The All-Too-Clever Osprey and Its Latest Crash

Photograph Source: U.S. Department of Defense Current Photos – Public Domain

On November 29 this year, a CV-22 tiltrotor aircraft belonging to the US Airforce crashed into the sea south of the Japanese island of Kyushu, killing all eight crew members on board. This is the latest in a string of crashes, many of them fatal, extending over decades, which have gained that aircraft the nickname, Widow-maker.  Because the Osprey, when it doesn’t crash, is a very handy tool in warfare, the military spokespeople have tended to place the blame on pilot error, a “blame the victim” policy that added humiliation to the bereavement of the crash victims’ families.  But it seems that the military may be changing its stance: in both the June, 2022 crash in California that killed five and in the August 2023 crash in Australia that killed three, the cause was determined to be a clutch problem.  The Osprey has a clever (all-too-clever) clutch system that makes it possible, in case one engine fails, to power both propellers with the other engine.  But as not only the engines, but also the wings themselves, are moving parts, this requires an immensely complex clutch system connecting them. This can malfunction, which, according to several accounts I have read, can cause the proprotors (propellers) to rotate at different velocities which, if the ship is in its helicopter mode, can cause it to flip upside down.  Surely there’s no way a pilot can prevent an upside-down helicopter from falling straight down.  The military has admitted that there had been, before the California crash, 16 cases of clutch malfunction.

In the case of the most recent crash south of Kyushu, an observer reported seeing the Osprey upside-down and burning before exploding and falling into the sea. The military spokesman was careful to say that there was no human error, and that the pilot did everything possible. It sounds like another case of clutch failure.

The design of the Osprey is wonderfully clever.  As its proponents like to repeat, it can take off and land like a helicopter and fly like an airplane.  What they mention less often is that it is not so good at taking off and landing like an airplane because when it is on the ground in the airplane mode, with the engines rotated forward, the proprotor blades are so long they hit the ground.  To land or take off in the airplane mode the pilot must rotate the engines back to an angle, which greatly reduces the power of their forward thrust.  Possible, it seems, but dangerous.

Also a helicopter, if its engine fails, can slow its descent and float to the ground by autorotation (think of a folded paper helicopter).   The Osprey can, as its proponents insist, also go into autorotation mode, but this does not slow it down sufficiently to prevent its damage when it hits the ground, as the wings act as a “windbreaker”, disturbing the air before it meets the descending proprotor.

After the December 2016 Osprey crash in the sea off the coast of Nago, in northern Okinawa, an Osprey pilot’s manual, along with a crewmember’s helmet, washed ashore nearby and a local resident found them.  He dried the manual and took it to a copy machine.  I had an opportunity to study it, and to get a glimpse of the situation the Osprey pilot is in.  The manual is titled Emergency Procedures, and is a list of the various accidents and malfunctions that could happen, and what the pilot should do about each.  Some of these are obvious and characteristic of any aircraft – engine failure, engine fire, leaking fuel tank – but some are special to the Osprey. Being of such clever design it is loaded with clever gadgetry, and each gadget adds one more thing that could malfunction.  Pumps force hydraulic fluid down hoses not only to move the engines and the wings but also to activate smaller, more delicate moving parts (any of which can leak). It has a computerized flight control system (that can initiate unauthorized actions). It has delicate gearboxes and gadgets (that can be shaken apart by the Osprey’s severe vibrations). It has voices telling the pilot what to do. For every clever function there is a possible malfunction.  The manual lists (by my count) 120 possible emergencies that call for unscheduled landing. These are divided into four types: 1) “land when practical”, 80 cases (this I take to mean, land when it can be done safely, with little or no damage; 2) “land when possible”, 39 cases  (this I take to mean, anyway, get it on the ground, even if that means damage); 3) “land immediately”, 5 cases (whatever you see on the ground below you, get it down there NOW!;  4) (no actions suggested) 2 cases: presumably that would include the case of being upside down and on fire.

A retired Japan Self-Defense Force veteran told me that he had carried a manual like that (though much briefer) when he was working as a fighter pilot. He told me that there is no way you can memorize all that detail, and in the case of a real emergency there is no time to take out the manual and look up what to do. You use your best judgment, and if you survive, then you take the manual out to check if your judgment had been correct.

You can also read this manual as a record of malfunctions that actually occurred; many are things that could not have been predicted until they happened (who would have guessed that vibration would cause a hydraulic hose to rub up and down against the wiring next to it until that wore a hole in it, which became a leak, causing the December, 2000 crash, which killed all four crew members).  The history of the Osprey has amounted to a history of trial-and-error, or, fly it and we’ll see what happens.  When it crashes, investigate, add new safety features, add a new paragraph to the Emergency Procedures Manual, and fly it again.  In this process fifty young US Marines and Airmen (and I presume, women) have been killed.

One would think that through this process the Osprey would gradually become safer. Recently, however, its safety record has been getting worse: four crashes, with twenty dead, in the last two years.

But now it seems that the US military has given up trying to fix it. They have announced that they will stop production of new models, and phase it out by 2050.  This amounts to admitting the truth of what many have been saying for years:  the Osprey is not safe.  And it means that this is a good time to renew the protest: 2050 is not soon enough.  It’s time to put an end to this bloody experiment.