Prop Clearance Procedure

[Andy Young]

A friend who is installing a different prop on his plane is looking for some information regarding complying with the clearance check procedure in CAR3. Specifically, he is asking how far the landing gear deflects at full travel. Does anyone here have that information?

Thanks.

[Undaunted]

It might be variable based on day and location.

I know that some days and landings mine deflect a lot more than other days !
😄😄

[andy]

I'm sure you already know this but here's the regulation.

§23.925 Propeller clearance.

Unless smaller clearances are substantiated, propeller clearances, with the airplane at the most adverse combination of weight and center of gravity, and with the propeller in the most adverse pitch position, may not be less than the following:

(a) Ground clearance. There must be a clearance of at least seven inches (for each airplane with nose wheel landing gear) or nine inches (for each airplane with tail wheel landing gear) between each propeller and the ground with the landing gear statically deflected and in the level, normal takeoff, or taxing attitude, whichever is most critical. In addition, for each airplane with conventional landing gear struts using fluid or mechanical means for absorbing landing shocks, there must be positive clearance between the propeller and the ground in the level takeoff attitude with the critical tire completely deflated and the corresponding landing gear strut bottomed. Positive clearance for airplanes using leaf spring struts is shown with a deflection corresponding to 1.5g.

I don't know how far oleo gear deflects at full travel. It sounds like there are several variables: weight, strut travel, tire inflation, attitude.

[MauleWacko]

[Andy Young]

Sounds like when your friend is done doing the propeller clearance test he will know. If he is just looking for numbers to put down and just guess on it without doing the proper way that the FAA calls for. It should be no surprise why it is getting harder to do any 337's these day's.
If you do what is asked for, there should be no reason for the answer because you will have it when you do the test. Being lazy and taking short cuts in aviation will get you in a grave or an aircraft that is an obvious pile of shit.

Wow, who pissed in YOUR Cheerios this morning?

[MauleWacko]

[Mog]

Why should he have to reinvent the wheel if someone has the info. It sure seams to me that he was just asking for a small amount of help with the assumption that someone must know the answer. Sure would save him a lot of trouble and should make anyone who helps him feel good about themselves for helping someone out.

I wish I had the answer, I would gladly share it with anyone who asked for it.

[Andy Young]

Thanks Andy,
Thanks Mog,

MauleWacko:
I was just trying to gather a key piece of information so my friend would have the clearest picture possible of what he was likely to find as he went through the process. The A&P/IA who is doing the work/paperwork is not overly familiar with Maules, so he asked me the innocent question of how far that gear deflects. He is an extremely qualified and careful mechanic, and I did not get the impression he was looking to shortcut the process. I think he just wanted as much information as possible going in, as any reasonable person would. When I land in fresh snow, I’m certainly going to find out how deep it is in the process of landing, but if someone has been there before me and can tell me how deep THEY sank in, I’m very glad to have that information beforehand...

[gbarrier]

I think that most of us here, had they done the research, would share it knowing that they may be in search of something down the road that would be shared with them. It's pretty much a good group. Copies of field approvals (337s) etc. flow freely and that helps everyone.

[Mog]

Recent experience does not feel that way to me. I’m not sure why, and it may have been a unique experience. I finally got what I needed by reaching out directly to a few people that had not read my thread. Not sure why people are grumpy at the moment regarding 337’s and such.

[Andy Young]

Interestingly, while people are often very guarded with their 337s, they are actually all publicly available. All you have to do is write the FAA and ask for copies of all 337s for a particular N number. Of course, you have to know what’s N number has a 337 for the work you are looking to emulate.

[Mog]

Crazy thing is that I now have a handful of 337’s for the C201 and they are all wildly different. Some with restrictions some without. If everyone shared more readily then future applicants can turn in identical paperwork which helps reduce the variables and keeps the feds happy. Having imported lots of vehicles and dealing with communities of people aspiring to do the same I find that the ones that go it alone tend to mess up the paperwork often and throw up red flags for others to import later. Land Rovers to one of the biggest hits not long ago for fraudulent imports, and Unimog’s get hit with non AG tax often because of some careless importers.

[MauleWacko]

[gbarrier]

Like Andy said, it’s all available if you know the tail number. Just go online to the FAA website and request (actually buy for $10 with your favorite credit card) a CD. Gives you all 337s and registrations. It’s also a good idea as part of any pre purchase.

[crbnunit]

We tried to start a 337 library here not long ago. There was a big outcry from a couple of folks and it stopped. I really don't see the problem. They are just used to give your mechanic a place to start so he/she doesn't have to make one from scratch. Is there something I'm missing here?