Lancair Legacy Landing Gear Collapse Risk from Bronze Bushings
Posted: Thu Apr 17, 2025 3:27 pm
Hey gang,
A year ago I responded to a LancairTalk post on the issue with the bronze bushings used in the Legacy's landing gear mechanism and their root cause in a number of nose landing gear collapse incidents. I've attached a pdf file of that writeup and recommend every Legacy and Lancair IV pilot/builder review it.
I tried to attach the writeup here but it looks like Lancair Live does not allow one to upload/attach a PDF. Here's a link to it on my Google Drive: https://drive.google.com/file/d/1786TS8 ... sp=sharing
For some history, the Legacy's landing gear design heritage was from the Lancair IV's nose gear mechanism design. The designers used a bronze bushing in the over center linkage mechanism, probably to provide a natural low friction joint with the dissimilar metals. But, bronze is too soft for the loads the mechanism experiences and over time they deform and the critically precise geometry necessary to achieve over center mechanism locking is undermined. This has resulted in collapse of too many Lancair IV/IVPs and Legacy nose gear mechanisms and results in propeller damage and at least a tear down of the engine to see if it is damaged -- a very expensive repair and months to get one's airplane back in flight status.
Anyway, I'm posting on this again because as I wrote in my write up, I'd planned to also change the bronze bushings in our Legacy's main landing gear once I received more stainless steel versions and at our condition inspection. I wasn't in a rush to do it because I hadn't heard of any Legacy main landing gear collapse incidents caused by deformed bronze bushings and it seemed the loading for the geometry of the mains compared to the nose gear may lower -- but, not based on any analysis.
So, I've been curious to know if we'd see any deformation of the bronze bushings in our MLGs. We're just completing our condition inspection and changed out the bronze for the stainless steel bushings. On both our left and right main landing gear, one of the two bushings showed some deformation and was enough that they'd compressed themselves into the linkages and had to be forced out for the replacement.
The bottom line, I recommend all Legacy RG owners also replace the bronze bushings in the main landing gear mechanisms with the stainless steel ones. The community has been very focused on the nose gear mechanism because for the Lancair IV/IVPs, that's the only landing gear mechanism they have with this design. But remember, all three Legacy gear mechanisms have this vulnerability!
Bob Pastusek has led the community's focus on this issue for several years now. Contact Bob for help sourcing stainless steel versions of the bushing.
A year ago I responded to a LancairTalk post on the issue with the bronze bushings used in the Legacy's landing gear mechanism and their root cause in a number of nose landing gear collapse incidents. I've attached a pdf file of that writeup and recommend every Legacy and Lancair IV pilot/builder review it.
I tried to attach the writeup here but it looks like Lancair Live does not allow one to upload/attach a PDF. Here's a link to it on my Google Drive: https://drive.google.com/file/d/1786TS8 ... sp=sharing
For some history, the Legacy's landing gear design heritage was from the Lancair IV's nose gear mechanism design. The designers used a bronze bushing in the over center linkage mechanism, probably to provide a natural low friction joint with the dissimilar metals. But, bronze is too soft for the loads the mechanism experiences and over time they deform and the critically precise geometry necessary to achieve over center mechanism locking is undermined. This has resulted in collapse of too many Lancair IV/IVPs and Legacy nose gear mechanisms and results in propeller damage and at least a tear down of the engine to see if it is damaged -- a very expensive repair and months to get one's airplane back in flight status.
Anyway, I'm posting on this again because as I wrote in my write up, I'd planned to also change the bronze bushings in our Legacy's main landing gear once I received more stainless steel versions and at our condition inspection. I wasn't in a rush to do it because I hadn't heard of any Legacy main landing gear collapse incidents caused by deformed bronze bushings and it seemed the loading for the geometry of the mains compared to the nose gear may lower -- but, not based on any analysis.
So, I've been curious to know if we'd see any deformation of the bronze bushings in our MLGs. We're just completing our condition inspection and changed out the bronze for the stainless steel bushings. On both our left and right main landing gear, one of the two bushings showed some deformation and was enough that they'd compressed themselves into the linkages and had to be forced out for the replacement.
- STARHAWK MLG Bronze Bushings After 600 Flight Hours.JPG (4.17 MiB) Viewed 100 times
Bob Pastusek has led the community's focus on this issue for several years now. Contact Bob for help sourcing stainless steel versions of the bushing.