woops!

[Ron Coleman]

Here are the facts.
Finished the annual on Monday. One hour test flight before flight to Alliance. One hour thirty two minute flight to Barber. Developed an oil leak in the tach cable. One hour fourty three minute flight home. Cleaned up the oil and took a test flight 13 minutes on Saturday. I flew into a neighboring 2000' grass strip and on leaving climbed to 50' and leveled off and the engine shut down. Pucker time! Slip left and right to kill speed, throttle back, carb heat on, nose down and kiss the grass with a french landing, tail high to slow the bird down and alternate left and right brake to get stopped before the road. The engine went to idle didn't quit. Investigation revealed that the clamp that locked the throttle cable had failed so that when I moved the yoke forward it rubbed the throttle cable pushing it forward and shutting down the engine. I am going to add a safety wire backup to the cable.

It wouldn't hurt to double check your setup.

RonC

[Howard Wilson]

Re: woops!

Ron, Glad you are ok! Sounds like an exciting landing.

[VictorBravo]

Re: woops!

Thank you for the heads-up Ron, and congratulations to you on a successful emergency landing. The more experienced mechanics here would probably agree that it's the little things like tying down a cable that can get you more often than the big things.

WARNING: Obnoxious Maintenance/Safety Rant to follow - my apologies for changing the thread focus...

Our little Continentals rarely have a "big failure" (like throwing a rod or breaking a crank). Little things like something rubbing on the fuel line, or vibration cracking an AN fitting, or something not safetied, water in the fuel, mud daubers in a vent, or nylon locknuts near a heat source... THOSE are the little "gremlins" that cause more tragedies than big engine parts breaking.

This is GOOD NEWS for the average Taylorcraft owner and mechanic. It means that a big majority of these "failure points" can be discovered easily by an owner or mechanic. All it takes is a little time and forcing yourself to be suspicious.

IMHO, for no particular reason whatsoever, an average light airplane owner should remove the cowlings from the airplane, pull up a comfortable chair and a flashlight, and spend an hour or two just looking for anything and everything that's loose or cracking from the firewall forward. Poke and tug on everything, see if you can shake something loose. TRY to twist something or push it out of position. Take a rag and wipe everything clean, ESPECIALLY the parts that are hard to reach and have accumulated really ugly greasy deposits! Think about it, the parts that are hard to reach are the ones that nobody has cleaned or inspected for a long time.

Again, in my opinion only, here are some of the things forward of the firewall that could cause a crash, which any owner could have found on their own without doing anything that requires an A&P license:

Small copper primer line vibrating, cracked at the fittings, not tied down enough, or tied down TOO much where engine movement will bend it

Abrasion on fuel line, old worn fuel line, cracked AN fuel fittings at gascolator/carburetor

Cracked gascolator (old glass style), clogged gascolator screen

Abrasion or cracks on aluminum fuel line at firewall, missing or broken rubber grommet allowing metal firewall to cut into the aluminum line

Gascolator mounting bracket (firewall style or engine mount style) cracked

Gascolator exposed to heat from exhaust (engine mount style)

#4 cylinder exhaust pipe abrading/burning through cowling, baffle rubber, etc.

Spark plug wires (or anything else) able to be pulled or pushed too close to exhaust pipes due to flight vibrations or air movement inside cowling in flight

Pushrod housing or pushrod tube oil leaks under cylinder bases (very common on Continentals)

Badly worn intake rubber hose connectors / loose Breeze worm screw clamps - which can also result in...

Cracked intake spider

Looseness of throttle / mixture / carb heat control clamps

Loose or un-safetied carb heat control at carb heat box lever

Nylon locknuts near heat source or on engine parts

Engine rocker box screws loose, not safetied, or without lockwashers

Engine cooling baffles and rubber seals cracked, worn, abraded through by vibrating on the engine, missing fasteners, not sealing against the engine and cowlings, etc.

Missing or loose inter-cylinder baffle cups

Upper spark plug wires able to whip back and forth, abrade against engine or baffles, rubber grommets at rear baffle missing or broken allowing the baffle to cut into the wire

Anyway, you get the drift... the airplane owner and/or mechanic can remove a large majority of the failures before they happen just by spending some quality time cleaning and very thoroughly inspecting the engine compartment. Time and suspicion, that's all you need. If you do not have an A&P mechanic's license, STILL do this suspicion trip, ad simply write down everything you find to show the mechanic later. The owner has every right to instruct the mechanic to replace stuff that is worn or wearing out, even if it has not worn out completely yet.

OK sorry for ranting like this, it's just that not every engine stoppage will occur over a grass runway like it did this time for Ron

[T.Taylor]

Re: woops!

[QUOTE=Ron Coleman;42240]Here are the facts.
Finished the annual on Monday. Investigation revealed that the clamp that locked the throttle cable had failed

Did the IA say if he looked the throttle cable over real well during the inspection, doesn't seem like the clamp would just up and fail that soon after an inspection ???, just a thought, T.T.

[Ron Coleman]

Re: woops!

Hi T T
the reason that I included the time line from the annual was to show that there were 5 + hours of flying time from the annual before the problem occured. A lot of our ittle planes do not get 5 hrs flying time a year. I had checked the throttle and cable for range of movement because I had removed and replaced the air exchange cover to examine the exhaust for leaks and naturally that inspection disturbs the throttle cable which passes over the cover. What failed on the cable clamp was the rubber on the inside of the cable clamp. Even though it was only three years old, it had gone soft and lost it's grip. Old motorcycles had a cable clamp which had teeth that matched the cable twist (thread) so that the cable couldn't slide (it could be threaded for adjustment) once the bolts were tightened even a little. One of those might find its way in there some how. The other thing that I found to be a help is a cable clamp on the cable on each side of the firewall. May be overkill but I'm not going to have the same problem again.

Bill is right. These planes are so simple and inexpensive to work on that it does not make good sense to passivley ignore anything on the airplane. Just don't mess with things you don't understand. A second pair of eyes is also a help expecially if they belong to an IA.

RonC

[VictorBravo]

Re: woops!

What failed on the cable clamp was the rubber on the inside of the cable clamp. Even though it was only three years old, it had gone soft and lost it's grip.

IMHO there should not be rubber less than two inches from a hot exhaust pipe, even with the aluminum cover under the rubber. The correct size plain aluminum Adel clamp (without rubber) is probably better in terms of grip, and no risk of melting rubber.

If you like the idea of rubber however, you can "repair" this problem if you like by slitting a piece of rubber tubing (use higher temp Silicone rubber for added safety), putting it around the throttle cable, then sliding it along the cable until the rubber tube is inside the Adel clamp. Then tighten the Adel clamp to hold it solid.

The throttle cable is a somewhat difficult thing on the T-craft, because it has to go through a small opening between the oil tank, the engine mounting "ear" and the exhaust heat muff. The throttle control on most of them is a large clunky thing that is apparently strong enough to lift the bombs into a B-52 bomb bay.

Most T-crafts have a ratty old Adel clamp on top of the exhaust, with an 8-32 screw and a plastic lock nut holding it together. The screw is always stripped, at the wrong angle to get a screwdriver to it, etc. etc. ... a nightmare for such a small and obvious part.

The alternative I used is to wire it to the engine mount tube. A piece of slit rubber tubing around the throttle cable, AND another piece of slit rubber tubing around the engine mount tube itself to prevent abrasion. Four wraps of .032 or .040 safety wire around all of it, twisted fairly tight, and that cable cannot move fore and aft at all. There has to be some rotational (swinging up and down) movement to allow it to follow the carburetor arm arc, and it always wants to hit the top of the oil tank too.

Another upgrade, which reduces the friction and resistance GREATLY, is a thick wall aluminum tube standoff between the carburetor arm and the ball bearing end on the throttle control. (On my airplane at least) by moving the throttle control end outboard an inch or two, you are allowing it to operate with less change in direction, less interference with the oil tank, etc.

The price you pay for this is that you have to use a long bolt through the standoff, large area washers to prevent ANY movement of the standoff, tighten the bolt quite a bit, and use a Cotter pin to maintain the tightness under all circumstances.

If I were rebuilding a T-craft, I would definitely use a smaller, lighter, and more flexible throttle control, and route it through a different place on the firewall. There is no true mechanical need for a huge clunky control there; a much lighter and low friction control, tied down more effectively, would be more than sufficient.

(I would cheerfully remind any concerned FAA types that the standard setup adds greatly to the hassle and heartache of removing the heat muff and inspecting the exhaust system as mandated, which results in the vast majority of Taylorcrafts not having the exhaust system inspected every 25 hours by a longshot! There is a far greater risk to flight safety, IMHO, from a corroded exhaust system going un-noticed, than from changing a 200 pound strength throttle cable to a 50 pound strength throttle cable on a zero-resistance carburetor.)

[PT13Pilot]

Re: woops!

Good job getting down! I've been safteying cable clamps for a long time, seemed like a good idea one day and now I just do them all. Spiral cased cables work the best. .032 wire works great, just don't twist/pull tight enough to spread the casing and rub the inner wire, let the grooves and wire do the work. Go around twice on one side of the clamp, twist to the other, twice around again, and tie off. Gives a nice secure secondary to often ill fitting clamps, it's cheap insurance, and costs nothing! Cable has nowhere to go. I do them all that way, throttle, carb heat, mixture.
And Bill's right, NO RUBBER clamps in any heat/oil area, they are worthless. No nylocks either! Slot headed worm clamps are also easily saftey wired with .032 wire. I do them after I make sure they're tight. There are a multitude of things to fail, don't let something like a loose cable/clamp which is easily preventable bring ya down. I see so many things let go, it's frightening. If your annual cost $200 and he's "done" in an afternoon, I'm not gonna feel sorry for you when you go down in a field. Well maintained things fail, don't up your odds by letting things go.
CJ

[Len Petterson]

Re: woops!

Nice to hear your emergency landing went well,
Ok no rubber in the clamp. Ok It will be gone!
But I did wire it 2 loops on either side of the clamp! When tied the ends toghter!
Why would the crossbar for the elevator control catch the trottle wire?
Did you feel anything when it happend?
Len

[Ron Coleman]

Re: woops!

Well Len, it seems that after a lot of sitting and looking, I found the one thing that lead to another. Remember that I said that I developed a tach cable leak, well some of that oil got blown around under the cowling, down the throttle cable and soaked the Adel cable clamp and the lubricated the rubber. The cable slipped back into the cabin and sagged in such a way that when the top tube of the "H" frame moved back and forth it rubbed the cable eventually pulling the cable sheath back and the throttle with it. Had I known that, I would reached under the throttle and pushed the sheath forward and kept going home. You will have to duck under the panel and move the yoke to see how it can happen.

I found tach seals (by factory number) at a local auto parts store for $7.59 plus shipping, so I bought 4 ea. in case I get 2 more T-Crafts.

RonC