Instructor not concerned about engine failure, restarted, and continued lesson.

[A Squared]

First off, I didn't say that throttle control failures were not going to happen. I said that a properly installed mixture control on a general aviation airplane wasn't likely to come loose.

Uhhh, splitting hairs here, yes you were responding to a comment about a mixture control, but you were certainly voicing the opinion that failures of the engine controls weren't something to be concerned with. The reality is that throttle and mixtiure control filures can and do happen for a variety of reasons.

You're going to have to show me in an IPC or a Stromberg PT series carburetor maintenance manual

Doubt that would prove anything as the CB series R-2800's use PR series carbs

I sure don't remember any springs installed to open the throttles.

That's because there aren't any, go back ad read what I wrote, this time for comprehension. I didn't say there was a spring, I said the throttle opens to about ¾ open. With all your R-2800 experience, I'm sure that you recall that there are 2 rectangular throttle plates, both mounted eccentrically on a shaft. The eccentric mounting results in them opening as a result of the pressure differential between the manifold and the atmosphere. (I don't suppose it ever occurred to you to wonder why the throttle plates were mounted off center on the shafts, did it?)They actually open against a spring which tends to keep them closed. The air load on the throttle plates balances against the spring tension at about ¾ throttle. It's done this way instead of spring loading it to open, because wide open throttle at or near sea level is will give you well above the maximum manifold pressure. (which requires you to shut it down immediately) ¾ throttle on the other hand is METO, in an emergency you can pull METO power indefinitely (until you don't need it any more, then you shut it down) It's designed that way, for that reason, and it works, I have personally flight tested it.


Now, I don't know how many airplanes will go to open throttle if control fails. I can state with great confidence that that it does on the DC-6. However from the beginning you have seemed to be making the case that it would be undesirable. surely, you are not so dense that you cannot see how it would be preferable to have full throttle, or METO, rather then no power at all?

Cessna requested this AD ( via a service letter) because they screwed up and didn't have a proper safety device installed at the factory. There were no failures, only potential failures.

Wow, you just spout any crap which pops into your head, without a clue if it's true or not, don't you? Kind of like when you claimed the Caribou had R-3350's or that the Buffalo was a turbine modification of the Caribou. Anyway, The NTSB files are full of accidents which happened because a throttle cable got disconnected, some are related to the AD, others are different failures, but in either case there's a bunch of them, Here's one which predated the issuance of the AD:
http://www.ntsb.gov/ntsb/brief.asp?ev_id=20001213X32943&key=1

Here's two which happened afterwards, but resulted because the AD was not complied with properly:

http://www.ntsb.gov/ntsb/brief.asp?ev_id=20010131X00374&key=1

http://www.ntsb.gov/ntsb/brief2.asp?ev_id=20010828X01798&ntsbno=MIA01LA219&akey=1

Yeah, I know the second is not a Cessna, but it's the same thing, improperly safetied nut on the throttle cable ball end.

The idea that there have been no failures is just preposterous

 

[rfeathe1]

I had the mixture control linkage come off on a CV 340 (R 2800) & it went to auto rich.