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Ops Check of Aircraft O2 System During Pre-Buy


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HonestlyI wouldn’t worry about it  There is only high pressure between the tank and regulator, after the regulator it’s really low pressure.

You may want to inspect the tank for the hydrostatic test date, I think they are required every five years and I believe composite tanks aren’t inspected, they are replaced when they time out, and it may not be five years for them. Some metal tanks may even time out.

‘In my opinion a pre-buy isn’t much of an actual inspection, if you really want to know, buy an Annual. An Annual is legally defined and has a checklist etc. There is no such thing as a pre-buy.

‘But either way in my opinion your looking for big high dollar gotcha’s, nickel and dime stuff I wouldn’t even worry about. There will be things like that. some will bother you and you’ll fix them, others may not and you’ll just let them be.

It all depends on price, and the level of perfection you expect in an older used aircraft, and of course the price should reflect condition.

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It took a year, fixing 3 separate issues, to get my O2 to not leak after I bought it. I would have it filled and monitor the gauge for a few days. Mine leaked down pretty quick. You could bring in a big O2 tank and a transfill hose or fly it to an FBO that has O2. Or, since it is empty assume it leaks and you will need to deal with it later.

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2 hours ago, A64Pilot said:

HonestlyI wouldn’t worry about it  There is only high pressure between the tank and regulator, after the regulator it’s really low pressure.

You may want to inspect the tank for the hydrostatic test date, I think they are required every five years and I believe composite tanks aren’t inspected, they are replaced when they time out, and it may not be five years for them. Some metal tanks may even time out.

‘In my opinion a pre-buy isn’t much of an actual inspection, if you really want to know, buy an Annual. An Annual is legally defined and has a checklist etc. There is no such thing as a pre-buy.

‘But either way in my opinion your looking for big high dollar gotcha’s, nickel and dime stuff I wouldn’t even worry about. There will be things like that. some will bother you and you’ll fix them, others may not and you’ll just let them be.

It all depends on price, and the level of perfection you expect in an older used aircraft, and of course the price should reflect condition.

The pre-buy, if satisfactory, will be the first part of an annual. That's my plan, anyway. Check for big issues (corrosion, engine making metal, etc) then complete the purchase and put the plane right in to annual. 

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5 hours ago, Stetson20 said:

The pre-buy, if satisfactory, will be the first part of an annual. That's my plan, anyway. Check for big issues (corrosion, engine making metal, etc) then complete the purchase and put the plane right in to annual. 

Then what is the recourse if you find thousands of dollars worth of repairs during the annual?

If found pre-purchase then you can negotiate or walk away, or buy it with money in escrow to address issues found in annual.

‘At least have a clause in the agreement that purchase is predicated on successful annual completion.

‘I’m thinking of the recent post where someone had just bought an airplane, then discovered corrosion that may require wing replacement for example. 

I was going to buy a Meyers 200D prior to buying the Mooney, We agreed on a price, a very good price actually and I was going to fly out and conduct an annual with a local IA. That’s when the deal began to get weird. Seller was unhappy that I was going to do an Annual, deal fell through, he pulled out.

‘Thinking back I feel certain that there was something wrong with that airplane, something that a good Annual would uncover, and he was afraid I’d uncover it, and walk away and he would have an aircraft with a logbook entry that would make it hard to sell.

‘I think wanting to do an Annual may have saved me a lot of money and heartache 

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On 3/20/2021 at 4:10 PM, A64Pilot said:

Then what is the recourse if you find thousands of dollars worth of repairs during the annual?

If found pre-purchase then you can negotiate or walk away, or buy it with money in escrow to address issues found in annual.

‘At least have a clause in the agreement that purchase is predicated on successful annual completion.

‘I’m thinking of the recent post where someone had just bought an airplane, then discovered corrosion that may require wing replacement for example. 

I was going to buy a Meyers 200D prior to buying the Mooney, We agreed on a price, a very good price actually and I was going to fly out and conduct an annual with a local IA. That’s when the deal began to get weird. Seller was unhappy that I was going to do an Annual, deal fell through, he pulled out.

‘Thinking back I feel certain that there was something wrong with that airplane, something that a good Annual would uncover, and he was afraid I’d uncover it, and walk away and he would have an aircraft with a logbook entry that would make it hard to sell.

‘I think wanting to do an Annual may have saved me a lot of money and heartache 

No Seller in their right mind, especially in this market would agree to that. A legitimate pre-buy will cost 1500-2000 by someone really Mooney savvy and it is looking for airworthy items that will cost thousands. They will list all discrepancies they find. The seller should cover the airworthy items according to the terms of the purchase agreement. 

 

Edit: I meant "seller" should cover airworthy items and changed it above. For the seller to have have a mechanic or shop, that he is unfamiliar with, do an "annual" and possibly hold the airplane hostage would be crazy. If you want to leave it open and turn it into an annual after money has changed hands, no problem if I'm the seller.

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1 hour ago, LANCECASPER said:

No Seller in their right mind, especially in this market would agree to that. A legitimate pre-buy will cost 1500-200 by someone really Mooney savvy and it is looking for airworthy items that will cost thousands. They will list all discrepancies they find. The buyer should cover the airworthy items according to the terms of the purchase agreement. 

Funny, I bought mine about two weeks ago doing an annual. Why would a seller care what kind of inspection you did?

So your saying the buyer should fix anything found wrong?

You sign a purchase agreement to buy without successful completion of an inspection and test flight?

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When I bought my Encore I had the pre-buy done at a well known MSC. It was close to the sellers home airport, and the broker was handling the details. The problem came when the shop refused to categorize the squawks as air-worthy or not. They didn't want to get involved in the negotiations. Yet my purchase contract said the seller was responsible for air-worthy squawks. Since I was planning to roll the inspection into an annual anyway, I asked them which of the squawks needed to be fixed to pass the annual. That became my air-worthy squawk list.  The cost of the repairs for the air-worthy squawks was subtracted from the sales price at closing.

Unfortunately for me they didn't notice the O2 was empty/leaking and the knob didn't work during the inspection/annual. I found that when I arrived for my test flight and transition training. There were a few other things missed as well. At this point, I just wanted to get the deal done and the plane home, so I dealt with them later on. I think you just have to expect the pre-buy and annual will miss things. 

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There's no need for a pre-buy inspection to be "legally binding". A pre-buy inspection should be what you want it to be. As a buyer, any pre-buy I get done will be more comprehensive than any annual inspection. It will be done by the shop of my choosing, airworthy issues will be called out and up for negotiation. As a seller, there will be no annual done nor anything entered in the logbook until money changes hands.

If you want to use an "annual" checklist for the pre-buy, be my guest. But it's not an annual unless it's written in the logbooks and nothing gets written in the logbooks until the sale is complete.

If the plane is out of annual, then it's a whole other story. But I wouldn't buy or sell a plane that's out of annual anyway.

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3 hours ago, gsxrpilot said:

There's no need for a pre-buy inspection to be "legally binding". A pre-buy inspection should be what you want it to be. As a buyer, any pre-buy I get done will be more comprehensive than any annual inspection. It will be done by the shop of my choosing, airworthy issues will be called out and up for negotiation. As a seller, there will be no annual done nor anything entered in the logbook until money changes hands.

If you want to use an "annual" checklist for the pre-buy, be my guest. But it's not an annual unless it's written in the logbooks and nothing gets written in the logbooks until the sale is complete.

If the plane is out of annual, then it's a whole other story. But I wouldn't buy or sell a plane that's out of annual anyway.

If it’s more comprehensive than an annual, then why would you not want it counted as one, reset the clock for another year?

As an IA if I sign off an Annual, there are minimum performance standards that I have to meet. 

‘There are none for a pre-buy, but your choice, your paying.

‘This makes as much sense as saying an engine repair meets the standards for an overhaul, but I don’t want an overhaul entered in the books, Why?

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31 minutes ago, A64Pilot said:

If it’s more comprehensive than an annual, then why would you not want it counted as one, reset the clock for another year?

As an IA if I sign off an Annual, there are minimum performance standards that I have to meet. 

‘There are none for a pre-buy, but your choice, your paying.

‘This makes as much sense as saying an engine repair meets the standards for an overhaul, but I don’t want an overhaul entered in the books, Why?

So many reasons... First of all, this whole situation is only happening in the context of a sale of the airplane. It's about to change owners. So there are only two possible outcomes.

1. The pre-buy goes well, and the sale goes through. The buyer paid for the pre-buy, his shop/mechanic did the pre-buy, and the buyer will own the airplane in a matter of days or hours even. In this scenario, it makes perfectly good sense for the buyer to ask the shop to pause, don't put anything back together, long enough for the funds to change hands, and then pick up where he left off to complete the work and sign off the annual. It's now the buyer's airplane, the buyer's choice of shop, and the buyer's log books.

2. The pre-buy doesn't go well and the deal is off. This is most likely because there is a difference of view on the opinion of the shop/mechanic doing the pre-buy. The seller doesn't agree that certain items are airworthy, or something is broken or is it just worn and normal? And we all know that 10 different IA's will have 10 different opinions on what passes and what doesn't. So in this case the owner is in disagreement one way or another with the guy who did the pre-buy. And it's a strong enough disagreement that the sale is off. So why would the seller let that guy sign his log books. He's gonna list all the discrepancies that the seller isn't in agreement with anyway. If the seller agreed to satisfy all the discrepancies that would result in a fresh annual sign off in the log books, then we're likely back at scenario #1 above and the plane would have sold. And what happens at the next pre-buy in a couple of weeks, does another IA sign off another annual? And resetting the clock doesn't do anything for the seller, the plane will still be sold in a matter of weeks anyway.

If the deal goes through, by all means, the buyer should turn the pre-buy into an annual and start ownership with a fresh clock. If the deal doesn't go through, the buyer doesn't care, and the seller probably doesn't want that mechanic near his log books for good reason.

I once had an A&P tell me my Mooney was grounded and not airworthy. I just let him know I wasn't asking his opinion, climbed in the plane and took off. If the annual is still current, the FAA says that the PIC determines airworthiness. 

Letting the buyer's IA sign log books that belong to the seller, with the buyer walking away, and the deal falling through, is like letting the other guys attorney make all the decisions in the case. 

Finally, you are correct that a pre-buy inspection can be anything you want it to be. But turning it into an annual no more guarantees a good airplane. Many IA's around here have said, the airplane is guaranteed airworthy until you push it out of their shop. Then you're on your own. There is no special protection afforded by that signature in the log book.

 

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On 3/20/2021 at 6:52 AM, Stetson20 said:

Looking at N58089 (M20K Rocket) and arranging a pre-buy. The O2 system is empty. How would you check it to make sure it maintains pressure if you're not at an airfield that has oxygen?

Thanks.

 

If I were the owner I would not allow anyone to pressurize the system with something other than O2, nor would a trained A&P allow it. O2 systems must be “O2 cleaned,” meaning that all traces of petroleum (typically petroleum based lubes for O rings, etc.) must be removed because it can spontaneously ignite in the presence of O2 over 40%. Other gases, such as compressed air, don’t have that restriction and the gas is usually compressed in a compressor that uses petroleum lube, so there may be traces of petroleum in the gas, in fact, some systems such as those that run power tools actually have oil injected into the airstream. If someone uses a non-O2 cleaned system to fill the tank in the aircraft, the aircraft tank will need to go through an expensive O2 cleaning process before it can be filled with O2 again.

You do need to check for leaks, the shut-off valve has a tendency to leak. Somebody on the field usually has pure O2, ask around. Maybe the seller knows, how did he keep the system filled?

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1 hour ago, gsxrpilot said:

So many reasons... First of all, this whole situation is only happening in the context of a sale of the airplane. It's about to change owners. So there are only two possible outcomes.

1. The pre-buy goes well, and the sale goes through. The buyer paid for the pre-buy, his shop/mechanic did the pre-buy, and the buyer will own the airplane in a matter of days or hours even. In this scenario, it makes perfectly good sense for the buyer to ask the shop to pause, don't put anything back together, long enough for the funds to change hands, and then pick up where he left off to complete the work and sign off the annual. It's now the buyer's airplane, the buyer's choice of shop, and the buyer's log books.

2. The pre-buy doesn't go well and the deal is off. This is most likely because there is a difference of view on the opinion of the shop/mechanic doing the pre-buy. The seller doesn't agree that certain items are airworthy, or something is broken or is it just worn and normal? And we all know that 10 different IA's will have 10 different opinions on what passes and what doesn't. So in this case the owner is in disagreement one way or another with the guy who did the pre-buy. And it's a strong enough disagreement that the sale is off. So why would the seller let that guy sign his log books. He's gonna list all the discrepancies that the seller isn't in agreement with anyway. If the seller agreed to satisfy all the discrepancies that would result in a fresh annual sign off in the log books, then we're likely back at scenario #1 above and the plane would have sold. And what happens at the next pre-buy in a couple of weeks, does another IA sign off another annual? And resetting the clock doesn't do anything for the seller, the plane will still be sold in a matter of weeks anyway.

If the deal goes through, by all means, the buyer should turn the pre-buy into an annual and start ownership with a fresh clock. If the deal doesn't go through, the buyer doesn't care, and the seller probably doesn't want that mechanic near his log books for good reason.

I once had an A&P tell me my Mooney was grounded and not airworthy. I just let him know I wasn't asking his opinion, climbed in the plane and took off. If the annual is still current, the FAA says that the PIC determines airworthiness. 

Letting the buyer's IA sign log books that belong to the seller, with the buyer walking away, and the deal falling through, is like letting the other guys attorney make all the decisions in the case. 

Finally, you are correct that a pre-buy inspection can be anything you want it to be. But turning it into an annual no more guarantees a good airplane. Many IA's around here have said, the airplane is guaranteed airworthy until you push it out of their shop. Then you're on your own. There is no special protection afforded by that signature in the log book.

 

What that A&P should have done is to give you a list in writing listing each un-airworthy item, I’d make a copy for my files as an A&P, that way when I’m proven correct and you crash, I can show that you were advised, but your right, this isn’t the Military, I don’t believe I have the authority to “ground” your aircraft, but if it’s bad your not leaving until your provided with a list of un-airworthy conditions.

‘But anyway a pre-buy should be really a formality, by that I mean any item you find should be minor or you picked a real dog of a airplane, plus 95% or the really expensive things like for instance severe corrosion is pretty easy to find pretty quickly, before you as a buyer have sunk a whole bunch of money into the inspection.

‘It’s sort of like saying I only want a 100 inspection and not an Annual, well the only difference is an IA signs off the Annual, but he or she can put A&P after their numbers instead of IA for a 100 hr

But I’ve seen on this forum that a good pre-buy typically runs 1500 -2,000, and assumption that’s labor only no parts.

‘Well for that kind of money, you should be getting an Annual is what I’m thinking.

‘I don’t know why you would have to stop and buy an airplane and then complete the Annual.

‘It’s not like I’ve bought many aircraft, I haven’t and this last one was done with a handshake between two good ole Southern boys, but we had an agreed on price prior to the inspection, and I wasn’t going to worry about nickel and dime stuff, for instance the blind encoder was bad, tires were flat spotted, little stuff like that I’ll 
“eat”

I was only worried about the big stuff, you know like the corrosion someone just found in a wing of an aircraft they just bought that may require new wings, burnt out lightbulbs, flat spotted tires, that’s not worth getting confrontational about, I already beat him down $6,000 and that was about all I was going to get, from that point I either buy or walk, so the Annual was completed and I left with a squeak list of things that I wanted to fix, like the blind encoder.

Edited by A64Pilot
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Here is the info. on different types of tanks, hydrostatic requirements (“testing interval”), and permissible life. Hydrostatic testing is required at set intervals depending on tank type for the tank to continue in service. The last hydro test is stamped into the tank up near the valve, although I do not know if that is true of composites, but it is for metal tanks. There may be several dates if the tank has been hydroed multiple times. You may wish to have the tank inspected (i.e. borescoped) if it has been sitting without pressure for very long. Tanks are always left with some pressure to prevent moisture being introduced and causing corrosion inside the tank, esp. steel obviously. The information comes from the AircraftStatusSheet, which is a really neat software for tracking maintenance published by the MooneyFlyer:

image.thumb.png.6c7099adefeaddc2404a3dfa291dfa75.png

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@A64Pilot at the end of the day, I think we're 95% in agreement. My first Mooney purchase was after a 3 week and $2000 pre-buy at Don Maxwell's shop. And it was the best thing I could have done. I didn't know anything. Don turned up about $6K worth of deferred maintenance and airworthy issues. The seller quickly came good and dropped the agreed price by $6K. It turned out to be a great airplane. 400 hours of good flying time and no issues. My second Mooney I bought with a handshake after looking it over myself. It's been awesome for me the last 5 years and no regrets.

Pre-buy inspections are only as good as you set them up to be, and also as good as the shop doing them. And even after all of that, shit can alway happen. Annuals are the same.

Airplane ownership is not for the faint of heart or light of wallet.

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There are three types of PPIs discussed around here often...

1) For the plane that is as expensive as your house...

2) For the plane that is as expensive as your car...

3) No PPI, because the plane is in such good condition, Ken doesn’t feel it’s necessary...  which has worked really well for him and his biennial plane exchange program...   :)


When to turn a PPI into an annual...

4) 2/3 of the above list wouldn’t qualify as an annual...  because it’s not even close...

5) An extensive PPI, is still a few steps short of an annual... as they have different purposes...  so for a few dollars more, sure, turn it into an annual... and enjoy the next year of flying...

6) When corrosion is discovered early in the PPI... everything stops, to discuss what’s next...

This is a procedure for buying and selling planes... as the buyer, you are already disappointed, and probably headed somewhere else... unless the discussions with the seller can continue...

It’s not your plane, so you aren’t interested in making log entries...  

You are in constant communication with the plane owner through the exercise... so it’s not like you found something and now it’s time to keep a secret...

7) The older the plane, the more complex the PPI can be...

8) The newer the plane... fewer ADs to review, log books are few... lesser number of prior owners... fewer maintenance shops...

9) If you go with the PPI to match the cost of a car... your risk level has increased tremendously...

10) Flat spotted tires, and other easy to swap pieces of hardware... yes they are part of the negotiations... if you want...

11) Negotiations aren’t magical... if you agree to all AW items be addressed by the owner... keep the lines of communication open...

12) Maybe you want new tires... of a particular brand, with a matching tube...   airworthiness, can be a used tire and matching tube...  the objective of negotiating isn’t to win a new set of tires...

13) The idea of putting air into the O2 system just fell to the wayside... lots of compressed air sources have oil entrained in it... oil and O2 Do Not go together...

PP thoughts only, not a mechanic...

Best regards,

-a-

 

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IF you can get the valve out of anOxygen bottle you can visually inspect the interior with just a flashlight, but the valve used on O2 bottles has interference or pipe threads and buddy it’s in there tight. They have a special holding fixture at the hydro place to remove the valve and a long pipe to turn the valve to remove it.

‘Don’t try to return on a Commercial flight with an O2 bottle, they will confiscate it unless the valve is removed and that’s nearly impossible.

Scuba tank valves are machine thread, and sealed with an O-ring and once the tank is empty are easy to remove, but this is no Scuba tank

‘If there is rust in side it can be removed by filling the tank with what looks like rocks and putting the tank on a rock tumbler, this will clean the interior to look like new. The Hydro shop can do this of you use the right shop, many sort of specialize in fire extinguishers and they may not, but the ones that specialize in Scuba tanks can and will.

To ensure the tank is “Oxygen” clean usually simple green is used to remove any possible trace of oil or grease at all it’s in there with the “rocks”, even a tiny bit of oil in a high pressure O2 will explode like a bomb and or burn with unbelievable intensity, so please nothing but O2 should be put in the bottle.

As an IA I disagree with the purpose of an Annual is different, many don’t understand but an Annual is an inspection, it’s not a list of maintenance items to  be done like lubrication of flight controls or repacking wheel bearings.

This matters in that the only part that the IA is required to do is the inspection, he or she cannot delegate that, the “work” from removing panels to packing wheel bearings can be done by someone else, but the inspection Must be done by an IA.

 

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