Legalities of flying with a collapsed strut?

Rgbeard

Rgbeard

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rgbeard
When I flew back to Phoenix from San Diego on Wednesday, I saw a trail of oil accompany me to the parking spot, and saw that I blew a seal on my right main oleo strut.

I certainly don’t intend on flying the airplane until it’s repaired. Parts have been ordered and I’m getting together with my mechanic on Monday to resolve.

However this turned into a conversation between my wife and I and I don’t really know the answer? I understand it’s not a good idea. But is it legal to fly the airplane?
 
Rgbeard said:
When I flew back to Phoenix from San Diego on Wednesday, I saw a trail of oil accompany me to the parking spot, and saw that I blew a seal on my right main oleo strut.

I certainly don’t intend on flying the airplane until it’s repaired. Parts have been ordered and I’m getting together with my mechanic on Monday to resolve.

However this turned into a conversation between my wife and I and I don’t really know the answer? I understand it’s not a good idea. But is it legal to fly the airplane?
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Yes. FAR 91.7. You be the one what gets to decide if it’s airworthy or not. If you decide wrong you may have some splainin’ to do under 91.13. Probably sumpin else somewhere says more about it. I say let the juice out of the other one and go for it.:fingerwag:
 
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Rusty is the strut completely collapsed? I had the same situation several years ago but noticed it leaking (slow drip) after landing on a breakfast run. I skipped breakfast and flew it back before it completely collapsed. It’s a judgment call. Do I fly it and possibly make it a lot worse on the next landing or do I try to have it fixed here? Personally I wouldn’t fly it until it was fixed if the hydraulic fluid was gushing out and or the strut was collapsed
 
Judgement call based on aircraft type and what metal is going to take the punishment of a hard landing with no strut pressure.

Often the components that would be damaged if even an accidental hard landing back at home base, are unobtainium or waaaaaaay more money than getting it fixed away from home and the hassles involved.

Something to ponder. Big bucks vs little bucks.
 
Rgbeard said:
But is it legal to fly the airplane?
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Legal = ferry permit. But as mentioned, landing with a collapsed strut can set you up for possible strut damage and landing control issues.
 
Thanks for the answers.

just to be doubly doubly clear, this was only an academic issue. I’m certainly not flying the aircraft.

9CA87E9C-FB1F-4877-A052-B1566C0ABFDB.jpeg

sigh. I give up on properly oriented photos
 
Bellanca_Pilot said:
Doesn’t it sit on a spring?
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No. MIL-H-5606 hydraulic fluid with nitrogen gas pressure (although I've seen some mechanics use air on the smaller, lighter Cherokees). It's similar to a gas shock absorber on a car.
Fortunately the Piper oleo isn't a very complicated assembly, and the seal kits don't cost half the price of the airplane.
 
Oleo rebuilt kits are under $50, assuming the issue is seals and scrappers. Biggest mistake people make is only replacing the lower seals which are cheaper and easier to access. The upper seal requires more disassembly. Not unusual to see log book entries for “strut rebuild”, only to find the upper seals completely flat spotted and useless. Eg. not changed since plane was born.
 
GRG55 said:
and the seal kits don't cost half the price of the airplane.
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Yeah the seal kit is peanuts, it’s much more labor intensive than anything.
 
GRG55 said:
No. MIL-H-5606 hydraulic fluid with nitrogen gas pressure (although I've seen some mechanics use air on the smaller, lighter Cherokees). It's similar to a gas shock absorber on a car.
Fortunately the Piper oleo isn't a very complicated assembly, and the seal kits don't cost half the price of the airplane.
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I use a special blend of nitrogen and oxygen with a little argon to round it out.
 
NordicDave said:
Oleo rebuilt kits are under $50, assuming the issue is seals and scrappers. Biggest mistake people make is only replacing the lower seals which are cheaper and easier to access. The upper seal requires more disassembly. Not unusual to see log book entries for “strut rebuild”, only to find the upper seals completely flat spotted and useless. Eg. not changed since plane was born.
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RyanB said:
Yeah the seal kit is peanuts, it’s much more labor intensive than anything.
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By airplane standards the labor to properly rebuild a Piper oleo is quite reasonable. I agree with @NordicDave that it's false economy not to rebuild it completely while you have it apart. It's a messy job working under the wing, but it's not complicated.
 
Matthew Rogers said:
Because it is called “air” and it is free.
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LOL As I said in my original post I've seen some mechanics use air on the smaller, lighter Cherokees. It's not a good idea on the heavier planes, such as the OP's Lance, and I certainly won't use air for the oleos on my Aztec.

Also, there's NOTHING that is free in aviation, other than the advice one receives on this forum.
 
Rgbeard said:
Thanks for the answers.

just to be doubly doubly clear, this was only an academic issue. I’m certainly not flying the aircraft.

View attachment 95272

sigh. I give up on properly oriented photos
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Keep in mind that the strut normally needs to be fully extended to fit in the wheel well properly, and strut pressure is a major factor in that. If you were to fly it, I’d definitely leave the gear down.
 
Ehh, I may or may not have done it.

My mechanic said it was safe, I asked was it smart? He said, basically, can you make one landing on a giant paved runway without putting it down on the nose wheel?

I may or may not have flown it to him for repair.
 
Rusty it must be PA32 strut collapsing week. Mine collapsed too....just as it went into annual. That was kinda convenient.
 
NealRomeoGolf said:
Rusty it must be PA32 strut collapsing week. Mine collapsed too....just as it went into annual. That was kinda convenient.
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How long has it been since all you folks have replaced the seals, O-rings and put fresh hydraulic fluid in your struts?

@NRG when they pull open the strut if the fluid looks and smells bad, you'll know its overdue.
 
GRG55 said:
How long has it been since all you folks have replaced the seals, O-rings and put fresh hydraulic fluid in your struts?

@NRG when they pull open the strut if the fluid looks and smells bad, you'll know its overdue.
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I'd have to look at the books. I've only owned it 9 months.
 
NealRomeoGolf said:
I'd have to look at the books. I've only owned it 9 months.
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Depending on what you find in the books and what your shop finds when they open it up, you may want to consider doing all 3 - or one each year over the next 3 annuals to spread the cost out.
 
Rgbeard said:
Thanks for the answers.

just to be doubly doubly clear, this was only an academic issue. I’m certainly not flying the aircraft.

View attachment 95272

sigh. I give up on properly oriented photos
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If you go to edit and rotate it 360º on your phone before you upload, it will upload in the correct orientation. Annoying, but it works.
 
GRG55 said:
Depending on what you find in the books and what your shop finds when they open it up, you may want to consider doing all 3 - or one each year over the next 3 annuals to spread the cost out.
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We are doing all 3. Ordered parts yesterday.
 
Dan Thomas said:
And it will contain more water than argon, too. It's only free for a limited time.
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That depends on where the air came from. In Arizona I'd be surprised in the summer if it contained any water at all. I don't call that state Aridzona for nothing. :p
 
Ghery said:
That depends on where the air came from. In Arizona I'd be surprised in the summer if it contained any water at all. I don't call that state Aridzona for nothing. :p
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Believe it or not, I definitely have to check my air compressor's drain regularly and still get a good dose of water from it.

It's currently 92 here, and 20% humidity if my weather station is to be believed.
 
A little off topic, but years ago at a Cessna Pilots Association fly-in to First Flight at Kitty Hawk one of the attendees had a collapsed nose wheel oleo strut on his 182. Another attendee who was an A&P used a length of radiator hose and slit it open so it would fit over the strut and held it in place with four hose clamps. It was a pretty clever way to get the 182 home without a prop strike or worse.

Legal? I dunno.
 
Rgbeard said:
Believe it or not, I definitely have to check my air compressor's drain regularly and still get a good dose of water from it.

It's currently 92 here, and 20% humidity if my weather station is to be believed.
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Yup. A good explanation here: https://www.thecompressedairblog.com/why-is-compressed-air-wet

There's always some water vapor, even in the desert. The compressor tank will accumulate it more slowly, but it will still accumulate. The bigger danger is water accumulating in low spots in the shop's plumbing and hoses, especially in low spots, during high air usage when the lines and hoses cool the still-warm compressed air and the water condenses out of it. Once it gets high enough in a low spot to start blocking airflow it will blast out of that hose and contaminate whatever you're doing with it, whether it's air tools or spray painting or an oleo strut. In one place I used to have to stop everything and go around and stick an open quick-coupler fitting in each air chuck and let air and water blast out, working my way downstream, and the hoses were last. I'd have water all over the floor. And that was in a fairly dry climate and with regular tank draining.
 
Stan Cooper said:
used a length of radiator hose
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Have seen a number of bush planes with added hose bumper guards on the nose. It's there as added protection for landing off airport. Whether to use it as a band-aid to get one home....
Stan Cooper said:
Legal?
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On the bush planes it's usually installed as a minor with an entry.
 
Ghery said:
That depends on where the air came from. In Arizona I'd be surprised in the summer if it contained any water at all. I don't call that state Aridzona for nothing. :p
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You'd probably be surprised. ;)
Rusty's correct.

The relationship between temperature and maximum moisture content is not linear. If you want dry air you'll have better success in Colorado in the winter than in Phoenix in the summer.

Rgbeard said:
Believe it or not, I definitely have to check my air compressor's drain regularly and still get a good dose of water from it...
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Phoenix, AZ has an average daily high temperature of 103.6 deg in July and an average relative humidity that same month of 31%. Maximum moisture content at 104 deg F (40 C) is 51.1 grams/cubic meter, or 15.8 grams/cubic meter actual water content at 31% relative humidity.

That's about the same mass of water in the air as a 70 deg F day at 85% relative humidity, and almost 25% more water content than a foggy 60 deg F day.
 
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Dan Thomas said:
Yup. A good explanation here: https://www.thecompressedairblog.com/why-is-compressed-air-wet

There's always some water vapor, even in the desert. The compressor tank will accumulate it more slowly, but it will still accumulate. The bigger danger is water accumulating in low spots in the shop's plumbing and hoses, especially in low spots, during high air usage when the lines and hoses cool the still-warm compressed air and the water condenses out of it. Once it gets high enough in a low spot to start blocking airflow it will blast out of that hose and contaminate whatever you're doing with it, whether it's air tools or spray painting or an oleo strut. In one place I used to have to stop everything and go around and stick an open quick-coupler fitting in each air chuck and let air and water blast out, working my way downstream, and the hoses were last. I'd have water all over the floor. And that was in a fairly dry climate and with regular tank draining.
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Yeah. Shop air in a strut is not a good idea.
 
Dan Thomas said:
Yup. A good explanation here: https://www.thecompressedairblog.com/why-is-compressed-air-wet

There's always some water vapor, even in the desert. The compressor tank will accumulate it more slowly, but it will still accumulate. The bigger danger is water accumulating in low spots in the shop's plumbing and hoses, especially in low spots, during high air usage when the lines and hoses cool the still-warm compressed air and the water condenses out of it. Once it gets high enough in a low spot to start blocking airflow it will blast out of that hose and contaminate whatever you're doing with it, whether it's air tools or spray painting or an oleo strut. In one place I used to have to stop everything and go around and stick an open quick-coupler fitting in each air chuck and let air and water blast out, working my way downstream, and the hoses were last. I'd have water all over the floor. And that was in a fairly dry climate and with regular tank draining.
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Well, I just used a hand pump, so no accumulated water in the lines or tank. I did so at 40 degrees and let's say 50% humidity (because I don't remember knowing that value). A total of 1.1664 g of water was present per pound of air on that day. Factor in the volume of the strut (adjusted for pressure and temperature) and I get 20-50 milligrams grams of moisture (water vapor) in the strut. A rounding error in my book.
 
GRG55 said:
The relationship between temperature and maximum moisture content is not linear. If you want dry air you'll have better success in Colorado in the winter than in Phoenix in the summer.
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I’m always shocked when I go places that wet towels don’t dry themselves just by hanging them up for an hour. LOL.
 
Matthew Rogers said:
...A total of 1.1664 g of water was present per pound of air on that day...
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Yes and let's be clear that 200 psi doesn't mean that you've put 200 pounds of air in your strut. Historically over the past 70 years or so I'd say that probably 95% of the GA Pipers and Cessnas have been flying around with "shop air" in their struts but nowadays even Les Schwab will try to convince you that you need nitrogen in your car tires.
 
Silvaire said:
Yes and let's be clear that 200 psi doesn't mean that you've put 200 pounds of air in your strut. Historically over the past 70 years or so I'd say that probably 95% of the GA Pipers and Cessnas have been flying around with "shop air" in their struts but nowadays even Les Schwab will try to convince you that you need nitrogen in your car tires.
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I love the car nitrogen guys. They always say the oxygen molecules are small enough they escape through the tire.

To which one answers, “Cool. So if I keep filling with air the tire will slowly make it all nitrogen inside as it leaks out the oxygen!”

Freaking idiots.
 
denverpilot said:
I love the car nitrogen guys. They always say the oxygen molecules are small enough they escape through the tire.

To which one answers, “Cool. So if I keep filling with air the tire will slowly make it all nitrogen inside as it leaks out the oxygen!”

Freaking idiots.
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Osmosis. I love it!

The version I heard was oxygen reacts with the inside of the tire and ages it. Not sure what's happening to the outside...
 
jsstevens said:
Osmosis. I love it!

The version I heard was oxygen reacts with the inside of the tire and ages it. Not sure what's happening to the outside...
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Outside where they are exposed to both oxygen AND sunlight? Nevermind that, just pay us the upcharge for the nitrogen fills! In a few years when you are replacing your cracked, worn-out tires, you'll be amazed at how good they look on the inside!
 
I used nitrogen in the race car tires.

Because the nitrogen does not get as hot as oxygenated air then expand when it gets hot, then raising the tire pressure.

Because the increasing tire pressure can throw off the suspension set up thereby slowing the car down and/or making it hard to handle through the turns.

I use nitrogen in the truck and trailer tires to keep the heat down in the tires when loaded and at highway speeds.

Heat eventually breaks down tires.
 
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