Why some engines fail in flight is the subject of a new NASA research program. “There is a question regarding the effect that moisture has on newer-technology engines. We’re trying to understand how much moisture actually exists in the atmosphere, where it comes from, and what effect it has on newer-technology engines,” Michael DiLullo, owner and CEO of Threshold Technologies, told AIN.

Threshold will be providing a GII and crew for NASA’s high ice water content (HIWC) flight campaign. In addition, Threshold and sister company Aviation Maintenance Group will provide maintenance and support for the aircraft throughout the project.

HIWC describes atmospheric conditions consisting of high concentrations of ice crystals typically associated with deep convection storms in the tropics and subtropics. These conditions are thought to have contributed to more than 100 jet-engine power-loss events since 1989 in which ice formed inside the core areas of the engine, leading to temporary shutdowns because of surge, stall or flameout. More…

Flight Test Associates (FTA) of Mojave, Calif., is the prime contractor on the project and will modify Threshold’s GII extensively. Modifications to the aircraft will include the installation of six under-wing pylons that will carry an array of test instruments.  Other modifications include the installation of fuselage instruments, advanced weather radar and communications equipment and engine-monitoring instruments.

A statement issued by FTA said, “…over the past 10 years there have been a significant number of jet engine power-loss events (flameout, stall, rollback and surge) occurring in and around areas of deep tropical convection at higher altitudes, mostly above 20,000 feet. It is now theorized that these flights were in areas of high concentrations of ice crystals, with little or no supercooled liquid water, and that the power loss resulted from ice crystals entering the engine core, melting and refreezing inside the engine.

“NASA, together with partner organizations, has proposed a field campaign using an instrumented research aircraft to characterize this environment. The primary objective for this research is to develop a statistical database of microphysical cloud properties to be used to certify engine operability in a high-ice-water-content environment. Currently, there are no standards for this kind of icing environment. The primary field campaign will be conducted out of Darwin, Australia, to coincide with the monsoon season between January and March. Before that field campaign, a trial research campaign will be conducted based out of a tropical region at least six months before the primary campaign.”

DiLullo said he’s charged with understanding and recognizing the potential hazards associated with the project and figuring out how to mitigate them.

“We’re going to take research scientists, a flight crew and support personnel to Darwin, Australia, with a highly modified GII. Darwin was chosen because it has a very wet, predictable monsoon season from January through the first part of April. Before that happening there’s an immense amount of training going on,” he said.

According to DiLullo, who will be the project’s chief pilot, all crewmembers are high-time Gulfstream pilots. “Both Art Barth, our safety officer, and Clark Slone are FAA DAR test pilots. NASA has also assigned two additional pilots as observers who are rated in the aircraft. The pre-operation training program will include aircraft and mission familiarization, and hazardous condition preparation including land and sea survival training.” 

DiLullo said NASA has designed a specialized grid pattern that will allow the team to maximize the sampling. The project calls for about 230 hours of flying in the weather conditions being studied. Each flight will last about five hours.

NASA and its research partners, the FAA, Environment Canada, Airbus and Boeing, will use the flight data to define new parameters for developing and certifying aircraft engines, air data systems and weather radar systems. The research also will support development of weather forecasting tools to help pilots avoid potentially hazardous icing conditions and of ground test facilities designed to simulate the high-ice-water-content environment.