Navy zeroing in on PE causes

PATUXENT RIVER, Md. – Teams utilizing a Root Cause Corrective Action (RCCA) analysis process as a cause of the physiological episodes (PEs), in F-A/18 Hornets and EA-18 Growlers, and T-45C Goshawk pilots, has eliminated contaminated breathing gas as a cause of those episodes. The teams, tasked with investigating the issue, continue to narrow the list of possible factors. Each RCCA Core team determined last fall that the quality of pilots’ onboard oxygen was unaffected by asphyxiates, carbon monoxide, and external/internal contaminants, such as fuel vapor or pyrolysis byproducts. "We are happy to see that contamination has been ruled out and that all Navy aircraft are delivering clean air to our aviators," said Rear Adm. Fredrick Luchtman, lead for the Physiological Episodes Action Team (PEAT). "We still have work to do,” he continued, “especially with the Hornets and Growlers. The T-45 team reached its conclusion in September and the F/A-18 team in October after a 16-month joint effort. The T-45 team closed more than 90 percent of nearly 350 branches on its RCCA “fault tree” - 50 was related to contamination. The team is now focusing on optimal breathing pressure and oxygen concentration as potential factors. The F/A-18 team is focused on two potential factors: (1) Cabin stability by preventing unexpected pressure fluctuations correlated with PE events, but not yet shown to be a causal factor; (2) Focus on breathing dynamics and factors that can impact gas exchange during respiration, such as hyper/hypocapnia, hypoxic hypoxia, work of breathing, and adsorption/acceleration atelectasis (collapsed lung). There appears to be no one single cause, but rather multiple contributors being worked by the F/A-18 team with near-term corrective actions. Other potential factors have been ruled out - such as electromagnetic exposure - while others were determined to have played a role in F/A-18 PEs, including maintenance-related issues and atelectasis. https://www.navy.mil/submit/display.asp?story_id=109080 Gulf Coast Note: T-45C instructors and student-aviators from both NAS Meridian, Miss., and NAS Pensacola, Fla., were among those experiencing some of these psychological episodes.