Team Edwards testing key to getting all Air Force Raptors back in the air

  • Published
  • By Kenji Thuloweit
  • 95th Air Base Wing Public Affairs
EDWARDS AIR FORCE BASE, Calif. --  When Air Combat Command directed a stand-down of the F-22 fleet May 3, the 411th Flight Test Squadron had already begun working around the clock to test and collect data on the Raptor's oxygen system in order to get it airborne again.

That critical work culminated in Secretary of the Air Force Michael Donley and Air Force Chief of Staff Gen. Norton Schwartz announcing an Edwards-supported implementation plan that will allow the F-22 Raptor to resume flight operations.

ACC ordered the stand-down following 12 reported incidents since April 2008, where pilots experienced hypoxia-like symptoms.

In conjunction with the System Program Office and contractor team, the 411th FLTS played the key role in providing the data to the Air Force's Safety Investigation Board and Scientific Advisory Board needed to recommend a return-to-flight solution.

"We're the responsible test organization here (and) were tasked to develop the tests and execute them, so we have been the go-to organization to develop these tests," said 1st. Lt. Austin Curtis, 411th FLTS lead subsystems engineer.

As the Air Force's primary developmental flight test and evaluation center, Edwards had the necessary assets to collect data required for the SIB and SAB report to the chief of staff.

"We have instrumented airplanes and the ability to modify them to look at particular questions the SIB and the SAB wanted answered before they recommended putting the F-22 back in the air," said Maj. Chris Keithley, 411th FLTS F-22 test pilot.

According to Keithley, the squadron spent the first 12 weeks evaluating the problem, designing the test and modifying the airplane.

"We had a two-pronged approach," Keithley said, "that looked at potential contaminants in the air that are (normally) provided to the pilot, (and) diminished oxygen production out of the on-board oxygen generation system. For the contaminants we had several instrumentation apparatuses on the airplane along with Summa canisters to collect air samples that were tested in a lab."

The 411th team used desorption tubes and carbon canisters to collect air samples, and a systems monitor to detect volatile organic compounds.

"We looked at several different regulatory standards to see what (constituted) good and bad levels of VOCs [volatile organic compounds]," said Keithley.

The on-board oxygen generation system, known as OBOGS, is designed to produce a certain amount of oxygen at various altitudes. Instrumentation on the test F-22 monitored and transmitted real-time data on the levels of oxygen it was producing. Also, as the F-22 engine provides bleed air to the environmental control system and the OBOGS, test missions sought to stress both the environmental control system and engine to see if any anomalies occurred within either system.

Curtis said that after each test an expediter drove the samples to the lab in order to turn data quickly. A local lab analyzed the samples for toxins and contaminants.

The squadron flew 15 sorties in 4 weeks in order to collect real-time oxygen data from the Raptor's test instrumentation. The 95th Aerospace Medicine Squadron also examined test pilots before and after flight tests and, as Curtis noted, the test airplane flew with components taken from Raptors that previously reported incidents in order to help rule out potential root causes.

"Basically we turned over every single rock we thought to turn over; we wanted to take a real broad brush approach to ensure we answered all questions," said Keithley.

Of the roughly 250 members in the 411th FLTS, 80 percent worked on the project at one time or another.

"It has been a non-stop work schedule. It has been one of the busier times at the 411th," Keithley said.

In August the squadron hosted an F-22 commander's conference where pilots and engineers interfaced with SIB and SAB members and developed a tool to significantly speed up data reduction and analysis.

According to Curtis, 411 FLTS engineers developed a software program that broke down raw data, extracted irrelevant information, and provided useable data faster and in a graphical format that proved extremely useful to the SIB. The tool allowed the SIB team to analyze massive quantities of data faster, ultimately decreasing the Raptor down time by increasing the speed in which testers and evaluators found a return-to-flight solution.

The 411th FLTS turned all data over to the SIB and SAB who reported their findings to Air Force leadership. Through the reports ACC developed a return-to-flight solution.

"We now have enough insight from recent studies and investigations that a return to flight is prudent and appropriate," Schwartz said. "We're managing the risks with our aircrews, and we're continuing to study the F-22's oxygen systems and collect data to improve its performance."