V-22 programmet lever videre til tross for mange havarier og tap av liv - AW&ST

 

Maskinens besøk i Norge nylig var tragisk. En nødlanding og et havari med tap av liv. Den flyr igjen nå, men her er for mye leamikk til at den kan bli et sikkert fremkomstmiddel. Mener jeg.  (Red.) 

V-22 Office Looks At Long-Term Upgrades Amid Near-Term Fixes

Brian Everstine April 30, 2024

U.S. Marine Corps MV-22 flies in Norway in April 2022. Credit: U.S. Marine Corps

The V-22 Program Office is starting a new study looking at long-term modernization of the tiltrotor, overhauling almost all of the aircraft except for the fuselage while also installing changes to the gearbox to try to fix vexing ongoing issues.

The long-term plan, which the office calls the Renewed V-22 Aircraft Modernization Program (ReVAMP), is in the early stages. It focuses on “if we had to do V-22 all over again, what would that look like,” says Col. Brian Taylor, program manager of the V-22 Program Office (PMA-275).

For now, it appears the V-22’s fuselage has largely unlimited life, while many of the maintenance issues and problems that limit the aircraft’s longevity are on its wings, engines and gearboxes.

“So if we put a new wing and nacelle on there, we’re probably good for another 40 years,” Taylor says.

The study targets research, development, test and evaluation in about 2036, with developmental testing around 2040 and installations in 2042. Broadly speaking, study areas include an improved drive system, new engines or new cores for the existing engines, improved ice protection, and modernization to the aircraft’s maintenance process, according to Taylor’s presentation at the Modern Day Marine expo in Washington April 30.

At the same time, the program office is also focusing on a nearer-term refresh to the V-22’s cockpit under an effort called the V-22 Cockpit Technology Replacement (VeCToR). This is largely to address obsolescence issues with cockpit displays, keyboards, weather radar and mission computers, among others.

Much of the current burden is on the V-22’s tilting nacelles, which create about 60% of the overall maintenance work. The Air Force is undertaking a nacelle replacement program, with about 20 aircraft already through the process. The U.S. Navy is also expected to go through the process. The Marine Corps, however, with the largest fleet, will not go through the full nacelle replacement. Instead, Marine Corps V-22s will have the wiring inside the nacelle replaced—a much easier and cheaper job that is still expected to achieve about 70% of the maintenance and reliability improvements that would result from a nacelle replacement.

The most urgent near-term fixes are inside the V-22’s gearbox, with proprotor gearbox problems linked to several high-profile crashes. The most notable problem has been with the input quill assembly (IQA), which has long had a problem causing the clutch to slip—known as a hard clutch engagement.

Within the past two years, the military services have been replacing the IQA every 800 hr., an expensive and time-consuming burden as the fleet has returned to flight after multiple groundings. The program office is early in the process of an IQA replacement, with about 15 changes in a new prototype that will be delivered within the next month or so, Taylor says.

While Taylor did not delineate specific changes, he did say it is informed by a prior effort to redesign the IQA. The Joint Program Office (JPO) started an IQA redesign in 2017 to try to fix the issue of hard clutch engagements that at the time had been known for about seven years, though the fix failed to be qualified in 2020, Aerospace DAILY has learned.

Taylor says the V-22’s clutch is unique and is “on a very tight edge of engaging when it needs to and releasing when it needs to.” The previous redesign effort had “gotten a little bit too far one way on that, so this one is informed by that.”

The Navy’s fiscal 2025 budget request outlines a plan to upgrade the input quill and purge the fleet of thin-dense chrome plating, which has long caused issues by becoming worn during use and chipping into the Osprey’s oil system.

The service expects to begin fielding new kits in fiscal 2026. Taylor says the kit covers replacements of “key degraders” to the overall gearbox. The cause of thin-dense chrome chipping is on the clutch’s pinion bearing, and this will be replaced with another type of steel that Taylor says is “really going to help us” with one particular instance of chipping. The office is also looking at replacing other metals inside the gearbox. Chipping has been linked to mishaps, and usually results in a proprotor gearbox change when discovered.

With the long-known issues of hard clutch engagements and chipping inside the gearbox, the JPO says it better understands the environment inside the clutch assembly—though no root cause to the problems have been announced. The V-22’s clutch is unique, and there has been a “decade-long study of this particular phenomenon,” Taylor says.

With the V-22 having been in service for more than two decades, engineers at Naval Air Systems command have had a “running list of things that hey, if I had to do it all over again, these are the things I would do” when asked about addressing V-22 reliability issues, Taylor says.

“I would say within about 10 min. of asking this question about 12 of the ideas were instantly brought to us because they had been kind of sitting out there for a while,” Taylor says. “But really all of this is data informed by what we have learned in the past and then really now it’s now about making sure that it’s actually going to be the solution that we need.”