Attention! All experts! Respected and others.

[jim cooper]

IF......IF an aircraft like a T-Craft has been totally.....totally rebuilt from the ground up....Sandblasted frame, all welds done probably better than factory if needed,oiled and painted correctly, not powder coated. Spars, carefully gone over, sanded, varnished, pulleys replaced, cables same, (also dipped in diluted Zeibart before installing. ETC, ETC. How important is total airframe time? My answer would be not very. Whats yours? Or... If total time is 2200 hours AND- TOTAL TIME SINCE REBUILD IS 600....WHICH IS MORE IMPORTANT. jc

[N96337]

Re: Attention! All experts! Respected and others.

I'm with you, Jim. I've seen some with huge numbers in the total block that were perfect and some that had low total time and were worn out. That being said, don't forget that every log entry has to have the total aircraft time recorded. I think it's kind of a "bragging rite" if yours has a high total time and it's in great shape!
John

[M Towsley]

Re: Attention! All experts! Respected and others.

I think metal fatigue is still a factor no matter how the welds were done or frame finished. Total time is still total time, though how it was taken care of and especially how it was flown I think would matter greatly. I am definitely not an expert though I am a reader and listener of others more knowledgeable than me.

[Ragwing nut]

Re: Attention! All experts! Respected and others.

total time on any antique that has been fully restored to me is irrelevant if properly done. What is more important is where and how the aircraft had been stored for the last 60 odd years

[Hank Jarrett]

Re: Attention! All experts! Respected and others.

Total time makes a lot more difference on a plane like a Bonanza than a Taylorcraft or Cub. On a tube and rag antique the primary structure is likely to be 1010 or 4130 steel which are more prone to holes wearing out than fatigue because the steel is pretty fatigue resistant. Wood doesn't fatigue (ever seen a tree with a fatigue crack?) so the wing spars are not as much of a total time problem.
On an old aluminum plane things are different. Aluminum and high strength steel ARE very prone to fatigue. The non-welded, machined forgings or billet steel parts on a Bonanza will have better bearing strength and probably have bushings to account for wear, but fatigue will break a part that "looks" perfect.
The down side of the older panes is their different failure modes. The holes in milder steels wear and go oversize. Wood spars suffer from dry rot, insect damage and "critter" chewing. The finishes break down and the wood splits. For the older planes most of the problems can be addressed by careful inspection and repair/replacement of the component.
Generalized short answer (thought I would never get there didn't you) is where there are machined parts total time is more important, on old planes inspection for condition is. The reason for tracking total time is, the Feds require it! It doesn't matter if the last annual is much more indicative of current safety than hours.
I didn't talk about the new composite planes like the Lancair and Cirrus, but they actually have finite lives after which the airframe is not considered airworthy. I think I will stick with tube and rag.
Hank

AND NO! You can NOT zero the total time on an airframe no matter how good a job you do or how much you replace.

[M Towsley]

Re: Attention! All experts! Respected and others.

Hank and Mike, I am glad you chimed in on this. Though it does not necessarily pertain to the fuselage, how do you feel about the magnesium parts on the plane? I have found disimilar metal corrosion before, say where an aluminum bracket was bolted to the magnesium part. Plus a recent incident comes to mind regarding magnesium parts. (Though nothing has been released regarding this).

I take it 1010 and 4130 is more of a mild steel, making it less prone to fatigue?

[Hank Jarrett]

Re: Attention! All experts! Respected and others.

1010 was used on a lot of the pre-war planes and my 45 is mostly 1010 (left over pre-war fuselage). it is definatly a low tensile strength, high fatigue resistant steel. 4130 is higher strength than 1010, but is not in the "high strength" category. That and it is pretty well annealed in the weld zones anyway. The problem with these is bearing stress around holes. They don't tend to crack or tear out at repeated low stress (fatigue) but the material wears causing wallowed out holes.
As for the magnesium castings, I think they are JUNK. When I was doing materials engineering we called Mag Castings a "cluster of cracks flying in close formation". My 41 has the welded tube hinge fittings and I think they are FAR SUPERIOR to the post war fittings. When I tore down my 45 wing the fittings were full of cracks and corrosion. My understanding is it is legal to use the pre-war fittings on later planes and I am looking for the HUGE bog of NOS welded fittings I know I saw somewhere in the barn. ;-)
They are dimensionally the same for all the holes and should be direct replacements. I need to talk to my welder and see how much he wants to help me "find" them.
Hank

[NY86]

Re: Attention! All experts! Respected and others.

I am looking for the HUGE bog of NOS welded fittings I know I saw somewhere in the barn. ;-)

Only a Scot would store fittings in a bog...

I always thought magnesium was corrosion in an unstable metallic form.

[Hank Jarrett]

Re: Attention! All experts! Respected and others.

Ya hides em in the bog so the FAA will think they are old!
Hank

Besides, the Mag ones just go away when you bury them. Every spare Magnesium fitting I have is cracked. I wouldn't use any of them on an airplane. If you take shavings from them they start a BBQ in a heart beat!

[flyguy]

Re: Attention! All experts! Respected and others.

I had an "early" 45 BC12 that I remember had the steel welded aileron fittings so I know what they look like.

I have had some concern about the bearings and wear in the aileron fittings, but this brings up an entirely new concern. "Every magnesium fitting I have is cracked," does not give one warm fuzzy feelings about those parts, never mind the inserts.

I cannot imagine any way to inspect them meaningfully with them in place. I thought those things were aluminium. Darn.

Do we have a really solid candidate for owner manufactured part here or will aftermarket mfgrs do the job after the FAA/NTSB accident report comes out.
DC

[Hank Jarrett]

Re: Attention! All experts! Respected and others.

Don't misunderstand! All of the EXCESS ONES in my parts box are cracked, NOT all the ones on the wings I have seen. I have seen uncracked ones and put some new uncracked ones on. When they crack they are replaced with new ones and I ended up with a bunch of damaged ones (couldn't see trashing all that magnesium). I have NEVER seen a cracked welded tube one but I HAVE seen a lot of cracked magnesium ones. Both my 41 and my 45 have welded ones. I don't like the magnesium ones, but the 41 and 45 came with welded ones originally.
Hank

[flyguy]

Re: Attention! All experts! Respected and others.

Actually I just came back, after consideration, to delete my last reply as I though it was a bit too reactionary. It is rather uninformed. I thought that I should take a closer look at the entire assembly before saying anything. Too late now. LOL,
and I didn't even drink any coffee this AM. Thanks for the reply though.
Darryl

[Hank Jarrett]

Re: Attention! All experts! Respected and others.

Never apologize for thinking safe! I just hope my welder is willing to help me "find" the box of welded ones and we can retrofit them as the magnesium ones are found cracked. The mag ones I have are mostly cracked through the bolt holes attaching them to the rear spar. When they break there you can feel it by moving the hinge fitting with the aileron up. I don't know about others, but I move the wing tips up and down and twist the tips (GENTLY) on every pre-flight listening for "funny" noises. I also lift each aileron and look at the push rods, bell.cranks and all of the hinges. My old instructor said I do very long pre-flights. I say I just like touching my plane.
How many of you guys unzip the headliner and use a flash light to look in the tail cone for uninvited passengers? One of the guys at the glider field had a rattle snake crawl out of the tail and up by his feet in flight! That gave me even MORE incentive to look around the cockpit before taking off! Of course a sailplane with the gear down is pretty easy to crawl into from the gear doors. Could one get in your tail through the hole in the last triangle in the belly you left uncovered to keep trash from collecting in the tail?
Hank

No, he didn't get a snake bite, but getting him out of the plane with a snake on his feet must have been interesting! I was told they told the pilot to just accept that he would probably get a bite and focus on flying the plane! "LAND and we will get you to a Dr.". Must have been a lot of people having one of those "spine shivers" while he was in the pattern!

[Ragwing nut]

Re: Attention! All experts! Respected and others.

I pay very close attention to the aileron brackets. They are prone to major corrosion under the hinge pin bracket. If they are not close to perfect in that area, I do not use them. You can have them welded up, but the welder better know how to weld mag. You also need to inspect the bolt hole in the control yoke closely for cracks as well. I have yet to see one come off, but have ran across a bunch of them that are cracked

[jim cooper]

Re: Attention! All experts! Respected and others.

as usual, many good insights! I also agree that storage plays a very important part of whats what. If its not properlyhangared...always... big trouble can occur fairly rapidly. Many thanks! JC