensive  cost estimate and assess  warfighter and initial operating  capability requirements. We  suggested that Congress require  DOD to tie annual procurement  requests to demonstrated  progress.
DOD continued  restructuring, increasing test  resources and lowering the  production rate. Independent  review teams evaluated  aircraft and engine  manufacturing processes.  Cost increases later resulted  in a Nunn-McCurdy breach.  Military services are  currently reviewing capability  requirements as we  recommended.
Restructuring continued  with additional  development cost  increases; schedule  growth; further reduction  in near-term procurement  quantities; and decreased  the rate for future  production. The Secretary  of Defense placed the  Short-takeoff Vertical  Landing (STOVL) variant  on a two-year probation;  decoupled STOVL from  the other variants; and  reduced STOVL  production plans for fiscal  years 2011 to 2013.
The restructuring actions were  positive and if implemented  properly should lead to more  achievable and predictable  outcomes. Concurrency of  development, test, and production  was substantial and provided risk  to the program. We recommended  the DOD maintain funding levels  as budgeted; establish criteria for  STOVL probation; and conduct an  independent review of software  development, integration, and test  processes.
DOD concurred with all three  of the recommendations.  DOD lifted STOVL probation  citing improved performance.  Subsequently, DOD further  reduced procurement  quantities, decreasing  funding requirements  through 2016. The initial  independent software  assessment began and  ongoing reviews were  planned to continue through  2012.
section_title: Estimated Development Costs Development Length Aircraft unit cost Key program event $55.2 Billion 18 years $137 Million
paragraphs: The program established  a new acquisition program  baseline and approved  the continuation of system  development, increasing  costs for development  and procurements and  extending the period of  planned procurements by  2 years.
Primary GAO  Conclusion/Recommendation   DOD response and actions   Extensive restructuring placed the  program on a more achievable  course. Most of the program’s  instability continued to be  concurrency of development, test,  and production. We recommended  the Cost Assessment Program  Evaluation office conduct an  analysis on the impact of lower  annual funding levels; and the  program office conduct an  assessment of the supply chain  and transportation network.
DOD partially concurred with  conducting an analysis on  the impact of lower annual  funding levels and concurred  with assessing the supply  chain and transportation  network.
The program continued to  move forward following a  new acquisition program  baseline in 2012. In doing  so, the program  incorporated positive and  more realistic  restructuring actions  taken since 2010  including more time and  funding for development  and deferred procurement  of more than 400 aircraft  to future years.
The program was moving in the  right direction but must fully  validate design and operational  performance and at the same time  make the system affordable. We  did not make recommendations to  DOD in this report.
DOD agreed with GAO’s  observations.
The services established  initial operational  capabilities dates in 2013.  The Marine Corps and Air  Force are planning to field  initial operational  capabilities in 2015 and  2016, respectively, and  the Navy plans to field its  initial capability in 2018.
DOD concurred with our  recommendation and is in  the process of conducting  the assessment.
section_title: Estimated Development Costs Development Length Aircraft unit cost Key program event Not reported
paragraphs: The Department of  Defense (DOD) currently  has or is developing  several plans and  analyses that will make up  its overall F-35  sustainment strategy,  which is expected to be  complete in fiscal year  2019.
Primary GAO  Conclusion/Recommendation   DOD response and actions   The annual F-35 operating and  support costs are estimated to be  considerably higher than the  combined annual costs of several  legacy aircraft. DOD had not fully  addressed several issues that  have an effect on affordability and  operational readiness. Operating  and support cost estimates may  not be reliable. We recommended  that DOD develop better informed  affordability constraints; address  three risks that could affect  sustainment, affordability, and  operational readiness; and take  steps to improve the reliability of  its cost estimates.
DOD concurred with all but  one recommendation and  partially concurred with the  recommendation to conduct  uncertainty analysis on one  of its cost estimates, stating  it already conducts a form of  uncertainty analysis. GAO  continues to believe that the  recommended analysis  would provide a more  comprehensive sense of the  uncertainty in the estimates.
section_title: Appendix II: Scope and Methodology
paragraphs: To assess the program’s ongoing development and testing we reviewed  the status of software development and integration and contractor  management improvement initiatives. We also interviewed officials from  the program office, Lockheed Martin, Pratt & Whitney, and the Defense  Contract Management Agency (DCMA) to discuss current development  status and software releases. In addition, we compared management  objectives to progress made on these objectives during the year. We  obtained and analyzed data on flights and test points, both planned and  accomplished during 2014. We compared test progress against the total  program plans to complete. In addition, we interviewed officials from the  F-35 program office, Lockheed Martin, Pratt & Whitney, and Director,  Operational Test and Evaluation office to discuss development test plans  and achievements. We also collected information from the program office,  prime contractor, engine contractor, and Department of Defense test  pilots regarding the program’s technical risks including the helmet  mounted display, autonomic logistics information system, carrier arresting  hook, structural durability, and engine. We analyzed reliability data and  discussed these issues with program and contractor officials.
To assess the program’s cost and affordability, we reviewed financial  management reports and monthly status reports available as of  December 2014. In addition, we reviewed total program funding  requirements from the December 2014 Selected Acquisition Report. We  used these data to project annual funding requirements through the  expected end of the F-35 acquisition in 2038. We also compared the  December 2014 Selected Acquisition Report data to prior Selected  Acquisition Reports to identify changes in cost and quantity. We obtained  life-cycle operating and support cost through the program’s Selected  Acquisition Report and projections made by the Cost Analysis and  Program Evaluation (CAPE) office. We discussed future plans of the  Department of Defense (DOD) and contractors to try and reduce life-cycle  sustainment costs with officials from the program office, Lockheed Martin,  and Pratt & Whitney.
To assess manufacturing and supply chain performance we obtained and  analyzed data related to aircraft delivery rates and work performance data  through the end of calendar year 2014. This data was compared to  program objectives identified in these areas and used to identify trends.  We reviewed data and briefings provided by the program office, Lockheed  Martin, Pratt & Whitney, and DCMA in order to identify issues in  manufacturing processes. We discussed reasons for delivery delays and  plans for improvement with Lockheed Martin and Pratt & Whitney. We  also toured Pratt and Whitney’s manufacturing facility in Middletown,  Connecticut and collected and analyzed data related to aircraft quality  through December 2014. We collected and analyzed supply chain  performance data and discussed plans taken to improve quality and  deliveries with Lockheed Martin and Pratt & Whitney.
We assessed the reliability of DOD and contractor data by reviewing  existing information about the data, and interviewing agency officials  knowledgeable about the data. We determined that the data were  sufficiently reliable for the purposes of this report. We conducted this  performance audit from July 2014 to April 2015 in accordance with  generally accepted government auditing standards. Those standards  require that we plan and perform the audit to obtain sufficient, appropriate  evidence to provide a reasonable basis for our findings and conclusions  based on our audit objectives. We believe that the evidence obtained  provides a reasonable basis for our findings and conclusions based on  our audit objectives.
section_title: Appendix III: DOD Comments
section_title: Appendix IV: GAO Contact and Staff Acknowledgments
subsections: section_title: GAO Contact
section_title: Acknowledgments
paragraphs: In addition the contact name above, the following staff members made  key contributions to this report: Travis Masters, Assistant Director; Peter  Anderson; James Bennett; Marvin Bonner; Kristine Hassinger; Megan  Porter; Marie Suding; and Abby Volk.
section_title: Related GAO Products
paragraphs: F-35 Sustainment: Need for Affordable Strategy, Greater Attention to  Risks, and Improved Cost Estimates. GAO-14-778. Washington, D.C.:  September 23, 2014.
F-35 Joint Strike Fighter: Slower Than Expected Progress in Software  Testing May Limit Initial Warfighting Capabilities. GAO-14-468T  Washington, D.C.: March 26 2014.
F-35 Joint Strike Fighter: Problems Completing Software Testing May  Hinder Delivery of Expected Warfighting Capabilities. GAO-14-322.  Washington, D.C.: March 24, 2014.
F-35 Joint Strike Fighter: Restructuring Has Improved the Program, but  Affordability Challenges and Other Risks Remain. GAO-13-690T.  Washington, D.C.: June 19, 2013.
F-35 Joint Strike Fighter: Program Has Improved in Some Areas, but  Affordability Challenges and Other Risks Remain. GAO-13-500T.  Washington, D.C.: April 17, 2013.
F-35 Joint Strike Fighter: Current Outlook Is Improved, but Long-Term  Affordability Is a Major Concern. GAO-13-309. Washington, D.C.: March  11, 2013.
Fighter Aircraft: Better Cost Estimates Needed for Extending the Service  Life of Selected F-16s and F/A-18s. GAO-13-51. Washington, D.C.:  November 15, 2012  Joint Strike Fighter: DOD Actions Needed to Further Enhance  Restructuring and Address Affordability Risks. GAO-12-437. Washington,  D.C.: June 14, 2012.
Defense Acquisitions: Assessments of Selected Weapon Programs.  GAO-12-400SP. Washington, D.C.: March 29, 2012.
Joint Strike Fighter: Restructuring Added Resources and Reduced Risk,  but Concurrency Is Still a Major Concern. GAO-12-525T. Washington,  D.C.: March 20, 2012.
Joint Strike Fighter: Implications of Program Restructuring and Other  Recent Developments on Key Aspects of DOD’s Prior Alternate Engine  Analyses. GAO-11-903R. Washington, D.C.: September 14, 2011.
Joint Strike Fighter: Restructuring Places Program on Firmer Footing, but  Progress Is Still Lagging. GAO-11-677T. Washington, D.C.: May 19,  2011.
Joint Strike Fighter: Restructuring Places Program on Firmer Footing, but  Progress Still Lags. GAO-11-325. Washington, D.C.: April 7, 2011.
Joint Strike Fighter: Restructuring Should Improve Outcomes, but  Progress Is Still Lagging Overall. GAO-11-450T. Washington, D.C.:  March 15, 2011.
Tactical Aircraft: Air Force Fighter Force Structure Reports Generally  Addressed Congressional Mandates, but Reflected Dated Plans and  Guidance, and Limited Analyses. GAO-11-323R. Washington, D.C.:  February 24, 2011.
Defense Management: DOD Needs to Monitor and Assess Corrective  Actions Resulting from Its Corrosion Study of the F-35 Joint Strike  Fighter. GAO-11-171R. Washington D.C.: December 16, 2010.
Joint Strike Fighter: Assessment of DOD’s Funding Projection for the  F136 Alternate Engine. GAO-10-1020R. Washington, D.C.: September  15, 2010.
Tactical Aircraft: DOD’s Ability to Meet Future Requirements is Uncertain,  with Key Analyses Needed to Inform Upcoming Investment Decisions.  GAO-10-789. Washington, D.C.: July 29, 2010.
Defense Acquisitions: Assessments of Selected Weapon Programs.  GAO-10-388SP. Washington, D.C.: March 30, 2010.
Joint Strike Fighter: Significant Challenges and Decisions Ahead.   GAO-10-478T. Washington, D.C.: March 24, 2010.
Joint Strike Fighter: Additional Costs and Delays Risk Not Meeting  Warfighter Requirements on Time. GAO-10-382. Washington, D.C.:  March 19, 2010.
Joint Strike Fighter: Significant Challenges Remain as DOD Restructures  Program. GAO-10-520T. Washington, D.C.: March 11, 2010.
Joint Strike Fighter: Strong Risk Management Essential as Program  Enters Most Challenging Phase. GAO-09-711T. Washington, D.C.: May  20, 2009.
Defense Acquisitions: Assessments of Selected Weapon Programs.  GAO-09-326SP. Washington, D.C.: March 30, 2009.
Joint Strike Fighter: Accelerating Procurement before Completing  Development Increases the Government’s Financial Risk. GAO-09-303.  Washington D.C.: March 12, 2009.
Defense Acquisitions: Better Weapon Program Outcomes Require  Discipline, Accountability, and Fundamental Changes in the Acquisition  Environment. GAO-08-782T. Washington, D.C.: June 3, 2008.
Defense Acquisitions: Assessments of Selected Weapon Programs.  GAO-08-467SP. Washington, D.C.: March 31, 2008.
Joint Strike Fighter: Impact of Recent Decisions on Program Risks.   GAO-08-569T. Washington, D.C.: March 11, 2008.
Joint Strike Fighter: Recent Decisions by DOD Add to Program Risks.  GAO-08-388. Washington, D.C.: March 11, 2008.
Tactical Aircraft: DOD Needs a Joint and Integrated Investment Strategy.  GAO-07-415. Washington, D.C.: April 2, 2007.
Defense Acquisitions: Analysis of Costs for the Joint Strike Fighter Engine  Program. GAO-07-656T. Washington, D.C.: March 22, 2007.
Joint Strike Fighter: Progress Made and Challenges Remain.   GAO-07-360. Washington, D.C.: March 15, 2007.
Tactical Aircraft: DOD’s Cancellation of the Joint Strike Fighter Alternate  Engine Program Was Not Based on a Comprehensive Analysis.   GAO-06-717R. Washington, D.C.: May 22, 2006.
Defense Acquisitions: Major Weapon Systems Continue to Experience  Cost and Schedule Problems under DOD’s Revised Policy. GAO-06-368.  Washington, D.C.: April 13, 2006.
Defense Acquisitions: Actions Needed to Get Better Results on Weapons  Systems Investments. GAO-06-585T. Washington, D.C.: April 5, 2006.
Tactical Aircraft: Recapitalization Goals Are Not Supported by  Knowledge-Based F-22A and JSF Business Cases. GAO-06-487T.  Washington, D.C.: March 16, 2006.
Joint Strike Fighter: DOD Plans to Enter Production before Testing  Demonstrates Acceptable Performance. GAO-06-356. Washington, D.C.:  March 15, 2006.
Joint Strike Fighter: Management of the Technology Transfer Process.  GAO-06-364. Washington, D.C.: March 14, 2006.
Tactical Aircraft: F/A-22 and JSF Acquisition Plans and Implications for  Tactical Aircraft Modernization. GAO-05-519T. Washington, D.C: April 6,  2005.
Tactical Aircraft: Opportunity to Reduce Risks in the Joint Strike Fighter  Program with Different Acquisition Strategy. GAO-05-271. Washington,  D.C.: March 15, 2005.