U.S. News: Osprey Flaws Vex Pentagon for Decades --- Fleet grounded after latest accident that killed 8 when aircraft crashed into ocean

"In late November, Amber Sax awoke to learn that eight more families were facing her nightmare. A deluge of messages told her that a U.S. military Osprey aircraft had crashed into the ocean near a Japanese island with eight crew on board.

Sax lost her husband, a 33-year-old Marine Corps pilot, in June 2022. The MV-22 Osprey co-piloted by Capt. John J. Sax reported a problem with an overheating gearbox and, moments later, plunged into the Southern California desert, killing all five aboard.

The Japan crash, in which all eight crew were later confirmed dead, led the U.S. military to ground its entire operational fleet of more than 400 Ospreys for the first time. 

In 11 crashes involving the aircraft since 1992, 61 service members and other passengers have died.

The crash has reignited doubts among some military families and engineers about whether the Osprey's unusual design -- a hybrid of helicopter and airplane -- can be made fully safe. The military has blamed some incidents, including the one in California, on faults in the aircraft's gearbox that can cause power surges to the rotors.

Amber Sax says the Marines haven't fully explained what the problem was and how it can be fixed.

"They haven't determined what the root cause is of the failure, and so if you don't understand the root cause, how is it being prevented?" she said.

The latest crash off Japan involving an Air Force Special Operations CV-22 is under investigation by the Pentagon. Seven of the eight airmen's bodies have been recovered. Initial findings point toward a mechanical problem with the aircraft, not pilot error, according to the Air Force.

By all accounts, the military isn't thinking of giving up on the Osprey or its unusual design. The Army last year selected a similar design to replace parts of its helicopter fleet, in a contract estimated by analysts to be worth up to $70 billion.

The Osprey's record of fatal crashes is worse than most military aircraft, but it isn't the only problem area. For the past two years, the Pentagon has been working to address a stubbornly high aviation incident rate across services.

In December 2020, a congressional commission into military aviation identified failings with training, aging aircraft and spare-parts shortages. In response, the Pentagon has grounded various aircraft to provide time for maintenance and equipment checks, added training and set up a special office so the armed services could share best practices.

The $90 million Osprey has become a workhorse, especially in the Marines, because of its unique attributes. Like a helicopter, it can take off, hover and land vertically. At the same time, it boasts the higher speed, range and altitude of a fixed-wing aircraft, with the ability to fly at up to 300 miles an hour for more than 400 miles while carrying up to 24 people.

It does all this with what are called tilt-rotors. After taking off vertically, the Osprey swivels its two engines so that the 38-foot rotors are facing forward, propelling the aircraft ahead. When it is time to land, the engines swivel back and the tilt-rotors face upward, allowing the Osprey to settle gently on a runway or aircraft-carrier deck.

The grounding of the entire Osprey fleet has created a logistical challenge for the Marines, who have about 300 of the aircraft, as well as for the Navy, which has started using them to supply aircraft carriers. The Air Force mainly deploys them for special forces.

Development of the Osprey began in the 1980s to replace the Navy's fleet of aging helicopters. More than 450 Ospreys have been produced by a joint venture between Textron's Bell unit and Boeing.

The Marines and Air Force have used Ospreys to rapidly deploy troops and supplies in Iraq and Afghanistan. Japan is the only other country with Ospreys, and it has grounded its fleet as it awaits safety assurances from the U.S.

Since the Osprey's early days, some military engineers have fretted about the challenges posed by its novel design, including the techniques used to keep its weight down and the risk it could tip over if the thrust of the two rotors becomes mismatched.

In an accident in April 2000, an Osprey spun onto its back while landing after its right rotor was unable to maintain enough downward force during a fast descent. The crash killed 19 Marines, the biggest loss of life in any single Osprey accident.

Safety steps were later introduced to warn pilots with visual and audio alerts if an Osprey is descending too quickly.

U.S. military officials say the Osprey remains a safe aircraft to fly, given the often-hazardous environments in which it operates.

"The military is focused on the mission and they can't just stop because of safety concerns," said Timothy Loranger, a lawyer at law firm Wisner Baum who represents families of service members killed in Osprey accidents.

Under the military's definition, Class A incidents -- the most serious -- encompass those in which someone was killed or permanently disabled, or in which damages topped $2.5 million.

In the decade through last year, the Osprey Class A incident rate in the Marines was 3.87 per 100,000 flying hours, compared with 2.45 for all crewed Marine flights. 

The rate in the Air Force, which flies the aircraft less often, for the Osprey was 5.08 per 100,000 flying hours in the decade through 2021.

The Pentagon said that for the Osprey, the rate of mishaps -- the term it uses to avoid prejudging the cause -- has been stable for a decade or even falling if one considers that $2.5 million buys less repair work than it used to.

Yet the military has fallen short of the improvements achieved by companies operating commercial helicopters serving the oil-and-gas industry, which also often fly in dangerous or hostile environments. After a spate of fatal helicopter crashes in the North Sea in the 2010s, the accident rate per 100,000 flight hours of these helicopters -- which includes a broader range of incidents than the military's Class A definition -- fell from 7.2 in 2013 to an average of 3 in the following nine years, according to HeliOffshore, a trade group.

"There's no reason the military can't do the same," said Bill Chiles, former chief executive of Houston-based Bristow, the biggest commercial-helicopter operator. To improve helicopter safety, companies put aside commercial rivalries to share flying data and develop best practices, and they started their quarterly earnings calls with a review of their safety record.

Chiles advised the congressional commission, which found that a lack of data sharing in the military was one of its biggest aircraft-safety problems.

One Osprey problem that has dogged the military since 2010 is a gearbox malfunction known as hard clutch engagement that can cause power to surge in one rotor, destabilizing the aircraft.

In two incidents in 2022, Air Force Ospreys were forced to make emergency landings because of the problem. The crash that killed Amber Sax's husband that year was linked to the same issue.

The official report into that crash said Ospreys suffered 15 hard clutch engagement failures in roughly 680,000 flight hours. The investigation couldn't find the root cause but found older aircraft tended to be more vulnerable, so the military mandated that a key gearbox part be replaced after 800 flight hours. It said that would reduce the odds of the problem occurring by 99%, without explaining how it reached that figure.

The Pentagon has awarded the joint venture between Textron's Bell unit and Boeing contracts worth more than $60 million for new gearbox designs and systems to detect vibrations that might lead to failures. The Pentagon has already undertaken a range of design fixes for the Osprey, many of them ongoing, and revised training programs. The companies, through a spokesman, said they were ready to assist the investigation into the crash off Japan. They declined to comment further.

The technical challenges of tilt-rotor aircraft didn't dissuade the Army from last year selecting Textron to replace parts of the Black Hawk helicopter fleet, made by Lockheed Martin, with Textron's Bell V-280 Valor aircraft. The Valor operates with tilt-rotors, similar to the Osprey, but can fly faster and farther.

The Osprey is due to fly until 2055, though production in Amarillo is set to end in 2026 with the final purchases for the Navy." [1]

1. U.S. News: Osprey Flaws Vex Pentagon for Decades --- Fleet grounded after latest accident that killed 8 when aircraft crashed into ocean. Gale, Alastair; Cameron, Doug.  Wall Street Journal, Eastern edition; New York, N.Y.. 20 Dec 2023: A.6.