PA-28R Arrow Nose Gear Strut Over-Extended?

Deelee

Deelee

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Deelee
So I know it isn’t a good thing for landing gear struts to be too compressed (or completely compressed), but what about struts that appear to be not compressed enough?

Today after a couple laps around the pattern, we landed, taxied back and noticed the nose gear strut standing taller than I think it should. Note this is a new-to-us aircraft, so maybe it is normal. But seeing six or seven inches of strut didn’t look right. My parter (who was flying) said the nose gear felt a little bouncy on rollout. Other things to note - here in the DC area it was about 95 degrees and humid. Maybe that had something to do with the strut not compressing all the way? Or maybe this is just normal? I did some googling and found a few posts from people who have noticed this with the main gear struts. People chalked it up as normal and a ‘Piper thing’.

so is this normal? Maybe just new owner looking at everything with a microscopic eye? Or something that should be addressed?

Thanks. Pic of strut below.

BE268CCF-7205-4971-B53B-E68C123BA563.jpeg
 
heat effects pressure, they appear taller when heated, then shrink when they cool.
 
Can't speak for the nose gear, but Piper struts in general can be a little funky

on more than one occasion I've walked out to the plane and seen it sitting at a 10 degree angle, once they come over to start putting fuel in it or you get in the plane one of the struts will suddenly drop 4 inches. It seems the Piper struts sometimes just get "stuck"
 
Tom and Tantalum thanks for the quick reply. And sorry for the rotated pic... doing this on my iPad and can’t get the pic right.

Probably just looking at everything on this plane with laser focus right now. And questioning everything that doesn’t look feel or smell quite right.
 
From the MX manual (Piper 753-586 MX PA-28-140,150,160,180,235,R180,R200.v2008) section 2.43 :
The nose gear strut must have approximately 2.75 inches of piston tube
exposed, while the main gear strut requires approximately 2.0 inches of tube exposure.
Click to expand...

Bounce the plane and see if the nose drops. Stuck struts are generally a main gear issue, but you never know. As for heat expansion, is the strut lower in the cool of morning?
 
Thanks, Domenick. Saw that in the mx manual. I wonder if that is a lower limit... as in... 'must have at least approx 2.75" ' Always have been mindful of compressed struts on the 172s I have flown and have seen some of those too low to fly. Just not sure if there is such a thing as having a nose gear strut too high to fly.

Will try bouncing the plane a little more to see if it goes down. Don't know if it is lower in the morning because we just got this plane and haven't been out in anything other than heat. But will be good to check. I'll see if I can get out there one morning this weekend to see.
 
I think the tolerance is plus/minus quarter inch? If running the engine with the brakes on doesn't collapse it to the range, that strut is probably overserviced. It happens, not a big deal. You can tell by the different coloration of the strut polish where it normally sits, so I think that strut is probably fine, if you measure from where the polish is not mirror like. Mine sits on the low side, but it was leaking and was rebuilt last year with mixed results.

You should be able to put your back under the spinner and lift and release, allowing the airplane to settle on the strut. It should not only be within tolerance, but immediately dampen so that you don't end up looking like this when going down the taxiway :D
tenor.gif
 
It looks OK to me - I would not worry.
 
On gravel you want a tall strut to protect the prop. In windy areas a low strut is better to keep the AoA low while taxiing and landing run out. No ideal height but maybe 3" is common.
 
Thanks for the suggestions and help, everyone. Flew yesterday and the strut looked a little more... normal. Probably the heat that caused it to expand and sit tall. But we are going to keep an eye on it for sure.
 
Snowmass said:
Or just forget the whole trivial thing and enjoy life.
Click to expand...

haha now that is good advice! Will try. Sort of looking at everything on this plane with a microscope since it is new to us.

but yeah good advice to actually remember to enjoy the plane!
 
hindsight2020 said:
I think the tolerance is plus/minus quarter inch? If running the engine with the brakes on doesn't collapse it to the range, that strut is probably overserviced. It happens, not a big deal. You can tell by the different coloration of the strut polish where it normally sits, so I think that strut is probably fine, if you measure from where the polish is not mirror like. Mine sits on the low side, but it was leaking and was rebuilt last year with mixed results.

You should be able to put your back under the spinner and lift and release, allowing the airplane to settle on the strut. It should not only be within tolerance, but immediately dampen so that you don't end up looking like this when going down the taxiway :D
tenor.gif
Click to expand...
Don't lift your plane with the spinner. Those spinner bulkhead plates are $$$. Instead, put some weight on the tail.
 
A couple things...

Strut should be filled with nitrogen, which is more stable regarding changing volume with temperature. If you DO find that temperature changes are noticeably influencing strut extension, maybe consider reservicing the strut with nitrogen just to make sure that's what's in there.

Much easier way of bouncing the front strut..put one foot on the top front of your nose tire, put a little weight on it and roll it backwards while you pull down/hang from the prop on either side of the spinner with your hands. Effortless, and it gets you a good bounce to see what's going on with your strut.
 
As I understand chemistry, whether a strut is filled with 80% N2 (i.e. air) vs 100% N2 doesn't change the adiabatic compression constant because both N2 and O2 are diatomic gases. Air that contains significant amounts of water (H20) will behave a little differently as water vapor is a triatomic gas - at least until you approach the freezing point.

The ideal gas to use in a strut would be inert and monotonic such as helium (leaky though) or Argon.
 
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