The missile guidance set on the Minuteman III ICBM is hard
to service. The problem lies not in the subsystem itself, but in its location
beneath the missile reentry system. To reach the guidance set, the Minuteman
silo door must be opened and the reentry system with its nuclear payload must
be removed—a procedure that requires five maintenance personnel, three
vehicles, eight security police, and daylight.
Designers of the Peacekeeper ICBM learned from this maintainability
problem. In the Peacekeeper, the missile guidance set also has been positioned
underneath the reentry system, but it is mounted in a sliding drawer. Repair
does not require warhead removal. The silo does not have to be opened, only
one security guard is needed, and work can be carried out any time, day or
By decreasing ICBM downtime, this designed-in
maintainability improvement, in effect, multiplies the US nuclear deterrent
force. It reflects one of the primary goals of the Air Force's R&M
(Reliability and Maintainability) 2000 initiative: increasing combat
capability by buying weapons that perform reliably over time, instead of
systems that promise much but are always in the shop.
The Air Force's headquarters office for R&M declares
that the policy for new weapons is "Double-R/Half-M," meaning that
next-generation systems should be twice as reliable and should require half
the maintenance of the generation they replace.
Making this quantum leap will require, among other things,
better design, more attention to quality, contractor incentives, and a commitment
by the Air Force leadership to make the requirement stick. "We're talking
about a cultural change, not just in the way the Air Force does business but in
the way industry does business," says Brig. Gen. William Collins, Air
Force Special Assistant for Reliability and Maintainability.
Official requirements for both the SRAM II (Short-Range
Attack Missile) and the Advanced Tactical Fighter (ATF) take the R&M benchmark
to heart. ATF requirements call for a break rate of eight to ten percent,
compared to fifteen percent for the F-15. Seventy-five percent of ATF problems
should be fixable in four hours, as opposed to forty-two percent for the F-15.
The requirement for ATF maintenance personnel is set at eight per aircraft, as
opposed to the F-15's eighteen.
Response on ATF
The ATF's contractors are taking these goals seriously,
according to the Air Force. General Electric is assigning top engineering
talent to work on the controls, actuators, and piping that hang on the outside
of its ATF engine prototypes. Although these units are the cause of most engine
maintenance actions, GE officials say they haven't made them a top priority in
the past. Pratt & Whitney says its ATF engine competition entrant will
have forty percent fewer parts and require sixty percent fewer depot- and
support-level tools than do current-generation fighter engines. Any main unit
on the ATF engine will be replaceable in twenty minutes, says Pratt &
Improved R&M isn't just the province of next-generation
systems, notes General Collins. Upgrades and retrofits can greatly ease the
burden of supporting currently deployed weapons. The new APG-68 Programmable
Signal Processor for the F-16 will use VHSIC (Very-High-Speed Integrated Circuit)
technology and have a mean time between failures of 2,000 hours. The MTBF rate
for the unit it replaces is about 200 hours. Two-thousand-hour reliability is
the goal for most fighter electronics. An Air Force R&M overview report
points out that "many operating commands project that 2,000 hours for
LRUs [Line Replaceable Units] would eliminate the requirement for
R&M retrofits don't have to be driven by new technology.
Take the case of LANTIRN (Low-Altitude Navigation and Targeting Infrared for
Night) Targeting Pod laser alignment. In initial production units, maintenance
personnel had to take off a large access panel held on by many small screws to
get at the laser adjustment screws. Putting the panel back on often knocked
the new adjustment out of whack. Laser adjustment often took longer than the
predicted four hours.
Later LANTIRN production models have a small hatch on the
access panel that can be quickly popped open. Average laser alignment time has
been reduced by over seventy-five percent. "It's so obvious. Why didn't
we do it in the first place?" says General Collins.
Poorly designed panel fasteners hold a particular horror for
aircraft technicians. One FB-111 panel is held on with 187 screws of six different
lengths. Nothing on the screw holes indicates which length fastener they take.
A mechanic who threads a long screw in a short hole can sever wires behind the
panel, grounding the plane for hours.
Trying to prevent such nightmares from happening in new systems
is "pick-and-shovel work," the daily fare of his office, says General
Five Main Objectives
The R&M 2000 initiative is a focus for Air Force efforts
to make reliability and maintainability of equal importance to weapon cost,
performance, and acquisition schedule. R&M 2000 goals are an attempt to get
away from traditional mean-time-between-failure bean-counting, says General
Collins, listing five main objectives:
Increase combat capability. The overarching point of better
R&M is to enable the Air Force to do more with less. Less time in the shop
means more time spent over target. Fighters should be able to fly ten straight
sorties without maintenance; ground radars should operate for thirty days
without a critical failure.
"If you double reliability, you only need half as many
planes to do the same job," says General Collins.
structure vulnerability. Destruction of vulnerable airfield maintenance
shops grounds airplanes. Aircraft that don't need so much field support are
more combat-capable, because if support structures don't have to be in place,
they are not vulnerable.
Destruction of base plants that supply liquid oxygen for
pilots' breathing would ground fighters in days. So the F-15E (as well as the
B-1B) has an on-board oxygen-generating system, which takes bleed air from the
engine and runs it through a molecular sieve, eliminating the liquid oxygen
requirements. Aircraft that are more reliable and maintainable don't need
so much logistics baggage. Hence, they're easier to shift between bases—multiplying
the force by improving its flexibility.
The Mobile Electronic Test Set for the F-15E is only
one-eighth the size of equipment fielded with other F-15 versions. In terms of
mobility, that represents one C-141 trip that doesn't have to be made. Requirements
call for an ATF squadron to be deployable with six to eight C-141-sized loads,
as opposed to the eighteen necessary for an F-15 squadron deployment.
manpower needs. The Air Force thinks it should be possible to reduce the
number of personnel needed to maintain new-generation systems by one-third to
one-half, freeing personnel slots for distribution throughout the rest of the
service. The KC-135 reengining program shows the possible effect: Reliability
improvements with the plane's new F108 engine have now saved fifty manpower
spaces in Strategic Air Command, according to the Air Force, with an additional
savings of forty spaces to materialize by 1991.
costs. Obviously, fewer maintenance actions taken for new systems can help
lower their overall maintenance costs. Less obviously, designing with R&M
in mind can lower the cost of individual parts. Advances in electronics can be
The redesigned Central Air Data Computer for the C-141 costs
$20,000 less than the original model, while providing ten times the reliability.
Use of VHSIC technology in the new F-111D Signal Transfer Unit has reduced
parts costs from $24,000 to $2,000.
Such new technologies are the breakthroughs that have
brought R&M 2000 goals within reach, says General Collins. Merely replacing
the old with the new can pack a large increase in R&M punch. Use of fiber
optics in place of copper cable in mobile ground radar, for instance, can save
1,000 pounds per set while increasing survivability and reliability.
The largest improvements may come just by keeping R&M in
mind during development. "That really pays big dividends," says
Take the C-17 transport aircraft. When McDonnell Douglas was
setting up the new airlifter's production line, it conducted a study of the
problems it had had manufacturing wide-body airliners in the past. One thing
the engineers found was that with big planes, assembly workers typically
crawled over fuselage sections and often slipped or dropped tools, causing
dents and damage.
So McDonnell Douglas built huge jigs to hold fuselage
sections and rotate them on stands in front of workers. That cuts down on dents
and quality problems, increasing C-17 reliability.
The "Blue Two" program for sending engineers out
to the field to see the real-world problems of maintaining systems is also a
crucial R&M tool, says General Collins. (See "Blue Two," April
'89 issue, p. 56.)
How can the Air Force ensure that its contractors take
R&M seriously? "The timing is with us," says General Collins.
"You're using their recognition that they're going to have to do this if
they're going to compete."
R&M incentives can be written into contracts.
Westinghouse recently won a $67 million bonus for meeting R&M goals on its
APG-68 F-16 radar. Warranties can be written to hold contractors responsible
for making sure their products perform up to standards over time. Effective
R&M warranties should include, among other things, provisions for fixed-price
repairs and no-cost retrofit of engineering changes.
Industrial cultural change, say officials, will have to be
part of the R&M revolution too. Without it, defense contractors may find it
next to impossible to produce systems with the built-in quality and reliability
the Air Force says it's going to demand. The US defense industry prides itself
on being the last bastion of American industrial superiority, but General
Collins says even weapons makers have a lot to learn from the Japanese.
When defective products start rolling off the assembly line,
Japanese manufacturers don't just tighten the inspection net. "They go
back and find out why," says General Collins.
As a result, Japanese weapons are as well-made as Japanese
VCRs. Last year, General Collins's office sponsored a joint industry-DoD trip
to study Japanese licensed production of an F-15 variant, the F-15J.
"There are some strong indications that the F-15J is more reliable than
its American counterpart," says an Air Force report on the trip. "The
predominant reason appears to be the emphasis on quality during manufacturing
and depot activities."
Japanese attention to detail is apparent. Workers sweep
their own space on the factory floor, says the Air Force report. Tools are
stored on rubber mats, with drill bits covered. Parts that aren't in use are
covered with clear plastic. Plastic sleeves are slipped over the threads of
At Mitsubishi Heavy Industries, one of four major Japanese
F-15J contractors, about two percent of domestically supplied parts are found
to be defective. In contrast, parts imported from the US prove to be defective
about nine percent of the time.
Improvement of F100 engine-turbine blades made at
Ishikawajima-Harima Heavy Industries shows the Japanese commitment to quality,
according to the Air Force. The problem was that too many blades were going
through the grinding process and coming out too long to be used.
Tracking the problem back to the factory floor, Japanese
managers discovered that they had one star grinding machine that was producing
virtually perfect parts. Ripping it apart to find out why, they discovered
that it was the only machine whose jig had been put together without locknuts.
That meant it held blank pieces more tightly, resulting in more accurate work.
The locknuts were quickly stripped from all the grinding machines.
Blade quality improved dramatically, to the point where none came out too
Quality improvements such as this can have a ripple effect that
increases reliability and saves money all down the line, says General Collins.
"If you get all the turbine blades right on target, you don't have to
balance the engine," he points out.
Weapon systems often fail because of variability in the
design and manufacturing process. Ishikawajima-Harima's turbine-blade detective
work is an example of what General Collins calls the Variability Reduction
Process (VRP). Use of VRP is a significant contributor to the F-15J's high
reliability, according to the Air Force report on the R&M 2000 trip to
Air Force leaders say that VRP is the sort of
quality-control technique that US contractors will have to make part of their
everyday routine if they want to remain competitive. General Collins says his
message to contractors is, "We're not going to pay more for quality.
You're going to have to learn how to do it."
Finding the Payoffs
R&M is a good thing not for its own sake but because of
what it makes possible. If total weapon sys tern reliability isn't improved,
then an R&M upgrade for a subsystem isn't worth making.
UHF radios are already the aircraft equivalent of an AM/FM
transistor: reliable, cheap, and not too glamorous. General Collins says he
probably wouldn't pay for a longer-lasting radio, because broken receivers
aren't keeping planes out of the air. Resources should be concentrated on more
delicate systems, where the payoff for improvement would be much greater.
The Air Force is developing a computer program named MARGI
(Methodology for Analyzing Reliability and Maintainability Goals and
Investments) to help it get the biggest increase in combat capability it can
out of R&M retrofit dollars. By analyzing the importance of a particular
subsystem to an aircraft's mission, then mixing in predicted parts failure
rates, the program can point to the things that most need to be made more
A MARGI analysis of the F-16A concluded that the plane's
combat capability could best be increased by improving the reliability of its
weapons delivery system. MARGI also calculates the estimated impact of specific
part changes. If ring-laser gyros were inserted in all F-16As, for instance,
the resulting increase in fleet reliability would be equivalent to the purchase
of seven new aircraft.
Strategic Air Command and Tactical Air Command are now
using the MARGI model, with Military Airlift Command to come on line soon.
General Collins says the software will be a valuable tool in the hunt for such
items as the F-111D Signal Transfer Unit, where a relatively small investment
in R&M has meant a big jump in aircraft availability.
After all, the ATF may represent a new level of reliability
and maintainability, but current-generation aircraft will be the backbone of
the Air Force for many years to come. Even next-generation systems will break
and undoubtedly will be worked on in the open, in bad weather, by crew chiefs
muttering about the boneheaded engineers who designed them.
"There's a lot more pick-and-shovel work still out
there," says General Collins.
Peter Grier is a
Washington-based defense correspondent for the Christian Science Monitor. His
most recent article for AIR FORCE Magazine was 'Squeezing More from the
Logistics Dollar" in the August '89 issue.
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