Monday, April 23, 2018

Mysterious cockpit problems continue, but Air Force trainers still fly




The Air Force says pilots flying its T-6A Texan II, a trainer that was grounded this year because of oxygen system problems, have reported 12 additional unexplained physiological episodes since March 1.

Experts are investigating but so far have found no root cause for the incidents. The plane, flown by the San Antonio-based Air Education and Training Command, was idled in February after 21 episodes were reported earlier in the year.

The Air Force said it was not considering another grounding of the plane “at this time,” expressing confidence that ongoing efforts — including an accelerated inspection and cleaning schedule for the Onboard Oxygen Generation System, or OBOGS — will ensure that the T-6 is safe to fly.



A series of in-air oxygen system failures in a variety of military aircraft over the past several years have raised concerns in the Pentagon about pilot safety, but until a sudden spike in January, the T-6, the Air Force’s principal trainer for novice pilots, had seen few such episodes.

Inspections found that the OBOGS’ shut-off valve, inlet filter and drain valves failed at rates much higher than expected. Air Force Materiel Command spokesman Derek Kaufman cautioned that experts could not directly link these failures to the unexplained physiological episodes and don’t believe that they caused a failure in the OBOGS or a separate backup emergency oxygen system.

“While our mission is to produce pilots, the safety of our pilots has been and always will be our number one priority,” AETC spokesman Dan Hawkins said in a statement released in response to questions about the newest incidents. “Proactive maintenance mitigation practices and inspections based on flight hours have been created and are being accomplished on a much more aggressive timeline.”



A physiological event takes place when aircrew experience symptoms that can hinder a pilot’s ability to fly safely. It can result from hypocapnia, hypercapnia or other factors. Hypocapnia is a state of reduced carbon dioxide in the blood. Hypercapnia is excessive carbon dioxide in the blood, usually caused by inadequate respiration.

Maj. Gen. Patrick Doherty, commander of the 19th Air Force at Joint Base San Antonio-Randolph, grounded the T-6 fleet after a cluster of such events occurred in planes flying out of Columbus AFB, Mississippi; Vance AFB, Oklahoma; and Sheppard AFB in Wichita Falls in late January.

The Air Force statement said that more than 400 planes in the 444-strong T-6 fleet have seen complete evaluations of the aircrew breathing system. In all, 85 percent of the shut-off valves, which allow air from the engine to bleed into the OBOGS, failed in the open position, allowing unrestricted air flow. Inlet filters, which capture water and contaminants from incoming “bleed air” from the engine, failed at the same rate.



One in every five drain valves, used to remove moisture from the system, was found to not fully close. The Air Force said that contributed to small amounts of bleed air leakage and added that components “have been mitigated or replaced as necessary to ensure continued safe system operation.”

“We’re finding issues with some of the parts. … We’re finding moisture in the condensers that shouldn’t be there,” Gen. Ellen Pawlikowski, who heads the Air Force Materiel Command, said last month. “We’re finding valves that are sticking. All of those things are things that we’re fixing, and we’re looking at what’s the right cycle, the number of hours before we replace the different components in them.”

Similar events last year caused the Navy to idle its T-45 Goshawk trainer for three months and have occurred in recent years in the F-22A, one of the Air Force’s newest fighters, and the F-15C/D, a much older plane.



The T-6, a single-engine, two-seat plane designed for joint primary pilot training in the Air Force and Navy, began flying at Randolph around 18 years ago. Its troubles have left turbulence beyond the flight line, prompting a personnel shakeup in the T-6 System Program Office. While the Air Force didn’t directly address a claim made in an online pilot forum that six people in the office were shuffled into less-visible jobs elsewhere, it did say in response to a question that “limited personnel shifts and additions were made to align experience with the magnitude, impact and difficulty of this challenge.”

The program office “remains keenly focused on ensuring the T-6 remains an operationally safe, suitable and effective platform,” the statement said.

February’s delay in training aviators came as the Air Force has been shedding veteran pilots at an alarming rate. Last year, it was 1,300 pilots below its goal of 5,300. AETC had projected that it would train about 1,200 during the current fiscal year, 1,300 in fiscal year 2019 and 1,400 for 2020. During the month the plane was grounded, the Air Force said it lost flying time for more than 100 pilots.



Besides inspecting and cleaning the OBOGS, the Air Force has conducted a root-cause evaluation that includes a comprehensive assessment of all aircraft encountering unexplained physiological episodes.

AETC and the T-6 System Program Office will launch a feasibility study this month into the possibility of including an automatic backup oxygen system in the plane. In the meantime, it has bought new testing equipment and increased the frequency of existing maintenance work. It also is educating pilots about physiological events.

Air Force Secretary Heather Wilson “has asked for a belt-and-suspenders approach,” said the Materiel Command’s Pawlikowski. “The OBOGS is an important system, and the engineers have confidence in it. There is no single point of failure, but it doesn’t hurt to have a backup, since no root cause has been determined.”

Original article can be found here ➤ https://www.expressnews.com

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