Your nuts

[Tailwind W10]

Yeah, that single shear also adds a bending element to a joint.  Except for the most benign joints, its just bad engineering.


BTW, the one question I didn't answer in my last post:


"Why as a pilot would you give a shit?"


Because your fucking life depends on it!!!!


Gerry

[JW Scud]

From another forum I frequent...

"Hey folks (note not gender specific) I moved from where I used to reside to a new area and have found new customers with lots of old problems that left uncorrected can lead to big problems. I will recap some of what I have found and they are easy to correct but need to not be overlooked.

1. Hoses harder than woodpecker lips. I don't mean just engine hoses which should be changed at least every 5-7 years, I mean the flex hoses on the master cylinders that have the original cure date on them. Check and change hoses as they deteriorate from the inside out and when flexed can break.
2. Control cable tensions. Or lack thereof. I find many airplanes that have not had the control cable tension checked since Orville was a young boy.
3. Control surface deflection. I have also found many aircraft that due to the above and other factors not making contact at the proper angle. Cessna 180s are problematic as the vertical stab bolts in the aft spar need to be installed from back to front. If not the bolt installed from front to aft tube locks on the torque tube limiting up travel. You almost need a parts book handy these days to do an annual as lots of hardware and the installation thereof is not as advertised.
4. High temp lock nuts firewall forward. This should go without saying but I still find fibre lock nuts on throttle. mixture and other flight critical controls. You need high temp locknuts or even in some mandatory cases, castle nuts and cotter pins to assure the control will be a control.
5. Correct hardware for repairs. I cannot tell you the number of times I have found non structural rivets in structural areas. Cherry max rivets are not usually allowed but sometimes necessary.
6. Dirty bellys. I mean the interior. Part 43 says that before performing an inspection you have to clean the aircraft. I clean the interior of bellies that have 50 plus years of accumulated grime rivets, washers screws, bolts, tools, you name it. DO yourselves and your aircraft a favor and clean the interior. You will stop corrosion and I can actually see what I am supposed to be inspecting. Or, don't and I can charge to clean it before inspection.

For now last but not least...STAINLESS HARDWARE...I love guys that put stainless hardware on their inspection panels. A very old and most likely dead teacher in A&P school did a very great demonstration. He took a piece of 2024 aluminum, just a small one inch piece, and a stainless steel screw. He then took a paper towel and put it in his coffee cup to wet it. He then sandwiched the aluminum paper and screw and put a voltmeter on them and had it on the volts scale and it measured 1/2 volt. He had made a battery and the sacrificial piece was the aluminum.

I love you guys because I get to replace aluminum panels and you get shiny hardware. Steel on the other hand is the sacrificial metal so it just rusts and you replace screws and not aluminum. Bummer for me."

[JW Scud]

Found another interesting post. Same forum, different guy,

"There are many standards which various fuel hoses may/may-not meet despite the fact they are mfr'd as fuel lines. An automotive fuel hose may handle alcohol-fuels well...while an aviation hose may not. An aviation hose may handle toluene (a required ingredient of avgas) while an automotive hose may not. Neither may meet the necessary requirements of the USCG for marine environements (such as flammability and permeability within bilge-compartments).

These, and others, are the reasons the CORRECT materials are best selected for the designed purpose....NOT the ready availability of NAPA or Pep Boys or price....when replacing aviation fuel lines in Cessnas.

Mil-Specs derive from Mil-STDs which are (in part) descendants of AN (Army/Navy) standards. The reason for standards...are in order to insure the appropriate materials are used for particular purposes...and that is why we should select aviation hoses for aviation fluids. Mil-H-5593 is appropriate for fuel vent lines."

[Colonel]

re: cleaning an airplane before inspection

I have had HUGE arguments with AME's about
this.  They maintain that they don't need to
clean to inspect (not true - see the CARs and
FARs) and say that if an owner wants his airplane
inspected, he has to clean it himself before the
annual.

This is nonsense.  A thrifty owner can clean his
aircraft spotlessly before inspection, and get
rid of all sorts of incriminating evidence like
smoking rivets, fluid leaks, etc which need to
be repaired, but won't be, because the evidence
has been removed beforehand.

This is what apprentice AME's are for - disassembling,
cleaning, re-assembling.  With a guy with some
grey hair watching over him.

An aircraft needs to be delivered for it's annual
in a condition which allows the AME to detect
problems.  At least, on my planet it does.

I've posted these images before (which resulted
in the thread being deleted by the AvCan thought
control Nazis):

[img width=375 height=500][/img]

That's the landing gear of a C421 which just
came out - not even flown, just towed out of
the hangar - after a $30,000+ annual.

Yep, the landing gear is filthy.  Hadn't been
cleaned or inspected.  But TC was happy with
the annual.

The very expensive AME did manage to screw
up the oil change on the right engine, however,
which resulted in 2 quarts of oil being vented
overboard after takeoff, requiring an emergency
landing due to the smoking engine, which looked
like it might have been on fire.

What a great $30,000 annual.

[Colonel]

re: stainless hardware in non-structural applications ...

If this is your biggest maintenance problem,
you've got it made.  I understand the theory
of the redox table and galvanic corrosion caused
by dissimilar metals (and I've seen plenty) but
in over 40 years of working on airplanes, I have
never seen a measurable amount of corrosion
caused by non-structural stainless hardware.

I use plastic washers on the stainless fasteners,
which go on top of paint, which are screwed into
metal nutplates rivetted to the aluminum.  No
corrosion from that, not even in Key West, which
is hot, humid and salty, and corrodes just about
everything else on the airplane.

If your airplane is parked outside, the hardware
is going to corrode and look like shit.  If you want
to go stainless, it's really not a problem.

If your aircraft spends long periods of time in
such a violently corrosive environment that your
stainless hardware is causing problems, the rest
of the aircraft is going to be junk long before the
stainless causes you problems.