Reliability – Page 2 – The OM Blog by Heizer, Render, & Munson

OM in the News: Just How Reliable are the Boeing 787 Batteries?

For an interesting discussion of reliability when you teach Chapter 17 in our text, we turn to The New York Times (Feb.27, 2013) article on how U.S. and Japanese aviation authorities have confronted a steep learning curve trying to unravel what caused last month’s battery failures on a pair of Boeing 787 Dreamliners. The lithium-ion batteries are commonplace in consumer electronics and electric vehicles, but despite being lighter and more efficient than older technology, they have never been used in aircraft as extensively as on Boeing’s flagship jetliner. After 7 weeks of nearly round-the-clock efforts, the National Transportation Safety Board has failed to find the root cause of the dangerous battery malfunctions that grounded the entire 787 fleet. Industry and government officials on both sides of the Pacific increasingly are skeptical a breakthrough is imminent.

Before approving the Dreamliner to begin carrying passengers in late 2011, regulators embraced Boeing’s risk assessment showing that the chance of a 787 battery meltdown was about one in 10 million flights (That means R= 0.9999999). That is roughly 100 times safer than some of the industry’s most reliable jet engines, which on average malfunction and have to be shut down roughly once every 100,000 flights.

But the U.S. Department of Energy (DOE) sees Boeing’s initial risk analysis as unrealistic, particularly considering variations among parts. “When carefully examining the nature of the material or the tolerance possible within the manufacturing process, it is difficult to arrive at those [risk] numbers,” writes DOE. In commercial use, the batteries have now ruptured and burned twice in less than 50,000 flights (or an R=0.99996). Contrary to FAA projections of an extraordinarily low likelihood of a serious airborne mishap, the Energy Department says the malfunction rate of the batteries has been higher than would be acceptable for uses on the ground. “That wouldn’t be a reasonable number for the auto industry.”

Discussion questions:

1. Why do Boeing’s reliability numbers differ so greatly from observed failures?

2. What are the options for operations managers at Boeing at this point?

Good OM Reading: Ford’s Strategy for Reliability–and Failure

From tires to hinges to helicopter blades, everything breaks eventually. The only question is when, writes Wired Magazine (Nov., 2012). This must-read article, titled “Why Things Fail,” is worth sharing with your students if you are teaching the topic of reliability (Chapter 17). Ford Motor knows product failure, and still recalls the 2000 disaster in which some 192 people died when their Explorers’ Firestone tires fell apart. But it is clear that, in the tragedy’s wake, the company learned something. As it overhauled its testing program, Ford’s warranty costs plummeted, and its vehicles went from having some of the worst reliability scores in 2000 to having some of the best today. From the embers of the Explorer disaster, Ford has become one of the best companies in the world at managing failure–equalling Honda and Toyota.

At Ford, learning exactly when and how things will fail—over many years and across a spectrum of millions of vehicles around the world—now saves billions of dollars (and, of course, many lives). So in Building 4, a massive complex in Dearborn, MI, called Ford’s Tough Testing Center, parts like the gas petal hinge endure a constant torrent–simulating years of use–until they finally fail. Building 4 is a monument to a dark truth of manufacturing: Even the best-engineered products fail. Some percentage of all mechanical devices will break before they’re expected to. “Companies say they want to be 100% failure-free after three years,” says one industry expert. “But that’s impossible. You can’t do it.”

Whenever a new part—like that gas-pedal hinge—is designed, the first question Ford asks is, how long does it need to last? Ford’s standard warranty guarantees parts for 3 years and the engine/transmission for 6. But to ensure that parts easily surpass warranty claims (and hopefully ensure that buyers feel they own a reliable product), Ford aims to have everything last 10 years. Upholstery, transmissions, paint—all of it is built to last at least a decade. Quite a change from the planned obsolescence of my father’s cars of the 1960’s!

OM in the News: Neil Armstrong and Reliability

To most Americans, especially those of us who used to work at NASA, Neil Armstrong’s death was the loss of an American hero, and a sad ending to our Moon exploration days. But the reason we mention the astronaut in today’s blog is his speech about the topic of Chapter 17, reliability. Surely someone who risked his life in every launch and who studied engineering understood the mathematics of reliability.

As reported in The Wall Street Journal (Aug. 26, 2012), here are Armstrong’s remarks: “Each of the components of our hardware were designed to certain reliability specifications, and far the majority, had a reliability requirement of 0.99996, which means that you have four failures in 100,000 operations. If every component met its reliability specifications precisely, a typical Apollo flight would have about 1,000 separate identifiable failures.”

“In fact, we had more like 150 failures per flight, substantially better than statistical methods would tell you that you might have. I can only attribute that to the fact that every guy in the project, every guy at the bench building something, every assembler, every inspector, every guy that’s setting up the tests, cranking the torque wrench, is saying, ‘If anything goes wrong here, it’s not going to be my fault, because my part is going to be better than I have to make it.’ And when you have hundreds of thousands of people all doing their job a little better than they have to, you get an improvement in performance.”

I appreciate Armstrong’s observations–and think your students may as well. In those days, you could stand outside a NASA Space Center and never tell when quitting time was. Engineers simply stayed each day till they felt their work was done–maybe at 6 pm or even 9 pm. When we work on projects we are all interested in and dedicated to, there is nothing we cannot accomplish.

Discussion questions:

1. What was the reliability of each Shuttle flight, given that 2 Space Shuttles crashed in about 140 flights?

2. In what other industries is reliability equally important?

OM in the News: Probability the Space Station Crashes

Now that the last Space Shuttle has been retired, much debate has focused on the reliability of the Russian Soyez capsules as the sole means of reaching the $100 billion International Space Station (ISS). Prior to that , our July 11th blog discussed the overall reliability of the Space Shuttle, which at Rs=.98 suggested one fatal crash every 50 missions (and indeed there were 2 crashes in the 135 flight life of the Shuttle). But, interestingly little has been mentioned in the press about the reliability and safety of the ISS itself.

Today’s Orlando Sentinel (July 25,2011) brings to light 3 important facts: (1) the ISS will be abandoned in any event by 2020 (if it lasts that long), (2) the probability of it taking a disabling strike from space debris is 16.6%, and (3) the probability of a fatal collision is 1 in 13. NASA’s own task force found slightly worse odds, with a 0.125 probability that an astronaut will die or the station would have to be abandoned.

The problem is space junk–those 1,000’s of pieces of old rockets and satellites that were destroyed in space. “The orbit they are flying in is the worst possible. The Russians blew up all kinds of things in that orbit”, says a retired NASA exec. (That 1 in 13 chance of a disastrous collision with space junk is, of course, the same as what a card player faces in drawing an Ace from a deck). NASA estimates that there are 500,000 pieces between 1-10 centimeters (large enough to do damage) floating around –and 20,000 more deadly pieces (larger than 10 cm). Just 4 weeks ago, a piece of debris caused a big enough scare to send the 6 astronauts on board the ISS scrambling to Soyez escape capsules. The debris passed within 1,100 feet of the Space Station–the closest near-miss yet.

Discussion questions:

1. Discuss the role of manned space exploration in light of the probabilities given.

2. What are the main operations issues vis-a-vis the ISS?

OM in the News: Service Quality vs. Maintenance Time at Disney World

You might not think that maintenance of Walt Disney World’s monorail line in Orlando would be a controversial topic (see Ch.17). But the Orlando Sentinel (July 12, 2011) reports that plans to give maintenance crews more time to work on the aging system are certain to anger Disney’s premium-paying hotel guests. Disney had previously kept its trains running until at least 1 1/2 hours after theme parks closed. Now service will shut down 1 hour after normal closing hours.

The beef is that guests who stay at these hotels on Disney property have “late night privileges”. This means the parks will stay open for them–and not for regular guests– as late as 3 am and then reopen at 7 am. But Disney says that trains take 90 minutes to “cycle down” and another 90 to “cycle up” the next morning, leaving only 1 hour of downtime for maintenance.

Reliability has suffered in recent years, perhaps because of the limited repair time. In 2009, the monorail system lost power at 1 am and it took Disney’s crews 3 hours to unload the weary passengers. “It’s been pretty obvious that transportation maintenance is one of the areas they cut back on during the recession”, says the popular website Disney Blog. The blog also predicts Disney will suffer a backlash from guests staying at the most expensive hotels on the property, since they are the ones who “expect the most preferential treatment”.

Discussion questions:

1. Discuss the tradeoff between customer service and the need for more maintenance time.

2. What else can Disney do to deal with the problem?

OM in the News: When New Medical Products Fail

In Chapter 5, we discuss both the importance of new products in a firm’s success (see Fig. 5.2) and the product development system (Fig. 5.3). One industry whose lifeblood is new and improved products is medicine– where high product demand and the need to gain a competitive edge results in a constant churning of new drugs, devices, and procedures. But the promise of innovation can also prove a trap, according to The New York Times (June 25, 2011), a situation now playing out with dire consequences for 10,000’s of people who received artificial hips in the last decade. “I don’t understand it, but there is a phenomenon in the U.S., for the latest and the greatest”, says a Swedish orthopedic surgeon.

The issue is metal-on-metal hip implants, designed by device makers as a supposedly major advance over a 50 year-old previous design that used metal and plastic. The older, relatively simple model consists of a metal “ball” that replaces the thigh bone, while a plastic “cup” serves as an artificial hip socket. This device is highly effective, with a 95% success rate a decade after surgery.

“The vast majority of the innovations with respect to orthopedics over the past 2 decades have not resulted in improved patient outcomes”, says one UC prof. But companies began promoting the new implants as “the next big step”. Patients, intrigued by ads featuring celebrity athletes doing strenuous physical activities, also wanted the metal-on-metal devices. All- metal implants now account for a 1/3 of the 250,000 hip replacements in the U.S..

Unfortunately FDA simulations to test the new product were based on idealized conditions, not real-world wear and tear. Now, debris from the grinding of the metal parts is causing crippling tissue and muscle damage, and even neurological problems. Of the half-million all-metal implants inserted, there is a likelihood that tens of thousands of patients will require painful replacements.

Discussion questions:

1. Why are metal implants failing at a high rate?

2. What other major drugs and medical products have imploded shortly after introduction?

OM in the News: How Reliable is the Engine on Your Jet?

It was hard to miss the front-page headlines in almost every paper around the world last week when a massive engine exploded on a Qantas Airways A380 superjumbo jet. Early in my career, I worked on the design team for the GE CF-6 engine, also an immense device. So the news blasts caught my attention for 2 reasons: (1) I wanted to make sure the plane landed safely, and (2) I wanted to make sure it wasn’t an engine I had somehow touched.

The Qantas issue raises the question of just how reliable jet engines are (Ch.17). This particular engine, the Trent 900, made by Rolls-Royce was developed for the Airbus double-decker A380. But is is still what we call an “immature engine”, which has yet to meet expected levels of reliability. It is installed in only 21 planes (meaning 84 engines are in use). Other A380s use the GV7000 engine, jointly developed in the US by GE and Pratt & Whitney. Just for background, an A380 retails for about $300 million, of which $50 million is the cost of engines.

Qantas immediately grounded its A380 fleet for engine testing by Rolls-Royce experts. Rolls, according to the linked WSJ article has “been buffeted by a series of design and reliability issues affecting engines it supplies for other jetliner types”.

That brings up another related reliability issue. Later in my career, I worked at NASA headquarters and wrote a series of case studies on the Space Shuttle. The Shuttle has a reliability of 0.98 overall. This, of course, translates to a major disaster in 1 out of every 50 flights….which has indeed been the reality, with Challenger and Columbia exploding during 130 or so flights to date. You may want to discuss the Ethical Dilemma in Ch.17 that relates to such a 98% reliability.

Discussion questions:

1. What has taken place since this article was published?

2. Compare the reliability of a jet engine or plane to a Shuttle flight.

OM in the News: Detroit Moves Up in Auto Reliability, But Asia Still Rules

People buy cars for all sorts of reasons: styling, prestige, safety, and even color. But a reputation for quality and reliability is the one constant to almost every consumer, according to The Wall Street Journal (Oct.27,2010). With this week’s release of Consumer Reports’ rankings of new auto reliability, there is some good news for Detroit.

Ford and GM have greatly improved the reliability of their vehicles, and in some sectors are ranked better than their Asian counterparts. The Ford Fusion, for example, is now tops in the “family car” segment–bettering the Toyota Camry, Honda Accord, and Nissan Altima. Ford is the top American company overall.

Chrysler, sadly, has still not taken off and is dead last in the rankings. Toyota’s once sterling reputation was also dinged; its Prius hybrid fell to “average” from its once high-rating because of recalls and brake problems. BMW ranked only 24 out of 27 brands, underlining how luxury car makers face quality challenges as they insert advanced technologies (that don’t always work perfectly) into their vehicles.

Good quality, as we in OM all know, creates an upward circle: the more reliable the car, the more people are willing to pay, and then the less discounts are needed. “It doesn’t take very long to lose a good reputation, but it takes 5 or 10 years to gain one”, says a Consumer Reports director.

Discussion questions:

1. Give some examples of products (cars included) where it took years to rebuild a damaged quality reputation.

2. Why is the Honda family of vehicles ranked consistently high?

3. Ford is now ranked 10th out of the 27 auto makers. What will it take to move to the top of the pack?