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Army and Marine Corps M198 Howitzer: Maintenance Problems Are Not Severe Enough to Accelerate Replacement System
(Letter Report, 12/27/95, GAO/NSIAD-96-59).

Pursuant to a congressional request, GAO examined whether the Marine
Corps' and Army's reported maintenance problems with the M198 howitzer
justify the rapid development of a replacement weapon.

GAO found that: (1) M198 maintenance problems alone do not justify the
rapid development of a replacement weapon, since most of the maintenance
problems have been resolved or identified but not funded; (2) the Army
and Marine Corps have reported 93 and 89 percent availability of the
M198 respectively over the past 6 years; (3) the Marine Corps wants to
replace the M198 howitzer because of its poor mobility, but air mobility
improvements are being developed; and (4) the Army plans to develop a
new munition in fiscal year 1998 with an improved firing range, but it
has not tested the munition against other lighter weight prototypes.

--------------------------- Indexing Terms -----------------------------

     TITLE:  Army and Marine Corps M198 Howitzer: Maintenance Problems 
             Are Not Severe Enough to Accelerate Replacement
      DATE:  12/27/95
   SUBJECT:  Air warfare
             Ground warfare
             Cost effectiveness analysis
             Weapons systems
             Defense capabilities
             Weapons research
             Military procurement
             Military cost control
             Equipment maintenance
IDENTIFIER:  M198 Howitzer Fire Control System
             XM982 Projectile
             CH-47D Helicopter
             Osprey Aircraft
             Multiple Launch Rocket System
             Desert Storm
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================================================================ COVER

Report to the Chairman, Committee on National Security, House of

December 1995



Army and Marine Corps M198 Howitzer


=============================================================== ABBREV

  ACALA - Army Chemical Acquisition and Logistics Activity
  DOD - Department of Defense
  JORD - Joint Operational Requirements Document

=============================================================== LETTER


December 27, 1995

The Honorable Floyd Spence
Chairman, Committee on National Security
House of Representatives

Dear Mr.  Chairman: 

As you requested, we obtained information on the Marine Corps' and
Army's reported maintenance problems with the M198 155-millimeter
(mm) towed howitzer to determine whether these reported problems
justify accelerating the development of a replacement weapon.  We
also obtained information regarding the Marine Corps' and the Army's
planned development of a new, light-weight 155-mm howitzer. 

------------------------------------------------------------ Letter :1

Active and reserve Marine Corps artillery units use the M198 howitzer
for all direct support, general support, and reinforcing artillery
missions.  Army light cavalry units use the M198 for direct support,
whereas airborne and airmobile infantry units use the M198 only for
general support and reinforcing missions.  The M198 howitzers, first
delivered to the services in 1979, are approaching the end of their
20-year service life. 

Marine Corps and Army users of the M198 want to replace the
15,600-pound howitzer with a lighter-weight weapon to ease the
operational burden on crews and to improve air and ground mobility. 
The Marines have found it difficult to tow the M198 over soft
terrain, and only their heavy-lift helicopter can move the weapon by
air.  With the Marine Corps leading the development of a new
light-weight howitzer, in September 1995, the two services signed a
joint operational requirements document calling for a 155-mm howitzer
that (1) weighs 9,000 pounds or less and (2) fires munitions at least
30, but preferably 40, kilometers.  Initially, the Marine Corps
wanted to accelerate development of a light-weight howitzer to enable
fielding by 2001 or earlier but found that acceleration would be too
costly.  The Marine Corps now plans to field the first light-weight
howitzers in fiscal year 2002, and the Army in fiscal year 2005.  The
Marine Corps wants to buy 598 of the light-weight howitzers and the
Army 347.  Development and procurement of these weapons is estimated
to cost about $1.4 billion. 

------------------------------------------------------------ Letter :2

By themselves, the maintenance problems with the M198 howitzer do not
justify accelerating the development of a replacement.  Although Army
and Marine Corps users of the M198 have experienced recurring
maintenance problems with the howitzer, some of these problems have
been resolved, and solutions to most of the remaining problems have
been identified but not funded.  Even with these problems,
availability of the M198 reported by Army and Marine Corps units over
the last 6 years averaged about 93 percent and 89 percent

The Marine Corps believes that the poor mobility of the M198 is a
more important reason than maintenance for replacing it with a
lighter-weight weapon.  However, the anticipated air mobility
improvements are dependent on the ability of the MV-22 medium-lift
aircraft, now in engineering and manufacturing development, to lift a
9,000-pound howitzer.  So far, the developmental aircraft has not
shown that it can lift that weight. 

Current light-weight howitzer candidates will fire projectiles to 30
kilometers, the same range as the M198.  To achieve the objective
firing range of 40 kilometers, the weight of the new howitzer would
have to be increased, but an increase in weight could negate mobility
improvements.  A new munition, the XM982, currently being developed
by the Army independent of the light-weight howitzer development
program and scheduled to become available in fiscal year 1998, is
expected to achieve the desired 40-kilometer range.  However, it has
not yet been tested in the competing light-weight howitzer

------------------------------------------------------------ Letter :3

Marine Corps and Army users of the M198 howitzer have reported a
variety of recurring maintenance problems.  Some of the more serious
problems have been resolved.  According to the Marine Corps and Army
weapon system managers, solutions have been identified for most of
the other problems, but funds have not been provided to make the
fixes.  Data compiled from Marine Corps and Army equipment readiness
reports indicate that despite these problems, the availability of the
M198 has not been substantially affected.  Although some units
reported availability dropping below 70 percent in some instances,
this condition was usually corrected within a few months. 

---------------------------------------------------------- Letter :3.1

In 1994, a joint Marine Corps and Army team of experts visited five
major active duty Marine Corps and Army artillery units to identify
and quantify the problems with the M198 howitzer, as reported by
using units.  This team found 15 recurring problems.  The most
serious recurring problems reported were the following: 

  Trunnion bearings were worn or had disintegrated.  Worn or disabled
     bearings affect the alignment of the gun tube and the accuracy
     of projectiles fired from the howitzer.  Improper alignment
     could cause projectiles to miss the target and could endanger
     friendly troops. 

  When firing the howitzer with the maximum powder charge, cracks
     were discovered in the towers of the upper carriage.  These
     towers hold the gun tube in place.  If the cracks in the towers
     are too severe, the gun tube could back up too far during recoil
     and injure the crew. 

  Travel locks crack and sometimes break when the M198 is being
     towed.  If the locks were to break completely during movement of
     the M198, the gun tube could fall to the ground.  Broken travel
     locks may damage the M198's elevation mechanism and
     equilibrators and make the weapon inoperable. 

  Leaks found in recoil mechanism seals could limit howitzer
     operations.  A properly operating recoil mechanism absorbs the
     shock of the weapon when it is fired and returns the tube to the
     proper position.  Severe leaks might cause metal contact, which
     could result in seizure of parts and general failure of the
     recoil mechanism. 

  Tires are prone to blowouts because they were not rated to carry
     the weight of the howitzer.  According to the Army weapons
     manager, during 1994, users of the M198 reported about 25 to 30
     blowouts a month.  When a blowout occurs, the howitzer cannot be
     fired, and crews must either wait for a new tire to be mounted
     by direct support maintenance personnel or use one of the prime
     mover's tires. 

In addition, delays in the delivery of certain parts have had an
adverse effect on the availability of the M198 fleet. 

      HAVE NOT
---------------------------------------------------------- Letter :3.2

According to the Army and Marine Corps weapons managers who are
responsible for maintaining the M198 howitzer, problems with the
trunnion bearings, upper carriage towers, and recoil mechanisms have
been or are being resolved.  They also said that they have identified
potential fixes to the travel locks and the tires but have not been
provided the funds to implement them. 

-------------------------------------------------------- Letter :3.2.1

Trunnion bearings can now be replaced by maintenance units located
near the users.  Until recently, only depot-level repair shops could
replace these bearings, but authority to replace the bearings was
delegated to the Marine Corps' fourth echelon maintenance units and
the Army's general support units, which are generally collocated with

In January 1994, the Marine Corps and the Army completed a
modification intended to keep upper carriage towers from cracking. 
According to the M198 weapons managers, users have not reported any
cracks in the towers since the repairs were completed. 

-------------------------------------------------------- Letter :3.2.2

According to the Department of Defense (DOD), the cause of recoil
mechanism leaks is not entirely understood.  For howitzers in long-
term storage, leaks have been attributed primarily to seals that
failed if the mechanism was not exercised regularly.  Exercisers for
the recoil mechanism are being developed and are expected to be
fielded by June 1996.  However, the cause of leaks found in howitzers
used on a daily basis has not been determined. 

According to the Army weapons manager, the Army's Armament and
Chemical Acquisition and Logistics Activity (ACALA) has considered
installing a shock-absorbing system on the M198 to resolve the
problem of cracks in the travel lock area.  However, ACALA has not
been provided the estimated $750,000 needed to fully study this
potential solution.  The manager said that although the Army and
Marine Corps could simply strengthen the travel lock area, stress
would be transferred to other points of the howitzer that could be
more difficult to identify and repair. 

Users have asked for better tires for the M198.  According to the
Army weapon system manager, several manufacturers have recently
offered the Army tires that may be capable of supporting the weight
of the M-198.  The Army is testing these tires.  However, the weapons
manager has not been provided funds to buy them. 

---------------------------------------------------------- Letter :3.3

Although recurring maintenance problems are reported, availability
data reported by using units to Marine Corps and Army weapons system
managers indicate that the M198 fleet has a high availability rate. 
The availability rate reported by Army users from January 1989
through August 1995 averaged about 93 percent.  During the same
period the availability rate reported by Marine Corps M198 units
averaged 89 percent. 

Army artillery unit officials said that the M198 could have
relatively high equipment availability rates and recurring
maintenance problems at the same time.  If a problem can be repaired
within 24 hours, it is not reflected in equipment readiness reports. 
Our examination of one active Army battalion's maintenance records
(June 1993 to March 1995) showed that seven of its 24 M198s had
problems that rendered them inoperable for more than 10 days.  Of the
seven, two were inoperable for 30 and 39 days, respectively. 
However, according to the maintenance officer of this battalion, a
majority of the problems were fixed within 24 hours. 

------------------------------------------------------------ Letter :4

There is no consistent view regarding the state of the M198.  Some
users of the M198 believe that these weapons will not last until a
new howitzer is fielded in fiscal year 2002.  Officials of the Army's
18th Field Artillery Brigade expressed concern that the howitzer may
not last its expected 20-year service life without a significant
life-extension or product improvement program.  They said that to
reduce maintenance problems and extend the service life of the M198,
about half of their oldest weapons are being sent to ACALA to be
rebuilt and are being replaced with newer M198s from lower priority
Army Reserve and National Guard units. 

Similarly, the Marine Corps has begun to rotate newer M198s from
maritime prepositioning stocks to active artillery units.  According
to the 1st Marine Division, the M198's 20-year service life is overly
optimistic because maintenance problems already identified may be
symptomatic of other problems that have not yet been identified.  In
addition, a former artillery battalion commander of the division
noted that the division's M198s receive the greatest use because in
addition to providing direct support, general support, and
reinforcing missions, they also lend their M198s to other Marine
artillery units for training in the rough terrain of 29 Palms,

Contrary to the views of Army and Marine Corps users, the Army's M198
weapons manager told us that the M198 can be maintained in service
indefinitely, since direct or general support repair facilities can
replace almost all parts, and enough M198-unique parts are available
to meet the services' peacetime needs for 2-1/2 years.  However,
according to DOD, nonavailability of common user parts procured and
distributed by the Defense Logistics Agency has created some
significant delays in the repair of some M198s. 

The Marine Corps' weapons manager does not believe that the M198s can
be sustained indefinitely but said that recent initiatives to repair
major problems have improved the availability of the howitzer. 
Availability rates for the Marines' M198s have remained above 91
percent from May through August 1995. 

------------------------------------------------------------ Letter :5

According to users, Marine Corps doctrine, and systems development
officials, poor mobility of the M198 is the main reason requiring its
replacement.  A new, light-weight howitzer, currently in development,
is expected to be easier to operate and move on the ground and in the
air.  However, a howitzer weighing 9,000 pounds may not be capable of
firing munitions any farther than the M198.  To achieve ranges beyond
those of the M198, the new howitzer would have to be made heavier, or
a new family of extended-range munitions would need to be developed. 
The XM982, an extended-range rocket-assisted projectile currently
being developed under a separate program and expected to be usable in
the new howitzer, may achieve the desired 40-kilometer range. 

---------------------------------------------------------- Letter :5.1

The 5-ton truck assigned as the Marine Corps' prime mover of the M198
has difficulty towing the 15,600-pound howitzer over soft terrain
such as sand.  According to an artillery systems development
official, although the Gulf War was the perfect situation for
artillery because there was no mud, the Marine Corps found it
difficult to move the M198 by land and air during Operation Desert
Storm.  To resolve the problem, the Marine Corps is remanufacturing
its 5-ton truck fleet with a stonger power train and a 22,000-pound
towing capacity, which will allow it to move the M198 over most types
of terrain.  This program is funded, and the first remanufactured
vehicles are expected to be delivered in fiscal year 2001. 

The Marines can now airlift the M198 only with its CH-53E heavy-lift
helicopter and only under optimal weather conditions.  The Marine
Corps has assumed that its new medium-lift aircraft now in
engineering and manufacturing development, the MV-22 Osprey, will be
able to lift the new light-weight howitzer.  However, Osprey
prototypes have not demonstrated that they can lift the required
8,300 pounds or demonstrated their ability to lift actual cargo.\1
Program officials are optimistic that the Osprey will be able to lift
a 9,000-pound load safely but told us that they do not know whether a
howitzer can be made sufficiently aerodynamic and stable to allow for
its safe movement by the Osprey. 

Although it uses the same truck, the Army has had fewer problems
towing the M198 than the Marine Corps.  The Army's 18th Airborne
Corps successfully transported the M198 in the sand throughout
Operation Desert Storm.  Army and Marine Corps officials told us that
the reason for the difference may lie in how the two services use the
M198.  The Marine Corps uses the M198 for direct support and general
support missions.  The direct support mission requires the M198 units
to closely follow supported units, often over difficult terrain.  The
Army uses the M198 only for general support missions, which may allow
firing units to avoid difficult terrain. 

The Army has no problem lifting the M198 with its medium-lift CH-47D
helicopter, a system the Marine Corps does not own.  The CH-47D can
lift up to 22,000 pounds of cargo and easily carries the M198, its
crew, and a limited load of ammunition, in all but the hottest

\1 Navy Aviation:  V-22 Development--Schedule Extended, Performance
Reduced, and Costs Increased (GAO/NSIAD-94-44, Jan.  13, 1994). 

      THE M198
---------------------------------------------------------- Letter :5.2

The Army and Marine Corps have been testing two light-weight howitzer
prototypes, and a third is expected to be available for a shoot-off
in fiscal year 1996.  While these prototypes are expected to meet the
weight requirement, they probably will not fire beyond 30 kilometers. 
DOD said that targets beyond 30 kilometers can be attacked with the
extended range Multiple Launch Rocket System, by aircraft, or by a
new rocket-assisted projectile currently in development. 

According to the Joint Operational Requirements Document (JORD) for a
new light-weight howitzer, it must be able to fire projectiles 30
kilometers, which is the same range as the M198's.  The Army agreed
to this range, although it had initially desired a light-weight
howitzer with a range of up to 40 kilometers to enable counterfire
against other countries' artillery that can currently fire to that
distance.  The JORD now states that 40 kilometers is the desired

However, views within the Marine Corps artillery community have
differed on what the range should be.  On one hand, several Marine
Corps officials told us that mobility is the primary reason for
wanting a lighter-weight howitzer.  Those artillerymen with a direct
support mission favored mobility over range.  On the other hand,
artillerymen with general support and reinforcing missions said they
need additional range to accomplish their counterfire mission.  One
artillery battalion commander told us that the Marine Corps should
not invest in a new howitzer that will not fire projectiles to
distances significantly greater than the M198. 

Not having the mobility problems of the Marine Corps, the Army had
wanted to take a more measured approach to the development of a
light-weight howitzer to gain additional range.  However, according
to an official of the Program Executive Office for the light-weight
howitzer development program, the Army concluded that insistence on a
40-kilometer range could delay the howitzer's development up to 3
years.  To avoid such a delay, the Army and Marine Corps agreed that
the JORD would specify a minimum range of 30 kilometers and a desired
range of 40 kilometers. 

According to DOD, technical and simulation work led to the
determination that the optimal range for a towed weapons system is 30
kilometers.  The JORD working group, composed of user representatives
and technical experts, determined that a towed howitzer weighing
9,000 pounds and firing 40 kilometers was not technically feasible. 
In addition to requiring a longer development time, achieving a
40-kilometer range would require a propellant development program,
which would greatly increase the cost and risk of the light-weight
howitzer development program. 

Under another program, the Army is developing the XM982, a 155-mm
rocket-assisted projectile that is expected to fire to a range of 40
kilometers.  Since the XM982 is not be a precision-guided projectile,
it will not be used for close support missions.  If it successfully
reaches the desired 40-kilometer range, the XM982 will primarily be
used for counterfire missions. 

------------------------------------------------------------ Letter :6

In written comments (see app.I) DOD agreed that maintenance problems
of the M198 alone do not warrant accelerating a replacement and
stated that accelerating the acquisition strategy would be cost

DOD disagreed on two counts with our conclusion that even with the
remaining problems the M198 availability rate remains high.  First,
DOD stated that operational reliability of the M198 over the last 2
years provides a much more realistic picture than the average
availability we calculated for a 6 year period.  Army officials said
that operational reliability refers to the reliability of individual
parts of the M198.  However, according to the Army weapons manager,
operational availability data on the M198 fleet is incomplete because
it has not been systematically collected.  He said that the
availability data reported in the Unit Readiness Reporting system
remains the most reliable indicator of the condition of the M198

Second, DOD said that the variability, rather than the average, of
the operational reliability and availability should be considered. 
DOD said that between April 1991 and June 1994, the average
availability rate for Army units was 91 percent and for generally the
same period the rate for the Marine Corps was 88 percent.  However,
DOD said that during these periods, the rate dropped to 72 percent in
some Army and 69 percent in some Marine Corps units.  Our review of
Army data indicates that the lowest availability rate reported for
the overall M198 fleet was 80.7 percent in the fourth quarter of
fiscal year 1991, but that the rate recovered to 91.7 percent the
following month.  Individual Army battalions and separate batteries
reported availability rates as low as 37 percent for any one month,
but in all cases, including for school support and reserve component
units, availability was restored to levels above 90 percent within 3

We did not review availability reports from individual Marine Corps
battalions and batteries but analyzed average monthly availability
rates of M198s reported to the weapons manager by each of the four
Marine Expeditionary Forces (MEF) from May 1993 through September
1995.  According to this data, the lowest availability rate was 68.1
percent, as reported by the 2d MEF in June 1993.  However, this unit
reported a 90.3 percent availability 3 months later. 

DOD stated that we appear to argue against the need for the
light-weight howitzer.  We were not asked for and are not offering an
opinion about whether a lighter-weight howitzer is needed.  Our
objectives were to determine whether maintenance problems with the
M-198 justify accelerating the development of a replacement and to
describe the current light-weight howitzer development program. 

Technical comments provided by the DOD have been incorporated in this
report as appropriate. 

------------------------------------------------------------ Letter :7

To obtain information on the current status of the M198 howitzer, we
interviewed officials and reviewed documents from the Office of the
Assistant Deputy Chief of Staff of the Army for Operations and Plans
in Washington, D.C.; the Marine Corps Combat Development and Marine
Corps Systems Commands in Quantico, Virginia; the U.S.  Army Armament
and Chemical Acquisition and Logistics Activity, Rock Island,
Illinois; and the Marine Corps Logistics Base, Albany, Georgia.  We
obtained an operational perspective and discussed maintenance issues
with officials from the Army's 18th Airborne Corps and its
subordinate units at Fort Bragg, North Carolina, and Fort Campbell,
Kentucky, and with officials from artillery and support units of the
1st and 2nd Marine Divisions at 29 Palms, California, and Camp
Lejeune, North Carolina.  Finally, officials of the Joint Program
Management Office, at Picatinny Arsenal, New Jersey; the Army staff;
and the Army Field Artillery School, Fort Sill, Oklahoma, provided us
with information on the Lightweight 155-mm Howitzer and XM982
development programs. 

We conducted our review between May and October 1995 in accordance
with generally accepted government auditing standards. 

---------------------------------------------------------- Letter :7.1

We are sending copies of this report to the Secretary of Defense, the
Secretaries of the Army and the Navy, and the Commandant of the
Marine Corps. 

Please contact me at (202) 512-3504 if you have questions about this
report.  The major contributors to this report are listed in appendix

Sincerely yours,

Richard Davis
Director, National Security

(See figure in printed edition.)Appendix I
============================================================== Letter 

(See figure in printed edition.)

========================================================== Appendix II

-------------------------------------------------------- Appendix II:1

Jess T.  Ford, Associate Director
Richard J.  Price, Assistant Director
Anton G.  Blieberger, Evaluator-in-Charge
Robert H.  Goldberg, Senior Evaluator
Karen S.  Blum, Communications Analyst

-------------------------------------------------------- Appendix II:2

R.  Gaines Hensley, Assignment Manager
Connie W.  Sawyer, Jr., Senior Evaluator

*** End of document. ***