The Navy is allowing the Boeing [BA] T-45 Goshawk trainer aircraft to fly again when they are outfitted with several new monitors for altitude and oxygen flow, Navy officials told reporters Friday.

In April the Navy grounded its T-45C fleet due to physiological episodes (PEs) related to the pilot breathing system. Initially announced in early April, the grounding continued for months because of a recent increase in PEs caused by an issue in the aircraft onboard oxygen generation system (OBOGS) (Defense Daily, April 10).

A T-45C Goshawk training jet approaches an aircraft carrier. (Photo courtesy of U.S. Navy)
A T-45C Goshawk training jet approaches an aircraft carrier. (Photo courtesy of U.S. Navy)

The planes were initially allowed to fly again later that month with altitude limits, severely impacting their training mission., while investigations have looked into the root causes of the problem (Defense Daily, April 17).

Later in April, Vice Chief of Naval Operations (VCNO) Adm. William Moran directed the commander of U.S. Pacific Fleet, Adm. Scott Swift, to lead a comprehensive review of the PE issues in both T-45s as well as similar issued that arose in F/A-18 fighters. One main recommendation in the resulting report was that a single organization should lead the efforts and be led by a flag or general officer (Defense Daily, June 16). The Navy appointed Capt. Sara Joyner, who was already nominated to rear admiral (lower half). She was the first woman to assume command of an operational fighter squadron in 2007 and the first woman carrier airwing commander in 2013 (Defense Daily, Aug. 11).

Most recently, the Navy confirmed on Sunday that a T-45 based at Naval Air Station (NAS) Meridian, Miss. crashed in eastern Tennessee. Two pilots, an instructor and student, were killed in the incident. The Navy said it will conduct an investigation into the cause of the mishap.

Joyner told reporters during a roundtable that the team expects to conclude its overall process in the August 2018 timeframe. She said U.S. Naval Air Systems Command (NAVAIR) is looking at what instruments to put into the airframes to precisely measure oxygen, pressure, and look for contamination. “We’re happy to say at this point that we haven’t found any of a significant level of any concern,” she said.

She acknowledged there have been four PEs since modifications were put in place, but highlighted in each case there were two people in the cockpit and only one was affected. The Navy looked at the pressure and oxygen being delivered for the humans operating the aircraft but found them “well-supported” by the aircraft based on new measurement equipment. She added one of the four events is debatable and “most” were based on human and not machine issues.

One of the new monitoring systems being installed in T-45s are the CRU-123 oxygen monitor system. This modifies the older CRU-99 system which monitors oxygen content in air to also monitor flow and provide a post-flight download of what the system saw during a flight.

“So NAVAIR was able to come up with a monitoring system and we were able to adjust fleet procedures or training procedures so they were able to stay in the regimes of flight that were most supportive,” Joyner said.

The Navy was also able to groom the aircraft “to make sure they were keeping that work of breathing to a supportable level for the human being.”

However, the Navy has not finished testing to see if the CRU-123 is the best device to install on F/A-18s. Capt. David Kindley, F/A-18 and EA-18G Program Office Program Manager, said the team is trying to define exactly what they need to monitor in the F/A-18 to watch out for PEs, which may be different from the T-45s.

After the team concludes what should be monitored, they will use the the Cockpit Pressure Oxygen Monitoring System process to define what kind of monitor should be used in the F/A-18.  Kindley said if the CRU-123 is found to be a good choice, they can install it almost right away. If something else is needed, like a device that allows for a nautomatic backup oxygen system, they have space in the aircraft for that as well.

Other devices being used to monitor to T-45s include a digital upgrade to the altimeter in the cockpit, altitude watches for the aircrew to monitor the altitude readings the cockpit, and Slamsticks.

The Slamstick is a martchbox-sized device that can be downloaded after a flight. It can compare aircraft altitude, cockpit altitude, and compare those against what the levels should have been in the flight.

Joyner said this allows them to look at post-flight anomalous readings to pay attention to.

Kindley said as manager of the F/A-18 program he can see what the baseline norms for the aircraft are, then over time see if any particular plane/personnel are sliding away from normal. That way he can address any issued before they become dangerous.

Joyner added this data collection is also helping the Navy design improvements into future aircraft models that may limit physiological episodes.