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04 Feb 2022 - 737-800, N817SY (30392/833), FF 12/4/2021 (21 Years old), operated by Sun Country suffered a MLG collapse on landing at Las Vegas, on 4th Feb 2022.

The aircraft appeared to take off normally from Las Vegas but the crew stopped the climb at 9500 feet and reportedan "unsafe right gear". After approximately 30 minutes the crew returned to Las Vegas. Video footage of the landing shows sparks from the right hand MLG during the landing roll as the gear collapsed.

There were no reported injuries.

NB the earlier generation of 737, the 737-3/4/500, has a history of MLG collapses on landing often induced by shimmy. This incident is believed to be unrelated as it appears to be a component failure on take-off.

There is speculation that this incident could be a failure of the trunnion pin. This is believed to have been the cause of a similar events to N87513, United 737-800 at Denver on 22 Dec 2019. Note that the event to EI-GXG, Ryanair 737-800 at Frankfurt on 29 Jan 2019 was found to have been a migration of the pivot pin from the walking beam hanger in the left MLG assembly.

There was an AD 2019-01-03 - We are superseding Airworthiness Directive (AD) 2016-18-01, which applied to certain The Boeing Company Model 737-600, -700, -700C, -800, -900, and -900ER series airplanes. AD 2016-18-01 required repetitive lubrication of the forward and aft trunnion pin assemblies of the right and left main landing gears (MLGs); repetitive inspection of these assemblies for corrosion and chrome damage, and related investigative and corrective actions if necessary; and installation of new or modified trunnion pin assembly components, which terminated the repetitive lubrication and repetitive inspections. Since we issued AD 2016-18-01, we have determined that rotable parts were not addressed in that AD, and it is therefore necessary to include all airplanes of the affected models in the applicability. This AD retains the requirements of AD 2016-18-01, adds airplanes to the applicability, and prohibits the installation of a MLG or MLG trunnion pin assembly under certain conditions. We are issuing this AD to address the unsafe condition on these products.... We are issuing this AD to address heavy corrosion and chrome damage on the forward and aft trunnion pin assemblies of the right and left MLGs, which could result in cracking of these assemblies and collapse of the MLGs.

More details here as I get them.

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*** Updated 14 Nov 2021 ***

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N817SY MLG Failure

N817SY after the incident (photo via Twitter)

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