Having followed this thread from inception, please allow me to present a plausible explanation for why these accidents MAY be occurring.
My sources are based on notes taken from articles in both the Wall Street Journal as well as Aviation Week & Space Technology over the past couple of years.
What’s disconcerting is the information that is bolded.
In July, the Marine Corps for the first time blamed one of the fatal Osprey crashes on a fleetwide problem that has been known for years but for which there’s still not a good fix. It’s known as hard clutch engagement, or HCE.
The Osprey’s two engines are linked by an interconnected drive shaft that runs inside the length of the wings. On each tip, by the engines, a component called a sprag clutch transfers torque, or power, from one proprotor to the other to make sure both rotors are spinning at the same speed. That keeps the Osprey’s flight in balance. If one of the two engines fails, the sprag clutch is also a safety feature: It will transfer power from the working side to the failing engine’s side to keep both rotors going.
But sprag clutches have also become a worrying element. As the Air Force, Navy and Marine Corps began looking at HCE events following incidents in 2022, they determined that the clutches may be wearing out faster than anticipated.
Since 2010, Osprey clutches have slipped at least 15 times. As the system re-engages, hard clutch engagement occurs. In just fractions of a second, an HCE event creates a power spike that surges power to the other engine, which can throw the Osprey into an uncontrolled roll or slide. A power spike can also destroy a sprag clutch, essentially severing the interconnected drive shaft. That could result in the complete loss of aircraft control with little or no time for the pilots to react and save their Osprey or crew, Rivolo said.
In the 2022 crash of a Marine Corps MV-22 in California that killed five Marines, hard clutch engagement created an “unrecoverable, catastrophic mechanical failure,” the investigation found. The fire was so intense it destroyed the Osprey’s flight data recorder — another issue the Marines have pushed to fix, by requiring new flight data recorders to be better able to survive a crash.
Neither the services nor defense contractors Bell Textron or Boeing, which jointly produce the Osprey, have found a root cause. The clutch “may be the manifestation of the problem,” but not the root cause, Slife said.
Materiel strength was the subject of a whistleblower lawsuit that Boeing settled with the Justice Department in September for $8.1 million. Two former Boeing V-22 composites fabricators had come forward with allegations that Boeing was falsifying records certifying that it had performed the testing necessary to ensure it maintained uniform temperatures required to ensure the Osprey’s composite parts were strengthened according to DOD specifications.
A certain temperature was needed for uniform molecular bonding of the composite surface.
Without that bond, “the components will contain resin voids, linear porosity, and other defects that are not visible to the eye; which compromise the strength and other characteristics of the material, and which can cause catastrophic structural failures,” the lawsuit alleged.
In its settlement, the Justice Department contended Boeing did not meet the Pentagon’s manufacturing standards from 2007 to 2018; the whistleblowers contended in their lawsuit that this affected more than 80 Ospreys that were delivered in that time frame.
www.lockheedmartin.com
