The U.S. Air Force is investigating whether maintenance problems with the T-6A’s pilot breathing system caused a recent surge in physiological episodes (PEs) that led to the grounding of the trainer aircraft fleet, according to a service official.

The Air Force suspects that technicians may need more training to maintain the plane’s on-board oxygen generation system (OBOGS), said Lt. Gen. Mark Nowland, deputy chief of staff for operations, who testified before the House Armed Services Committee’s tactical air and land forces panel Feb. 6. 

The T-6A Texan II trainer. (U.S. Air Force photo)
The T-6A Texan II trainer. (U.S. Air Force photo)

“The system and the way the systems work is sound,” Nowland told lawmakers. “Maintaining it is the critical factor.”

The T-6A fleet, which has amassed 2.1 million flight hours, experienced a relatively low 1.95 PEs per 100,000 hours until the recent surge, Nowland noted. Raytheon [RTN] Aircraft, now Textron [TXT] Aviation, finished building the planes in 2010.

The Air Force grounded its 444 T-6As on Feb. 1 after 10 physiological events occurred at three bases in January (Defense Daily, Feb. 1). The first of those incidents occurred Jan. 19 at Columbus Air Force Base in Mississippi.

In the current fiscal year, the T-6A has experienced 22 “hypoxia-like events” so far, up from four events in all of FY 2017, Nowland testified. The Air Force concluded that maintenance was behind a smaller surge in such oxygen-deprivation incidents that led to the grounding of some A-10 attack-aircraft last year.

Nowland said the Air Force is also looking at using instrumentation to increase pilot data collection. Such information could lead to the earlier detection of potential PE problems.

To address PEs with the Navy’s F/A-18 Hornets and F/A-18E/F Super Hornets, a recent NASA report recommended gathering more data, such as measuring breathing patterns during flight, recording cabin pressure, measuring oxygen in the breathing gas system and recording carbon dioxide in the oxygen mask (Defense Daily, Dec. 13, 2017). 

Nowland indicated that the Air Force is exploring interim measures to safely return the T-6A to flight as quickly as possible. It is losing 700 sorties a day due to the fleet’s grounding, which “will have effect on our pilot training,” he said.