Prebuy Inspection

[Freddb34]

Well, it's finally here.  The pre buy is scheduled for tomorrow on my 64 M20E.  I've spoken with the A&P and asked what he intends to look at and it's looking pretty standard fare.  He want to pull the oil filter and check for metal, do compression test, (we're not going to swing the gear since it's a manual gear E).  I know about the potential for corrosion in the tube frame so I'm going to ask him to pull those interior panels and check. (I don't think that's asking too much.)  It's got the 3 bladed Hartzell prop so wanting him to check the hub.   He wants to review the logs last, which to me seems a bit weird as he could check for AD compliance and then look at the plane and double check the AD's afterwards.  Is there anything specific I should ask him to check?  Hoping this will be my last plane so don't want anything getting missed that may give me massive headaches down the road.  Thanks all. 

[Andy95W]

Look for aluminum corrosion in the tail and wings.  Pay special attention to the main spar (red) and stub spar (green).

 

[MikeOH]

My first question would be how many Mooneys has this particular A&P worked on?

The eddy current hub inspection, to my knowledge, is only on the Hartzell 2 blade props. Maybe there is something else for 3 blade?

I agree, reviewing the logs should be first.

Added thought, there is some amount of interior disassembly required to access the rear spar and the tube frame (SB-208), make certain the A&P is signed up for this.  It wouldn't be a bad idea to be there to see for yourself.  IOW, if this is a 'fixed price' pre-buy make sure this inspection is actually included in the price!

[Fritz1]

yes, as stated before check for corrosion on steel tubes under side windows, on main spar, on stub spar,

nose gear leg and truss tend to get dinged when airplane is jackknived, think max allowable dent is 1/32"

I keep fingers crossed!

[Freddb34]

5 hours ago, Andy95W said:

Look for aluminum corrosion in the tail and wings.  Pay special attention to the main spar (red) and stub spar (green).

 

Hey!  Thanks for the pic.  I'm going to print this off and make sure he pops a few of these panels along the spars to check.  

[cliffy]

Here's my take on a pre-buy inspection-

Check that all the model numbers and serial numbers match on everything with the log book, engine, prop, airframe, I do radios also. Actually read the data plates and compare to the logs. Check that the parts actually installed match what is contained in the TCDS and/or the logs show an STC change for the big stuff and changes for radios and electronics. Anything added like engine monitors, fuel flow gauges, etc should show an STC listing in the log books. 

Pull the rear seat bottom and open up the inspection holes to check for corrosion on the spar caps. Look at the spars real well in the main wheel wells for same. 

As noted fill up fuel tanks the night before and look for leaks the next day.

If you can jack the airplane do a gear over center torque check. Make sure the A&P has the correct tools to do it.

While on jacks, move the main gears in and out toward the wing tips for excessive movement. Lift the main wheels to check for play in the donuts. The donuts should expand enough after 5 mins unloaded to not have much movement. Check the mouse boots for condition in the main wheel wells. While down by the main gear look at the spar bottom between the fuselage and wheel wells. Look for smoking rivets there. The rivets that hold the spar sandwich together. That can be a big $$$$$$. I found one in AU with almost every rivet loose on the bottom of the spar. It was grounded by the owner when Kerrville said it had to be repaired. 

Nose gear area - if on jacks this is easy- twist the nose wheel left and right to check for excessive play in the steering linkage. More than about 10-15 degrees either side of center before tightening up on the linkage is too much. You will see the slop way at the top of the nose gear on the rod end linkage up there.  

Most important on the nose gear! Look and feel for dents where the steering system touches on the tubing for dents where it touches. Turn the wheel by hand and you will see where it touches and stops. MAKE SURE THERE ARE NO DENTS THERE!

The limit is 1/32" depression. Any dents and the nose gear comes out for repair $$$$

On the tail surfaces grab the tip of the stabilizer and try to move it up and down and fore and aft. If it moves or clicks you might have work to do. Limits are about 1/10th of an inch either way. Usually fixed by changing out the "close tolerance bolts' in the hinge. As noted lift up on the rudder to check for play in the jackscrew. Same limit about 1/10 of an inch. Lots of times it is wear on the 2 bolt hinge bracket at the aft end of the jackscrew and not the jackscrew it self. I found one stabilizer that moved 1/2 inch either side of center!

Look over the outside surface of the entire airplane for dents, filliform corrosion, hangar rash (the elevator tips seem to be especially susceptible to this damage and NO repairs are allowed to control surfaces (no patches, partial skin replacement, etc). The FAA in one case here on MS made a big thing out of this stuff on a routine ramp check on one of our posters. Basically they said it didn't come that way from the factory so fix it. 

I check all the exterior control surface rod ends to see if they are loose enough to move or if dry and frozen. If dry and frozen I start looking at the logs real close to see if the lube and gear swing AD had been being done. 

One item missed almost always due to the effort but it can cause big headaches, is pulling the sidewalls inside and actually looking at the steel tubing frame for rust. If the windows are not sealed well, water gets in there and runs down inside on the tubes and rusts them. The insulation SB aside. There is actually a SB describing how to check for leaks by pulling the sidewalls and directing a water hose at the windows looking for leaks. 

Make sure everything, and I mean every switch, knob and button works as designed! Put power to it and try all radios in all modes, all lights, all warnings (landing gear warning horn, stall warning horn, etc), all exterior lights, everything that can be turned on or off or moved in and out. There was one write up on here a while back where someone bought a Mooney and the stall warning didn't work nor did the gear warning (IIRC). That makes the airplane unairworthy. 

If on jacks (and it should be) do a gear swing and make sure the gear works properly. I've seen them signed off 3 months ago and they hang 3" from the wells when sucked up. If its electric gear do a manual drop also to make sure it works. Had a couple on this board recently that went in for annual and the manual gear drop didn't work. So check it out. Look to see if the gear actuator has ever been removed, cleaned, checked for proper gear lash and relubed. If it hasn't you may be doing that on the next annual yourself  It's that important. Disregard if its a manual gear.

It goes without saying that a full log book check is required for all applicable ADs and required inspections even though the annual has just been done. The logs tell a story and knowing how to read them is a skill. Make sure you know what to look for or have someone that does. 

The engine stuff is the normal stuff. Compression check, oil filter inspection, looking for leaks, cracks, anything not normal. Pull the plugs and read them, they too have a story to tell. 

My caution to any whom I help buy an airplane? Trust no one selling an airplane period. Take nothing for granted. Don't trust anything even though it just had an annual. If you do, it will bite you in the arse. Check and verify everything before money changes hands. Once you pay for it , its yours!

Good luck and show us pictures even of the prebuy!   :-) :-)

[varlajo]

54 minutes ago, cliffy said:

Here's my take on a pre-buy inspection-

10 hours ago, Freddb34 said:

Hoping this will be my last plane so don't want anything getting missed that may give me massive headaches down the road.  Thanks all. 

...or just hire @cliffy ... 

[DCarlton]

50 minutes ago, cliffy said:

Here's my take on a pre-buy inspection-

Check that all the model numbers and serial numbers match on everything with the log book, engine, prop, airframe, I do radios also. Actually read the data plates and compare to the logs. Check that the parts actually installed match what is contained in the TCDS and/or the logs show an STC change for the big stuff and changes for radios and electronics. Anything added like engine monitors, fuel flow gauges, etc should show an STC listing in the log books. 

Pull the rear seat bottom and open up the inspection holes to check for corrosion on the spar caps. Look at the spars real well in the main wheel wells for same. 

As noted fill up fuel tanks the night before and look for leaks the next day.

If you can jack the airplane do a gear over center torque check. Make sure the A&P has the correct tools to do it.

While on jacks, move the main gears in and out toward the wing tips for excessive movement. Lift the main wheels to check for play in the donuts. The donuts should expand enough after 5 mins unloaded to not have much movement. Check the mouse boots for condition in the main wheel wells. While down by the main gear look at the spar bottom between the fuselage and wheel wells. Look for smoking rivets there. The rivets that hold the spar sandwich together. That can be a big $$$$$$. I found one in AU with almost every rivet loose on the bottom of the spar. It was grounded by the owner when Kerrville said it had to be repaired. 

Nose gear area - if on jacks this is easy- twist the nose wheel left and right to check for excessive play in the steering linkage. More than about 10-15 degrees either side of center before tightening up on the linkage is too much. You will see the slop way at the top of the nose gear on the rod end linkage up there.  

Most important on the nose gear! Look and feel for dents where the steering system touches on the tubing for dents where it touches. Turn the wheel by hand and you will see where it touches and stops. MAKE SURE THERE ARE NO DENTS THERE!

The limit is 1/32" depression. Any dents and the nose gear comes out for repair $$$$

On the tail surfaces grab the tip of the stabilizer and try to move it up and down and fore and aft. If it moves or clicks you might have work to do. Limits are about 1/10th of an inch either way. Usually fixed by changing out the "close tolerance bolts' in the hinge. As noted lift up on the rudder to check for play in the jackscrew. Same limit about 1/10 of an inch. Lots of times it is wear on the 2 bolt hinge bracket at the aft end of the jackscrew and not the jackscrew it self. I found one stabilizer that moved 1/2 inch either side of center!

Look over the outside surface of the entire airplane for dents, filliform corrosion, hangar rash (the elevator tips seem to be especially susceptible to this damage and NO repairs are allowed to control surfaces (no patches, partial skin replacement, etc). The FAA in one case here on MS made a big thing out of this stuff on a routine ramp check on one of our posters. Basically they said it didn't come that way from the factory so fix it. 

I check all the exterior control surface rod ends to see if they are loose enough to move or if dry and frozen. If dry and frozen I start looking at the logs real close to see if the lube and gear swing AD had been being done. 

One item missed almost always due to the effort but it can cause big headaches, is pulling the sidewalls inside and actually looking at the steel tubing frame for rust. If the windows are not sealed well, water gets in there and runs down inside on the tubes and rusts them. The insulation SB aside. There is actually a SB describing how to check for leaks by pulling the sidewalls and directing a water hose at the windows looking for leaks. 

Make sure everything, and I mean every switch, knob and button works as designed! Put power to it and try all radios in all modes, all lights, all warnings (landing gear warning horn, stall warning horn, etc), all exterior lights, everything that can be turned on or off or moved in and out. There was one write up on here a while back where someone bought a Mooney and the stall warning didn't work nor did the gear warning (IIRC). That makes the airplane unairworthy. 

If on jacks (and it should be) do a gear swing and make sure the gear works properly. I've seen them signed off 3 months ago and they hang 3" from the wells when sucked up. If its electric gear do a manual drop also to make sure it works. Had a couple on this board recently that went in for annual and the manual gear drop didn't work. So check it out. Look to see if the gear actuator has ever been removed, cleaned, checked for proper gear lash and relubed. If it hasn't you may be doing that on the next annual yourself  It's that important. Disregard if its a manual gear.

It goes without saying that a full log book check is required for all applicable ADs and required inspections even though the annual has just been done. The logs tell a story and knowing how to read them is a skill. Make sure you know what to look for or have someone that does. 

The engine stuff is the normal stuff. Compression check, oil filter inspection, looking for leaks, cracks, anything not normal. Pull the plugs and read them, they too have a story to tell. 

My caution to any whom I help buy an airplane? Trust no one selling an airplane period. Take nothing for granted. Don't trust anything even though it just had an annual. If you do, it will bite you in the arse. Check and verify everything before money changes hands. Once you pay for it , its yours!

Good luck and show us pictures even of the prebuy!   :-) :-)

This is excellent. However I’m really curious how many hours you would plan for this effort to include the usual engine checks and any documentation of findings.   

[Fly Boomer]

10 hours ago, cliffy said:

10 hours ago, cliffy said:

Here's my take on a pre-buy inspection-

This is a great post!  Woe unto the incautious buyer who fails to heed these words.

[Freddb34]

9 hours ago, DCarlton said:

This is excellent. However I’m really curious how many hours you would plan for this effort to include the usual engine checks and any documentation of findings.   

I'm paying just over $1000 for this prebuy, so at $100 an hour thinking this could be (and should be) done over the course of a day.  I wasn't planning on swinging the gear but now that you bring up all the things that should be inspected, I'm beginning to think maybe we should.  I'm very concerned about the corrosion on the frame and I know that pulling all those panels will be one massive PITA, but I am going to insist that it be done, even if I have to pull the panels myself (under AP supervision of course.)  Was really hoping that the person I'm buying from (a friend who is an AP/IA by the way and did the last annual) pulled the interior before he purchased it last year.  He did say he checked it but as Reagan once said, "Trust.  But verify."   Really appreciate all the good info.  May just print it off and take it as a guide to the AP and say, "Here you go.  Do all this!"  

[Slick Nick]

Any money you end up spending on a prebuy now will be worth it in the end. 

[Freddb34]

1 hour ago, Slick Nick said:

Any money you end up spending on a prebuy now will be worth it in the end. 

Totally agree.  The bank account I save, may be my own.  (And if you remember that PSA, you're as old as my "soon to be my" plane!!)    

[Fritz1]

pre-purchase should be more thorough than an annual, focus is different though and directed to identifying show stoppers, if you find one early, stop the pre-buy, if things keep looking promising complete the prebuy and have it signed off as an annual after you bought the airplane, this is your one and only chance to get to the bottom of the story without having to pay for somebody else's sins, annual on a short body is typically 25-30h, pay for the prebuy, selling price then gets negotiated in view of the findings, if no deal you are much better prepared for the next pre-buy, an E built new today would probably cost in excess of $500k, the maintenance responsibility you are getting into is commensurate with that amount, caveat emptor = buyer beware

[cliffy]

14 hours ago, DCarlton said:

This is excellent. However I’m really curious how many hours you would plan for this effort to include the usual engine checks and any documentation of findings.   

No more than 10 hrs for everything

The most time consuming part of the job is reading the log books and  removing the interior

If you find stuff unairworthy you have negotiating power to reduce the sale price OR just walk away.

Even if you drop $1500 on the pre-buy and walk away you have saved lots of money in the long run.

There have been several cases right here on Mooneyspace  of quick or no pre-buy and the first annual

winds up costing  $10-$20,000 or more 

Words to remember-

                  If every one did the proper maintenance per the book we would not need  any

                  pre-buy inspections.

 

[EricJ]

48 minutes ago, cliffy said:

There have been several cases right here on Mooneyspace  of quick or no pre-buy and the first annual

winds up costing  $10-$20,000 or more 

Or airplanes that wound up being parted out due to corrosion.  

[DCarlton]

2 hours ago, cliffy said:

No more than 10 hrs for everything

The most time consuming part of the job is reading the log books and  removing the interior

If you find stuff unairworthy you have negotiating power to reduce the sale price OR just walk away.

Even if you drop $1500 on the pre-buy and walk away you have saved lots of money in the long run.

There have been several cases right here on Mooneyspace  of quick or no pre-buy and the first annual

winds up costing  $10-$20,000 or more 

Words to remember-

                  If every one did the proper maintenance per the book we would not need  any

                  pre-buy inspections.

 

I've grown exceedingly pessimistic over the years.  I had to develop cost estimates at work before I retired; materials, labor, travel, etc.  After a while I learned that if you didn't triple whatever you thought it should take you'd come up short; everyone around me joked and agreed; triple it and you'll be about right.  I've found aircraft maintenance to be very similar.  Even if you're lucky enough to be billed 10 hours, you'll get the plane back together in a week; maybe three days minimum.  Based on Mooneyspace recommendations, I pulled the aft two inspection plates behind the stub spar during my last annual.  Apparently they hadn't been removed for years; screws were frozen.  By the time we got the plates off, and vacuumed out all of the carpet residue and debris that had accumulated in the area behind the spar, that alone was at least a two hour task.  Whatever you touch seems to lead to more work.  I'm not saying don't do it, I'm just suggesting folks plan on more work than they expect.  I guess you'll know if you'll buy it and have a chance to do the work before you put it back together.  I've wondered what it would be like to inspect and buy a plane that's only a few years old; that would be a joy; thin log books; squeaky clean airframes.  I've also thought how great it would be to buy a solid airframe, gut it, and restore it ground up.  That too would be a joy.  Everything in the middle feels like a compromise.  

[jetdriven]

2/3 of the airplanes for clients don’t even make it to the shop for a PPI because there’s so many glaring things wrong in the history.  Fishy Shadetree overhauls from 25 years ago and then a top with Gibson chrome cylinders half halfway between now and then., For example.   But if you get past that you need to spend 15 hours looking at it. And anything that gets missed, the buyer owns. There is no upper limit to what this might cost.  
 

I have a landing gear actuator at Lasar right now with a bent jackscrew and it’s chattering on the down stroke. It’s gonna cost $4000 to get this thing out of the shop. And that’s just to fix the actuator that we already have. That’s not even replacing in the back spring. That would be two grand more.

[76Srat]

Sorry to sound somewhat preachy about the perspective of a pre-buy, but I've always viewed pre-buys as a chance to identify weaknesses, not strengths.  Find reasons not to buy the airplane instead of finding reasons to support an emotional hope that it is a "good buy".  See it as a deposition, as it were, as in what do you not know about your case?  Don't use a pre-buy as a chance to argue in favor of buying the plane.  Use it as the chance to find any and every reason not to buy it.  If it passes that high hurdle, then you'll more likely than not end up with fewer regrets.

 

 

[Jim Peace]

18 hours ago, varlajo said:

...or just hire @cliffy ... 

Or MDOC....whatever happend to him?

[Flyler]

Write the items down in a list, and start with the big show stoppers. Check for a corroded spar before you waste much time reading plugs and such.

[Utah20Gflyer]

I would agree with the notion that you should get the plane on jacks so you can evaluate the landing gear.  You won’t be able to determine what kind of play there is unless you do.  In my case the first annual I had to go through the whole system and replace lots of parts to get it airworthy again.  That was very time consuming.  

[MB65E]

Swing the gear.

Otherwise this could be you!

-Matt

[Slick Nick]

You should listen to Mike Busch's podcast on YouTube on a proper prebuy. He outlines exactly how it should differ from an annual inspection, and what he recommends looking for.