Efficiency Through Modernization-Cost Benefits of Re-Engining the B-52_CaptPApplegate

AU/OLMP/2013
AIR COMMAND AND STAFF COLLEGE
AIR UNIVERSITY
Efficiency Through Modernization:
Examining the Cost Benefits of Replacing B-52H Engines
BY
Captain Patrick R. Applegate
A Research Report Submitted to the Faculty
In Partial Fulfillment of the Graduation Requirements
Advisor: Dr. Dennis Duffin
Maxwell Air Force Base, Alabama
March 2013
APPROVED FOR PUBLIC RELEASE: DISTRIBUTION UNLIMITED

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DISCLAIMER
The views expressed in this academic research paper are those of the author and do not
reflect the official policy or position of the US government or the Department of Defense. In
accordance with Air Force Instruction 51-303, it is not copyrighted, but is the property of the
United States government.

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TABLE OF CONTENTS
TITLE PAGE................................................................................................................................... i
DISCLAIMER ................................................................................................................................ ii
TABLE OF CONTENTS...............................................................................................................iii
TABLE OF FIGURES................................................................................................................... iv
ABSTRACT.................................................................................................................................... v
SECTION 1: Introduction............................................................................................................... 1
Research Question: ................................................................................................................. 1
Introduction............................................................................................................................. 1
Assumptions............................................................................................................................ 3
SECTION 2: Background............................................................................................................... 4
Aviation Gas Turbine Development History.......................................................................... 4
B-52H Historic Data ............................................................................................................... 5
SECTION 3: Analysis..................................................................................................................... 8
Future B-52H Operations........................................................................................................ 8
Civilian re-engine programs ................................................................................................. 12
Proposed engine technology ................................................................................................. 12
Potential Replacement .......................................................................................................... 14
Future Costs Current Configuration...................................................................................... 16
Future Savings Proposed Configuration............................................................................... 18
SECTION 4: Compilation and Comparison ................................................................................. 19
Installation Limitations......................................................................................................... 19
Current Engine Cost Summary............................................................................................. 19
Proposed Engine Cost Summary .......................................................................................... 20
Realized Costs....................................................................................................................... 21
SECTION 5: Conclusion .............................................................................................................. 27
Conclusion ............................................................................................................................ 27
Recommendation .................................................................................................................. 28
END NOTES ................................................................................................................................ 30
BIBLIOGRAPHY......................................................................................................................... 33

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TABLE OF FIGURES
Figure 1: Expected Costs for TF33 Overhaul and Fuel ................................................................ 17
Figure 2: Realized Lifetime Costs Using Ideal Model, 2020 Installation .................................... 22
Figure 3: Lifetime Costs Using Secondary Model, 2020 Installation .......................................... 22
Figure 4: Realized Total Costs With Delay Using "Ideal Model"................................................ 23
Figure 5: Realized Total Costs With Delay Using "Secondary Model"....................................... 23
Figure 6: Cumulative Realized Savings using Ideal Model.......................................................... 25
Figure 7: Cumulative Realized Savings Using Secondary Model................................................ 25

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ABSTRACT
The B-52H has been the predominant strategic bomber in the United States since 1960.
Since that time there have been several upgrades covering avionics and weaponry. One change
notably absent has been the engines. The B-52H engines, TF33s, were developed during the
1950’s, and have never been modified. Since the TF33 entered production there have been
several decades of research and development invested in civilian market to create jet engines
which are more efficient, more powerful, and more reliable. Currently, there are still enough
engines remaining in inventory to support the current B-52H fleet until retirement from the Air
Force inventory in 2045. Replacement parts are not the sole reason for modification and
modernization. Due to increased labor costs, rising fuel prices, and low reliability of inventory,
the costs associated with maintaining these engines continues to rise. Modern engines, on the
other hand, provide not only efficiency increases, but also require significantly lower
maintenance requirements both day-to-day and long term. These factors when converted to a
dollar value indicate that engine replacement of the B-52H is still cost effective, especially
taking into account the longevity of the aircraft with no replacement readily available. The B-
52H and the Air Force can still benefit from re-engining in a finite timeline, and associated costs
of delay significantly reduce realized savings. In light of current fiscal and budgetary
constraints, re-engining the B-52H is an economical decision that will save critical Air Force
resources.

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SECTION 1: Introduction
Research Question:
This research uses a quantitative framework to answer the question “Is it more cost
effective to replace the engines on the B-52H or keep the current variant, given the aircrafts
predicted service life through 2045?”. Current and past B-52H operations were used to predict
future flight requirements for cost analysis. A comparative analysis was conducted using the
KC-135 re-engine program to reasonably estimate the costs associated with research,
development and installation. Due to the scope of this research, examination was limited to a
single potential replacement engine. A quantitative measure of this engine was derived based on
current operations information in civilian fleets. Using a quantitative framework, future costs
were compared for the current and proposed engine. Lastly, this research examined the
operating costs and realized savings to determine overall economy and answer the research
question.
Introduction
Over the last decade, oil and fuel prices have steadily risen while USAF budgets have
decreased. The biggest consumer of fuel and oil in the Air Force is the aircraft fleet. The B-52H
has been using the same engine model since rolling off the factory floor in 1962, with no
significant changes or modernization. When the B-52H engine was initially developed, gas
turbines had only been in production for a decade. Since then, over 60 years of research and
development has yielded more efficient and more reliable models used in both military and
civilian applications. Some studies have estimated that gas turbine development has yielded
efficiency in fuel alone at 60% over the last seven decades.1
In that same time due to
proliferation to more than just military aviation, reliability and safety have also increased. These

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efficiency and reliability factors are what would make a new engine economical, yielding
significantly reduced day-to-day and long term operating costs. The Air Force plans to keep the
B-52H in service until 2045 or beyond and expects to utilize the current engine variant until the
aircraft is retired.2
This research paper examines the cost associated with B-52H operations with respect to
maintaining the current engine and compare them with the costs associated with B-52H
operations using a new engine. If the new engine long term cost benefit over the current engine
exceeds the procurement costs over the expected lifetime, then the modification would be
economical. Additionally, any savings found would directly influence future Air Force budgets
and enable additional strategic purchases, or planned budgetary decreases. Due to the time
involved, this could equate to billions of dollars. Initially this research examines and compares
these costs to determine annual cost savings. The final part of the paper examines this savings to
answer the question of whether it is more cost effective to replace the engines on the B-52H or
keep the current variant.
Primary sources directly related to the research material come from Air Force budgetary
and maintenance documentation to show current and past operating and logistical costs
associated with the B-52 fleet and engines. Additionally prime contractor reports to the Air
Force and congress will be used for past, current and future engineering analysis. Finally,
technical data from engine manufactures GE, and Pratt & Whitney will be used as primary
sources for future cost estimates and efficiency analysis.
Understanding that some of the information from contractors and manufacturers may be
biased, these primary sources are backed up and supported by secondary sources. These
secondary source journal articles come from technical journals, including International

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Aeronautical Engineering Association symposiums and conference proceeding, about gas turbine
and jet engine technology. Additionally some supporting information comes from general
scientific journals, including the International Journal of Materials, Manufacturing and
Mechanical Engineering, regarding manufacturing and maintenance to demonstrate newer
technology has lower operating, maintenance and replacement part costs. Additional secondary
sources include research papers on commercial and military fleet maintenance, modernization
and budgetary concerns. These sources are used to emphasize the importance of the subject
matter and support the argument.
The final supportive sources are personal interviews with Air Force maintenance
personnel, and aviators. These interviews further support primary source claims and strengthen
the research. Interviews were conducted with only those subjects that have a detailed and
historic background in the B-52, or gas turbine technology.
Assumptions
This research, covering future cost calculations, utilized several assumptions in
calculations and quantitative analysis. The first assumptions is that the rate of inflation for fiscal
year dollars (FY$) from 2010-2045 will remain relatively constant at 2%.3
The second
assumption is that the B-52 will maintain a relatively stable operations tempo over the remainder
of its expected life. This assumption is the same used by the AF Systems Center to determine
the expected lifecycle of the B-52. Should the B-52 Operations tempo increase or decrease the
lifespan would change as well, however total flight hours over that lifespan would remain the
same. To mitigate confusion, research and analysis was predominately based on overall hours,
the defining factor in the B-52H operation life, and the driving force behind fuel costs, overhaul
timelines and maintenance costs.

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SECTION 2: Background
Aviation Gas Turbine Development History
The first jet engines for aviation use were developed in the closing days of World War II
(WWII) with the first production model being put in to service in the Messerschmitt 262. After
WWII ended there was an incredible increase in the rate at which new aircraft were developed.
From WWII to the 1950s, the USAF and Strategic Command had gone through several propeller
bombers including the B-17 and B-29. The first all jet bomber in the United States was the B-47
flown in 1947. The B-47’s engines were inefficient and did not have the required thrust to even
get the aircraft in the air at most airfields, necessitating the need for Jet Assisted Take-off.4
The
first truly strategic bomber was the B-36 produced in 1949. The B-36 had four jet engines
matched with six piston driven engines to provide adequate thrust to get into the air. After the B-
36, the Air Force created the first strategic all jet bomber, the B-52. Originally designed as a
straight wing propeller driven aircraft, Boeing engineers literally re-designed overnight the eight
engine swept wing model that would eventually go into flight-testing.5
Over the course of
production, the B-52 went through several design changes until the final variant, the B-52H,
rolled out of the assembly plant in 1962. The engines on the B-52H, the TF33 high bypass
turbofan, were first developed in the early 1950s and entered production in 1960, still the dawn
of the jet age.6
Since the 1960s, jet engine technology has increased significantly with gas turbine
engines being found on tanks, ships, and aircraft, both civilian and military. While the TF33 was
utilized on KC-135, E-3, E-8 and RC-135 aircraft, each of these was developed during the 1960s
and 1970s. The last production TF-33 came from the assembly plant in the late 1970s.7
As
research and development into jet engines progressed, efficiency and advancement came out as

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well. Since 1960, General Electric, a single gas turbine manufacturer, has produced over 20
military production engines and numerous test engines each more efficient that the last.8
These advances in jet engines have given aircraft greater capabilities as far as thrust,
cruise performance, and fuel efficiency. These capabilities directly relate to a military aircraft’s
ability to perform combat aviation, with increased payloads, longer loiter time, and greater
performance envelopes. A B-52H with modern engines would be more lethal, over a larger area
of the globe using fewer resources in a financial sense as well as integration and support
requirements from other Air Force assets.
B-52H Historic Data
The B-52H is the workhorse of the Air Force, having been in service for over 50 years.
With looming cuts to the defense budget, and the inability to fund a replacement bomber
program, the B-52H can be expected to remain valuable for the foreseeable future. In fact,
current estimates have the B-52H remaining in service until 2040-2045.9
One of the biggest
factors to this incredible longevity is the expected flight hours per aircraft. Currently the B-52H
fleet is considered relatively young with an average time of 18,000-22,000 hours, although some
aircraft have higher and lower airframe time.10
The majority of the B-52H’s early life was spent
conducting nuclear alert with limited flying operations. The first use of the B-52H in
conventional operations was Desert Storm in 1991. Since then, the B-52 has been called into
service for numerous military operations around the globe, participating in combat operations
supporting Operations Allied Force, Enduring Freedom, and Iraqi Freedom. Additionally the B-
52H is supporting continuous presence in the Pacific Area of Operations on Andersen AFB,
Guam.

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Based on engineering analysis conducted by Boeing and the Air Force the B-52H has a
structural service life approaching 35,000 flight hours without any structural component changes.
This is based on the upper wing surface structure. Under current training conditions, this extends
the airframe life of the majority of the fleet past 2050.11
Based on these assessments, the B-52H
will fly at least another 12,000 hrs per aircraft after 2012 without any life extensions. When
taking into account the fleet of 76 aircraft, not including attrition reserve aircraft, the B-52H fleet
will fly for a combined 912,000 more hours before retirement.
“The B-52H is the aircraft equivalent of an iPAD….. Whatever the Air Force or United States
needs there is an app for that”
– LtGen James M. Kowalski, Commander Air Force Global Strike Command, Global
Strike Symposium, 7 Nov 2012
The B-52H has evolved significantly since first entering service as a nuclear only
bomber. The B-52H is currently the only aircraft capable of carrying the AGM-86C,
Conventional Air-Launched Cruise Missile, and the powered ADM-160, Miniature Air
Launched Decoy, both critical weapons systems for future conventional conflicts. Additionally,
the B-52H carries almost every other air to surface weapon in the Air Force inventory12
. This
flexibility and adaptability ensures that the B-52H will be part of any major combat operations in
the future and will remain a part of the USAF inventory until it reaches its service life.13
One of the major components never replaced since entering service is the TF33 engine.
While current inventory predictions have this engine lasting the remainder of the B-52H service
life, it is an antiquated high bypass turbofan, unimproved in 60 years. The engine itself has

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proven reliable, to a point, and the Air Force has several thousand in storage due to a wide
variety of legacy aircraft that utilized them. Some of the major failings of the TF33 are high
overhaul and operational costs. Additionally, the TF33 is inefficient by current standards,
developed at the dawn of the jet age when efficiency was a trade-off for power.
The B-52H has been a candidate for re-engining in the past, but allocation of funding
never occurred. In 2002 the Government accounting office recommended immediately re-
engining the B-52 for an expected savings of $9 billion through 2037. This proposal was not
carried forward however because Air Force officials were skeptical of the actual savings.14
Additionally, the Air Force was trying to ensure funding for the F-22 and tanker leasing.15
In the current fiscal environment, if there is a means to save anywhere in the Department
of Defense budget it should be examined. Utilizing wasteful components just because they are
available is not a justifiable excuse, especially if the cost of replacement combined with
operation is lower than current configurations.

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SECTION 3: Analysis
Future B-52H Operations
Current B-52 operations are governed by the defense budget under the flying hours
program. Additionally after 50 years of use the reliability, and consistency of operations has
yielded stable numbers from which cost calculations and future predictions can be made. At
maximum combat thrust, the TF33 has a thrust specific fuel consumption (TSFC) of .52, which
equates to a fuel consumption of 34,000 lbs an hour.16
At a more modest cruising thrust ratio,
assuming all eight engines are operating, the B-52H utilizes just over 20,000 lbs or 3,100 gallons
per hour of JP-8.17
Given that each B-52H flies approximately 500 hrs annually this figure adds
up quickly. The entire B-52H fleet flies 38,000 hrs annually utilizing 117.8 million gallons of
fuel. While synthetic fuel is approved for the B-52H, the primary fuel source is JP-8, currently
priced at $2.31 per gallon.18
Applied against the previously mentioned flying rates and expected
fuel consumption, means the total cost for fuel alone to operate the fleet runs the Air Force
$272.1 million annually. This is no small sum when considering the current fiscal environment.
Additionally inflation will influence fuel prices as well. This does not include cost of man-hours
involved in day to day operations.
The economics of labor is another cost associated with the B-52H. Some might argue
that active duty military personnel receive pay regardless of where they work. The fact is, if they
were not used to service the B-52H and its engines, maintenance personnel could be assigned
another post or career field potentially saving the need to hire civilians, or preventing the Air
Force from exceeding authorized end strength. Consequently, while potentially not a 1-1 savings
it is still a real savings if less personnel are required for maintenance operations. During
operational use, the engines for the B-52H require three personnel to pre- and post-flight every

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sortie, for a combined man-hour accumulation of 6 hours per flight.19
This mostly involves
checking and securing access doors, checking and filling fluid levels, and repairing seals for oil
and fuel leaks, and requires lots of movement of equipment across all eight engines. The average
rank of these personnel is E-4 meaning that they have an annual salary of $27,600 in FY13$.20
Each aircraft is prepared to fly approximately 130 days each year, giving 9880 fly days across
the fleet. While some of these days the aircraft are ground or engine running spares, the
maintenance actions that need to be completed are the same as if it is going to fly and therefore
still counted towards the total. This number of fly days requires 59,280 man-hours of labor for
engine upkeep and maintenance annually. On average, military personnel are expected to work
40hrs a week for 46 weeks a year taking into account federal holidays and annual leave. This
sum yields an average of 1840 hours per year. Combing this number with the hours required to
maintain engines means that to maintain engine operations on the B-52H the Air Force accepts a
person-hour cost of 32 full time Airmen, or $889,200 in personnel costs. While this number may
seem staggering for the combined fleet, it must be put into perspective that it is spread across
four wings, three bases, and eight flying squadrons.
One of the last costs associated with engine operations on the B-52H is overhaul and
replacement of the TF33. While there is no more procurement of TF33 engines, they do still
require overhaul every 1,100hrs at the Oklahoma City Air Logistics Center, near Tinker AFB.21
During previous studies of engine replacement for the B-52H, overhaul costs of the TF33 were
estimated to be relatively stable for the remainder of the B-52H lifecycle. This lead Air Force
leadership, in disagreement with Government Accounting Office and Boeing estimates, to reject
B-52H re-engining recommendations. This however has proven to be a tragically false
assumption. The last study conducted in 2000 used an overhaul cost of $257,000 (FY96$) per

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engine with expected costs through 2037 to rise no higher than $300,000.22
This contrasts
significantly with the current cost, which exceeds $832,000(FY04$) per engine with an estimated
increase of 5% annually.23
Using previous calculations for flying hours, and a maximum flight
time of 1100 hours per engine, at a minimum the Air Force will have to overhaul 34 engines
annually for a cost of $28.56 million. On average, the reliability rate is significantly lower than
estimated. The Air Force has an actual requirement to overhaul 87 engines annually, for a total
cost of $73.1 million.24
Research and Development
Research and development costs for a new engine can vary widely. There is an infinite
number of significant fluctuations based on designer, technology used, manufacturing processes,
quantity bought, contractual changes, and congressional input. For the sake of this research,
there is a limitation on these fluctuations imposed. Due to the age of the aircraft and the costs
associated with major structural and interior changes, this research examines the costs with using
off the shelf technology. Additionally this research examines a one for one engine swap utilizing
the same nacelles, covers, inlets and cockpit configuration. This is a similar model used for the
KC-135E engine replacement. While this does potentially limit some options that exist, it is also
the most realistic scenario given the costs associated with new acquisition, the risk of
aerodynamic changes, and the training costs associated with re-training all pilots to operate in a
different cockpit configuration. This is especially true in the current fiscal constraints of a
recession economy, and sequestration.
KC-135 re-engine program
The KC-135E and the B-52H both had early development jet engines after initial
production. During the late 1980’s a study was conducted to determine if it would be

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economically feasible to re-engine the KC-135E with modern advanced engines to improve
payload, range, and efficiency. Many of the reasons for this upgrade are the same as for the B-
52H. At the same time, the KC-135E had an expected service life until 2035-2040, rising gas
prices, and reliability issues. Additionally the improved performance and efficiency of newer
engines increased operational capability, and lowered maintenance costs associated with engine
replacement and servicing.25
Given the KC-135E engine modification, from 1960 to 1985 the engine technology
improved such that the entire fleet experienced a 12% increase in fuel economy, on top of a
higher payload capability due to increased thrust.26
The KC-135E re-engine program utilized
specific criteria to limit installation and development costs. During the selection process,
bidding contractors had a requirement to utilize the same engine pods, fuel inputs, and engine
instrumentation sensors. While there were some cockpit modifications, none was significant or
affected the avionics programs. With the KC-135E modernization, the total cost of the program
to modify 116 aircraft in the National Guard and Air Force Reserve was $500 million (FY85$).27
This equates to a unit cost of $4.3 million per aircraft.
The KC-135R was another successful re-engine program for the tanker inventory. This
program was larger in size and scope than the KC-135E, replacing the engine struts, pylons,
associated components and engine instrumentation with commercial off-the-shelf CFM-56
engines from General Electric.28
This program covered 390 aircraft at a cost of $8.2 billion, or
$21 million per aircraft.29
The previous B-52H re-engining proposal started in 2003 utilized a
proposal similar to the KC-135R, with changes to significant structural components and cockpit
configuration.30
This is a significantly larger scale program with much higher initial costs and a
longer period before realizing a net return.

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Civilian re-engine programs
Utilizing off-the-shelf civilian components reduces the required testing to compatibility
and modification requirements as opposed to a full research and development program starting
with a new design. This approach speeds up the required time to modification, while allowing
for a significant amount of reliability and emergency information to be readily available. Due to
the high flight time of most commercial engines, there is already significant knowledge that will
help indicate expected failure rates, root causes, and mitigation procedures that will ultimately be
incorporated into any maintenance procedures and timelines. Additionally, there is also a ready
supply of potential outside instructors and experts that can be utilized during the military
conversion limiting downtime normally required to train new systems.
Another advantage to utilizing commercial engines is that there is virtually no
requirement to purchase or maintain a large supply system of parts, or entire engines. These
materials can be purchased as needed from the civilian supply chain. Only in remote, or wartime
conditions would a supply network need to be implemented to ensure rapid availability. While
the potential savings of this is beyond the scope of this research it would need to be examined
and valued should the Air Force pursue re-engining.
Proposed engine technology
Commercial engine technology has been refined over the last seven decades to account
for efficiencies, and maximize power per pound of fuel. This enables airlines to transport more
people and cargo at lower costs to maximize profit margins. Based on the KC-135 lessons
learned, the B-52H could be expected to see at least a 12% increase in fuel efficiency. This
efficiency can significantly lower operating costs. Additionally, the day-to-day labor costs
associated with operations of the engine will significantly decrease. Utilizing the commercial

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airline for an example, there is nothing beyond refueling required to service an aircraft over
several days of operation. This saves both labor and consumable resources. There is no daily
requirement to add oil, check compression sections, replace hydraulic fluids, or to check
generator sections, all part of B-52H pre and post-flight maintenance.
Maintenance costs savings is one of the prime benefits of utilizing commercial
technology. Because airlines operate their aircraft for several cycles a day, every day of the year,
any downtime for maintenance is significantly costly to production and risks the cancelation of
flights, and connections, which in turn has an impact on customer service, which has an
additional related economic impact. Many of the engines designed for civilian carriers are built
to minimize maintenance and have high engine time before requiring any service work. Based
on civilian operational requirements, there is the potential that a new engine might never require
replacement once installed based on the expected lifetime of the B-52H.31
Additionally many
modern engines have built in diagnostic modules, computer hook-up and health assessment
capabilities that can aid maintenance in diagnosing a problem before it becomes a major issue, or
speeding up the troubleshooting timeline by automatically testing certain functions and
components.32
Fuel efficiency is another area where a new engine could have significant cost savings.
In the B-52H, the current engines can already produce more thrust that the aircraft can take due
to an airspeed limitation of 390 knots indicated airspeed or .84 Mach, whichever is lower.
Additionally, the maximum gross weight is limited by structural strength, not thrust to weight.33
With newer engines, aircrew could achieve the same thrust at a much lower power setting,
thereby consuming less fuel. This, coupled with advances in engine technology over the past
two decades, increases the potential fuel efficiency and overall cost savings.

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One of the most difficult areas to estimate is the potential cost of research, development
and installation. The biggest factors for this are any changes in aerodynamic components,
testing, and certification. The assumptions that a new engine must fit into the current cowling,
connect to the current fuel supply systems, and integrate with current monitoring assemblies,
significantly lower the cost of installation. These same criteria were used during the KC-135E
re-engine program. Because the process is essentially the same both in scope and fleet size, KC-
135E costs can be used as a best estimate modified for inflation between 1985 and 2013. This
would be the “ideal model” when considering a major aircraft modification, on a cost
perspective.
While the KC-135E re-engine most similarly resembles the best option for the B-52H, the
KC-135R re-engine program represents a secondary example. While potentially viable, this kind
of a program has increased inherent risks and costs associated with the level of complexity.
Using both models and comparing them to current configuration costs is required. This provides
a more complete analysis regarding any potential replacement.
Potential Replacement
Based on the criteria of minimum modification to the aircraft to limit cost the General
Electric CF34-10 is a prime candidate for a re-engining program. This engine flies on civilian
fleets around the world for both regional and cross-country operations.34
Due to its size and
shape it can readily fit into the current B-52 engine pods, and it offers 3000 pounds-force more
thrust than the TF33 with slightly less weight.35
All of these factors indicate that this engine can
offer performance increases, fuel savings, and maintenance cost savings over the life of the B-
52H.

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Comparing the CF34 to the TF33, one of the most important aspects is specific fuel
consumption to determine efficiency. Since fuel is currently the highest cost associated with B-
52H operations any savings in fuel efficiency can dramatically escalate the value of re-engining.
The CF34 has a TSFC at sea level of 0.38 compared to the TF33’s 0.52.36
Since TSFC
specifically relates to engine efficiency, theoretically the CF34 will allow for fuel savings of
approximately 27%. Because these savings are calculated at maximum thrust, and for the
majority of flight the B-52H would be below this, there is realistically additional efficiency that
cannot be determined without testing.
The second largest projected cost for the B-52H is TF33 engine overhaul. One distinct
advantage of the CF34-10 over the TF33 is the expected time between engine overhaul.
Currently there are over 1000 CF34-10 engines in commercial fleets worldwide with a combined
3 million flight hours. The entire CF34 line has over 5000 engines and 72 million flight hours
boasting a 99.95% reliability rate.37
This makes it unlikely that the B-52H will ever lose an
engine for other than hostile action or foreign object damage (FOD), so it will probably not be
necessary to overhaul or replace any engines for the remainder of the B-52H service life.
The last major cost associated with B-52H operations is personnel costs. Utilizing the
CF34 engine the B-52H would drastically reduce man-hour requirements. There are no
requirements to service the engine after every flight. However, due to Air Force safety concerns
and the inherent risk of military aviation; there should be some visual inspections pre and post
flight to protect against FOD and other abnormalities. Instead of utilizing three Airmen for a
man-hour total of 6 hours for pre and post maintenance, it is more realistic to expect a single
Airman working for less than one hour, most likely in conjunction with normal crew chief
operations.

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Based on the KC-135E modification there will be an initial upfront cost associated with
any engine modification to both buy the engines and then modify the aircraft. Because of the
similarities in programs adjusting the KC-135E total cost for inflation and then doubling it to
account for the number of engines being modified give an estimate of $1.74 billion (FY13$).
Dividing this between the fleet to be modified gives an estimate of $22.9 million per aircraft.
Currently the engines themselves are approximately $1.8 million each leaving, $646.6 million
for research and development costs, well in line with the expectations based on the KC-135E.38
Analysis based on this program is referenced as the “Ideal Model”, as it is the least complex and
most cost effective option.
A previous estimate of re-engining in 2003 by Boeing assumed a total cost of $3.3 billion
but comprised a change in the number of engines requiring a complete aerodynamic change of
the wings, struts, nacelles, and cockpit configuration.39
This is similar in both size and scope to
the KC-135R model. Applying per aircraft costs to the current B-52H fleet and then modifying
for inflation, a project of this magnitude would be expected to cost approximately $5.3 billion
(FY13$). In this case, using the same cost for the physical engine, $4.4 billion would be
available for research, development and testing. This is approximately $1 billion more than the
most recent Boeing proposal adjusted for inflation. Analysis based on this program is referenced
as the “Secondary Model”, as it is the most complex, more prone to risk, and most expensive
option.
Future Costs Current Configuration
As the years progress and inflation, and other economic factors change, there is
reasonable assumption that costs for goods and services will increase. Over time, the B-52H
supply and maintenance chain has demonstrated this several times. In previous studies on B-

17
52H re-engining, these future costs have been sorely misunderstood, underestimated and
subsequently incorrectly analyzed. If these costs had been properly examined it is possible that
the B-52H may have been re-engined already. Using historical basis, the Air Force now
estimates that the costs associated with engine overhaul will significantly increase at a rate of 5%
per year through the life of the TF33.40
Based on this estimate over the remaining life of the B-
52H the cost of annual engine overhaul will exceed $400 million by 2040, with a lifetime cost of
$8.7 billion by 2045 as demonstrated in figure 1.
Figure 1: Expected Costs for TF33 Overhaul and Fuel
It is exceedingly difficult to predict future costs for fuel and personnel due market
volatility and political influence. One can make a reasonable assumption however that both will
track in line with expected inflation. While there may be some fluctuations this is a common
method, and falls in line with historical norms.41
Utilizing the rate of inflation against fuel and
personnel costs it can be estimated that under current configuration and practices the Air Force
will spend over $464 million on fuel and $1.5 million on personnel for engine operations. Over
the remaining service life, this leads to a total cost of $12.5 billion for fuel costs and $41 million
for personnel. These are not small sums by any stretch. This is a relatively conservative
$100,000,000
$150,000,000
$200,000,000
$250,000,000
$300,000,000
$350,000,000
$400,000,000
$450,000,000
$500,000,000
$550,000,000
2013 2018 2023 2028 2033 2038 2043
Fuel
TF33 Overhaul

18
estimate for fuel considering that over the last decade the cost has actually increased over 51%
even after adjusting for inflation.42
Future Savings Proposed Configuration
Due to the efficiencies of the CF34 there can be significant savings over the life of the
program. One of the first major areas where costs are significantly lower is in the maintenance
costs. Due the reliability of modern engines and the CF34 in particular there is no expected
overhaul costs for the remainder of the B-52H service life. The probability of a loss of engine
due to hostile fire or FOD is the same regardless of engine and therefore will not be measured or
estimated. Associated with maintenance costs is the person hour cost of a new engine. Using
the estimate of one-person hour per sortie the annual cost adjusted for inflation will be
$279,289(FY40$) for the entire fleet. Over the life of the program, this could be $6.8 million.
Fuel costs per gallon will be the same regardless of engine type. Where fuel costs will
differ is in the expected efficiency of the CF34 over the TF33. Based on the previous
calculations for TSFC there can be an expected fuel savings of at least 28%. In addition, there
are additional savings that cannot be calculated in the scope of this research related to lower air
refueling requirements, and greater range. Additionally based on maximum thrust of the CF34-
10 being 17% higher than the TF33, there will be additional savings that cannot be calculated
without testing due to significantly lower throttle settings over the duration of flight.

19
SECTION 4: Compilation and Comparison
Installation Limitations
The previous estimates on costs and associated savings were based on an immediate
installation of engines across the entire fleet. While good for theory, it is not practical in realistic
terms for several reasons. To truly prove or disprove the overall cost benefits of re-engining one
must examine the costs and savings over several timelines. This gives a more accurate picture of
potential savings for decision makers, and allows for a determination of the crossover point
where potential savings are equal to future costs without modification. Failure to implement the
program by this crossover point may still yield performance benefits but negates any cost benefit
to the program.
Current Engine Cost Summary
For the KC-135E program, complete installation on all aircraft from contract acceptance
through final installation was six years.43
The 2004 Defense Science Board assessment of a B-
52H re-engine program also determined six years to be optimum.44
Based on these examples and
assuming that the contract could be awarded by the end of 2014, then 2020 would be the first
year that any re-engine program could be completed. As such, this research examines the costs
associated with current engines through 2020, 2030, and 2045, the expected retirement date.
The current engine costs to operate the B-52H through 2020 are estimated using
acceptable levels of inflation applied to the previously calculated figures for maintenance, fuel
and personnel. Using these numbers, baseline costs can be determined from present time
through 2020, 2030, and 2045 respectively. From 2013 to 2020, the cost of engine overhauls,
labor, and fuel will increase to $153 million, $1 million, and $312 million respectively annually,
for a total expenditure of $3.38 billion over the next seven years.

20
Assuming that a re-engining did not occur by this time the Air Force will continue to
experience cost growth for maintenance, labor, and fuel. By 2030, annual costs for engine
overhaul, labor, and fuel will further increase to $249 million, $1.2 million, and $631 million
respectively. Overall total expenditure from 2013-2030 will exceed $8.9 billion.
Keeping the current configuration throughout the remainder of the B-52H service life
further increases costs. By retirement, the cost of engine overhaul will exceed fuel expenses.
TF33 overhaul will rise to $518 million annually, labor to $1.6 billion, and fuel to $513 million.
Total expenditures over the total remaining service life would exceed $21.3 billion. Engine
overhaul costs over the remainder of the B-52H life are a significant portion of the total
operating costs that the Air Force will need to absorb maintaining the current configuration. If
engine overhaul costs had remained as previously estimated, no higher than $300,000 per engine,
the total engine operating costs through 2045 would be $13.4 billion. This total cost difference
of $7.9 billion was not included in the previous re-engining study.
Proposed Engine Cost Summary
As discussed previously, based on a historic model the soonest that a complete engine
modification could occur across the fleet is by 2020. While there would be marginal savings as
aircraft finish installation, the first year of operational savings would be at that time. Based on
the previous analysis, there should be no costs associated with engine overhaul using CF34
engines. Due to the exceptional reliability of the CF34 it is unlikely that a catastrophic incident
will even occur over the remainder of the B-52H service life. One of the advantages of utilizing
a widely available commercial engine is that there is virtually no need for the Air Force to
purchase spare engines to sit in storage, further reducing costs of re-engining. If a catastrophic
failure occurred requiring a new engine, one could simply be purchased on the commercial

21
market. The primary expenses associated with operating the new engines would be fuel and
labor. Adjusted to FY20$, and taking into account the man-hour and efficiency savings, the first
year operation costs can be estimated at $170,235 for labor and $228.2 million for fuel. This
yields an operational savings of $238.7 million in a single year. Cumulative operational savings
through 2045 would be $10.7 billion.
Realized Costs
Realized costs savings are the overall assessment of savings taking into account
additional factors beyond operational costs. These factors include installation as well as research
and development costs. Additionally, the costs to operate in the current configuration until
installation is completed must be included into the new configuration costs because the Air Force
will still be required to assume this cost while undergoing modification.
Figures 2 and 3 represent the realized costs utilizing the “Ideal Model” patterned after the
KC-135E re-engining program and the “Secondary Model” patterned after the more complex
KC-135R re-engining program. These figures demonstrate the break-even point, or the point at
which the cumulative lifetime cost of re-engining is equal to the cumulative lifetime cost of
maintaining the current engines. After this point, or date, the difference in programs can be
considered net savings for the remaining B-52H service life. The ideal model, having lower
initial costs, yields an earlier return on investment and greater overall cumulative realized
savings of $9.3 billion. The secondary model, having higher initial costs, yields a later return on
investment but still a sizable realized cost savings of $5.6 billion.

22
Figure 2: Realized Lifetime Costs Using Ideal Model, 2020 Installation
Figure 3: Lifetime Costs Using Secondary Model, 2020 Installation
Should the Air Force not implement a re-engining program immediately, there are
additional associated costs of delay which factor into realized costs and savings. Factoring in
these costs to determine total cost of re-engining at a later date is critical to the decision making
process. The costs of delay are a combination of the current operating costs of the current
configuration until new engines are implemented, as well as inflationary costs against total re-
engining program costs. This in effect increases the overall program costs over the lifetime and
delays the return on investment point. While time is dependent on the scope of the program,
$0
$5
$10
$15
$20
$25
2013 2018 2023 2028 2033 2038 2043
Billions
TF33 Lifetime
Costs
CF34 Lifetime
Costs
$0
$5
$10
$15
$20
$25
2013 2018 2023 2028 2033 2038 2043
Billions
TF33 Lifetime
Costs
CF34 Lifetime
Costs

23
these costs of delay will eventually invalidate any potential savings and render the program
uneconomical.
Figures 4 and 5 show the cumulative costs and demonstrate the impact of costs of delay
using an installation completion of 2025, 2030, and 2035 for both “Ideal Model” and “Secondary
Model”. The total overall cost of re-engining increases for each year of delay. Matching these
against TF33 costs shows the decrease in overall savings as the program is delayed until such
time as the program becomes ineffective economically.
Figure 4: Realized Total Costs With Delay Using "Ideal Model"
Figure 5: Realized Total Costs With Delay Using "Secondary Model"
$0
$5
$10
$15
$20
$25
2013 2018 2023 2028 2033 2038 2043
Billions
TF33 Lifetime
Costs
CF34 Lifetime
Costs 2025
CF34 Lifetime
Costs 2030
CF34 Lifetime
Costs 2035
$0
$5
$10
$15
$20
$25
2013 2018 2023 2028 2033 2038 2043
Billions
TF33 Lifetime
Costs
CF34 Lifetime
Costs 2025
CF34 Lifetime
Costs 2030
CF34 Lifetime
Costs 2035

24
Figures 4 and 5 give a clear graphical depiction on why delays in implementation can be
costly. One note to these charts is that they assume an even split of research and installation
costs across the six years prior to final installation. While this ultimately does not change the
return on investment point, it does impact initial costs and budgeting on the Air Force as a
whole. .
The last thing that must be calculated is the minimum required cost savings to make the
acquisition program economically viable. An understanding of the fluidity of economics is
required before undertaking any acquisition programs. There will be some variables that cannot
be accounted for and always the potential for unforeseen complications. Even when using means
of preventing cost overruns such as fixed contract costs, and the Nunn-McCurdy Process, major
Air Force programs historically run 20% over cost.45
Given this fact in order to determine if re-
engining is economically viable the desired savings should be greater than the costs of
implementation plus 20%. This percentage can be lowered depending on the value of
unsubstantiated benefits such as improved performance, duration, range, or in the case of the B-
52H lower reliance on support aircraft. The percentage may even be increased to account for
additional risk such as unproven technology.
Since this analysis already incorporates expected cost using a realized savings
calculation, the realized savings, displayed in figures 6 and 7, will need to exceed 20% of the
implementation costs to ensure the program is still economically viable under average cost
overrun. This yields a realized savings requirement under the ideal model of $348 million.
Utilizing the secondary model, the desired savings would be $1.08 billion. Cumulative realized
savings are shown based on expected year of completed installation.

25
Figure 6: Cumulative Realized Savings using Ideal Model
Figure 7: Cumulative Realized Savings Using Secondary Model
It can be seen from figure 6 that conducting a form-fit-function engine replacement
program, under the assumptions of an ideal case model, allow for program implementation
through 2035. This does not allow for any changes to the baseline calculations concerning
inflation and labor costs so delay in implementation still carries additional risk. Furthermore
delaying implementation from 2020 to 2035 effectively yields a loss in realized savings of $5.8
billion.
-$4
-$2
$0
$2
$4
$6
$8
$10
2014 2019 2024 2029 2034 2039 2044
Billions
CF34 Realized
Savings 2020
CF34 Lifetime
Savings 2025
CF34 Realized
Savings 2030
CF34 Realized
Savings 2035
-$8
-$6
-$4
-$2
$0
$2
$4
$6
2014 2019 2024 2029 2034 2039 2044
Billions
CF34 Realized
Savings 2020
CF34 Lifetime
Savings 2025
CF34 Realized
Savings 2030
CF34 Realized
Savings 2035

26
Due to the higher initial costs associated with a complex re-engining program, as
described under the secondary model, there is significantly less allowance for delay than under
the ideal model. Figure 7 shows that while a delay from 2020 to 2030 is feasible using a 20%
cost overrun, this allows little room for other unforeseen circumstances. Additionally if any of
the planning assumptions are incorrect the entire program could become cost prohibitive after
initial investment, leading to a point where the Air Force would accept a net loss because it is
still less expensive to move forward than it would be to return back to before the engine
modifications started. Failure to implement re-engining by 2020 would effective yield a loss in
realized savings of $4.5 billion by 2030.
There is inherent risk assumed by decision makers anytime that fiscal decisions are
delayed. Based on the previous miscalculations on the cost of fuel and the cost of engine
overhaul, there is a chance that these could rise significantly higher than projected again.
Inflation in a global economy can also change rapidly and without much foresight. Lastly fuel
prices are heavily dependent on the market in the middle-east but the region is volatile and
unstable which could increase costs rapidly for not just fuel, but maintenance transportation cost,
and the price of material goods.

27
SECTION 5: Conclusion
Conclusion
There is definitive cost savings in the re-engining of the B-52H. Many of the arguments
for re-engining proposed in the past are still valid today. High fuel costs associated with
inefficient engines will continue to drain Air Force funding. Maintenance costs will continue to
increase for antiquated parts based on inflation, wage rates, and resource requirements. The B-
52H will continue to fly until 2045. Previous re-engining studies failed to adequately capture the
true costs of maintaining a 60-year-old engine.
While previous engine modification proposals were for major overhauls to the aircraft,
following the KC-135E example and using an ideal model, limiting the modification to the
minimum amount, can significantly reduce initial costs and significantly improve overall savings
of the program. This coupled with the savings of using readily available commercial
components with proven reliability and efficiency just bolsters the value of re-engining. A
realized cost savings of $9.3 billion demonstrates the viability of re-engining the B-52 in this
method.
There is an opportunity however to still see savings and conduct a major modification to
the aircraft. Following the KC-135R example and implementing a secondary model example is
still a viable option. This choice would allow additional benefits, beyond the scope of this
research, that come from having newer cockpit instrumentation and a wider selection of potential
engine replacements. The more modest realized cost savings of $5.6 billion of the secondary
model are still attractive. The main detractor from implementation is the long, 20-year return on
investment time.

28
There is a critical need however to implement a re-engining program immediately. While
costs savings exist significantly into the future, to realize the greatest return on investment the
installations need to occur in the near future. Failure to do this continues to waste resources
needed in other critical areas in the Air Force.
While the fundamental cost savings of re-engining the B-52H could be felt across the Air
Force, the intangible savings are also significant. Improved performance of the aircraft saves
reliance on other legacy systems to support operations, increases operational capabilities across
the battle space, and allows for consolidation or removal of several legacy inventory systems,
components, and infrastructure saving indirect resources of people and money. If the Air Force
can find a way to implement a B-52H re-engine program, the benefits will far outweigh the costs.
Recommendation
Based on the current fiscal environment under sequestration, major acquisition programs
are a cause for concern in the Department of Defense. With that in mind however, the cost
savings that could be realized by re-engining the B-52H should be considered. Utilizing the
ideal model the Air Force could save $9.3 billion over 30 years. This is enough to purchase 71
Joint Strike Fighter aircraft at current cost or 142 at projected final cost over the same period.46
There are numerous other programs in the Air Force that would be aided by these savings over
time. Additionally the 10-year return on investment could potentially be managed by the
Department of Defense since the overall costs per year would not be excessively above current
costs, and is still less expensive that many other acquisition programs. Even if the current fiscal
environment cannot support investment now, there is still a window of opportunity in the future.
While a major engine modification in line with the secondary model would be beneficial
to the B-52H, there is little value added to the Air Force in a timeline suitable to the current fiscal

29
environment. B-52H crew members would greatly benefit from an updated cockpit
configuration and the potential combat related improvements that a major structural change may
bring, but this level of modification is not required. While realized savings of $5.6 billion is no
small figure, the Department of Defense cannot afford the 20-year return on investment.
Additionally there is only a small window of opportunity to implement this kind of modification
past 2020.
Should the Air Force pursue re-engining of the B-52H, utilizing commercial off-the-shelf
technology would be the most economic route. The engines used in commercial aviation have
millions of cumulative hours with significant reliability. They have been proven to be safe, and
reliable with years of available use data, significantly reducing the requirements for research and
development. Additionally there are unrealized savings that the Air Force could experience by
reducing warehouse requirements for spare parts and entire engines, as well as the personnel
savings by re-allocating Airmen that may have worked in the positions.
The Air Force should examine re-engining the B-52H immediately. Based on the
continuing rationale used in previous studies and current information presented in this research it
is cost effective, and executable. Further research should be conducted to determine additional
savings beyond the direct costs of operating the B-52H to develop a more comprehensive view
of total savings across the Air Force. Furthermore, if additional study agrees with this research,
the Air Force should immediately start the acquisition process to maximize potential cost savings
over the remaining service life of the B-52H.

30
END NOTES
(All notes appear in shortened form. For full details, see the appropriate entry in the
bibliography)
1. Gössling, S., and Peeters, P. M, It Does Not Harm the Environment, 4
2. USAF, B-52H Stratofortress Fact Sheet.
3. R.A. The Inflation Picture.
4. Boeing. History of the B-47.
5. Boeing. History of the B-52.
6. Air Force Studies Board. Improving the Efficiency of Engines, 40.
7. Ibid
8. General Electric. History of GE Aviation.
10. Montulli, L.T Dr., Lessons Learned from the B-52 Program, 8.
11. United States Air Force. White Paper on Strategic Bomber Force, 21.
13. Ibid
14. Jane's, USAF Fresh Interest Brews to Re-Engine B-52s.
15. Jane's, USAF Sees No Need to Re-Engine the B-52 Bombers.
16. Directorate of Propulsion, The Engine Handbook,72
17. Maj Ron Dagley, interview
19. SMSgt Kevin Wilson, interview
20. Ibid

31
22. Defense Science Board. Defense Science Board Task Force, ES2.
23. Ibid
24. Ibid
25. Ibid, ES1
26. Congressional Budget Office Staff, Analysis of Aerial Tanker Re-Engining Programs, 2.
27. Ibid
30. Jane's, USAF Sees No Need to Re-Engine the B-52 Bombers.
32. McConnell, Vicki P, Commercial: Engine Prognostics
33. United States Air Force. White Paper on Strategic Bomber Force, 21.
34. General Electric, History of GE Aviation
35. Ibid
36. Purdue AAE, General Electric CF34
37. General Electric. History of GE Aviation
39. Defense Science Board. Defense Science Board Task Force, 1.
40. Ibid, ES9
41. R.A. The Inflation Picture
42. Firestine, Theresa, and Jenny Guarino. A decade of Change in Fuel Prices

32
45. Hofbauer, et al., Cost and Time Overruns, 9.
46. Abramson, Larry, At $130 Million A Plane.

33
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Gössling, S., and Peeters, P. M. "“It Does Not Harm the Environment!” - An analysis of
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