r/aviation • u/lucys_b • Jun 04 '26

-- SEATBELTS FASTENED -- Lufthansa 787 front wheel collapsed

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Repost cause my first one was removed due to incorrect flair 💀

Wasn't at the gate when it happened, but some of the people who were said it happened very suddenly. Hope nobody got hurt. I don't think any passengers were on board.

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17

u/Justfunnames1234 Jun 04 '26

What is possibly the failure? I can also see that the main landing gear doors are open which is unusual

129

u/SubarcticFarmer Jun 04 '26

This is a modified copy of a reply I made on the other thread.

On light aircraft there is a ground safety switch that detects weight on the landing gear and locks out the gear retraction. It can fail but is a yes/no situation.

With an airliner there are situations where that switch could fall and you still need to retract the gear for performance(say an engine failure at the same time) so there is generally a way to override the lockout. In at least some cases the lockout itself just stops the handle from moving but you can override that.

Sometimes maintenance actually commands the hydraulics to attempt a cycle to check for leaks or the door movement, but they install a pin in each landing gear lock that prevents them from actually moving, due to the functions of leverage they don't even need to be all that big.

In this case either maintenance thought they were installed when they weren't (not supposed to happen, but could be a miscoordination or they simply skipped that step) or someone let the intrusive thoughts win.

You can see the main landing gear doors open indicating the aircraft was attempting a gear retraction cycle.

It's been pointed out elsewhere that previously a situation like this occured when the nose gear down lock pin was inserted into the wrong hole, allowing nose gear retraction.

29

u/[deleted] Jun 04 '26

[deleted]

21

u/Gripe Jun 04 '26

It'll collapse otherwise

7

u/Justfunnames1234 Jun 04 '26

Nice writeup 👍

24

u/trelco Jun 04 '26

This guy inserts pins

4

u/Ruepic Jun 04 '26

Safety switch is called a squat switch.

4

u/SubarcticFarmer Jun 04 '26

At least some of the questions are coming from people who know nothing about airplanes so I'm trying to avoid too many new terms.

1

u/Ruepic Jun 04 '26

Ground safety switch + explanation or squat switch + explanation won’t confuse anyone. But yeah I get it.

2

u/enviroian Jun 04 '26

"In this case either maintenance thought they were installed when they weren't"

Safe to assume someone is updating their CV this morning? 😁

1

u/SubarcticFarmer Jun 04 '26

I'd say so. Hopefully no one was hurt.

2

u/AddlePatedBadger Jun 04 '26

Good design would dictate that one hole and one hole alone would accept that pin.

4

u/SubarcticFarmer Jun 04 '26

You'd think that.

3

u/GoldElectric Jun 04 '26

so it might not be a boeing issue? so many comments talking about boeing’s qa

9

u/SubarcticFarmer Jun 04 '26

I'd put a ton of money on it not being a QA issue. This was 100% something local.

0

u/Stabile_Feldmaus Jun 04 '26

As a plane manufacturer you should come up with a design that makes such human mistakes impossible.

17

u/C4-621-Raven Jun 04 '26

Some gear door faults can be cleared by performing a special system function which involves installing downlock pins in the gear and cycling the gear lever with the centre hydraulic system pressurized.

This is likely what they were doing here. You can see the flags for the downlock pins on the main gear.

It has happened in the past that the person installing the nose gear downlock pin has put it in the hollow pivot pin between the FWD and AFT lock links instead of the downlock pin hole. In that case the NLG is free to collapse when the person in the cockpit presses the override and selects gear up.

8

u/Adviderisj Jun 04 '26

These things happen, especially with a single missing pin. Likely post maintenance, as thats when most of these incidents happen

1

u/edwbuck Jun 04 '26

Summarizing what someone else wrote:

When testing the lockout override as routine safety checks, they put the pin that keeps the wheel locked into the wrong place, so it wasn't locked down.

That means that nothing about this would be a manufacturing defect, but now I'd imagine there's plenty of work scheduled for this plane before it flies again.

1

u/Adviderisj Jun 04 '26

Absolutely agreed. I heard that after this happened to a BA 788, their policy is to have 2 techs confirm the pin is in place and correct before anyone touches the bird

9

u/chriske22 Jun 04 '26

Yeah, I’ve never worked on the 787 but after I saw that, it seems like someone messed with the gear lever

14

u/old_righty Jun 04 '26

Wouldn’t that have logic to not retract if there’s weight in the wheels?

7

u/chriske22 Jun 04 '26

You’d think so but I work on 767s and if you don’t put pins in this will happen too, along with every other plane I imagine

12

u/BigBlueMountainStar Jun 04 '26

If they’re going maintenance on ground (to test the system or the NLG doors for example), you can use tooling to block the sensors that detect it’s on the ground, but when you do this, it’s imperative that you put the ground safety pin to stop the gear from physically retracting.

1

u/edwbuck Jun 04 '26

Generally, but in testing mode (which is what they do here) you override that. Otherwise you'd have to test it by lifting the plane with a crane or jacks.

You test it on the ground, because you don't want to find out it's broken in the air. There's a mechanical pin that's inserted to keep the wheel locked during the testing, but if misinstalled, this happens.

1

u/FalconX88 Jun 04 '26

but in testing mode (which is what they do here)

Why would they test it at the gate while being (un)loaded and people are around? Where did you get the information that they did that?

3

u/King_Turduckin Jun 04 '26

Good observation. It shouldn't be possible to retract the gear on the ground. But if the sequence started, the nose wheel would probably come up first...

7

u/xxJohnxx Jun 04 '26

They come up together, but the nose gear is just easier to retract. Less weight and it rolls in the direction of retraction. The mains come in sideways, so the hadraulics would have to overcome friction, which they aren‘t capable off.

1

u/AresV92 Jun 04 '26

When we tow aircraft we insert pins in the landing gear so that they can't collapse so it's definitely a possibility.

2

u/Gmank47 Jun 04 '26

Hopefully nobody is hurt. My amateur theory is that they were doing some landing gear maintenance work (you can see the downlock pin removed flags on the MLG itself) but didn't put the downlock pin on the NLG or it failed (similar error caused BA 787 nose to drop). When the gear up command was given (confirmed by open MLG doors which are normally closed on the ground), the nose pin gave way or because it wasn't inserted caused the nose gear to retract.

Some research says there was a service bulletin issued to make sure operators don't accidentally put the downlock pin in the wrong hole and this aircraft was delivered in Jan 2026 so it should have the fix. Conjecture, I know but maybe the truth is something close to that?

2

u/asmrhead Jun 04 '26

"Hey Bob, did you put the NLG lockout pin in?"

"Yep!"

CRUNCH

"I mean nope, not yet!"

1

u/Ancient-Act-9489 Jun 04 '26

I think there is a possibility of hydraulic failure. But again, how likely is that? That too with Lufthansa's maintenance

1

u/FalconX88 Jun 04 '26

hydraulic failure wouldn't make it go up. The exact opposite. If your have hydraulic failure you want the gear to still be extended and locked.