Have landing gear collapsed at the gate?

I do not include after emergency landings, but just while "sitting at the gate."

• I rather doubt it, it's more likely that it will tip over by badly balanced boarding/loading – ratchet freak Aug 23 '14 at 20:08
• There have been quite a few incidents. Here's one, nycaviation.com/2013/08/…, Google will find others. – Simon Aug 23 '14 at 20:40
• I witnessed a Fokker 50 retracting its gear while parked at the gate. The aircraft made only one flight after that; a ferry flight to the scrapyard. It wasn't loading passengers at the time though. – DeltaLima Aug 25 '14 at 15:45
• @Simon Could you please turn your comment into an answer? I cannot accept any of the existing as answers to my question, while your comment is one. – CGCampbell Aug 27 '14 at 14:17

There have been quite a few incidents. Here's one,

http://www.nycaviation.com/2013/08/pictures-nose-gear-of-united-boeing-767-300-collapsed-at-gate-at-iah/

I can't find links, but do know that there have been incidents caused by different issues such as ground locks not in place, failed struts, WoW logic failures and so on where when hydraulic power was applied, the gear retracted or collapsed.

• A World of Warcraft logic failure??? (Newbie: What a WoW logic failure?) – RoboKaren Aug 26 '15 at 12:42
• @RoboKaren Sorry, just seen this! WoW, weight on wheels. A set of logic which tells the aircraft that it is done flying and firmly on the ground, or alternatively, started flying and no longer firmly on the ground. – Simon Oct 13 '15 at 11:09

A good landing gear design locks it into the extended position under the aircraft's weight. This makes it physically impossible to retract it at the gate, but when the switch is in the wrong position the gear starts to retract during liftoff, when the wings take over the duty of carrying the weight.

This doesn't mean that careless operation or maintenance procedures can't make it retract, however. When the aircraft is poorly balanced, say during loading and unloading, the weight on the nose gear might not suffice to lock it, so a wrong switch position can cause an unintended retraction.

• This makes it physically impossible to retract it at the gate - should be This makes it theoretically impossible to retract it at the gate. There are several instances where it has indeed happened - I linked to one in my comment above. There are at least 2 others. – Simon Aug 24 '14 at 10:30
• @Simon: Please read the 2nd paragraph of my answer. – Peter Kämpf Aug 24 '14 at 10:37
• Landing gear has collapsed at the gate for reasons other than overload on the nose leg. Your post intimates that it cannot collapse unless poorly balanced which is simply not true. – Simon Aug 24 '14 at 21:11
• I did not expect anyone to understand it this way. I spoke of unintended landing gear movement when there is too little load on the gear. This should have been obvious. – Peter Kämpf Aug 25 '14 at 5:43
• Shouldn't the first sentence of the second paragraph read “This doesn't mean that careless operation […] can't make it retract”? – Relaxed Aug 27 '14 at 10:37

Not so much in Airliners, but I have seen the result with a GA Aircraft when the pilot was demonstrating to a student (type endorsement) how the squat switch works. Well, squat switch wasn't working, and the gear retracted.. Not pretty..

For reference, a squat switch is attached the the landing gear, and detects when there is pressure on the landing gear (as if there is pressure on the gear, it must be on the ground). If the switch detects pressure, the gear won't retract regardless of the Gear Selector position.

The guy in the hangar next to me had one of his friend's retract the gear on his beautifully restored P-40. Luckily the mains did not retract, but the tailwheel did and bent quite a bit of metal. Ouch!