As a former maintenance guy who did work on this aircraft type and going from the photos it would appear that the oleo piston itself has failed either during landing or previously during takeoff. From what I could see the right body gear truck was not in its normal tilted position and I speculate that the gear truck was at least partially hanging from the body gear actuators and that might be the reason for the tilt sensors preventing a gear up selection. The lower scissor link below the body gear actuators has clearly broken away from the gear truck and one of the other photos appears to show part of the oleo fractured above the separated gear truck. I think this failure occurred before landing during takeoff rather than during the landing. I would be interested to know if the landing gears had been changed since the incident with the ground vehicle as of course the gears do have a overhaul life. I wouldn’t personally think that much damage could be caused by the collision with the van but I suppose it is possible.
yeah it was definitely hanging lower than the left side. Something had come undone or was broken taking off. Wow it really ripped off and whipped around when that gear touched down! That's not going to buff out or be fixed with speed tape. hindsight says that that side needed a bit more work after the last two events. Thanks for your insight!
Landing gears have hrs and cycles on them. When overhauled they go from x-ray to different classes of NDT. I believe this is a result from a hard landing way before 2010 and landing gear replacement.
If the bogie fails it will result in a forward tilt many times. When it hits the ground it will be ripped away. Cannot tell from this video the exact position of the truck?
Agree. Cargolux does frequently land at or close to MLW, unlike the pax config 747. Our full freighters were maintained by the same maintenance group that also maintained the pax 747, they found that the cargo version does show earlier wear issues like on the flaps, gear etc due to generally higher weights and higher trust settings.
Amazing! the separated bogie found its way to the cargo hanger before the airplane did. Thank you Juan for your excellent and informative aviation videos.
I have overhauled a couple of these, and it could be quite a number of things. . . The question will be, why did the thing let go on landing? Did the body steering mechanism fail to center the bogie after takeoff, did one of the steering actuators fail, thus allowing the bogie to turn (not center out). If the bogie was aligned with the centerline, it would not have sheered off at touchdown. . . then again, the strut was extended visibly longer than its left hand counterpart. The gear’s strut could have cracked allowing the inner strut to extend to the full drag link extension. . . that purple fluid flash at touchdown is the strut fluid as the inner strut literally sheered off the outer sleeve of the strut. I’m sure other camera footage will surface, from tower cams and such, which will be even more awesome. . . damn, I just remembered that I helped deliver a 747 from Boeing to Cargolux back in 2013. It’s good to be retired. . . Watching Juan, Mentor and Kelsey while chilling horizontal on my couch.
Yes I posted same before reading other comments. Strut extended too far after takeoff and was not going back up on landing leading to instant failure and detachment.
Joe, Boeing retiree here, yep good to be done with Boeing. Back on the late 80s and 90s I delivered 19 747s to Cathay Pacific. Those were some good times.
The body gear steering actuators have hydraulic operated locks that activate when the actuators are centred, they should be locked centred before takeoff indeed it is a requirement that the aircraft be taxied forward a short distance to ensure they have locked before takeoff and after the aircraft has entered the runway. If they are not locked centred it will trigger a config warning when takeoff power is selected. I personally doubt they were a factor but I won’t sulk if I’m proven wrong.
There's another video out there closer to the runway threshold that shows that the right body gear was tilted forwards rather than backwards prior to touchdown.
#Captain Kevin: I’ll be looking for that video, very plausible. . . the still pictures show the steering actuators in neutral (centered) but the drag link broke off just below them. . .
I couldn't get my gear up once flying a Piper Arrow. Cycled the handle, checked the breaker but no bueno. As I'm contemplating a very slow trip back home, I'm running through the system in my head and concluded the safety extension mechanism was keeping me from retracting the gear. I think it uses a combination of manifold pressure and it's own pitot static system to decide if you're on approach without the gear down and drops it for you. So I reached by my right leg to engage the override switch and the gear retracted. The best I could figure is that it had ice somewhere in the system since it was the middle of winter.
Well for those who watch NASCAR, that's 8 lap penalty (2 per wheel) and 8 race suspension (2 per wheel) for 8 crew members (You guess it, 2 per wheel) Jokes aside, let's appreciate Juan's job that basically shows everything we need to know for the people that works on the area and just people that doesn't know anything (like myself) and make everything easy to understand. So good. So well put together. Thank you.
The design, engineering, reliability, redundancy and durability of gear retraction and extension is an aviation marvel. Thanks for the abbreviated landing gear ground school.
Not many people could say they've had a Boeing 747 literally land on their head and live to tell the tale! 😳 Glad everyone was ok in both incidents 😊 Thanks for another excellent video, Juan 💜
I really want to know what the rest of the day was like for the van driver. Did he just sit and stare for a few hours? Imagine almost being crushed by a 747 going 150 knots.
Thank you Juan. I can’t get enough of your chanel. You have your finger on the pulse of aviation information and on the water levels of our California dams, in good times and in bad. Keep up your fantastic work.
Love your usual in cheek humour re: where the bogey ended after "departure" (not bale out - LOL) separation from the 747. Thanks again for the detailed update. You'll make a pilot out this old "wannbe" yet. Take care, stay well and fly safe. 🤟🏼🖖🏼
2010 for the van incident seems like a long time ago, especially for the gear to not have been overhauled since then. These landing gear are made from ultra-high strength steel (250+ksi or close to 300ksi), 4330M or 4340M (modified with silicone to help improve toughness since they can be brittle at those strength levels). New make and reman processes for these types of steels are very specific, these steels are susceptible to hydrogen embrittlement from plating, the formation of over tempered martensite/untempered martensite from abusive grinding, etc...landing gear are highly engineered items on large commercial and military aircraft. Double vacuum melted to be ultra pure too...don't want inclusions or stringers!
@@hoghogwild Boeing used a lot of 4330M and 4340M, Douglas used some 300M. Boeing did go to some Ti on the 777 for some drag link or side struts...don't recall exactly. Brake anti-rotation pins were using Aermet 100 at one point in time. I want to think D6AC was Douglas, but not sure anymore.
@@DillonPrecisionFan I remember that D6AC was/is used on the Space Shuttle now SLS booster cases. Each SLS launch uses 10 steel segments, 5 per booster, 2 boosters per SLS stack. Shuttle used 4 fueled segments per booster, SLS now uses 5 segments per booster. Something like 1200psi peak pressure over a 177feet long, 12 ft diameter average 1/2" thick wall. Peak thrust is 15 seconds post liftoff and 4 million pounds force thrust is achieved per booster. There was 80 segments left over from Shuttle, enough for 8 SLS launches then NASA is switching to a wound filament case. Metalworks is fascinating. Those landing gear take some immense forces, yet must remain light and durable. Amazing stuff.
DPF I used to do sheetmetal repair and we were always warned about getting alodine on high strength steel....which I assume would include the landing gear. We used Alodine as a corrosion protection after grinding the alclad off of aluminum when cleaning corrosion. Back in the day when we did overhaul in-house, there were dozens of us doing all sorts of repairs.....around the clock. I always wondered about whether any alodine accidentally washed down under the fairing panels we worked on and dripped down on the gear. The sfaety data sheet says it like this, "Alodine will cause .....instantaneous hydrogen embrittlement....on contact with high strength steel." Is that true?
@@rael5469 anything acidic is a no-no on high strength steel (160ksi UTS and above). Anything with free hydrogen present. Approved aircraft cleaning agents must pass HE testing...that is why the cleaning agents are all alkaline in nature. Some airlines like D-Limonene (citrus) based degreasers, but have to mask up the LG and other high strength steel components to prevent contact with the acid.
Um… that’s not quite right …. At that point the legs are removed and extensively examined , reconditioned, then put back in service … boeing deliberately built them like a “ brick shithouse “ , and effectively they could live on with no lifespan limitations, if undamaged , and no cracking was found …. Cracking from the inside out though has been a problem in the past .. and is bloody difficult to detect
@@stumackenzie8492 I'm an A&P mechanic that works for a competitor cargo airline, and just changed a gear one week ago due to 10 year life. While yes, the gear post their 10 year life get reconditioned, they do not go back on the same airplane as the time it takes to recondition them would put the plane "down" for much longer then a normal "C-Check" time of 28 days. Everyone always has servicable gear waiting for a quick 2 day swap.
@@hangmann747tinmann8 I assume that's a ton of cycles in 10 years. I've seen car parts last decades with the right owner. But every one of these landings seems to involve a concussion. What other part on a heavy plane takes this much punishment?
It is interesting that in aviation this wheel assembly is called a bogie. For trains in the UK, it would be called a bogie, but in the US, it would be called a truck.
Great recap of this incident. There were two people using the van to replace runway lights. In CATIII conditions you can only imagine how eerily quiet the runway was, so when they hear a 747 approaching you can also imagine their transition to terror. They both ran off the runway and after the plane passed and landed, returned to the van, drove it off and reported the strike. The Pilots saw the van but never knew they hit it until Tower informed them.
What do those landing gear weight? Yeh, it flew to the convenient place. And I know the ground crew in airports have some risk in their jobs. But that bogie flying is a bit like some TRUCK going airborne.
When I see videos like these I am just in awe of what these huge jets are capable of withstanding while still being able to perform a safe landing. That’s some insane damage. Glad the pilots and crew are safe and will be interesting indeed if the damage in 2010 caused this catastrophic failure.
Multiple redundant and fail-safe systems. We must continue to require and demand nothing less, especially in the present age of "simplifiying" designs under guise of cost saving or "environmental preservation". Redundancy is necessary! And, by the way, we still need Reed-Hillview regardless of noise or akr quality talk!
I can agree with you regarding the robustness of the 747 some years ago I witnessed an overweight landing of a 747-400 at Kai Tak airport in HKG The A/C had departed for Frankfurt and experienced a serious engine fire immediately after take off the captain immediately returned without dumping fuel. Most of the tyres burst due to heavy braking but everything else was OK except for the No2 engine thrust reverse that had disappeared and the hole on the top of the engine combustion section that had caused the fire warning.
They did in fact manage to dump some fuel in the short airborne time available, principally due to the presence of the heavy crew. The limitations of flap selection and fuel dumping made this even more remarkable The crew flew the approach with no landing aids (at night) as it transpired that the flaps had, at that stage, to be cycled through ‘up’ before the FMC would accept any nav/rad inputs - Boeing sorted that within the week! Subsequently a number of C&T crews tried to replicate this ultra quick return in the simulator with an initially un-contained engine fire - but with a singular lack of success … mind you, it is difficult to simulate adrenaline!
Would love to hear from Captain Joe who flies for Cargolux! Or, maybe he is the one sitting in the office, explaining this whole incident to his boss. ;-) Thanks again for this excellent run-through of events!
As far as I can see, the important illustration from this story is the company loyalty of the bogie even after giving management trouble and being detached from its aircraft. 😊
There's no way around, if you want to have the most objective and professional observations on any incident, look for Juan's. Again, thanks Juan. Keep the good reporting on. Not only in aviation.
Nice overview Juan. Conjecture only surrounding the untilt etc: but I'd have dumped fuel as well given the multiple threats. As an aside, in normal ops - while both forgiving - I found the B747 easier to grease on than B777 😎
Thank you for the way that you explain these events so we can stay on the same page with you. Very interesting. Can't imagine what it was like to have a 747 hit a vehicle. Would certainly scare the stuffing out of me.
The pilots didn't even know they had hit the van; the two maintenance workers, however, apparently heard the plane coming and ran off the side of the runway before the van got hit.
The gears are overhauled every 10 years as per the CPCP (Corrosion) program. Usually swapped out with a fresh overhauled unit, so probably not the same gear.
Thank you again Juan. I reckon this shows just how much time & effort the legendary Joe Sutter (R.I.P.) & the others put into DESIGNING FOR SAFETY. The B747 remains epic!
Dumping fuel was the most prudent thing to do, the lighter the better and the there was no imminent catastrophic emergency forcing you to land at full gross fuel weight.
For a gear problem, reducing stresses to the component in a failure mode seems prudent (at minimum). If it were an engine or hydraulic issue, dumping the weight would likely be of less benefit.
Juan did a video about a Cargolux 747-400 "smash and go" in April 2023. I wonder if that was the same plane. That is a lot more recent than the 2010 incident.
So amazing to see the video of the bogey (basically the size of a large SUV) bouncing down the runway like a basketball. And then come to rest upright as if nothing happened! Could you imagine having that thing bounce right next to you?
I saw cctv footage of a BP petrol/gas station on the A1 in UK, where a wheel had come loose on the road and had bounced high enough to go right through the sunflower on the overhead BP sign. You couldn't have made a better shot if you had tried.
WOW ! Found the video (You Tube has removed the one at your link Juan) and you can see the bogie bouncing off the fuselage as it tears away. Good thing this was a cargo flight because otherwise the maintenance crews would have had A LOT to clean up in a passenger cabin. That noise must have been REALLY loud inside the cabin.
I’ve seen this happen on a B737 aircraft. In that case it was a failure of the gland nut that secures the inner member. In fact, the outer member had been reworked to a larger thread and required an over-sized gland nut to fit properly but the original gland nut was installed despite the outer member being identified as reworked by having a yellow ring painted around its lower diameter. On take off, the gland nut failed and the inner member pulled away from the outer member. The pins securing the torque links sheared on landing leaving the wheels, brakes and inner member to bounce along the ground.
Wow Juan I bet that van driver needed a change of undies after that he'll how lucky was he that van could have been dragged down the runway like FOD ,as always Mate great content ,were still waiting for a meet and greet here when your in Sydney ,I would fly over from Adelaide any excuse to jump on a Boeing to meet you . Cheers Kym Adelaide
The amount of energy contained in the severed bogey and wheels must have been immense! I really wonder what damage was caused, it hits the airframe but still contains enough kinetic to bounce it's way all the way down the runway and to the hangar. And these things contain a crap load of mass!
@@gasdive Same here - not sure what happens with the wing gear when the fuselage gear is turning - I guess they just scrub along. Can you imagine being the guy in the van when you get hit by a 747? And he lived to tell the tale!
Looks like that piston/bogie assembly just fell out which tells me that there was fatigue cracking in the strut, possibly exacerbated by corrosion. Gland nuts and threads are notorious for that. Which begs the question when was the last overhaul and had the gland nut been properly sealed or has there been any work done after overhaul like a seal replacement. Technical records will tell
Very nice. I got the emergency alert on FR24 but it of course doesn't detail the nature of the emergency or outcome. Was interesting to note this 747 was in trail of an A380 on the way back to the airport. Must have been a sight to see. We don't get 380s where I am.
Regarding the lengthy code brown discussion, from the report: "The two maintenance crew, who had been working on the runway center line lights and had become aware of the arriving aircraft by the noise of the engines, ran off the side of the runway upon the increasing sound." So apparently nobody was inside the van. Not to say that it wasn't a code brown event.
I can't imagine the shock when the pilots saw that van in the runway (or when the driver of the van saw the 74). Even though nobody was injured, the collision would have resulted in multiple code brown events.
They can't watch out for everything. Especially with this drumbeat about trusting your instruments. Instruments won't say much about ground crews repairing airport features. I can imagine where they could, but I bet they don't. I've heard some airports even have features to scare birds off. Not all, just some.
I'm sure 74Gear (Kelsey) could give you some input as to the procedures for this type of situation. I'm just glad nobody was hurt. That airplane will be down for maintenance for a bit...
Kelsey is a scruffy freighter co-pilot with no training or accident investigation qualification. .... He just happens to fly the B747 for a small freighter outfit. . Armchair love him....
@@daftvader4218 I'm not sure I'd describe Atlas Air as a "small freighter outfit". My brother is a 747 pilot there also. Kelsey did put out a video the other day about this... I think he made some good points. Obviously, none of us know exactly what went down in the cockpit, so anything anyone says is pure speculation.
An interesting story told to me by one of the engineers on the patent for the steerable boogies on the 747. As initially designed the 747 did not have steerable boogies, a subject of disagreement within the design group. During initial ground run and flight testing the test pilots commented it took what seemed to them excessive power or thrust to ground maneuver the bird. Then in preparation for an aft C of G flight test the pilots were unable to turn the aircraft and the nose wheel just scrubbed sideways. Steerable boogies were back on the table and then the challenge was to find real estate in the hull to accommodate the frantic redesign.
Airbus also decided to skip steerable struts on the body gear of the A380. In at least one flight test incident, a tire(s?) twisted off its wheel. Now that's some serious scrub!
IIRC from Joe Suter's book, he initially designed it with body gear steering. However as the weight ballooned it got removed. Rather than bin it, it was parked on the shelf so that when they had trouble manoeuvering the aircraft on the ground Joe said "I have a solution for that", and it was put back on!
I'm so glad my little citabria isn't so complicated. That cargo company needs to repair that aircraft and use it for marketing. Not always on time but always in one piece.
Thanks Juan as you are educating us non flyboys! When this story first broke I wondered why they dumped fuel as I remember you and the pilot sitting in the cabin of that firefighting 747 from a year or so back. Pilot told how that ex-cargo plane didn't care if it was loaded or empty when landing. See we are learning from you!
Not sure if you've seen or not, but there was another video taken of the landing from further up the runway about where it touched down, and in this video, you can see that the right body gear is tiled downwards with about the same degree of tilt that it should have upwards. Definitely looking forward to see what the investigator's initial findings of this one were, and I agree that they'll probably be looking very closely at the maintenance on this one, especially where it concerns that previous incident over a decade ago.
That “earlier” right main bogie van incident was apparently 13 years ago. Given the decade plus time interval, it would appear that it’s Almost certainly NOT related to the current problem.🤔 P.S. Wonder what “Capt. Joe’s” input/view on this event will be?😳In any event Glad no one was injured.
10:40 The damage to the yellow Van looks minor, like if he hit a tree branch at 5mph. When you compare the size and weight of a 747, I don't think that Van hit could do much damage to the landing gear of a 747.
That -is- WILD! I saw unedited video the day it happened, and still wonder who will get fired for an INTIRE bogey separating! Glad no aircraft were near on "bogey bounce" , and safe stop for aircraft and crew.. unbelievable. 👍🏿
Man that van at the end there. Didnt even bust the windshield. In juuust the right spot to get the roof slapped in as a, gentle, but extremely stern warning that someone goofed on procedure in a big way.
There's another video out there of the same incident from a different position along the runway, closer to the runway threshold. As soon as the 747 passes that aircraft, you can see that the right body gear is tilted forwards rather than backwards, kind of like on the 767.
Things break ! Boeing had a 767 retract cylinder break in two when the gear was about 90% up . Gear came down hard and locked in position. Another 767 was being towed out of the hangar and th rear axle on the right gear snapped in two . I looked at the ID numbers and that is the same 47 that did the smash and go a couple weeks ago !
"Gear came down hard and locked in position." Freefall-operative is an FAA certification requirement and test BTW. The only certification examples I know of involved test rigs with deadweight for tires/wheels/brakes, rather than an operational gear installed on an aircraft. Not the sort of shock loads you want to put into an actual airliner's structure if you don't have to.
"Things break ! (Part Deux)" In the early 80's a couple of DC-10-30s had their center main landing gear shock strut pistons snap off at low speed. That turned out, after much study, to be an interaction between the antiskid's pressure modulation and the extremely nonlinear friction-vs-speed characteristic for rubber on pavement at very low speed (below say 1 m/s). The solution was to cut off brake pressure to the CLG below 5 kt.
Juan , now that it think about it , the last occasion that I mentioned , in Rome ( Fumachino ) , around 1990 , it was roughly midnight local time , Good Friday ( the start of Easter , darn ! ) and it was the right “ wing gear “ that failed ….. Fortunately it let go , following a 180 degree “ line up turn “ at the runway threshold , failing as the twisting stress was being relieved ( it was a right hand line up turn , so the most stressed gear , being the most inside bogie ) about 60 degrees off runway QDM …. The body gear was still displaced .. So the aircraft ( B747-300 VH-EBW ) dropped onto the No 3 engine , with the No 4 “ slapping slightly , the ground as a result of wing bend from the drop .. The failure was “ explosive “ .. An investigation followed , of course , the results of which are available through the Italian & Australian ATSB .. Initially the whole crew ( ie: Tech & Cabin Crew ) where placed “ under arrest “ … There was no injuries to any aircraft occupants .. It was VERY fortunate that it occurred when it did .. During the “ line up turn , we where “ cleared for take-off RW 16 L , at max TOW , roughly 168000 kgs of barbecue-fuel , and pointing at the centre of the Rome city area including Vatican …….. gulp
Does this mean that the wing bogies are raised slightly to keep them from getting scrubbed in a tight turn (or maybe the geometry is not that extreme.) Also, an old 747 cargo pilot, acting as the lead docent at the Palm Springs aerospace museum, told a story about a 747 cargo plane running right over a ground crew pick up, killing two people, on a 00 approach into Anchorage. Apparently the pilots never saw the pickup, they just reported to the tower that they needed assistance, a tow-in, as they had blown some tires on landing. When the tower heard this request, the "lights" started to come on in the tower.
They do not. The wing gear wouldn't really experience any scrubbing. On the 777, the rear most axle can steer. 3-axle coach buses also have steering on the rear most axle, albeit not as much as the front axle.
@@CaptainKevin - Depends on the 3-axle motor coach model. In the US, Prevost coaches do not have steerable tag axles, but the tags can be lifted off the ground. The 45-foot MCI "E" and "J" models have steerable tag axles, 35' and 40' models do not. MCI's steerable tags use an adjustable castering system that changes the caster depending on forward or backing movement, and also locks the tags in centered position above 15 mph. There is no "steering mechanism" on these, they simply caster like the front wheels on a shopping cart. I'm not familiar with Temsa and Van Hool buses, so I can't comment on their tag axles. Also not familiar with European makes/models either. HTH. . .
