Landing gear/ankle stress

[melcessna]

I am restoring a 48 with slightly less than 2000 hours. I have the plane all drilled apart and it is time to put it in a fixture, take the gear off and go through the gearbox. I've read from time to time that the ankle has a tendency to stress fracture around 3000 hours. I fly a B with 180 gear, which are oversized even for a 180 by 1/32, but I don't really like how it lands. It is sorta springy. I feel like the 48 performs better when landing. So, I am pondering putting the existing gear back on after inspection versus putting on 180 gear. I am open to thoughts. Thank you, Mike

[Bruce Fenstermacher]

Mike, there is no real conclusive history to say the ankle of these gears will snap at any time. Hollow axles yes.

If you are counting ALL Cessna flat spring gear the same. And you care to count 150 main gear with a step that had caused a rust pitted line across it, causing a stress riser where the gear snapped, and you think two such examples of this is a problem for all Cessna gear, then you might think there is a problem.

OK I confess, there may have been more than 2 cases of these gear snapping but I haven't heard of them other than the 150 gear mentioned several years ago.

I have the same gear on my A that you have. The type that are drilled through the middle for the brake clip. Considered the least desirable cause of imagined issues. I have no plan to replace mine and have no fear of them snapping more than any other part of the airframe.

And yours, with less than 2000 hours, have half the time and stress than most 170s today at over 4000. Your gear are practically new.

I would take a lesson from the 150 gear. Rust and stress risers are not good.

[melcessna]

Thanks for your thoughts. Mike

[ghostflyer]

I have the 180 gear type and it's has done over 9000 hours with heaps of very heavy landings. During my SIDS [compulsory in Oz] inspection they were stripped back of paint and x rayed . No cracks or stress lines , I am very satisfied that another 6000 landings are there. I have seen seen Cessna 206 undercarriage springs x-rayed after a heavy landing where the gear box was badly distorted and fuselage contacted the runway and they showed no stress or cracking . Even there dimensions were not changed . This is the best undercarriage design for rough strips . But they will bend with real abuse .the gear box is the first to go .

[counsellj]

I would never purposely take 180 gear off of a -170. They land different, but all it takes is practice to make this an absolute positive asset with no negative impacts.

Jughead

[GAHorn]

I respectfully disagree with Jughead on this subject. The 180 gear weighs more (reducing useful load) and puts the airplane in an unusually nose-high attitude and is too stiff for such a light plane as a 170. The only reason I'd want a 180/185 gear would be if I operated mostly out of the outback/rough country and needed the ground-to-prop clearance.

Mike, If you do this right, you'll get an original gear cheap and make money selling your 180 gear. (But I'm surprised you consider the 180 gear "springy". That's the usual reason many give for dispensing with the original gear and getting a stiffer 180 gear. Many complain of the difficulty in wheel-landing the early gear and swap for that reason. Personally, I think it's a better investment to practice landings than put the "wrong" gear on a 170.)

[melcessna]

Thank you. I don't have the nose high attitude issue as my B has the 360 conversion and constant speed prop. Hence, I moved the battery box back into the fuselage to assist weight and balance. Thanks for your comments. I plan to keep the original configuration on this 48 I am restoring. Best, Mike