Bruce Fenstermacher wrote:... but one of these days I have to remove my tanks to install the door stops my partner decided not to reinstall. Big mistake.
Bruce have you considered installing door stewards instead? They work like a charm and you won't have to pull those tanks again.
Funny that thought occurred to me as I was typing. But that takes $$$ and we have perfectly good door stops in the collection of stuff.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
I'm guessing the Door Steward requires an STC or field approval because you have to drill holes in the forward door post, which is a structural component of the airframe.
High-strength bonding tape is a proven alternative to screws, rivets, welds and other forms of mechanical fasteners.
No modification to the airframe. Heck, it could be argued that it's temporary and not permanently attached at all. That makes something like the Door Steward a cheap modification.
170C wrote:David, Bruce has given you some excellant pointers/techniques that will help with your project. I also had a few screws that required using a Dremel to cut a slot into the head of a screw that stripped. I purchased a NEW long handled screwdriver for my project which helped a bunch. I did have one that snapped off and after removal of the fuel tank cover, I soaked the remaining shank with mouse milk and it screwed out into the fuel tank bay as Bruce mentioned. One other technique I used, which seemed to help, was after cleaning out the Phillips screw head of dirt/paint, etc., was to dip the screwdriver bit into some valve lapping compound. That can make the screwdriver bit bite a bit more.
Has anybody tried one of these? If so, how well did it work? I see ATS also has this to extract stubborn screws.
The unit that uses the rivet gun would appear to be a good item to use. Years ago while disassembling a B-36 we used a homemade unit that worked like the one you posted and it seemed to reduce the number of screws that had to be drilled out by a big margin. If I had to remove a bunch of screws like this tank removal cover I would probably buy one of these.
Gary have used hand impact screw removers, not this one. And I'd have to give them a 50/50 rating. some time they worked sometimes they didn't. I'd never use a hand impact on any screws in my plane. As for this unit maybe if you dialed down the hammer to minimum.
As for the screw extractors I've used other similar ones, not that brand. Again I'd give it a 50/50. If the screw was going to come out but it was just stripped at the top they work. If the screw is stuck and that is why they were stripped out I'd rather not take a chance these extractors would make it worse. I'd rather cut a good slot with in the meat of the screw that is left.
CAUTION - My forum posts may be worth what you paid for them!
Bruce Fenstermacher, Past President, TIC170A
Email: brucefenster at gmail.com
The problem with a "rattler" is as Bruce mentions you have to sufficient downward pressure to keep the bit in the screw head, if not it will jump out of the screw and likely act like a lightly held machine gun. Its just too easy to mar the surrounding area. In other words, this tool is the answer on big stuff, some might make successful use if they are extremely careful but I think our aircraft skins and panels are generally too light for this approach.
Screw extractors are great until they break, imbedded in a screw shank you'll not be happy.
I didn't get to enjoy Jim's tank removal presentation and I maybe stating the obvious to everyone but some of the nut plates can be accessed and sprayed with products such as release-all by removing panels under the wing and at the wing trailing edge. Its best to try to pre-extract lube as much as possible. I also use an X-acto knife (definitely use eye protection) to remove heavy paint coatings from the bottom recesses of the screw heads. Often your first try at a screw, is you best try.
As previously mentioned, liberal amounts of thread penetrant of some kind allowed to sit overnight often does the trick. If I suspect frozen screws, it sometimes will break loose better if it is tightened slightly first, the idea being the threads under the head may not be as corroded as those below. Just that slightest movement to tighten the screw will break corrosion's hold, then it can be worked out with back and forth twisting and more penetrant.
Those hammer/impact extractors work real good on cast iron, not so good on thin aluminum sheet metal.
Richard Pulley
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
2023 Best Original 170A at Sault Ste. Marie
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
It's not for sale!
hilltop170 wrote:As previously mentioned, liberal amounts of thread penetrant of some kind allowed to sit overnight often does the trick. If I suspect frozen screws, it sometimes will break loose better if it is tightened slightly first, the idea being the threads under the head may not be as corroded as those below. Just that slightest movement to tighten the screw will break corrosion's hold, then it can be worked out with back and forth twisting and more penetrant.
Those hammer/impact extractors work real good on cast iron, not so good on thin aluminum sheet metal.
Agreed. I can't see pounding on a somewhat fragile aluminum structure with a impact tool.
Aryana wrote: You don't have to take a sledgehammer to it!
Very true! Like my first flight instructoer said whenever I asked him "How much?", his answer was always, "Just enough but not too much".
Aryana wrote:You have to be a sort of "screw whisperer" to know when they're about to break and switch to another method.
Well said! And very true.
Aryana wrote:Years of working on rusty British sports cars taught me...but more than likely it's because I just have a few screws loose myself
That's also how I got my start, MGAs, MBGs, Jags. And after working on those, it's a wonder I still went into engineering, they were such a pain to work on. Or maybe that's why I did it, loose screws.
Richard Pulley
2014-2016 TIC170A Past President
1951 170A, N1715D, s/n 20158, O-300D
2023 Best Original 170A at Sault Ste. Marie
Owned from 1973 to 1984.
Bought again in 2006 after 22 years.
It's not for sale!
That hand screw extractor shown above for $25 at sears can be had from harbor freight for about $5. I've had one for years. Craftsman tools have a great warranty, but it isn't worth $20 on that tool.
I once spent a pleasant week removing the fuel tanks from a Cherokee. Every screw was rusted in place. I found the slot method to be best, but one screw required drilling. I used a left-hand flute drill, which through a combination of torque and vibration backed the screw right out. I never had to use an extractor on it. Of course, you should always start with a shot of penetrating oil at least one day in advance.
clean out the screw head so the driver bit fits tightly and full depth. use a good quality bit, either the Snap-on removal bits or other good quality. Use some valve grinding compound to keep it from slipping. and use a speed handle with a knob on the end which allows you to push down hard and gives you better leverage.
at least the day before, use Kroil or Mouse Milk on all the screws.
things like stuck screws can really drive up the labor bill on annuals etc and many owners (you guys excepted of course) don't understand how much time it can take. I fired a mechanic once who when reinstalling panels would cam out all the screws with his drill driver and then laughed about it, "It would stink to be the guy that has to take these out!"
'56 "C170 and change"
'52 Packard 200
'68 Arctic Cat P12 Panther
"He's a menace to everything in the air. Yes, birds too." - Airplane
I removed my tanks about 18 years ago to inspect for corrosion. All the screws on the front spar portion of the tank cover came out with no problems. The screws on the wing tip and aft end of the tank panel were the more difficult ones to get out. You can see these screws through the wing inspection panel. I used a rivet gun and the screw driver like attachment on a very low setting. Some screws it helped others it didn't and I ended up rendering many of the screw slots unusable.
I was able to just grab the screw head on a few with a pair of vise grips and got a few more out. At least two or three I ended up drilling the head to the point I was able to chip off the head with the tap of a chissel. These screws I later removed by using vise grips, clamping to the threaded end of the screw and twisting the screw as if tightning it until it threads all the way through so as not to damage the nut plate threads.
After you have disconnected both rubbers hoses from the outlet and vent line, as well as removing the sump drain be very careful you don't bend or damage the two outline extensions coming out of the tank. These are 2" to 3" in length and must clear that rib before you lift the outer end of the tank up. I became impatient and bent my vent line so bad it ripped a very small opening in the tank where its welded on. I had to take the tank to a shop and have it repaired. I used an angle grinder with the roll lock scotch brite pads and cleaned the entire cavity. I painted the tank compartment with zinc chromate, spray can. If I had it to do over again, which I probably should, I would brush on the Dupont Vari Prime, there would be no overspray issues and it would probably be a better overall coating.
With the tank removed it would be a good time to replace or rebuild your fuel gauges, I have read how-to topics on that in other areas of the forum. In addition to replacing the gasket at the filler neck I found the tank restraining straps needed the anti-chaf material replaced as well. Remember the screws are structural so be sure you get the correct part number screws. Give yourself plenty of time for the project, in my case a day was not enough.
Last edited by cpolsley on Tue Nov 20, 2012 11:30 pm, edited 1 time in total.
If anyone is planning on doing an inspection of their spars as mentioned here I would recommend using a corrosion inhibiting compound on the hardware during reassembly to prevent the hardware issues diescribed here. There are several products that can be used. My favorite is Cor-Ban 27L. It comes in a small squeeze tube similar to the small rtv tubes you are familiar with. Mastinox in also commonly used in commercial aviation but is very carcinogenic.
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