STATEMENT BY
LT. GENERAL ZETTLER
DEPUTY CHIEF OF STAFF FOR
INSTALLATIONS AND LOGISTICS
BEFORE THE
PROJECTION FORCES SUBCOMMITTEE
UNITED STATES HOUSE OF REPRESENTATIVES
AIR REFUELING TANKER
REQUIREMENTS AND STATUS OF TANKER FLEET
JUNE 24, 2003
Chairman Bartlett, Ranking Member Taylor and Members of the Subcommittee:
Thank you for the opportunity to appear before you today. General Essex and I have come before you to discuss the Air Force's aerial refueling requirements, the status of the KC-135 fleet, and our current plans and programs in the fiscal year 2004 budget request to upgrade and sustain the aerial refueling fleet. My testimony will discuss the status and health of the KC-135 fleet, General Essex will discuss the requirement, and our current plans and programs in our 2004 budget request.
At an average age of over 40 years, the KC-135 fleet is the oldest combat weapon system in the United States Air Force (USAF). As this tanker fleet ages, ensuring warfighters have the required number of tankers to perform their wartime mission is a growing challenge. Through the nineties, the KC-135 fleet started to show its age. In 1991, Air Force Materiel Command initiated an Aging Aircraft Program to analyze the potential growth in major structural repairs of the aging fleet. By 2000, 32% of the KC-135 fleet (29% of the entire USAF refueling fleet) was unavailable due to depot level maintenance. This reduced the refueling capability to the warfighter and caused a backlog at depot facilities, increasing the average number of days in depot level maintenance to over 400.
The USAF Chief of Staff challenged Air Force Materiel Command and Air Mobility Command to reverse this trend immediately. Air Force Materiel Command radically restructured their processes, maintained depot repair lines, and with the concurrence of Air Mobility Command, deferred depot inputs. The annual KC-135 depot price per aircraft grew by 18% compounded annually, and the fleet availability decreased by 1% per year. We reached the conclusion that the fleet had entered into a fiscal and availability challenging period and some recapitializing of the fleet was the only path to assure combatant commanders mission success.
KC-135 Background
In 1954 the Air Force initiated the KC-135 Air Refueling program to replace its aging fleet of WWII-era KB-50 and Korean War-era KC-97 air refueling tankers. Between 1957 and 1965 over 700 C-135 and KC-135 aircraft were delivered. The peak delivery was 118 KC-135 aircraft in 1959. Today, the USAF is still maintaining and flying 544 of these aircraft. In addition, there are 59 KC-10s purchased in the early 1980s as an insurance policy against structural type failure within the KC-135 fleet. Today there are four models of KC-135s: R-models, E-models, D-models, and T-models. The D-models and E-models are 95% similar from a maintenance and sustainment position; therefore, they will be referred to as E-models. The R-models and T-models are also almost identical from a maintenance and sustainment position; therefore, they will be referred to as R-models. The R-models and E-models resulted from different modernization and re-engining programs initiated in the 1980s. There are 411 KC-135Rs that received new engines and changes to 25 other associated systems. The 133 KC-135Es were fitted with used commercial B-707 engines and pylon struts with 50-60 thousand hours of wear. Within the air refueling fleet, the KC-135E-models have experienced the most maintenance and corrosion problems and are more costly to maintain. With an average aircraft age of 43 years, the KC-135E fleet is the oldest combat weapon system in the Air Force inventory. It is also the oldest large fleet of heavy jet aircraft in aviation history.
Maintaining Aging KC-135s
Faced with the reality that all USAF aircraft type fleets are aging, Air Force Materiel Command established an Aging Aircraft Enterprise Office to assess, predict, and attempt to prevent the onset of age-related supportability issues. Aircraft life is measured three ways: 1) Usage--defined as flight hours; 2) Age--defined as corrosion and material degradation; and 3) Utility--defined as capabilities in the operating environment.
The first measurement is flight usage. For their first 30 years, the KC-135 supported the manned-bomber leg of the strategic Single Integrated Operations Plan (SIOP) and thus, during the prime of their life, the aircraft spent 30% of their time on nuclear alert and did not accrue high flight hours. Over time, the mission of the KC-135 has changed significantly to support global operations of all strike and cargo aircraft. Nonetheless, flight hours on KC-135 aircraft are relatively low compared to commercial airline standards. Generally, commercial airlines do not fly aircraft over 40 years old. To assess the impact of flying hours we perform Periodic Inspections similar to the scheduled A/B/C checks done by the commercial airlines.
The second critical measurement that defines aircraft life is physical age. In this fleet, corrosion is a function of age. Accurately predicting the extent of corrosion is difficult and this lack of predictability severely limits the ability to efficiently sustain aging fleets. To help weapon systems in the future, USAF engineering and research facilities are currently developing new tools and techniques to predict and evaluate corrosion. In the meantime, the KC-135 is particularly challenging since its 1950s design, materials, and construction did not consider corrosion prevention measures. In order to maintain a viable weapon system, major inspections are performed during PDM at our depot facilities to allow engineers access to evaluate aircraft condition.
The third measurement of aircraft life is utility (ability to accomplish the intended mission in the current operational environment). Aircraft must be constantly updated to reflect current technology, to be sustainable with currently available spares, to comply with mandated safety, environmental, and air traffic control requirements, to interface with other DoD systems and forces, and to effectively accomplish a validated mission within the current joint-warfighting framework. At some point, it becomes no longer economically feasible to continually modify and upgrade a weapon system to operate in the current environment.
The most critical KC-135 tanker metric is age, and the most pressing KC-135 problems are corrosion and stress corrosion cracking-both age related. Stress corrosion cracking is one of the most difficult structural failures to predict. One can only predict this type of failure by essentially "cutting" into the actual member and performing destructive inspection. These types of failures are largely unpredictable and as the aircraft ages, the number of material failures will also be unpredictable. Therefore, considerable conservatism is placed upon scheduled inspections and replacement frequencies. This in turn drives additional aircraft downtime and increased costs.
The KC-135 performed its air refueling and SIOP missions admirably over its 40-year history. It was designed to quickly provide thousands of gallons of jet fuel to strategic bombers like the - B-47, B-58, B-66 and B-52 through a "flying boom." However, its missions continue to evolve and grow as the US Air Force's requirements to project Global Power and Global Mobility have increased. The KC-135's ability to perform its global mission requires significant modifications. At no time in the life of the KC-135 have modifications been more prevalent. Air Mobility Command just finished a ten-year modification upgrading the aircraft's compass, radar, and Global Positioning Systems. The requirement for additional upgrades continues. Global Air Traffic Management (GATM) and Large Aircraft Infrared Countermeasures (LAIRCM) modifications planned back-to-back will require aircraft to be removed from service (for at least 90 days) to provide these increased capabilities for the operating environment.
Additionally, maintenance issues and "technical surprises" also plague availability. Some examples of recent maintenance problems and costs include:
Stabilizer trim actuator: Approximately 40 percent of the fleet were grounded from September 1999 to February 2000 until overhauled actuators were installed. Investigation results recommended immediate and long-term action to correct the discrepancy and prevent future stabilizer failures. Long-term fixes totaled $50M, but initiation was delayed until FY03 due to budget constraints; $15M remains unfunded.
Fuel System: The fuel system is the largest driver of non-mission capable (NMC) aircraft in recent years. Fuel tank and fuel bladder leaks continually plague the warfighter. Between Jan 98 and Jun 02, the fleet averaged 120 fuel leak repairs per month utilizing 3, 245 man-hours per month at a cost of 41,050,000. Also, the original fuel tank "corrosion preventative" topcoat installed 40 years ago began to deteriorate causing fuel contamination and aircraft down time. Currently, 60-hour fuel filter inspections are conducted and if there is loose topcoat the fuel tanks are entered by maintenance personnel to remove loose topcoat. Technicians take 2,870 man-hours per month to scotch-brite scrub the fuel tanks to remove flaking material. Fuel tank leaks are also a major driver of NMC time.
In dealing with these maintenance issues over the last five years, the KC-135 E Mission Capable (MC) Rate has averaged 71.9 percent and the KC-135R MC Rate averaged 78.0 percent with the maintenance workload of the KC-135E consistently higher (FY03 E-model hours are approximately 10% higher) than the KC-135R.
Faced with continuing degradation from aging and newly emerging operational requirements, the USAF recognized that tanker fleet recapitalization is needed. Recapitalization of the KC-135 fleet (544 aircraft) will take between 30 and 40 years given current DoD and USAF budget projections and constraints. This 30 to 40 year effort is limited by a maximum affordable rate of between 15 and 18 aircraft per year. The net effect of this extended recapitalization process is that some of today's 43-year-old KC-135s may be maintained and operated until they are 70-80 years old. Given the irreversible annual increases in operations and maintenance costs and the annual decreases in combat availability, financial and operational options must be explored to maximize existing capability within existing fiscal and physical resources.
KC-135 Business Case Analysis
Earlier in my written testimony I mentioned that the USAF saw an annual depot price per aircraft grow by 18% compounded annually. This is based on a recently completed SecAF directed KC-135 Business Case Analysis (BCA) based on the FY04 President's Budget (PB) examining three scenarios for retirement of the KC-135Es. It compares cost savings and operational capabilities of three different retirement cases, and assesses cost capability tradeoffs.
The team reviewed the 2001 Economic Service Life Study results and accepted all but the PDM estimates, aircraft modifications, and military personnel estimates. The team chose to update the original ESLS estimates for PDM based on trends drawn from FY91-04 depot unit sales prices, revise the military personnel estimates using FY04 PB submissions, update the modifications to reflect the PB04 position, and convert the ESLS constant-year dollars to then-year (TY) dollars.
Programmed Depot Maintenance
The ESLS PDM analysis assumed that PDM sales rate would grow in the future at one percent a year above inflation and that the work package man-hours would grow at approximately 2.5% per year. That rate is much lower than history indicates. The original ESLS model significantly underestimated the increases in the actual FY03 and projected FY04 sales prices. Therefore, the TRIG used a more realistic sales-price growth rate based on updated sales rates from FY91-FY04.
A more accurate PDM estimate was produced by first calculating an historic average unit sales price (USP) rate for the KC-135 fleet, then developing a PDM growth rate model for forecasting USP out to FY17, and finally, applying the forecast USP to the projected PDM inputs to estimate the PDM cost in the out years. The result of this analysis determined that the 40+ year old KC-135 fleet has experienced an 18% depot cost growth per aircraft over the last 14 years, from $0.8M per aircraft in FY91 to a projected $7.3M per aircraft in FY04!
Military Personnel and Aircraft Modifications
The team changed the ESLS projections to reflect military personnel changes and actual KC-135 aircraft modifications reflected in the FY04PB.
A review of the 2001 KC-135 ESLS estimates as a means of projecting future costs determined that retiring 68 KC-135Es instead of starting retirement in FY09 as was originally planned, will result in a $4.5B cost savings between now and FY17.
As critical as the major structural issues are, the engine strut corrosion problem is the most pressing problem. In 1982-1990, TF-33 engines and struts were removed from retired commercial 707 aircraft (with an average 60,000 flight hours) and, as an interim upgrade, installed on KC-135A aircraft (thus becoming a KC-135E aircraft). This action was taken pending the decision to perform the extensive re-engining effort required to convert them to KC-135Rs.
In 2000, severe corrosion was observed after the partial disassembly of 16 of these KC-135E engine struts during PDM at Boeing Aerospace Service Center (BASC). SPO/Boeing engineering estimated some struts at/near a zero margin of safety and developed an interim repair that must be performed no later than Sep 04 at a cost of $150K per aircraft. Until this is completed, the KC-135Es must operate under a flight restriction. This repair should allow the struts to fly up to 5 years until they must be replaced at a cost of $2.9M per aircraft.
The Air Force's position is that recapitalization needs to begin as soon as possible. This recapitalization should begin with the KC-135E, the oldest and least-capable tanker.
Conclusion
Ideally, the USAF would be able to maintain the entire KC-135 fleet to maximize refueling capability until a follow-on aircraft enters the inventory. However, in the budget-constrained environment of today, the USAF must determine if it is viable to retire the aging KC-135E models in order to save constrained funds for recapitalization. In the worst-case scenario, the USAF would continue to fund ever-increasing costs associated with an aging fleet with declining availability. Eventually the USAF would be forced to start retiring KC-135Es to stay within budget and would not have any funds left for recapitalization.
I appreciate the support provided by Congress and look forward to working with this Committee to best satisfy our warfighter needs in the future.
Thank you for the opportunity to provide this statement for the record.
2120 Rayburn House Office Building
Washington, D.C. 20515
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