NASA researchers are planning to put the engines of a C-17 cargo transport plane on a diet of cereal and crayons as part of a series of tests of new health diagnostic sensors that they hope will become an early warning system for potential engine failure.
The space agency says its Aviation Safety Program is working on new engine diagnostic technology that will identify early symptoms of glitches in jet engines, including changes in vibration, speed, temperature, and emissions. The goal of the new sensors is to help ground crew and jet mechanics identify potential problems sooner and repair them before they threaten the safety of pilots, crew, and passengers.
Technicians prepare a US Air Force C-17 for engine health monitoring tests as part of the Vehicle Integrated Propulsion Research program -- a collaboration by NASA, the Air Force, and Pratt & Whitney to create a sensor system for early diagnosis of engine problems. (Source: NASA)
The new sensor system is being designed and developed as part of the Vehicle Integrated Propulsion Research (VIPR) program, a joint project of NASA, the Air Force, and Pratt & Whitney, the company that developed the C-17 engines. A number of engine health sensors are being tested as part of the project, including a model-based performance estimation and diagnostics system; an emissions sensor system to monitor the output of carbon, oxygen, and other gases; a self-diagnostic accelerometer; and high-frequency vibration sensors. Other sensors are tracking the effects of foreign materials on legacy instrumentation, including an inlet debris monitoring system and high-fidelity fuel flow measurement.
Engineers are putting the sensors through a series of ground tests at NASA's Dryden Air Flight Research Center using the engines of a retired C-17 on loan from the Air Force. The first test, conducted in December, activated the sensors on one of the C-17's two turbofan engines and ran water through it to see how the sensors would react. In a second test scheduled for early next year, the plane's engines will suck up crayons and cereal to monitor the ability to detect small bits of debris. The cereal and crayons will leave a colorful trail of grains and wax that the researchers can see and study to gauge how well the sensors work.
Following that, a final test on the system will introduce hard, glass-like particles that will simulate volcanic ash, which is too small for the eye to see. NASA says researchers will evaluate how early the sensors and related software can detect the particles and report a problem.
In fact, volcanic ash is one of the reasons for interest in developing a diagnostic sensor system. In 2009, an ash cloud from the Eyjafjallajökull volcano eruption in Iceland caused major air travel disruptions. Airlines would not fly through the cloud, because of the potential damage to jet engines, and they were forced to cancel an unprecedented number of flights. NASA says researchers are trying to determine the effects of ash early on to avoid such issues in the future.
The Air Force has conducted tests in the past on the effects of ash on jet engines, but this is the first time sensors are being used as part of that testing.
I agree - thanks for the article This sort of testing is the unglamorous "grunt work" that leads to advances in safety and improved performance over time. Kudos for highlighting a critical part of the design process - understanding how products perform in the real world.
Great article.I am always amazed at the resourcefulness engineers bring to the table when developing tests and executing programs.Several years ago, the Air Force had a program to evaluate bird strikes when ingested into inlets of jet engines. This came after several near-fatal accidents at Shaw Air Force Base in South Carolina.I was in basic training shortly before one such incident occurred.The pilot ejected successfully but the F-4 was lost. He was making touch and go landings when a swamp buzzard got into the act.It happens in a heartbeat but can be devastating.To get some idea as to severity, dead chickens were tossed into stationary aircraft, with engines running, to see what damage might result.The test was aborted due to PETA.(The chickens were dead, by the way.) This program is much more structured; consequently, you would expect the results to be much more beneficial to investigators in the process of proving sensors. I do know also that volcanic ash although infrequent, represents a real problem to aircraft engines.Again, great article.
Yes, Chuck, I remember at the time reading about the serious danger. So caution made sense, especially since they didn't know exactly where the ash was or how dense it was. Presumably, sensors in the turbines would allow the aircraft to divert from an ash cloud before the engines were destroyed.
Elizabeth, thanks for this article. The first A in NASA stands for Aeronautics, yet NASA's aeronautics programs get much less attention than the space program.
I have to admit, Rob, I too thought they were being too cautious at the time. But after reading TJ's comment below, I'm not so sure. Apparently, one aircraft had four engines flame out after encountering an ash cloud in 1982, it says.
Yes, Chuck, the big carriers lost tons. They were furious with the government, beliving they were being overly cautious. The advantage of these sensors is that the decision to fly or not could be made based on evidence rather than speculation.
I did notice--as no doubt others did--the statement in the article about what cereal and crayons will accomplish. What I'd like to know is why cereal and crayons for this purpose, instead of something else? For example, was the choice based on size of particles, consistency, or other factors?
There is a Suit of sensors in your everyday jet engine now. These sensors can help you monitor, control, and plan maintenance. Some are even indicator only. I don't know what this extra suit of sensors will do for us? Maybe increases cost and adds weight? Other than research purposes I don't think this research has much to offer. Just an opinion, I would like to see the report to this when all is done.
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