BGSU professor finds changing common aircraft maintenance practice could save lives

Dr. Hokey Min says extracting necessary parts from existing aircraft for repairs reduces maintenance efficiency

By Julie Carle

Aircraft maintenance errors have been among the causes of plane crashes about 20% of the time, according to recent Federal Aviation Administration statistics.  

A Bowling Green State University management professor helped analyze more than three years of U.S. Air Force data and found that a specific practice might be one of the main issues.

Dr. Hokey Min, the James R. Good Chair in Global Supply Chain Strategy in the Allen W. and Carol M. Schmidthorst College of Business, said the practice of extracting necessary parts from existing aircraft and using them for repairs in other planes was found to reduce maintenance efficiency.

Using parts from another plane to fix a problem in a plane that is preparing for flight is an accepted practice in the military and commercial airlines industries and referred to as “cannibalization,” Min said.

He and colleagues from the U.S. Air Force Institute of Technology (Thomas O’Neal, Daniel Cherobini and Dr. Seong-Jong Joo) collaborated on the study, “Benchmarking Aircraft Maintenance Performances Using Data Envelopment Analysis,” that was published in the November 2020 issue of the International Journal of Quality and Reliability Management.

According to Min, this is one of the first studies on aircraft maintenance that considered the cannibalization practice as a specific variable for assessing the aircraft maintenance efficiency.

Data envelopment analysis (DEA), the methodology used for the study, is often used for measuring operational efficiency; in this study it was used for benchmarking the performance of aircraft maintenance programs to suggest best practices in the industry.

Min is careful to point out the study is not meant to put anyone in a bad light, especially since the practice of cannibalizing maintenance/repair parts from existing aircraft is not uncommon. However, he emphasized that the purpose of the study is about saving people’s lives.

The study also found in the Air Force data that the number of mission-capable aircraft was the most important factor for combat readiness in the air service branch.

He became interested in the study during conversations when he was a guest lecturer for the Air Force institute of Technology. Colleagues brought up some issues and asked for his help because of his expertise in mathematical modeling and quantitative analysis, not to mention military logistics and air transportation.

“Air safety is really important because it’s a matter of life and death, especially in the military setting where they spend millions of dollars to train pilots,” Min said. Personal safety and the safety of the country are also at issue.

“If a military aircraft is not combat ready, we can’t be engaged in war. It’s a serious matter,” he said.

Min knew that maintenance errors were potential issues for aircraft crashes, but they could be preventable.

“I wanted to figure out why they make maintenance errors,” he said. “Was it that the maintenance crews are not properly trained, that they are not committed to periodic preventive maintenance?”

What he found is a dilemma with having necessary parts available when a repair need is identified, whether for a military aircraft or a commercial airlines plane.

“Aircraft are comprised of tens of thousands of different parts,” he said. “Usually when one part of a car doesn’t work, the car stops. When one part fails in an aircraft, it is possible to cause a crash and the fatality of airplane crews and passengers.”

He suspected that a lack of time or personnel might have contributed to maintenance errors, but that was not the case.

“Man-hours dedicated to maintenance is not necessarily the main cause of a problem,” Min said, “but the clear source of the problem is cannibalization.”

Proper time-phased inventory planning and maintaining inventory systematically are fundamental to the issue, he said, and they could be a “game changer” for the military and airline industries.  

Time-phased Inventory planning takes time and can be challenging; the issue won’t be resolved quickly, he said.

“With this study, I tried to send a message that while people in the industry think that the habit of cannibalism is OK because it is an industry norm, but it is no longer OK," Min said. "It’s a serious matter that we need to pay attention to."

His statistics contradict the general assumption that the airplane crash rate is declining.

“My data shows it’s actually increasing by roughly maybe 20 to 30 more accidents per year during the last several years," Min said. "What we need to realize is that even one critical accident is going to kill many people.

“I’m really concerned about the future. As I grow older, after four decades of teaching and research with more than 210 published research articles, it’s become more important to think about what kind of impact we have on society.”

Often, his research in the world of business has been about saving money for companies.

“Saving a half million dollars or a million dollars is great in business,” he said. “but for me, I don’t want to focus on how much money we’ve saved them but on how many people’s lives can be saved and/or how much their quality of life can be improved. That’s the contribution that I’d like to make.”