Bizzare accident onboard Truman

The USS Harry S. Truman is currently doing carrier qualifications off the East Coast of the US, which include taxi tests of the X-47B. On Sunday, December 9, two E-2C Hawkeyes were involved in a highly unusual accident, causing damage to both aircraft.

The two aircraft were chocked, chained, wings folded, and no crew on board, when one of them suffered an uncommanded wing unfold, which caused the wing to come down and strike the spinning propeller of the other aircraft. There's no word on what caused the wing to start to unfold.

Usually, when the wings are folded, hydraulic pressure and lock pins keep the wings locked in place so that they can't move on their own.

My question now is, did the X-47 have something to do with this, unintentionally.

The X-47 was put through anechoic testing at a significantly higher level than most planes go through, and passed, but did it send some signal that was similar to the wing fold that activated the wing swing mechanism? Is this going to be a problem for other UAVs that they're going to have to overcome?

I wasn't aware that our manned aircraft are set up to receive wireless commands.

Do they? Weird incident.

human error would be my guess.

reply to post by munkey66


Most likely, but it's an interesting coincidence that they have the X-47 on board, and a weird accident like this happens.

I think that some signal caused this. Where the signal came from is my question. Something unlocked the wing. I think we are being too reliant on electronics nowadays. It's like your garage door opening or closing when someone presses a remote down the street. My guess is radio interference of some sort. Could also be a short in the microcircuitry.

Originally posted by rickymouse
I think that some signal caused this.

Why?

Originally posted by Aloysius the Gaul

Originally posted by rickymouse
I think that some signal caused this.

Why?

I don't know why, but wings don't usually go down by themselves. I've had the trunk open on the car with nobody even close. Didn't even have a remote control for it, just an electronic button in the glovebox. Something had to release the wing, maybe it was a ghost

It is found that anything that can go wrong at sea generally does go wrong sooner or later, so it is not to be wondered that owners prefer the safe to the scientific. It is also found that it is almost as bad to have too many parts as too few; that arrangements which are for exceptional and occasional use are rarely available when wanted, and have the disadvantage of requiring additional care.

November 13, 1877 - Murphy's Law

I'm not trying to invoke 'weirdness' as an explanation, but sometimes technology just goes wrong at the wrong time.

The two aircraft were chocked, chained, wings folded, and no crew on board, when one of them suffered an uncommanded wing unfold, which caused the wing to come down and strike the spinning propeller of the other aircraft. There's no word on what caused the wing to start to unfold.

You say:

BOTH aircraft unmanned and "parked"

Then aircraft one unfolds wing , hitting RUNNING propeller of (unmanned) parked aircraft two?

Is it normal to let unmanned aircraft's sit around with spinning props?

reply to post by EartOccupant


Turbo-props can rotate in the wind - it's called windmilling, unsurprisingly Piston engine props do not because the compression of the pistons acts as a bake.

In civvie life they are generally strapped with a boot over them hooked to structure somewhere to stop this - I would assume the military would usually do the same, & don't know why not here.

EMI is a credible cause of system malfunction if systems are poorly designed and hardened. But susceptibility is dealt with in testing. The US Navy has an extremely impressive facility for this and naval aircraft standards are very demanding in this area.

While the X-47 will undoubtedly have emitters its unlikely to be the major EMI threat on the ship deck, not by a long way.

Interesting case.

Adding a video of a HawkEye wing unfolding.
Enjoy.

Originally posted by rickymouse

Originally posted by Aloysius the Gaul

Originally posted by rickymouse
I think that some signal caused this.

Why?

I don't know why, but wings don't usually go down by themselves. I've had the trunk open on the car with nobody even close. Didn't even have a remote control for it, just an electronic button in the glovebox. Something had to release the wing, maybe it was a ghost

But why a signal?

Things wear out, or miss-align, or have all sorts of other things happen. I'd be looking at seals in the hydraulics in the fist instance - especially has there been any maintenance on them recently (sadly recent maintenance probably causes more problems than anything else!!)

reply to post by Aloysius the Gaul


The Depot has been at least as dangerous as anyone we've fought in recent years.

Just a few accidents off the top of my head caused by the depot (in no particular order).

F-117 at Maryland (?) airshow. The pilot had made several passes over the crowd, with no problem. On his last pass, he pulled up into a climbing left hand turn. As he applied Gs to the aircraft, the outboard right wing began to flutter, and snapped off at the join. The pilot and aircraft landed in the yard of several houses in the area. The ultimate cause was found to be improperly installed wing fasteners. At the time of the accident, there was only one fastener left holding the wing in place. The G forces applied were enough to cause the others to separate, and the stress was too much for the remaining fastener.

C-141 at Nashville. A C-141B Starlifter transiting to Europe landed at Nashville to refuel before heading out over the Atlantic, where it would meet several tankers along the way. During the refueling, the ground crew heard a large bang, and the left wing blew apart at the wing root, dropping the right wingtip onto the ground. The cause was a fuel vent plug that had been left in the fuel tank after the Depot finished a maintenance check.

C-130 in Europe. A C-130E had recently come out of the depot, and was approaching its destination loading with passengers and crew, when the wing separated from the aircraft. The depot had failed to torque down and fasten the bolts holding the wing on. A QA supervisor committed suicide shortly after because he had signed off on the work being properly completed. There were no survivors.

KC-135 at the depot. A pressurization test was being conducted on a KC-135 that had recently completed some work at the depot. During the test, the aft fuselage shattered, dropping the tail to the ground. An outflow valve had been plugged, and the plug left in place. There was no where for the pressure to go, and the fuselage shattered.

E-8 in the UAE. An E-8 J-STARS that had completed depot level maintenance about a month prior was on its first mission out of the UAE. After take off, they were refueling from a KC-135, when the crew heard a bang, and the aircraft began to shudder. The crew backed off from the tanker, and all indicators were normal, so they started to refuel again. The boomer on the tanker notified the crew of the E-8 that they had a large hole in the left wing, and fuel was pouring out of it. The crew declared an emergency, and returned to base. Upon further inspection it was found that a plug had been left in the fuel tank, causing an over pressure event, and the inside of the wing had suffered enough damage that it was several months before the Air Force made the decision to repair the aircraft, due to the cost of rebuilding the wing. There were several holes on both the top and bottom of the wing, and on the inside, ribs, and spars had suffered significant damage.

The original Hawkeyes were flying in the 60's. You;d think they got the bugs worked out by now. It'll be interesting to see the results.

Originally posted by Zaphod58
reply to post by Aloysius the Gaul

 

The Depot has been at least as dangerous as anyone we've fought in recent years.

It doesn't even need to be "the depot"

When I was a mechanic once at the end of a 20 day shift I was distracted by a mate while I was topping up the oil of a DHC-8 engine between flights, and forgot to put the oil cap back on.

Fortunately the plane didn't take off before the low pressure light came on - and for my sins I had to clean that engine/undercarriage cowl out every night for 3 weeks - 8 quarts of Jet 2 gets into EVERY nook and cranny!!

But I wasn't the last - it happened at least 3 other times I know of to that airline over the next 3-4 years - and they only had 2 DHC-8's!! Eventually they instituted a mod and a procedure to make it impossible to shut the access panel if the oil cap hadn't been refitted!

reply to post by Aloysius the Gaul


No, it doesn't, but the vast majority of these accidents happen after they return from the depot. We had some stupid incidents post phase, and post unit level maintenance, but nothing like what happened when they came out of the depot.

I think it's highly unlikely any kind of EM transmission from the X-47 could cause this. If the E-2 was sitting there with no power on then it could have been a mechanical fault in the wing locking system and maybe the wind got hold of it. Gets very windy on ships out at see the wind could've even broken a fatigued part. All just speculation and probably not a common fault for such an old plane. Lucky it didn't happen in the air, imagine the wing folding airborne that would really suck! Instant unrecoverable spin.

One Hawkeye’s starboard wing unfurled from a folded position and collided with the spinning port propeller of an adjacent Hawkeye

The accident occurred after the plane on the left was shut down and chained

The one which unfolded the wing.

No one was inside the aircraft with the wings that descended, but the aircrew was in the plane with the spinning propeller.

www.navytimes.com...

Skynet?

reply to post by JimTSpock


It most likely was a simple parts failure, but what I found interesting was that when they did the anechoic testing on the X-47, they tested it to something like ten times what is normal. And the arm controller that is used to taxi it on deck has the potential to send a spurious signal that might be received by an aircraft on deck that could cause an EM issue. It's just something that may come into play at some point, if it is from the X-47, better to find it now, than at some point later.