Maintenance nightmares

[Henning]

Why would you believe that, since the seals are made of the same material as automotive brake seals ... ??

Jim

Give it a try and see what happens. Why do you believe the compounds are the same?

 

[SoloEqs]

Why would you believe that, since the seals are made of the same material as automotive brake seals ... ??

Yeah, and all electricity is made out of the same stuff, too. That doesn't make it interchangeable.

Go ask anyone who maintains his own pre-1980 British car about brake seals and fluid.

 

[David]

Why would you believe that, since the seals are made of the same material as automotive brake seals ... ??

Jim

I went through this when I was trying to find an alternate source for the seals in the old Dunlap brakes on my DHC-1. Automotive seals and airplane brake seals are not made of the same material. The automotive seals are probably an EPDM and the seals for 5606 are typically Buna. They don't mix and match.

http://www.marcorubber.com/compatibility.htm

Besides, 5606 is a better choice in my view simply because it doesn't hurt your paint if you spill it

 

[David]

Yeah, and all electricity is made out of the same stuff, too. That doesn't make it interchangeable.

Go ask anyone who maintains his own pre-1980 British car about brake seals and fluid.

Not to pick nits but electricity is interchangeable and that's why it's so easily distributed. We do it all the time mostly thanks to Nikola Tesla - transformers to change AC voltages and rectifiers/inverters to switch between AC and DC.

 

[wabower]

Then why do I take all those adaptors when I fly to Europe or use certain devices in the planes?

Not to pick nits but electricity is interchangeable and that's why it's so easily distributed. We do it all the time mostly thanks to Nikola Tesla - transformers to change AC voltages and rectifiers/inverters to switch between AC and DC.

 

[ronnieh]

Actually DOT 3, 4, and 5.1 are hygroscopic and the charts give both a wet and dry boiling point. Silicone based/DOT 5 are hydrophobic and do not absorb water.

 

[pmanton]

The owner of an Ercoupe called me. The transfer pump that pumped fuel from the wing tanks to the header had been failing for quite some time. It now wouldn't pump at all and he didn't have enough fuel in the header tank to bring the plane to me. Would I come to his airport and fix it??

Upon arrival I found the front cylinder directly behind the fuel pump (Continental C-85) stained blue from the 100 LL. The cork gasket on the top of the fuel pump was leaking and he had been flying the plane only calling me when the pump was sucking so much air that it wouldn't function at all.

 

[kontiki]

My first job as an A&P, I was fired for not putting a voltage regulator on a 182. The whole plane was a nightmare. Initial complaint was dead battery. Found dry battery, and contactor points in voltage regulator had welded closed.

Then noticed, alternator cooling fan turned backwards, I couldn't imagine WTF was going on. Then locals that got wind of my confusion started coming out of the background (maybe like Dicken's ghosts).

Oh yeah, this airplane used to have a DC generator and Buddy, modified it using an alternator from a local auto place. It's never really worked right. Then another local expert fixed it wiring it up like an old Chevy using a chiltons manual. So I looked, and found the Cessna Hi voltage light had been disconnected and stowed, and there was a ballast resistor in the system that didn't belong.

Buddy tried to tell me the regulator he got at Roses Auto was the same as the Cessna one. It was same size and shape, but internally was vastly different. Cessna VR was mostly circuit card with components and contactors, VR from Roses was 3 coils with a few extra bits.

That was my last day. Broke and not in home state, It led to some interesting situations. This gay ex-Woman Marine and her girlfriend took me in, i knew the family from when I was in, they didn't really mind having one more meat eating rapist around the house, they already had a couple dogs. We all got along great, brother was also ex Marine, the dad still worked at the Cape, he had help build Saturn 5s. Life was beer drinking, fishing and shrimping until Eastern Airlines hired me to Miami a couple months later.

I didn't know jack right out of A&P school, but I felt good about not doing the VR installation, although I know it probably went right in after I left.

The dad was a great guy. I ate with the family for Thanksgiving that year, I still remember the turkey sandwich care package they gave me after hearing about the tofu turkey the girls tried to make.

Sorry to ket off track, but the whole situation is a very distant and fond memory, minus the creep not taking care of his airplanes.

 

[kontiki]

Then there was a Cessna 402, operated by a small outfit in Miami. DOM was dilligent, he had his own story after walking away from flying jobs.

One night the chief pilot heard me ask if there was anything to do (I was part timing while working on my EE degree). He went off about one ship that had been all over the sky and no one had been able to fix it in weeks.

I went through the log and there was history of the usual riging and cable tension checks, no real fix. I started walking around wiggling control surfaces looking for anything unusual, and found the tips of the horizontal stab moved up and down an awful lot more than any of the others.

I told the DOM I thought we needed to pull it off entirely to have a look, he OKd it, we had it off by the end of my shift. The mount brackets on aircraft side of the empenage were solid.

It was the end of the shift, when I left I recommended opening the stab to see if we could find anything inside. And as it was, I never went to work there again.

I took a new job at an electronics outfit to get some experience related to my degree, I gave them very little notice, and mentally moved on.

About a month later I went back to get my roll away, and the DOM was effusive, he wanted me back, I could work any hours, do what I wanted, he didn't care. I really couldn't schedule wise, I just wanted my tools, but I rememberd the stab and asked him about it.

He pointed to a corner and invited me to look for myself. The spar of the horizontal stab was cracked to pieces, it was mush. The DER they hired wouldn't touch trying to develop a repair for it, it was scrap, a new one was coming.

Good management, old plane, most of the full time people there were pretty inexperienced. Eastern had closed, I had worked there for 10 years, and was just hopping around while trying to start a new career.

Rev A - Spelling

 

[kontiki]

Going back to my first job as an A&P, before I was fired for the voltage regulator, the owner of the FBO also had a Rockwell Aerocomander 500 (series). I didn't know jack, there was an IA that also worked there but wasn't there every day.

They wanted me to do a 100 hour inspection of the Aerocommander. So I diligenly took the book that outlined the check and started the inspection. The first thing was the burn pit marks on the top of the wing. The airplane lost a prop before I got there, and I was told it was from power lines after landing on US1.

I had zero clue what to do about that. Then one hydraluic pump had no pressure, the highschool kid that installed the pump, didn't know about the plugs you had to change to adjust for direction of rotation. The alt air on one engine was safety wired open, the push pull the ownere wanted me to install was a cheap piece of junk from a local auto parts store.

Then , as I was out there alone with the airplane, this old timer pedaled up on a bycycle. He was an A&P and an IA, now working at the local McDonald Douglas plant. He mentioned that he declined a job there, but he had heard there was a new full time guy and he wanted to have a look see.

He asked me if Buddy had mentioned the battery that exploded in the airplane. I hadn't been told, I didn't even know where the battery was. He showed me the shelf in the empenage and suggested I crawl back behind the cargo bulkhead and have a look in the tail cone. And he pedaled off.

So I did. It was horrible. All of the aluminum in the tail cone top to bottom was turning to white powder. It was obvious someone had tried to paint over it, it was all peeling off, corrosion dust was every where.

On a platform mounted on in the bottom of the tail come was an autopilot. It was pretty good size, red with rust like it had been dredged from the bottom of the Atlantic. It had cables coming from it, still connected to the main flight control cables.

I wrote up my findings, but never signed anything. This was when I really started to realize I was in the wrong place and way over my head, but I had no clue how to handle things.

Then I came in one day after that and was told one of the customers had taken an airplane over the weekend and landed it in the Indian River. The secretary was OK, his dog died. Buddy mentioned that the IA had just done a 100 hour inspection on that airplane a couple days before, but haddn't got around to signing the log yet. I declined.

Fortunately, it wasn't long before the Voltage Regulator incident (from my prev post) and I no longer had to deal with it. It was all the stuff of nightmares.

 

[weirdjim]

Yeah, and all electricity is made out of the same stuff, too. That doesn't make it interchangeable.

I came in here for a discussion, not to start a holy war, but that is about the dumbest analogy I've ever heard ... even from freshman history majors.

Go ask anyone who maintains his own pre-1980 British car about brake seals and fluid.

The discussion isn't Brit cars, it is airplanes and "normal" vehicles.

.....

 

[weirdjim]

for 10 years, and was just hopping around while trying to start a new carrier.

And those new carriers, man, they are a BUGGER to start. Gotta get tugs and stuff to tow them out to sea, then trying to get the reactors lit to turn the screws is a real bother.

 

[weirdjim]

Actually DOT 3, 4, and 5.1 are hygroscopic and the charts give both a wet and dry boiling point. Silicone based/DOT 5 are hydrophobic and do not absorb water.

I've looked for the "charts" and can't find them. Source, please?

THanks,

Jim

 

[weirdjim]

Upon arrival I found the front cylinder directly behind the fuel pump (Continental C-85) stained blue from the 100 LL. The cork gasket on the top of the fuel pump was leaking and he had been flying the plane only calling me when the pump was sucking so much air that it wouldn't function at all.

Doesn't that scare the bejesus out of you, leaking fuel onto a hot cylinder?

Jim

 

[SoloEqs]

Not to pick nits but electricity is interchangeable and that's why it's so easily distributed. We do it all the time mostly thanks to Nikola Tesla - transformers to change AC voltages and rectifiers/inverters to switch between AC and DC.

Electricity is NOT interchangeable -- if it won't work in the form it arrives, you have to change it into another form.

 

[SoloEqs]

.....

Okay, in small words, just for you:

There is no one material that brake seals are made out of, for cars or airplanes.

Different material has different reactions to different chemicals -- which any British car owner can tell you.

Just because it's "brake seal material" doesn't mean it's the same as any other brake seal material.

Just like electricity (try to stay with me here, Jim), to those unfamiliar with the differences, the different values may not be apparent. Just because something is right for one use doesn't mean that it's right for any other use. Electricity is electricity, brake seal material is brake seal material, metal is metal . . .but the details can be VERY important.

BTW, the "dumbest analogy you ever heard" was on a poster that I saw at JPL . . .it wasn't posted by a freshman history major, it was posted by a guy who was tired of being told things like "just make it out of aluminum."

 

[kmead]

Okay, I could tell you so many stories. One of my favorites is the one where a Malibu owner told this mechanic that was filing away on his MT propeller." I don't think you should be filing on this prop". The mechanic said " we do it this way all of the time". Things went to bad when the file started to pick up wood. It seems he filed completely through the thin metal leading edge. He wasn't my employee.

An owner came in one day and asked me if his Mirage should have the wing jack positioned on the jack point and not the wing skin. It seems my guy missed the point. I fired him on the spot when he got back from lunch.

I should just write a book. I hope I've seen it all.

 

[weirdjim]

Electricity is NOT interchangeable -- if it won't work in the form it arrives, you have to change it into another form.

Think about what you just wrote, simpleton. If it isn't interchangeable, how can you change it into another form?

interchange === change. Think about it.

 

[weirdjim]

BTW, the "dumbest analogy you ever heard" was on a poster that I saw at JPL . . .it wasn't posted by a freshman history major, it was posted by a guy who was tired of being told things like "just make it out of aluminum."

I'll bet you saw that when you were sweeping up the floor on your janitor shift, weren't you?

Jim

 

[Dan Thomas]

Okay, in small words, just for you:

There is no one material that brake seals are made out of, for cars or airplanes.

Different material has different reactions to different chemicals -- which any British car owner can tell you.

Just because it's "brake seal material" doesn't mean it's the same as any other brake seal material.

Just like electricity (try to stay with me here, Jim), to those unfamiliar with the differences, the different values may not be apparent. Just because something is right for one use doesn't mean that it's right for any other use. Electricity is electricity, brake seal material is brake seal material, metal is metal . . .but the details can be VERY important.

I spent 12 years working in a brake overhaul plant, with both air and hydraulic brake systems, and oversaw the rebuilding of thousands (many thousands ) of components. I can confirm that there are many different "rubber" materials that are compatible with limited types of fluids, and if you put the wrong stuff in (like DOT3 into a 5606 system) you will pay dearly for it. We made much money rebuilding automotive and medium truck components that had been topped up with motor oil or power steering fluid or transmission fluid; the latter two can be closely related to 5606.

DOT3 is a vegetable-based fluid, which means it has some powerful alcohols in it. It will eat paints, and will attack many synthetic rubbers like the Buna stuff in aircraft systems. It is used with natural rubber or EPDM. And natural rubber suffers terribly in the presence of synthetic oils; it swells up or crumbles.

And, having alcohol in it, DOT3 absorbs water, so auto systems are sealed. The cap on the master cylinder has a diaphragm in it to allow the fluid to rise and fall while keeping it sealed off from the atmosphere. Very old cars didn't have that and the systems didn't last too long. Water vapor, or water, gets in and forms sludge and acids that eat the metals alive.

Aircraft systems are vented, too, and the lighter components of the 5606 can evaporate and thicken the oil. Ever notice the sticky residue on an oleo barrel?

Dan

Edit: A bit more info on DOT3 and and compatibility of several seal compounds with many fluids:

DOT3: http://en.wikipedia.org/wiki/Brake_fluid

O-ring and seal materials (big pdf file): http://www.google.ca/url?sa=t&rct=j...0ZgNqMWwjzp7Vxw&bvm=bv.51495398,d.cGE&cad=rja

Dan

 

[Dan Thomas]

Got any real good helo ones?

Not from me, but this guy has a dandy:

http://www.avweb.com/news/safety/183041-1.html

Dan

 

[Silvaire]

The owner of an Ercoupe called me. The transfer pump that pumped fuel from the wing tanks to the header had been failing for quite some time. It now wouldn't pump at all and he didn't have enough fuel in the header tank to bring the plane to me. Would I come to his airport and fix it??

Upon arrival I found the front cylinder directly behind the fuel pump (Continental C-85) stained blue from the 100 LL. The cork gasket on the top of the fuel pump was leaking and he had been flying the plane only calling me when the pump was sucking so much air that it wouldn't function at all.

First Ercoupe I did an annual on I couldn't help but notice that he had a length of green Orchard Supply garden hose as his fuel line. They are a special breed, if you have an event called "Gathering of Taildraggers" all the Ercoupe owners within 100 miles will show up - go figure

 

[SoloEqs]

Think about what you just wrote, simpleton. If it isn't interchangeable, how can you change it into another form?

interchange === change. Think about it.

Must be a semantic thing -- to me, "interchangeable" means that you can swap back and forth between things, without having to modify them.

That was the spirit of the original poster, that just because something looks like it should work doesn't mean that it will.

After all, it's possible to string 50 resistors together to match a particular value, but that string isn't necessarily interchangeable with R7 in one of your intercom kits.

 

[SoloEqs]

I'll bet you saw that when you were sweeping up the floor on your janitor shift, weren't you?

Yeah, Jim, that must have been it.

 

[weirdjim]

After all, it's possible to string 50 resistors together to match a particular value, but that string isn't necessarily interchangeable with R7 in one of your intercom kits.

Sure they will. My Monte Carlo analysis lets each component vary by p/m 20%, using 10% values with 5% tolerance in the product. I doubt you could get that string outside the 20% brackets if you tried.

Jim

 

[Tom-D]

One late night cruising down taxiway alpha in a fuel truck, I came upon a complete Ham Standard 4 bladed hydromatic propeller just lying on the taxiway.

I call my dispatch and explain what I have, they call VP-69 (the only PV squadron on the station at the time) and ask if they are missing a prop.

Lots of sailors were worried about that maintenance mishap.

 

[SoloEqs]

Sure they will. My Monte Carlo analysis lets each component vary by p/m 20%, using 10% values with 5% tolerance in the product. I doubt you could get that string outside the 20% brackets if you tried.

The string wouldn't fit into the box. Thus, non-interchangeable. Re-engineering the box wouldn't work for the guys who had designed the smaller box into their panel. Thus, non-interchangeable.

For that matter, I have a Mitchell radio in my 150. It's a drop-in replacement for the original. That's interchangeability.

I helped a couple of guys build your kits. Sorry you got away from that.

BTW, about 1980, I built an infrared scope, starting with an RCA 6032 imaging tube and a very high voltage power supply (based around a color TV flyback). There were several different voltages needed, and I got them with a string of various resistors and pots, mostly in series, tapped in the appropriate places.

 

[SoloEqs]

One late night cruising down taxiway alpha in a fuel truck, I came upon a complete Ham Standard 4 bladed hydromatic propeller just lying on the taxiway.

. . .and your first thought was "eBay" . . ?

 

[weirdjim]

The string wouldn't fit into the box.

I'll bet I could string together 47 1k 0602 SMD resistors and replace that 47k quarter watt in the same volume.

I helped a couple of guys build your kits. Sorry you got away from that.

Well, there is a long story that goes with that; suffice it to say that the obstacle to producing the kits has been removed. It was a rather expensive excavation, but well worth it. It should take us less than a year to rebuild to where it was.

.....

 

[SoloEqs]

.....

I don't know any of the story, but I'm glad you're bringing it back. Looking at the avionics market for experimentals, I see a bigtime need for you to fill. I have a buddy who has spent more on the avionics than he spent on the airframe. Anyone who can build an airplane from a kit can build avionics from a kit.

Something new to look at would be interfaces to turn for Android pads into glass panels. You also might do an AOA indicator kit that uses a light wheel for the sensor, with a Bluetooth option (BT transmitters are cheap) for clean or temporary installation. Could something like that (which was temporarily attached and used no wiring) be used on a Cessna without needing an STC or 337?

 

[weirdjim]

I don't know any of the story,

The "story" had blonde hair and blue eyes. Enough?

.

 

[weirdjim]

Could something like that (which was temporarily attached and used no wiring) be used on a Cessna without needing an STC or 337?

In general, yes. Even if it is attached, 21.303 (b)(2) gives the owner of an aircraft the right to owner-produced parts, which includes avionics.

.

 

[Skylane81E]

. . .and your first thought was "eBay" . . ?

It would be another 75 years before Al Gore would invent the Internet

 

[SoloEqs]

The "story" had blonde hair and blue eyes. Enough?

Remember the animated version of "The Jungle Book" . . ? Where Baloo (Phil Harris) tells Mowgli "Stay away from those things, they're nothin' but TROUBLE!"

In my case, the "story" had black hair, brown eyes, and failed geography (she thinks that "fidelity" is that town in Pennsylvania where they have the Liberty Bell).

And there's a connection -- she got her nose out of joint the one time I stopped by your shop, back about 1984, because she didn't want to waste any time on our visit to my dad (who lived in Weimar).

 

[SoloEqs]

In general, yes. Even if it is attached, 21.303 (b)(2) gives the owner of an aircraft the right to owner-produced parts, which includes avionics.

Yep, that works!

 

[weirdjim]

Remember the animated version of "The Jungle Book" . . ? Where Baloo (Phil Harris) tells Mowgli "Stay away from those things, they're nothin' but TROUBLE!"

Or, to quote FlyingRon (another regular on these boards):

"If it has tires, t!t$, or t@$t!cle$ it's going to give you trouble."

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