DVIDS – News – Creative Engineering Solution at FRCE Overcomes V-22 APU Filter Shortage

MARINE CORPS AIR STATION CHERRY POINT, NC – A shortage of clutch servo valve filter supplies for V-22 Osprey Auxiliary Power Units (APUs) threatened to keep a number of aircraft grounded, until that the V-22 Fleet APU Group Fleet Readiness Center East (FRCE) support team found a way to clean the disposable filters and reinstall them on the aircraft.

The APU filter is a consumable which is replaced after 1,120 flight hours; it is usually used during a cycle and eliminated after removal. With 375 aircraft in the Marine Corps fleet, the filter is a commonly used item, with a replacement rate of about 100 per month. The quarter-size metal filter is available from a single source, and due to supply chain issues, the supplier was unable to meet demand. With no filters in the supply system, APU engineering and logistics personnel had to find a creative solution to meet the needs of the V-22 aircraft and APUs being overhauled at FRCE.

“We searched for retail assets or hidden assets that we might have stored somewhere, but found nothing,” said Joe Carson, V-22 Power and Propulsion logistics team manager at FRCE. . “The filter was a consumable item, so the last option would usually be to ask engineering to reuse something that is a disposable item – but in this case, that was the last option we had.”

The filter is part of an essential oil line that helps engage the APU clutch in the mid-wing gearbox to start the V-22’s main engines. Fleet maintainers are instructed to replace filters when they are found to be clogged during inspection, but the supplier did not expect deliveries until March 2022. This meant several planes would not fly not until the filters could be found.

“Most engineers don’t like to reuse something that’s expendable, because it’s expendable for a reason,” said FRCE’s V-22 Power and Propulsion APU principal engineer Rob Wansker. “So we’re considering, what’s the consequence of using this for an extended period of time? Can we push back the replacement time? We weighed our short and long term options, and decided to see if we could clean and recertify the filters we had.

Engineering consulted with FRCE’s Materials Engineering Lab to determine the best way to clean the fine mesh filter. After experimenting with a few scrap filters, FRCE chemist Megan Goold found a procedure that would allow filters to be cleaned and reused if new filters were not available.

“I wanted to make the cleanup as simple as possible, using materials that the APU shop already had on hand that would also be easily and readily available to the fleet,” Goold said. “The easiest thing would be to wash your hands, so we tried different things in the lab until we found something that worked.” Isopropyl alcohol and a commonly used degreasing solvent did the trick, and engineering created a temporary instruction for depot and fleet managers to follow until filters are more readily available through supply.

Another obstacle to solving this problem was that used filters were not readily available for cleaning. Disposable items such as filters are usually discarded after maintenance procedures, meaning there was no inventory of used filters. Wansker coordinated with depot and fleet mechanics working on V-22 APUs to encourage them to set aside used filters in case they were needed for inspection and cleaning.

“We then took the filters that seemed like good candidates, and cleaned and tested them according to the temporary procedure we had created,” Wansker said. “Once we were able to get a clean batch of engineering-approved filters, we were able to send them directly to squadrons to be installed on an APU.”

The engineering and logistics team implemented a temporary solution a few weeks after identifying the supply problem. Meanwhile, four aircraft had been grounded awaiting APU servovalve filters, and the ability to clean and reissue filters quickly brought those V-22 Ospreys back into service.

Members of the V-22 team say the incident reminds them that even seemingly routine projects can have a profound impact on the combatants they serve.

“The V-22 Osprey is a massive aircraft, and to think that our team’s help with this project was able to get these aircraft back into the air helps put into perspective the importance of what we’re doing,” Wansker said.

FRCE is North Carolina’s largest provider of maintenance, repair, overhaul, and technical services, with more than 4,000 civilian, military, and contract workers. Its annual turnover exceeds 1 billion dollars. The depot provides services to the fleet while functioning as an integral part of the larger United States Navy; Naval Air Systems Command; and Commander of Fleet Readiness Centers.

Date taken: 21.01.2022
Date posted: 21.01.2022 11:37
Story ID: 413214
Site: CHERRY POINT, North Carolina, USA

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